Lens driving device

[Detailed Description of the Invention]

[Industrial Application] The present invention relates to the lens drive which drives a plurality of lens groups independently respectively for focusing or zooming.

[Description of the Prior Art] The applicant of the present invention indicated previously the device which drives each lens group independently in Japanese Patent Application No. No. 170234 [ two to ], and Japanese Patent Application No. No. 106393 [ two to ]. The former drives other groups parallel, while an existence position is based on the position of one lens group corresponding to 1 to 1 in a zoom state or the focal state. When the latter drives each one group of every in order serially by an ultrasonic motor, it repeats the minute drive of each group in order by making 1 time of drive quantity into slight quantity, holding the physical relationship of each group. In such a drive, since it drives while maintaining the mutual physical relationship of each group, a lens group comrade's interference (collision) has an advantage not occurring.

[Problem(s) to be Solved by the Invention] However, in the above-mentioned drive, when failure or malfunction occurs in one of the encoders which detect the position of a lens, there may be [ carrying out Oba Laon, without stopping to a predetermined stop position, and colliding with other lens groups, or ] a lens group corresponding to it. In the lens using the drive mechanism currently indicated by Japanese Patent Application No. No. 106393 [ two to ] etc., i.e., the lens it was made to drive each group by a linear type ultrasonic wave motor independently, When drive voltage is impressed to the vibrator of an ultrasonic motor, as compared with the case where it is stood still by stillness frictional force, driven load becomes small. For this reason, for example, when the 1st group (forefront group) is pushed in by force by a hand etc., it is possible to collide with the 2nd group that moves regardless of control and is standing it still. Thus, a serious damage will be given to the optical system and drive mechanism of each lens group if that other lens groups collide should start in a stationary lens group. As this measure, switch SW which detects proximity is formed in each lens group, and it is possible by intercepting driving force just before a collision to prevent a collision. By this method, when a motor with the sufficient stop characteristic like an ultrasonic motor is used, it is satisfactory, but when a DC motor etc. are used, it thinks [ colliding without the ability to finish stopping because of inertia, or ]. When the 1st group is pushed in and driving force is intercepted just before a collision, in the case of the lens which uses the ultrasonic motor as drive mechanism even if it can prevent a collision, the danger of damaging the actuator of the 1st group conversely is high. The place which the lens drive of the present invention was made paying attention to such a subject, and is made into the object, Even when the collision of lens groups occurs, it is in providing the lens drive which the shock added to each lens group is reduced, and can hold down the damage to an optical system or drive mechanism to the minimum.

[Means for solving problem] In order to solve the above-mentioned subject, a lens drive of the present invention is provided with the following. A plurality of lens groups with a field which a moving range of a lens frame which supports an adjacent lens group overlaps, A plurality of driving means [ that even installation can drive Re and each lens group independently for every lens group of these lens groups of a plurality of ], A proximity detection means to detect proximity of a plurality of above-mentioned lens groups, and to output a detection signal, A load reduction means to reduce one driven load of a lens frame which approached based on a detection signal of this proximity detection means.

