Autofocus device and method, and program

The present invention relates to an autofocus device and an autofocus method and program. Specifically, when performing the focusing operation for moving the focus position to the focusing position based on the detected focus position, distance measurement result, and evaluation value, the focusing operation is performed according to the setting conditions set in the user interface. It is a thing.

Conventionally, an imaging device such as a video camera or a digital camera is provided with an autofocus mechanism that automatically focuses on a subject. In this autofocus mechanism, for example, as shown in Patent Document 1, an evaluation value is calculated by adding the frequency components of the video signal in a specific region provided in the image pickup image frame, and the focus is set so that the evaluation value becomes maximum. The lens is moved. Therefore, if a specific area is set in the center of the imaging image frame and the composition is determined so that the subject is located in the center of the imaging image frame for imaging, the focus position is set to the in-focus position. It can be moved to automatically focus on the subject.

<patcit num="1"><text>Japanese Unexamined Patent Publication No. 10-213736</text></patcit>

<p> By the way, the performance of the autofocus operation required for business use and broadcasting station imaging devices differs greatly depending on the work content. For example, a so-called weather camera that captures a landscape so that the state of the weather can be grasped is fixedly installed on a tall tower or on the roof of a building and used continuously 24 hours a day. Therefore, the demand for life is high, and the demand for focus adjustment ability when shaking or the like occurs is not so high. In addition, the demand for agility and focusing time when starting the autofocus operation is not so high.</p><p> On the other hand, since the image pickup device used in sports programs and news programs is not used continuously for 24 hours, the demand for life is not high compared to the weather camera. However, in order not to miss a photo opportunity, there is a high demand for agility and focusing time when starting the autofocus operation. Further, since a handy type imaging device is often used, there is a high demand for focus adjustment ability when shaking or the like occurs.</p><p> In an imaging device used in movie production, etc., there is a high demand for focusing accuracy, quality of image quality up to focusing, and smooth focusing operation rather than focusing time so that a shot image with good quality can be obtained. Become.</p><p> In this way, the requirements for the autofocus operation are diverse depending on the business content in which the imaging device is used, and if an imaging device specialized for each business content is individually supplied, high-mix low-volume production is possible and imaging is inexpensive. It becomes difficult to provide the device.</p><p> Therefore, the present invention provides an autofocus device, an autofocus operation, and a program capable of performing an autofocus operation according to an application.</p>

<p> The autofocus device according to the present invention is provided in a lens driving unit for driving a lens, a position detecting unit for detecting the focus position of the lens, a distance measuring sensor for measuring the distance to a subject, and an imaging image frame. Based on the evaluation value calculation unit that calculates the evaluation value using the frequency component of the video signal in the specific region, the user interface, the evaluation value, or the evaluation value, the focus position, and the distance measurement result of the distance measurement sensor. The control unit has a control unit that drives the lens drive unit to perform a focusing operation for moving the focus position of the lens to the focusing position, and the control unit has the control unit according to the setting contents set in the user interface. By controlling the operations of the lens driving unit, the distance measuring sensor, and the evaluation value calculation unit, the focusing operation is performed according to the set contents.</p><p> Further, the autofocus method or program according to the present invention includes a position detection step of detecting the focus position of the lens, a distance measuring step of measuring the distance to the subject, and a video signal in a specific region provided in the imaging image frame. The focus position of the lens is set to the in-focus position based on the evaluation value calculation process of calculating the evaluation value using the frequency component, the evaluation value, or the evaluation value, the focus position, and the distance measurement result of the distance measurement sensor. The focusing operation is set by switching between the distance measuring process, the evaluation value calculation process, and the lens driving process according to the lens driving process for moving the focusing operation and the setting contents set in the user interface. It has an operation switching step of switching to a focusing operation according to the content, or is executed by a computer.</p><p> In the present invention, according to the setting contents set in the user interface, the speed when driving the lens, the distance measuring frame size of the distance measuring sensor, the restart determination standard when restarting the focusing operation, and the distance measuring sensor The selection of the lens drive process that uses the distance measurement result or does not use the distance measurement result is controlled, and the focusing operation is performed according to the set contents. Further, one or a plurality of setting contents are stored in the setting contents storage unit, and the focusing operation is switched by reading the setting contents from the setting contents storage unit and using the setting contents.</p>

<p> According to the present invention, the operations of the lens driving unit, the distance measuring sensor, and the evaluation value calculation unit are controlled according to the setting contents set in the user interface, and the focusing operation is performed according to the setting contents. Therefore, if the setting contents according to the application of the image pickup apparatus are set in the user interface, the autofocus operation can be performed according to the application.</p>

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows the overall configuration of an image pickup device having an autofocus mechanism, for example, a video camera 10.

The lens block 20 of the video camera 10 is configured by using an image pickup lens, a lens position detection unit that detects the position of the image pickup lens, a lens drive unit that drives the image pickup lens, and the like. In the lens block 20 shown in FIG. 1, the focus lens 21 for focusing the subject image on the image pickup surface of the image sensor and the wobbling lens used for determining the direction of the focus position are used as the image pickup lens. It shows the case of having 22.

The focus lens 21 is provided with a position detection unit 21a for detecting the position of the focus lens 21, that is, a focus position, and a lens drive unit 21b for moving the lens position in the optical axis direction. Similarly, the wobbling lens 22 is also provided with a position detecting unit 22a and a lens driving unit 22b for moving the lens position in the optical axis direction so that wobbling can be performed correctly. Further, the lens block 20 has an iris 23 for adjusting the amount of light, and the iris 23 also has an iris position detection unit 23a for detecting the opening state of the iris and an iris drive unit 23b for opening and closing the iris. Is provided.

The lens block control unit 51 receives a detection signal RSf indicating the focus position from the position detection unit 21a, a detection signal RSw indicating the wobbling amount from the position detection unit 22a, and a detection signal RSi indicating the opening state of the iris from the iris position detection unit 23a. Each is supplied. Further, a user interface 55 for setting the autofocus operation mode and starting the autofocus operation is connected to the lens block control unit 51, and an operation signal PSL is sent to the lens block control unit 51 in response to the operation of the user interface 55. Supplied to 51. The lens block control unit 51 is provided with a storage unit (not shown) configured by using ROM (or EEPROM) or the like, and has focal length data and aperture ratio data of the focus lens 21 and the wobbling lens 22. , Information such as the manufacturer name and serial number of the lens block is stored.

The lens block control unit 51 sets the lens based on the stored information, the detection signals RSf, RSw, RSi, the operation signal PSL, and the focus control signal CTf and wobbling control signal CTw supplied from the camera block control unit 52 described later. Generates drive signals RDf and RDw. Further, the generated lens drive signal RDf is supplied to the lens drive unit 21b to move the focus lens 21 so as to focus on a desired subject. Further, the generated lens drive signal RDw is supplied to the lens drive unit 22b to wobble the wobbling lens 22 so that the direction of the focusing position can be detected. Further, the lens block control unit 51 controls the aperture amount of the iris by generating the iris drive signal RDi and supplying it to the iris drive unit 23b.

The color separation prism 31 of the camera block 30 decomposes the incident light from the lens block 20 into three primary colors of R (red), G (green), and B (blue), and separates the light of the R component into the image sensor 32R, The light of the G component is supplied to the image sensor 32G, and the light of the B component is supplied to the image sensor 32B, respectively.

The image sensor 32R generates an image pickup signal SR corresponding to the light of the R component by photoelectric conversion and supplies it to the preamplifier unit 33R. The image sensor 32G generates an image pickup signal SG corresponding to the light of the G component by photoelectric conversion and supplies it to the preamplifier unit 33G. The image sensor 32B generates an image pickup signal SB corresponding to the light of the B component by photoelectric conversion and supplies it to the preamplifier unit 33B.

The preamplifier unit 33R amplifies the level of the imaging signal SR, performs correlated double sampling to remove reset noise, and supplies the image to the A / D conversion unit 34R. The A / D conversion unit 34R converts the supplied imaging signal SR into a digital video signal DRa and supplies it to the preprocessing unit 35. The preamplifier unit 33G amplifies the level of the imaging signal SG, performs correlated double sampling to remove reset noise, and supplies it to the A / D conversion unit 34G. The A / D conversion unit 34G converts the supplied imaging signal SG into a digital video signal DGa and supplies it to the preprocessing unit 35. The preamplifier unit 33B amplifies the level of the image pickup signal SB, performs correlated double sampling to remove reset noise, and supplies the image to the A / D conversion unit 34B. The A / D conversion unit 34B converts the supplied imaging signal SB into a digital video signal DBa and supplies it to the preprocessing unit 35.

The preprocessing unit 35 adjusts the gain of the supplied video signals DRa, DGa, DBa, stabilizes the black level, adjusts the dynamic range, etc., and uses the obtained video signals DRb, DGb, DBb as the signal processing unit 36. It is supplied to the evaluation value calculation unit 37.

The signal processing unit 36 performs various signal processing on the video signals DRb, DGb, and DBb supplied from the preprocessing unit 35 to generate a video output signal DVout. For example, knee correction that compresses a certain level or higher of the video signal, γ correction that corrects the level of the video signal according to the set γ curve, white clip processing that limits the signal level of the video signal to a predetermined range, and black. Perform clip processing, etc. Further, the signal processing unit 36 performs contour enhancement processing, linear matrix processing, encoding processing for generating a video output signal DVout in a desired format, and the like. Further, the signal processing unit 36 generates a video signal DVvf for the Beefinder and supplies it to the display drive unit 47 so that the captured image can be confirmed.

The evaluation value calculation unit 37 generates a luminance signal DY based on the video signals DRb, DGb, DBb supplied from the preprocessing unit 35, calculates an evaluation value ID based on the luminance signal DY, and is a camera block control unit. Supply to 52.

FIG. 2 shows the configuration of the evaluation value calculation unit. The evaluation value calculation unit 37 includes a luminance signal generation circuit 371 that generates a luminance signal DY based on the video signals DRb, DGb, and DBb, and evaluation values for generating 14 types of evaluation values ID0 to ID13, for example, as will be described later. It has an interface circuit 373 that communicates with the generation circuits 372-ID0 to 372-ID13 and the camera block control unit 52 and supplies the generated evaluation value in response to a request from the camera block control unit 52.

The luminance signal generation circuit 371 performs an operation (DY = 0.30DRb + 0.59DGb + 0.11DBb) using the video signals DRb, DGb, DBb supplied from the preprocessing unit 35, and generates a luminance signal DY. In order to determine whether the luminance signal DY is generated in this way, it is sufficient to determine whether the contrast is high or low, and the change in contrast is the level change of the luminance signal DY. This is because it only needs to be detected.

The evaluation value generation circuit 372-ID0 generates the evaluation value ID0. Similarly, the evaluation value generation circuits 372-ID1 to 372-ID13 generate evaluation values ID1 to ID13. These evaluation values are basically the sum of the frequency components of the video signal in the specific region (hereinafter referred to as "evaluation frame") provided in the image pickup image frame, and indicate the values corresponding to the blur of the image. Is.

Evaluation value ID0: Evaluation value name "IIR1_W1_HPeak" Evaluation value ID1: Evaluation value name "IIR1_W2_HPeak" Evaluation value ID2: Evaluation value name "IIR1_W2_HPeak" Evaluation value ID3: Evaluation value name "IIR4_W3_HPeak" Evaluation value ID4: Evaluation value name "IIR0_W1 Evaluation value ID5: Evaluation value name "IIR3_W1_VIntg" Evaluation value ID6: Evaluation value name "IIR1_W1_HIntg" Evaluation value ID7: Evaluation value name "Y_W1_HIntg" Evaluation value ID8: Evaluation value name "Y_W1_Satul" Evaluation value ID9: Evaluation value name "IIR1_W3_HPeak" Evaluation value ID10: Evaluation value name "IIR1_W4_HPeak" Evaluation value ID11: Evaluation value name "IIR1_W5_HPeak" Evaluation value ID12: Evaluation value name "Y_W3_HIntg" Evaluation value ID13: Evaluation value name "Y_W3_HIntg" , The evaluation value name indicating the attribute of the evaluation value (use data_evaluation frame size_evaluation value calculation method) is given.

The usage data of the evaluation value name is roughly classified into "IIR" and "Y". There are IIR, which uses high-frequency component data extracted from the luminance signal DY using an HPF (high-pass filter), and Y, which uses the frequency component of the luminance signal DY as it is without using HPF.