[Function] That is, in the case where each of a plurality of lens groups with the field which the moving range of the lens frame which supports an adjacent lens group in the present invention overlaps is driven independently, Proximity of a plurality of above-mentioned lens groups is detected, a detection signal is outputted, and one driven load of the lens frame which approached is reduced based on this detection signal. This enables it to reduce the shock added to each lens group, even when the collision of lens groups occurs. C example] Below, the desirable example of the present invention is described with reference to drawings. 101~103 is the 1st, 2nd, and 3rd lens group, respectively, 104~106 is a frame of the 1st, 2nd, and 3rd lens group, and 107 is [ in / using a linear type ultrasonic wave motor (hereafter referred to as LUM) as the 1st example of the present invention / in Drawing 1 / a figure ] a fixed frame, respectively. 111~11B is LUM and drives the 1st, 2nd, and 3rd lens group, respectively. By the structure and the principle of operation of this LUM being the same as that of what these people indicate in Japanese Patent Application No. No. 195767 [ one to ] which applied previously, and this motor taking, since With of a method is the same as that of what was shown in the 1st example of Japanese Patent Application No. No. 106393 [ two to ], explanation is omitted. Base material 108~110 directs lens frame 104~106 arranged in the direction which counters LUM111~113, respectively. It will contact, if switch contact pieces 121 and 122 are attached to the both sides of the 1st group lens 104, the 2nd group lens frame 105 and the 2nd group lens frame 105, and the 3rd group lens frame 106, respectively and it approaches. It is. in a figure, 121a gives those with In contact by the side of the 1st group lens frame 104, and spring nature, and comes out. 121b is a contact piece by the side of the 2nd group lens frame 105. 123a and 123b are the leads connected to switch contact pieces 121a and 121b. Drawing 3 is a figure showing the movement magnitude of each lens group in Drawing 1. In order for each lens group to move like a solid line in connection with Scaling and to unite a focus, a RUNS group is repeated like a dashed line from infinity corresponding to near. Drawing 4 is a general view of a camera which used the lens of this example. A finder for which a photographing lens part containing a lens group which explained 96 in Drawing 1, and 92 used a Release button for, and 93 used a pentaprism, and 94 are quick return mirrors which lead light which passed along a lens to a finder. 91 is a main part of a camera. Focusing operation input section 601 is electric, and performs focusing, zooming operation input section 603 performs Scaling, and focusing and zooming are performed by these button operations. Drawing 5 is a block diagram showing the composition of an electric circuit system. In the figure, 111~113 corresponds to LUM shown in Drawing 1. Encoder 521~523 is attached to each lens group, and outputs a pulse with movement of an optical axis direction. To this encoder, a scale shifts a phase, it is written in two rows, and that phase inversion shows a direction. detecting and outputting this direction -- direction detector circuit 531~53 -- it comes out. Counter 54□~54. counts the pulse of the above-mentioned encoder, and outputs the position of a lens. Drive circuit 55.~553 generates the drive voltage which should be impressed to LUMl 11~113 based on the signal from operation control part (hereafter referred to as CPU) 59. 60. And 601 is the above-mentioned zooming operation input section and focusing operation input section, respectively. ROM56 memorizes a program, a constant, etc. which CPU59 uses. CPU59 reads the output of the memory value of above-mentioned zooming operation input section 603, focusing operation input section 601, and counter 54 *~543 and ROM 56, and switch contact piece 121.122, etc., and outputs a control signal to drive circuit 551~553. Drawing 6 shows the details of the drive circuit of Drawing 5. Since this circuit is almost the same as the 3rd example of Japanese Patent Application No. No. 337024 [ one to ] for which these people applied previously, explanation is omitted, but power amplifier 1 is connected to crookedness vibrator 123, and power amplifier 2 is connected to longitudinal oscillation child 124, respectively. Below, based on the flow chart of Drawing 7, operation of CPU59 at the time of focusing operation is explained. First, if focusing operation input section 60, is operated, interruption will start CPU59 and focusing mode will start (F201). If delivery operation is performed, the parameter of the delivery to drive circuit 55 will be written in (F202, F205), and the 1st group lens which performs focusing will move ahead. On the contrary, if it marches in and operation is performed, it will march in to 55□, a parameter will be written in, and the 1st group lens will move back. F206~F211 is a step which performs proximity detection mode, and if it read first whether switch contact piece 121 would touch (F 206) and the contact signal has come out, it will write crookedness oscillating zero and the parameter used as longitudinal oscillation full open in drive circuit 55□. In other words, this means that PWM (Pulse Density Modulation) writes the value which will be 100% in dividers 3 (Drawing 6), and PWM writes the value which will be 0% in dividers 4 (Drawing 6). Here, the driven load of LUM is explained. Although the frame is held with the bearing and the holder of the elastic thin board holding LUM, when vibration is given to LUM, although the lens group which drives by LUM has the few intervals of LUM and a frame by the vibration, it changes. Since the holder of an elastic thin board cannot answer the drive frequency (or resonance frequency) of LUM at this time, a crevice is generated when the interval of LUM and a frame becomes large. Therefore, when vibration is given to LUM, compared with the time of vibration not being given but standing it still, it becomes small in the frictional force of a lens group and LUM. In other words, it excels slight time, contact with a frame and LUM is lost, and it will be in the state where it has floated ((A) of Drawing 8, and state of (E)). Therefore, driven load becomes small from the state of (I) usually stopped also in the drive which results in (A)~ (H). In addition, if crookedness vibration is stopped, it will become the motion (C)-(C')-(G), but from this, there is no driving force of the LUM itself and only driven load becomes small. It returns to a flow chart and proximity detection is similarly performed about switch contact piece 122, if close, crookedness oscillating zero and the parameter used as longitudinal oscillation full open will be written in drive circuit 55., and the driven load of three group frames will be reduced. As mentioned above, when according to the 1st example of the present invention external force is added from the front into focusing in the state of a call and a lens is pushed in, for example, it is shown in Drawing 3, If the 1st group is pushed in by Bahama when, dl is the distance of the maximum proximity mostly, and since it is dl>d2, the 1st group and the 2nd group will collide by frame entirety. Since the 2nd group is under stop at this time, holding power is large, and the burden at the time of a collision, or since it is altogether applied to the longitudinal oscillation child of LUM of the 2nd group, it is a possibility that it may be damaged, or size. Since a proximity signal is emitted from switch contact piece 121 and LUM of the 2nd group carries out a longitudinal oscillation at this time, it can do [ driven load becoming small, and it being reduced in the shock at the time of a collision, and preventing damage to the 2nd group LUM, or ]. Thus, in the 1st example, also when carrying out the independent drive of the moving lens group and taking the lens drive controlling method with which external force and lens frame entirety may contact, it is effective in the ability to prevent damage to a lens or an actuator. Next, the 2nd example of the present invention is described. The 2nd lens and its frame composition of an example are shown in Drawing 9. Although the lens composition of this example is almost the same as that of the 1st example, the motor which drives each lens frame is not LUM but a stepping motor, and the places which drive a lens frame via a roller differ. As for 111'~113', in a figure, a motor unit, 111M1~113M, a Adsorption magnet, and 111M2~113M2 are rebounding magnets. The details near this motor unit are shown in Drawing 10. With axis 1124, in the direction of the circumference of an axis, main part 1121 of a motor is supported so that rotation is possible. 112. is a control board of axis 1124, and is being fixed to fixed frame 107. 1122 is a power transmission shaft which connects iron rollers 1123 to the main part of a motor, and rotation of a motor drives 2 solution frames 105 via power transmission shaft 1122 and roller 112. Here, frame 107.105 is a mold and 112M1 is adsorbing roller 112. with the permanent magnet. For this reason, frictional force occurs between a roller and frame 105, and frame 105 drives with rotation of a roller to it. On the other hand, proximity arrangement is carried out with 112M1 with the electromagnet, and 112M2 is connected with the power supply via the switch contact piece. If one group frame and two group frames approach, a switch contact piece will turn on and a magnetic field opposite to 112 M+ will occur. For this reason, adsorption of roller 112. can be weakened, and when it collides, since driven load decreases like the 1st example, it can stop the damage to a lens, the roller surface, a motor, etc. In the 1st and 2nd above-mentioned examples, a method as shown in Drawing 11 may be used, not using the proximity detection means using a switch contact piece. That is, the difference is outputted by the digital difference circuit which takes the difference of the value of a position counter, the value and difference circuit output which show beforehand the proximity written in the latch are measured with a digital comparator, and when equal, a proximity signal is outputted to CPU59. It is also possible to detect proximity, when CPU59 takes difference by software and compares the value of a counter with a constant.