When using the HPF, the IIR type (infinite impulse response type) HPF is used. Depending on the type of HPF, the evaluation values are divided into IIR0, IIR1, IIR3 and IIR4, and these represent HPFs with different cutoff frequencies. By setting HPFs with different cutoff frequencies in this way, for example, by using an HPF with a high cutoff frequency in the vicinity of the in-focus position, it is evaluated as compared with the case of using an HPF with a low cutoff frequency. The change in value can be made large. Further, in a place where the focus is greatly deviated, by using an HPF having a low cutoff frequency, it is possible to make a large change in the evaluation value as compared with the case of using an HPF having a high cutoff frequency. In this way, HPFs with different cutoff frequencies are set so that the optimum evaluation value can be selected according to the focus state in the process of autofocus operation.

The evaluation frame size is the size of the image area used for generating the evaluation value. As shown in FIG. 3, five types of evaluation frame sizes W1 to W5 are provided, and the center of each evaluation frame coincides with the center of the captured image. Note that FIG. 3 shows the evaluation frame sizes W1 to W5 when the screen size of one field is 768 pixels × 240 pixels.

Evaluation frame size W1: 116 pixels x 60 pixels Evaluation frame size W2: 96 pixels x 60 pixels Evaluation frame size W3: 232 pixels x 120 pixels Evaluation frame size W4: 192 pixels x 120 pixels Evaluation frame size W5: 576 pixels x 180 pixels

By setting a plurality of types of frame sizes in this way, it is possible to generate different evaluation values corresponding to each frame size. Therefore, regardless of the size of the target subject, an appropriate evaluation value can be obtained by any of the evaluation values ID0 to ID13.

There are HPeak, HIntg, VIntg and Satul methods for calculating the evaluation value. The HPeak method indicates the peak horizontal evaluation value calculation method, the HIntg method indicates the total integration method horizontal evaluation value calculation method, the VIntg method indicates the integration method vertical evaluation value calculation method, and the Satul method indicates the number of saturated luminances. ing.

The HPeak method is an evaluation value calculation method for obtaining a high frequency component from a horizontal video signal using an HPF, and is used for calculating evaluation values ID0, ID1, ID2, ID3, ID9, ID10 and ID11.

Figure 4 shows the configuration of the horizontal evaluation value calculation filter used in the HPeak method. The horizontal evaluation value calculation filter consists of HPF381, which extracts only the high-frequency component from the brightness signal DY of the brightness signal generation circuit, absolute value processing circuit 382, which takes the absolute value of this high-frequency component, and horizontal frame control for the absolute valued high-frequency component. It has a multiplication circuit 383 that multiplies the signal WH, a line peak hold circuit 384 that holds one peak value per line, and a vertical integration circuit 386 that vertically integrates each peak value for all lines in the evaluation frame. are doing.

The high-frequency component of the luminance signal DY is extracted by HPF381 and converted to absolute value by the absolute value processing circuit 382. Next, the horizontal frame control signal WH is multiplied by the multiplication circuit 383 to obtain an absolute value high frequency component in the evaluation frame. That is, if the frame control signal WH whose multiplication value is "0" outside the evaluation frame is supplied to the multiplication circuit 383, only the absolute valued high frequency component in the evaluation frame in the horizontal direction can be supplied to the line peak hold circuit 384. In addition, if the frame control signal WH is set so that the multiplication value becomes smaller in the peripheral portion of the evaluation frame, the out-of-frame edge (high-brightness edge around the evaluation frame) located in the peripheral portion of the evaluation frame as the focus progresses. It is possible to eliminate noise of the evaluation value due to the influence of intrusion into the frame and sudden change of the evaluation value due to the shaking of the subject. The line peak hold circuit 384 holds the peak value for each line.

The vertical integrator circuit 386 adds the held peak values to each line in the vertical evaluation frame based on the vertical frame control signal WV to obtain an evaluation value. This method is called the HPeak method because the peak in the horizontal direction (H) is held once.

The HIntg method is a horizontal evaluation value calculation method obtained by the full integration method. FIG. 5 shows the configuration of the full integration method horizontal evaluation value calculation filter. Compared with the HPeak method horizontal evaluation value calculation filter in Fig. 4, this filter is the same up to the multiplication circuit 383, but the horizontal addition circuit 385 uses the absolute value high frequency component in the horizontal evaluation frame. The difference is that all are added, and then the addition result of all the vertical lines in the evaluation frame is integrated in the vertical direction by the vertical integrator circuit 386.

This fully integrated horizontal evaluation value calculation filter is used to calculate the evaluation values ID6, ID7, ID12 and ID13. Compared to the HPeak method, the HPeak method finds one peak value per line and adds them vertically, whereas the HIntg method finds the absolute value within the horizontal evaluation frame of each line. The difference is that all the high frequency components are added and they are added vertically.

The HIntg method is classified into IIR1 which uses high frequency components and Y which uses the luminance signal DY itself as it is. The brightness addition value is obtained by the brightness addition value calculation filter circuit in which the HPF381 is removed from the full integration method horizontal evaluation value calculation filter shown in FIG.

The VIntg method is a vertical evaluation value calculation method of the full integration method, and is used for evaluation values ID4 and ID5. Both the HPeak method and the HIntg method generate evaluation values by adding them in the horizontal direction, while the VIntg method is the evaluation values generated by adding high-frequency components in the vertical direction. For example, depending on the scene, such as an image in which the upper half of the screen is white and the lower half is black, or an image of a horizontal line, if there is only a high frequency component in the vertical direction and no high frequency component in the horizontal direction, the HPeak method horizontal evaluation value does not work effectively. .. Therefore, the evaluation value of the VIntg method defines that autofocus works effectively even in such a scene.

FIG. 6 shows the configuration of the vertical evaluation value calculation filter that calculates the vertical evaluation value. The vertical evaluation value calculation filter includes a horizontal mean value calculation filter 391, an IIR type HPF392, an absolute value processing circuit 393, and an integration circuit 394.

The horizontal mean value calculation filter 391 selects the luminance signal of the pixel (for example, 64 pixels) in the center of the horizontal evaluation frame from the luminance signal DY of each line based on the frame control signal WHc, and averages (total). The same applies to the value.) Is calculated and output once in one horizontal period. Here, the reason why the number of pixels is set to 64 in the center is to remove noise in the periphery of the evaluation frame. Here, since only 64 pixels are sequentially accumulated and finally one average value is output, the configuration is simple and does not require a memory device such as a line memory or a frame memory. Next, this is synchronized with the line frequency, the high frequency component is extracted by HPF392, and the absolute value processing circuit 393 is used as the absolute value high frequency component. Further, the integrator circuit 394 integrates all the lines in the evaluation frame in the vertical direction.

The Satul method is a calculation method for obtaining the number of saturated (specifically, the brightness level is equal to or higher than a predetermined amount) brightness signal DY in the evaluation frame, and is used for calculating the evaluation value ID 8. In the calculation of the evaluation value ID8, the luminance signal DY and the threshold value α are compared, and the number of pixels in which the luminance signal DY is equal to or greater than the threshold value α is counted for each field to obtain the evaluation value ID8. To do.

The reference signal generation unit 40 generates the vertical synchronization signal VD, the horizontal synchronization signal HD, and the reference signal CLK, which are the reference for the operation of each unit in the video camera 10, and supplies them to the image sensor drive unit 42. The image sensor drive unit 42 generates a drive signal RIR based on the supplied vertical synchronization signal VD, horizontal synchronization signal HD, and reference signal CLK and supplies the drive signal RIR to the image sensor 32R to drive the image sensor 32R. Similarly, drive signals RIG and RIB are generated and supplied to the image sensors 32G and 32B to drive the image sensors 32G and 32B. The preamplifier section 33R, 33G, 33B, the A / D conversion section 34R, 34G, 34B, the preprocessing section 35, the signal processing section 36, the evaluation value calculation section 37, etc. are vertical synchronized with the video signal supplied from the previous stage. Processing is performed using the synchronization signal VD, the horizontal synchronization signal HD, and the reference signal CLK. These signals may be supplied from the reference signal generation unit 40, or may be supplied from the previous stage together with the video signal.

The distance measurement sensor 45 measures the distance in response to a request from the camera block control unit 52, and supplies the distance measurement result Mag indicating the distance to the subject to the camera block control unit 52. If distance measurement is not possible, data indicating that distance measurement is not possible (hereinafter referred to as "distance measurement impossible data NG") is output as the distance measurement result Mag. The ranging sensor 45 is an active ranging sensor that measures the distance to the subject by utilizing the reflection when infrared rays, radio waves, etc. are output, and the brightness obtained by detecting the brightness information of the subject with the sensor. A passive distance measuring sensor that measures the distance to the subject from signal deviation and sharpness is used.

A display unit 48 is connected to the display drive unit 47. The display drive unit 47 generates a display drive signal RDM based on the video signal DVvf supplied from the signal processing unit 36 or the display signal DVmm supplied from the camera block control unit 52 described later, and supplies the display drive signal RDM to the display unit 48. To do.

The display unit 48 is configured by using an image display element such as a liquid crystal display element or a cathode ray tube, and drives the image display element based on the display drive signal RDM to display an captured image or a captured image on the screen of the display unit 48. Various information and a setting menu display for making various settings on the imaging device are displayed.

A user interface 56 is connected to the camera block control unit 52, and a control signal is generated based on an operation signal PSC or the like supplied from the user interface 56 and supplied to each unit to operate the video camera 10. Is controlled so that the operation is based on the operation signal PSC or the like.

Further, the lens block control unit 51 and the camera block control unit 52 described above can communicate with each other using a predetermined format, protocol, or the like, and the lens block control unit 51 and the camera block control unit 52 automatically perform communication. Controls the focus operation.

Here, as described above, the lens block control unit 51 supplies various information (for example, focus position, iris value, etc.) QF to the camera block control unit 52, for example, upon request. Further, the lens drive signals RDf and RDw are generated based on the focus control signal CTf, the wobbling control signal CTw, and the like supplied from the camera block control unit 52, and the focus lens 21 and the wobbling lens 22 are driven. The camera block control unit 52 is a focus lens based on the evaluation value ID calculated by the evaluation value calculation unit 37, the distance measurement result Mag obtained by the distance measurement sensor 45, and various information read from the lens block control unit 51. The focus control signal CTf for driving and controlling the 21 and the wobbling control signal CTw for driving and controlling the wobbling lens 22 are generated and supplied to the lens block control unit 51.

Further, the camera block control unit 52 changes the setting contents related to the autofocus operation and generates a display signal DVmm for displaying the setting content change menu screen so that the autofocus operation can be performed according to the user's request. It is supplied to the display drive unit 47. Further, the camera block control unit 52 is connected to a setting content storage unit 58 that stores the setting content related to the autofocus operation, and the setting content storage unit 58 stores new setting content or is stored. By selectively reading and using the contents, the autofocus operation is switched, and the autofocus operation is performed according to the application of the video camera 10.

The lens block control unit 51 and the camera block control unit 52 may be integrally configured. In the following description, the lens block control unit 51 and the camera block control unit 52 are collectively referred to as a control unit 50. To do. Further, the control unit 50 may be configured by using a microcomputer, a memory, or the like, and may perform an autofocus operation by reading and executing a program stored in the memory.

Next, the autofocus operation will be described. FIG. 7 shows a flowchart of the autofocus operation.

In step ST1, the control unit 50 performs distance measurement processing using the distance measurement sensor 45, causes the distance measurement sensor 45 to measure the distance to the subject, and reads out the distance measurement result Mag from the distance measurement sensor 45. In step ST2, the control unit 50 detects the current focus position FPs based on the detection signal RSf from the position detection unit 21a.

In step ST3, the control unit 50 performs the lens drive setting process. In this lens drive setting process, the moving direction and moving speed of the focus lens 21 are set based on the current focus position FPs and the distance measurement result Mag.

FIG. 8 is a flowchart showing the lens drive setting process. In step ST51, the control unit 50 determines whether or not the distance measurement result Mag is the distance measurement impossible data NG. Here, if the distance measurement result Mag is not the distance measurement impossible data NG, the process proceeds to step ST52, and if the distance measurement result Mag is the distance measurement impossible data NG, the process proceeds to step ST56.