The effect of [invention] As mentioned above, in the present invention, as explained in full detail, even when the collision of lens groups occurs, the lens drive which the shock added to each lens group is reduced, and can hold down the damage to an optical system or drive mechanism to the minimum can be provided.

[Brief Description of the Drawings]

Drawings 1 thru/or 8 are the useless things explaining the 1st example of the present invention, Drawing 1 is a figure showing a lens and its frame composition, and Drawing 2 is an enlarged drawing of a switch contact piece, Drawing 3 is a figure showing the movement magnitude of each lens group, and Drawing 4 is a figure showing a general view of a camera which used the lens drive of the present invention, Drawing 5 is a block diagram showing an electric circuit, and Drawing 6 is a figure showing the circuit composition of the drive circuit of Drawing 5, Drawing 7 is a flow chart which shows operation of CPU at the time of focusing operation, and Drawing 8 is a figure for explaining change of the driven load of LUM, and it is for Drawings 9 and 10 illustrating the 2nd example of the present invention, Drawing 9 is a figure showing a lens and its frame composition, Drawing 10 is a figure showing the composition near a stepping motor, and Drawing 11 is a block diagram showing other examples of a proximity detection means. 55 ~55 .... A drive circuit and 59-CP U. 601 ... focusing operation input section, 603 ... zooming operation input section, 101~103 ... the -- The 1~3rd lens group and 104~106 ... the -- the frame of the 1~3rd lens group, 107 ... A fixed frame, 111~113 ... LUM, 111'~113' ... Stepping motor unit, 111M1~113M and ... An adsorption magnet and 111M2~111M2 ... a rebounding magnet and 121.122 ... a switch contact piece and 123 ... a crookedness vibrator and 124 ... a longitudinal oscillation child. Applicant representative Patent attorney Tsuboi Drawing 1 of Jun The 2nd ill luck. the -- 71i (A) (E) (B)(F) (C) (G) (C') (H) (D) (1) Drawing 8 Written amendment Heisei Method of year 3 Ba-eight days