In step ST52, the control unit 50 determines whether or not the current focus position FPs is farther than the first determination distance LD1 from the focus position range FJA based on the distance measurement result Mag. Here, if the distance LE from the current focus position FPs to the focus position range FJA based on the distance measurement result Mag is larger than the first discrimination distance LD1, the process proceeds to step ST53, and if it is less than or equal to the discrimination distance LD1, the step Proceed to ST54.

The focus position range FJA is set for the distance measurement result Mag so that the in-focus position FPj for the subject corresponding to the distance measurement result Mag is included. For example, let the focus position range FJA be the distance measurement error range in the distance measurement result Mag. Alternatively, it is set wider than the distance measurement error range in the distance measurement result Mag. The size of the discrimination distance LD1 is set in consideration of the controllability of the focus lens 21. That is, when the focus lens 21 is moved at the first speed Va as described later, if the discrimination distance LD1 is short, the focus lens 21 approaches the focusing position FPj before reaching the first speed Va. Further, when the moving speed of the focus lens 21 is fast, it takes a long time to stop the focus lens 21, so even if the focus lens 21 is stopped when approaching the focusing position FPj, the focusing position FPj is set. There is a risk that it will pass by and the focus operation will be uncomfortable. Therefore, the discrimination distance LD1 is set according to the maximum speed and controllability when moving the focus lens 21. Further, since the maximum speed and controllability differ depending on the focal length and the iris value, the discrimination distance LD1 is adjusted according to the focal length and the iris value.

In step ST53, the control unit 50 moves the focus lens 21 so that the focus position FPs quickly approach the focus position FPj because the current focus position FPs is farther from the focus position range FJA than the discrimination distance LD1. Is set to the first velocity Va. Further, the moving direction of the focus lens 21 is set so that the focus position FPs move in the direction based on the distance measurement result Mag, that is, in the direction of the focus position FPm indicated by the distance measurement result Mag. Further, since the moving direction of the focus lens 21 can be correctly determined based on the distance measuring result Mag of the distance measuring sensor 45, wobbling for determining the moving direction becomes unnecessary.

The first velocity Va is intended to quickly bring the focus position closer to the in-focus position, and the evaluation value is updated only once per field, so it may pass through a mountain of evaluation values. There is no need to limit the movement speed so that there is no such thing. Therefore, the first speed Va is the fastest speed that can be tolerated when driving the focus lens 21.

From step ST52 to step ST54, in step ST54, the control unit 50 determines whether or not the current focus position FPs are included in the focus position range FJA. Here, when the current focus position FPs are not included in the focus position range FJA, the process proceeds to step ST55. If it is included in the focus position range FJA, the process proceeds to step ST56.

In step ST55, the control unit 50 sets the moving speed of the focus lens 21 to the second speed Vb, which is slower than the first speed Va. Further, the moving direction is set so that the focus position FPs move in the direction based on the distance measurement result Mag, that is, in the direction of the focus position FPm indicated by the distance measurement result Mag. This second velocity Vb is slower than the second velocity Vb from the second velocity Vb because the evaluation value curve showing the change in the evaluation value when the focus lens 21 is moved is crushed. Set the speed so that the speed switching to Vc does not get stuck. For example, when the depth of focus is Fs, the second velocity Vb is set to "12Fs / field". The third speed Vc is a speed at which the peak of the evaluation value can be detected with high accuracy, and is set to, for example, "2Fs / field". When the fastest allowable speed for driving the focus lens 21 is "12 Fs / field" or less, the first speed Va and the second speed Vb are equal speeds.

When the process proceeds from step ST51 or step ST54 to step ST56, the control unit 50 performs wobbling as in the conventional case, and sets the moving direction of the focus lens 21 based on the change in the evaluation value when the wobbling lens 22 is moved. Further, the moving speed of the focus lens 21 is set to the second speed Vb. If the distance between the current focus position FPs and the focus position FPm is short, the current focus position FPs is close to the focusing position FPj, so the moving speed of the focus lens 21 is set to the third speed Vc. It may be the one to do.

In step ST4 of FIG. 7, the control unit 50 performs lens drive processing. In this lens drive processing, the movement speed of the focus lens 21 is switched, and the mountain climbing control processing is performed as in the conventional case to perform the focusing operation of moving the focus position FPs to the focusing position FPj.

To switch the movement speed, when the distance from the focus position FPs to the above-mentioned focus position range FJA is shorter than the second discrimination distance LD2, which is shorter than the discrimination distance LD1, the movement speed is changed from the first speed Va to the second. Switch to speed Vb. Here, the discrimination distance LD2 is set to the focus position when the movement speed is switched from the first speed Va to the second speed Vb described later, for example, at a position separated by the discrimination distance LD2 from the focus position range FJA. Set the range FJA to be decelerated to the second speed Vb. With this setting, it is possible to prevent the focus position range FJA from passing over a mountain of evaluation values due to a small number of evaluation values.

In the mountain climbing control process, the increase / decrease in the evaluation value calculated by the evaluation value calculation unit 37 is detected, the focus position FPs are moved so as to maximize the evaluation value, and the focus position FPj is driven. In the mountain climbing control process using this evaluation value, for example, the focus lens 21 is moved so that the above-mentioned evaluation values ID0, ID2, etc. are maximized. Also, using the evaluation value ID8, when the number of pixels with high brightness increases, the focus lens 21 is switched from the evaluation frame size W1 to the evaluation frame size W5 so that the focus lens 21 does not move in the direction in which blurring occurs. Calculate the evaluation value. Furthermore, by using the evaluation value ID0 and other evaluation values ID1 to ID7 and ID9 to ID13, it is possible to switch the lens movement speed, judge the shaking, judge the reverse feed, judge the arrival of the Near end or Far end of the lens, etc. Then, the driving operation of the focus lens 21 is controlled so that the focusing is performed accurately based on the determination result. In this way, the mountain climbing control process is performed to drive the focus position FPs to the focusing position FPj and end the focusing operation.

FIG. 9 is a diagram for explaining an autofocus operation using the distance measurement result. When the current focus position FPs is farther than the first discrimination distance LD1 from the focus position range FJA based on the distance measurement result Mag, that is, from the current focus position FPs to the focus position range FJA based on the distance measurement result Mag. When the distance LE is larger than the first discrimination distance LD1, the focus lens 21 is moved at the first speed Va without wobbling, and then switched to the second speed Vb or the third speed Vc. Then, when the time Tafu elapses, the focus position FPs are driven to the focus position FPj. The broken line indicates the conventional autofocus operation. After wobbling is performed to determine the moving direction, the focus lens 21 is moved at the second speed Vb, and the focus position FPs is changed when the time Tafv elapses. Driven into the in-focus position FPj. Therefore, the focusing time can be shortened. Also, even if the current focus position FPs is outside the focus position range FJA and is not farther than the discrimination distance LD1, the focus lens 21 is moved at the second speed Vb without wobbling. The focusing time can be shortened as compared with the conventional autofocus operation in which wobbling is performed at the start of the focus operation.

In step ST5, the control unit 50 determines whether or not the restart condition for restarting the autofocus operation is satisfied, and when the restart condition is satisfied, returns to step ST1 and repeats the above process. Then, the focus lens 21 is moved so that the focus position FPs becomes the focus position FPj. If the restart conditions are not met, the process proceeds to step ST6.

Next, the restart condition will be described. In the present invention, a scene stabilization mode and an unstable mode are provided, and when the change in brightness exceeds a preset threshold value, for example, panning is performed by shaking the video camera 10 in the horizontal direction, or the subject is large. Judge that it is moving and set it to unstable mode. Further, when the change in brightness becomes small and the transition condition for transitioning from the unstable mode to the scene stable mode is satisfied, the transition from the unstable mode to the scene stable mode is performed. In this scene stabilization mode, it is determined that the change in brightness is small, and that panning is not performed, or even if panning is performed, slow panning or the subject is not moving. It shall not be restarted when it is in unstable mode, and it will be restarted when it shifts from unstable mode to scene stable mode.

If the restart is performed using the brightness change in this way, the brightness integrated value hardly changes because the angle of view does not change even if the focus position approaches the in-focus position during the autofocus operation, so the restart is performed. Misjudgment can be reduced.

Here, as the luminance integral value, for example, the normalized difference p0 of the luminance integral is used. This normalized difference p0 can be calculated based on Eq. (1). p0 = (Yadd_W5_f0-Yadd_W5_f1) / Ynow_W5_f0 / N1 (1) Yadd_W5_f0 is the total luminance integral value of the video signal in the evaluation frame size W5 from the current field to the period before the N1 field. The value. "Yadd_W5_f1" is the sum of the luminance integral values of the evaluation frame size W5 in the period from the (N1 + 1) field to the period before the (2 × N1) field. "Ynow_W5_f0" is the luminance integral value of the evaluation frame size W5 in the current field.

When the absolute value ABS (p0) of the normalized difference p0 becomes larger than the preset threshold value β1 in the scene stable mode, the scene stable mode is switched to the unstable mode. Also, when the absolute value ABS (p0) becomes smaller than the preset threshold value β2 in the unstable mode, the unstable mode is switched to the scene stable mode, the autofocus operation is restarted, and the focus position is adjusted. Move to the focus position and end the autofocus operation. Furthermore, change to the scene stabilization mode.

Further, the change in the evaluation value may be used as the restart condition. Here, in the scene stabilization mode, for example, the average value in the time direction of the evaluation value ID0 changes by a predetermined ratio with respect to the evaluation value at the end of the autofocus operation (immediately after the focus lens is driven to the in-focus position). Reboot when it occurs.

When the video camera 10 is fixed and the change in the scene is small, for example, when the subject approaches the fixed video camera 10, the brightness integral value does not change much, and the normalized difference of the brightness integral is seen. Rebooting does not occur just by being there. However, by using the average value of the evaluation values in the time direction, it is possible to restart the system even in such a case.

The evaluation value change q0 can be calculated based on Eq. (2). q0 = Hadd_W1_f1 / Hadd_W1_f0 (2) Hadd_W1_f0 is an evaluation value calculated using the frequency component of the video signal in the evaluation frame size W1 from immediately after the scene is stable to between the M fields, for example, the frequency component is added. The total value of the evaluation values obtained by the above is shown. In addition, "Hadd_W1_f1" indicates the total value of the evaluation values from the present to before the M field.

Here, when the evaluation value change q0 becomes smaller than 1 / γ or larger than γ, the restart is performed. Note that "γ" and "M" are constants.

In this way, by using the change in the average value of the evaluation values in the time direction, the influence of the shaking can be reduced and the system can be restarted.

Furthermore, when the normalized difference is used, in a very slow panning, the change in the normalized difference is small and it is difficult to restart. Therefore, when the brightness integral value changes by a predetermined ratio with respect to the evaluation value at the end of the autofocus operation (immediately after the focus lens is driven to the in-focus position), the restart may be performed.

The brightness integral value change r0 can be calculated based on Eq. (3). r0 = Y_now / Y_jp (3) Y_now indicates the current luminance integral value. Further, "Y_jp" indicates the luminance integral value at the end of the autofocus operation.

Here, when the brightness integral value change r0 becomes smaller than "1 / δ" or larger than "δ", the restart is performed. Note that "δ" is a constant. By using the change in the integrated brightness value in this way, it is possible to restart even in a very slow panning.

From step ST5 to step ST6, in step ST6, the control unit 50 performs distance measurement processing using the distance measurement sensor 45 in the same manner as in step ST1, and measures the distance to the subject with the distance measurement sensor 45. The distance result Mag is read from the distance measurement sensor 45.

In step ST7, the control unit 50 determines whether or not the subject has been switched. Here, when it is determined that the subject has been switched, the process returns to step ST3, and the lens drive setting process and the lens drive process are performed based on the distance measurement result Mag to perform an autofocus operation so that the switched subject is in focus. Is done. If the subject has not been switched, the process returns to step ST5.

The determination of subject switching is to determine whether or not a subject whose distance is different from this subject position is imaged with respect to the subject position that is in focus in the focus position FPs when the lens drive process of step ST4 is completed. Is what you do. For example, when the deviation between the focus position FPm based on the distance measurement result Mag and the current focus position FPs is equal to or greater than a preset threshold value and this state continues longer than the discrimination reference period, subject switching is performed. Determine as a thing. Further, even if the deviation between the focus position based on the distance measurement result Mag and the current focus position FPs is smaller than the preset threshold value or greater than or equal to the preset threshold value, this state is shorter than the discrimination reference period. Occasionally, it is determined that the subject has not been switched. Here, the discrimination reference period is set so that the restart will not be performed when a subject different from the desired subject is included in the ranging angle of view of the ranging sensor 45 for a short time. For example, if the discrimination reference period is set to about 2 to 3 seconds, even if a person crosses in front of the video camera 10, it is possible to prevent the restart so as to focus on this person.

When it is determined that the subject has been switched by setting the discrimination reference period and the threshold value in this way, the autofocus operation can be performed again using the distance measurement result Mag, so that the background can be escaped from the scratched state. .. That is, as shown in FIG. 10A, when there is a tree OB2 behind the person OB1 imaged by the video camera 10, if the tree OB2 is in focus, the person OB1 in the foreground is shown in FIG. 10B. Is a blurred image. Here, when the distance measurement angle of view of the distance measurement sensor 45 is adjusted to the person OB1 in front, the deviation between the focus position FPm based on the distance measurement result Mag and the current focus position FPs is greater than or equal to the preset switching discrimination distance. If this state continues for longer than the discrimination reference period, the current focus position FPs are moved to the focus position range FJA based on the distance measurement result Mag, and the mountain climbing control process is performed. Therefore, as shown in FIG. 10C, the background tree OB2 becomes a blurred image in a state where the person OB1 in the foreground is in focus, and it is possible to escape from the background scratch.

By the way, when the above-mentioned autofocus operation is performed with a fixed setting in advance, the video camera 10 may not be able to perform the autofocus operation according to the application of the video camera 10. For example, if the autofocus operation of the video camera 10 is set to be suitable for a weather camera, using this video camera 10 in sports programs and news programs will take time for the focus to reach the subject. You may miss a photo opportunity. Therefore, it is possible to change the setting contents related to the autofocus operation so that the autofocus operation can be performed according to the application. Further, by making it possible to store a plurality of setting contents and reading out and using the desired setting contents from the plurality of stored setting contents, it is possible to easily realize the autofocus operation according to the application of the video camera 10.

FIG. 11 is a flowchart showing a setting content changing process that enables the setting content to be changed by user operation.

In step ST71, the control unit 50 determines whether or not the stored setting contents are specified. Here, when the stored setting contents are specified, for example, the setting identification information used for identifying the setting contents is stored in relation to the setting contents, and the stored setting identification information is specified. If so, proceed to step ST72. If no setting contents are specified, the process proceeds to step ST73.

In step ST72, the control unit 50 reads the specified setting contents and proceeds to step ST74. Further, in step ST73, the control unit 50 reads out the current setting contents and proceeds to step ST74.

In step ST74, the control unit 50 displays the setting content change menu display on the screen of the display unit 48. Further, in the setting content change menu display, the read setting content is displayed for each setting item.

FIG. 12 illustrates the setting content change menu screen. On the setting content change menu screen, the display area GA for displaying the setting identification information used for identifying the setting content, the display area GB for displaying the setting items, and the display area GC for displaying the setting status of each setting item. Is provided.

For example, the setting title, the setting number, and the user identification information are displayed in the display area GA as the setting identification information. In the display area GB, for example, the setting item "AF SPEED" related to the focus operation speed, the setting item "AF SENSOR" related to the use of the ranging sensor 45, and the setting item related to the size of the ranging frame in the ranging sensor 45. "AF WINDOW SIZE", setting item "AF SENSITIVITY" related to restarting the autofocus operation, etc. are displayed. In the display area GC, the setting status of the setting items displayed in the display area GB is displayed corresponding to the setting items. Further, when the setting is changed, the display area GC displays the setting contents that can be selected so that it can be determined what kind of setting is possible.

In step ST75, the control unit 50 changes the setting contents according to the user operation. Here, when the operation of moving the position of the cursor display in FIG. 12 up and down is performed on the user interface 55 or the user interface 56, the control unit 50 moves the cursor display up and down according to the operation. Move to. In addition, the cursor display "" is moved in conjunction with the movement of the cursor display "". The cursor display "" indicates the display position of the setting state related to the setting item indicated by the cursor display "". Assuming that a rotary encoder (rotary switch) or the like is provided in the user interfaces 55 and 56, if the cursor display "" is moved up and down according to the rotation operation of the rotary encoder, the cursor display "" is moved. Can be easily performed.

After the cursor display "" is moved to the position of the desired setting item, when the operation of selecting the setting item at the position of the cursor display "" is performed, the control unit 50 points to the display position of the set state. Change the cursor display "" to the cursor display "?" (Not shown) indicating that the setting status can be changed to allow the setting status to be changed. For example, a push switch is provided on the rotary encoder so that the push switch is operated when the rotary encoder is pressed, and when the rotary encoder is pressed after moving the position of the cursor display , the control unit 50 Allows the change of the setting state, assuming that the operation of selecting the setting item indicated by the cursor display "" has been performed.

Further, when the setting switching operation is performed by the rotary encoder while the setting state change is permitted, the control unit 50 repeatedly displays the selectable setting contents in the display area GC in order, and how. It is possible to determine whether various setting contents can be selected. Further, when the operation of selecting the setting content is performed with the push switch while the desired setting content is displayed, the setting content of the setting item is changed to the displayed setting content.

Here, the setting items and the setting contents will be described. For example, the setting item "AF In "SPEED", one of high speed "FAST", medium speed "NORMAL", and low speed "SLOW" can be selected. The high-speed "FAST" is a setting state in which the focusing time is prioritized. For example, the above-mentioned second speed Vb is set to "12Fs / field". By setting the second speed Vb in this way, the focusing time is shortened and it becomes easier to focus on a subject with a large movement. The medium speed "NORMAL" is a setting state in which the smoothness of operation is prioritized. For example, the above-mentioned second speed Vb is set to "6Fs / field". By setting the second speed Vb in this way, more evaluation values can be obtained than in the high-speed "FAST" setting state, so the evaluation value peak is excessively exceeded compared to the high-speed "FAST" setting state. There are few cases where it will be lost, and the operation will be smooth. For this reason, it is suitable for production systems (including movies) that shoot and record the process of focusing. The low speed "SLOW" is a setting state in which the focus accuracy is prioritized. For example, the above-mentioned second speed Vb is set to the third speed Vc. By setting the second speed Vb in this way, it is possible to perform an accurate autofocus operation without overshooting the evaluation value peak.

In the setting item "AF SENSOR", either valid "ON" or invalid "OFF" can be selected. When it is "ON", the distance measurement sensor 45 is used to measure the distance, and the distance measurement result is used to perform the autofocus operation as described above. When it is enabled "ON", the distance measuring operation by the distance measuring sensor 45 is stopped, or the distance measuring result is set to "NG" and the autofocus operation without using the distance measuring result is performed.

In the setting item "AF WINDOW SIZE", one of automatic "AUTO", large frame "LARGE", middle frame "MID", and small frame "SMALL" can be selected. When it is set to automatic "AUTO", distance measurement is performed with a preset standard distance measurement angle of view. When the outline is "LARGE", the angle of view is set to a large angle (for example, the entire screen). When the middle frame is "MID", the angle of view is set to 1/2 of the screen. When the small frame is "SMALL", the angle of view is set to 1/4 of the screen. There is a trade-off between the size of the AF frame and the stability of the autofocus operation, and if you select the large frame "LARGE", you can improve the stability of the autofocus operation (less operation that you feel is a malfunction). , A subject different from the desired subject is included in the AF frame, and the probability of focusing on a different subject increases. Further, when the small frame "SMALL" is selected, since the ranging frame is small, if the imaging is performed so that the desired subject is included in the ranging frame, the focus can be accurately focused on the desired subject.

In the setting item "AF SENSITIVITY", one of sensitive "HIGH", normal "NORMAL", insensitive "LOW", and threshold input "INPUT" can be selected. When the sensitivity is "HIGH", the above-mentioned threshold value "β2" is set larger than the case of the normal "NORMAL", or the above-mentioned threshold value "γ" or the threshold value "δ" is set smaller than the case of the normal "NORMAL". To make it easier for a reboot to occur. When the insensitivity is "LOW", the above-mentioned threshold value "β2" is set smaller than the case of the normal "NORMAL", or the above-mentioned threshold value "γ" or the threshold value "δ" is set larger than the case of the normal "NORMAL". Set to make restarts less likely to occur. Further, at the time of the threshold input "INPUT", the threshold "β1" "β2", the threshold "γ" or the threshold "δ" can be input from the user interface 55 or the user interface 56.

Further, not only when restarting is performed according to the absolute value of the normalized difference of the luminance integral, the evaluation value, and the change of the luminance integral value with respect to the recorded evaluation value, an angular velocity sensor is provided in the imaging device, and the angular velocity sensor of this angular velocity sensor is provided. The restart may be performed using the angular velocity detection result, and the threshold value may be selectable for this angular velocity detection result.

When the sensitive "HIGH" is selected in the setting item "AF SENSITIVITY", the autofocus operation is likely to restart, making it suitable for shooting applications where a photo opportunity is important. In addition, when the insensitivity "LOW" is selected, it is difficult for the autofocus operation to restart, which makes it possible to extend the life of the focus lens and is suitable for applications such as weather cameras that do not require prompt autofocus operation. .. Further, when the threshold input "INPUT" is selected, the user can make detailed settings .

In step ST76, the control unit 50 determines whether or not the setting content change completion operation has been performed, proceeds to step ST77 when the setting content change completion operation is performed, and steps when the setting content change completion operation has not been performed. Return to ST75 In step ST77, the control unit 50 registers the setting contents and stores the setting identification information and the setting contents in association with each other. For example, when updating the already registered setting contents, the already registered setting contents can be updated by registering the updated setting contents in relation to the setting identification information before the update. Further, when storing the new setting contents, new setting identification information is provided for the setting contents selected in step ST75, and the setting identification information and the setting contents are registered in association with each other.

In this way, if the setting contents according to the use of the video camera 10 are set in the user interface, the autofocus operation according to the use can be performed. Further, if the setting contents are stored in the setting contents storage unit 58, even when the video camera 10 is used for a different purpose, the setting contents according to the purpose can be read from the setting contents storage unit 58 and used according to the purpose. It is possible to perform the autofocus operation.

In the above-described embodiment, the case where the image pickup device is a video camera has been described, but it goes without saying that the same applies to an image pickup device such as a digital camera.

<figref num="1">It is a figure which shows the structure of a video camera.</figref><figref num="2">It is a figure which shows the structure of the evaluation value calculation part.</figref><figref num="3">It is a figure which shows the evaluation value size.</figref><figref num="4">It is a figure which shows the structure of the horizontal evaluation value calculation filter.</figref><figref num="5">It is a figure which shows the structure of the total integration method horizontal evaluation value calculation filter.</figref><figref num="6">It is a figure which shows the structure of the vertical evaluation value calculation filter.</figref><figref num="7">It is a flowchart which shows the autofocus operation.</figref><figref num="8">It is a flowchart which shows the lens drive setting process.</figref><figref num="9">It is a figure which shows the autofocus operation using the distance measurement result.</figref><figref num="10">It is a figure for demonstrating the background pulling escape operation.</figref><figref num="11">It is a flowchart which shows the setting content change process.</figref><figref num="12">It is a figure which shows the setting content change menu screen.</figref>

Code description

10 Video camera, 20 Lens block, 21 Focus lens, 21a, 22a Position detector, 21b, 22b Lens drive unit, 22 Wobbling lens, 23 Iris, 23a Iris position detector, 23b Iris drive unit, 30 Camera block, 31 Color separation prism, 32R, 32B, 32B Image sensor, 33R, 33G , 33B Preamplifier part, 34R, 34G, 34B A / D conversion part, 35 Pre-processing part, 36 Signal processing part, 37 Evaluation value calculation part, 40 Reference signal generator, 42 Image sensor drive unit, 45 Distance measurement sensor, 47 Display drive unit, 48 Display unit, 51 Lens block control unit, 52 Camera block control unit, 55,56 User interface, 58 Setting contents storage unit, 371 Brightness signal generation circuit, 372-ID0 to 372-ID13 Evaluation value generation circuit, 373 Interface circuit, 381,392 High frequency pass filter, 382,393 Absolute value processing circuit, 383 Multiplication circuit, 384 Line peak hold circuit, 385 Horizontal addition circuit, 386 Vertical integrator circuit, 391 Horizontal average value calculation filter, 394 Integrator circuit