Method and apparatus for printing a colored image

Description: TECHNICAL FIELD [Detailed description of the invention]

[Industrial application field] The present invention relates to a color image duplication method and apparatus.

[Conventional technology] Conventionally, a method of scanning a color original image point by point along rows and columns to generate an electronic image signal has been known. The signals are divided into three signals corresponding to the red, green, and blue components for each original image. These signals are electronically processed and converted into an optical image by a cathodic tube with a screen coated with a luminescent material. The luminescent material generates light that is imaged through an objective lens on a negative color print material that has a relatively small sensitivity in the red spectral region. The recording material is exposed to the red, green, and blue components by sequentially inserting three color filters into the optical path from the luminescent substance to the recording material. Electronic image processing, that is, processing an electronic image signal obtained by scanning an original image, has been remarkably used in recent years when reproducing a color original image and converting a color positive to a color negative. In this case, the original image is electronically scanned along the rows and columns, that is, point by point, and the obtained image signal is corrected or corrected according to a predetermined reference. Subsequently, the modified image signal is sent to the color exposure unit, the image signal is converted into an optical image, and printed on a photographic recording material such as color negative paper. A device that implements this type of method is, for example, an "experimental cathode ray tube printer" Journal of Imaging. Technology), Vol. 12, No. 3, pp. 135-139. In such a device, the electronic image signal is converted into an optical image using a cathode ray tube having a screen coated with a substance capable of emitting light and printing an image. This material contains known materials such as P45 phosphorescent and europium-doped yttrium sulfide. About a quarter of the print light is generated by phosphorescence, 74% of which is produced by yttrium sulfide. The resulting emission spectrum is accompanied by distinct peaks with different amplitudes in the range 380-720 nm. During printing, different color filters are sequentially inserted into the printing optical path. The filter used in the conventional apparatus is a gelatin filter having a relatively flat side portion and exhibiting remarkable absorption of residual light even in the wavelength range corresponding to the color in which the filter has the maximum transmittance.

[Problems that the invention tries to solve] Due to the differences in the sensitivity of the photographic recording material, the radiation characteristics of the luminescent substance, and the absorption characteristics of the filter in the three primary colors, the print light required for each color when reproducing or duplicating the original image is significantly different. In principle, it is possible to increase the brightness or intensity of the image points on the screen of the cathode ray tube by increasing the current flowing through the cathode, but such an increase in intensity causes the cathode ray tube to overload. Furthermore, the size of the image point increases as the intensity increases, which deteriorates the sharpness of the image, so that the increase in intensity is limited. Since it is not possible to obtain light radiation having a uniform concentration over the entire wavelength range by using a single luminescent substance in practice, a plurality of luminescent substances must be mixed. In order to be able to do so, there is a problem that the cost of the cathode ray tube is remarkably increased and that the deterioration of each component is different when the luminescent substance is mixed. Therefore, the radiant intensity of each color will be different while using the cathode ray tube. Further, when the amount of print light is changed by controlling only the exposure time, the exposure time becomes relatively long, which reduces the amount of image duplication. Therefore, it is an object of the present invention to provide a color image duplication method capable of increasing the print output. Another object of the present invention is to provide a color image duplication method capable of reducing the difference in exposure time for different colors. Still another object of the present invention is to provide a color image duplicating apparatus capable of increasing the print output and obtaining a high quality print without making the exposure time for each color so different. Another object of the present invention is to provide a color image duplicating apparatus capable of reducing the difference in exposure time for different colors. Still another object of the present invention is to provide a color image duplication apparatus capable of printing a high image with a high print output and having a small difference in exposure time for each color.

[Means to solve the problem] In the present invention, in order to solve this problem, Rare earth luminescent substances that generate strong light in the red spectrum region and weak light in the blue and green spectrum regions are sequentially emitted point by point according to the red, green, and blue image signals to emit red, green, and blue. The print light corresponding to the image signal of is generated along a predetermined optical path. In the first portion of the optical path, the print light corresponding to the red image signal has a large transmittance in the red dichroic filter, and the print light corresponding to the green and blue image signals has a large transmission in the green and blue spectral regions, respectively. Pass through a green and blue dichroic filter In the second portion of the optical path downstream of the first portion, the print light corresponding to the red, green, and blue image signals is sequentially incident on a recording material having a small sensitivity in the spectral region of the light. In that case, a luminescent material having a radiation intensity in the blue and green spectral regions of about 1/30 of the radiation intensity in the red spectral region is used as the luminescent material, and the recording material has a blue sensitivity to red light. Using a negative color photographic recording material, which has about 1/30 of the sensitivity to light and about 1/6 of the sensitivity to blue light. A configuration was adopted in which the exposure times of the print lights corresponding to the red, green, and blue image signals for the recording material were substantially the same. Further, in the present invention, Rare earth luminescent substances that generate strong light in the red spectrum region and weak light in the blue and green spectrum regions are sequentially emitted point by point according to the red, green, and blue image signals to emit red, green, and blue. A means for generating print light corresponding to the image signal of the above along a predetermined optical path, and A red dichroic filter arranged in the first part of the optical path through which the print light corresponding to the red image signal is passed, A green and blue dichroic filter arranged in the first part of the optical path having a large transmittance in the green and blue spectral regions through which the print light corresponding to the green and blue image signals is passed, respectively. With a recording material located in the second portion of the optical path downstream of the first portion and having a small sensitivity in the red spectral region. As the luminescent material, a luminescent material having a radiation intensity in the blue and green spectral regions of about 1/30 of the radiation intensity in the red spectral region is used, and as a recording material, the sensitivity to red light is sensitive to blue light. Negative color photographic recording material is used, which has a sensitivity of about 1 in 30 and a sensitivity to green light about 1/6 that of blue light. The recording material is sequentially exposed by the print light corresponding to the red, green, and blue image signals that have passed through each of the dichroic filters, and the exposure time of the print light corresponding to the red, green, and blue image signals on the recording material is exposed. The configuration is also adopted so that they are almost the same.

[Activity] The image to be printed in the present invention is formed from an electronic image signal obtained by scanning the original image photoelectrically. This image signal is divided into three signals corresponding to the red, green, and blue components of the image, respectively. An image is formed by converting this electronic image signal into optical information. This is done, for example, using a cathode ray tube. This image is also formed along rows and columns, or point-to-point (point-wise). The print light is preferably produced by emitting a normal rare earth luminescent material that emits strong light in the red spectral region and weak light in the blue and green spectral regions. The luminescent material has one or more emission peaks in the red region, and the emission intensity in the blue and green regions does not exceed 1/30 of the intensity in the red region. The emission peaks of the luminescent material used in the present invention in the blue and green regions are not described in ordinary data sheets. The luminescent material is applied onto the screen of the cathode ray tube, and is emitted by exciting the luminescent material with a cathode ray beam. The filtering process is performed using a dichroic filter, and the print light is sequentially applied to the filters of the three primary colors of red, green, and blue. This is done by sequentially inserting each of the three dichroic color filters into the print path. Two of these filters are selected for high transmittance in the green and blue spectral regions. Since the light emitting substance emits strong light in the red spectrum region, the exposure time for the red image component can be remarkably reduced in the present invention as compared with the conventional apparatus. At the same time, since a dichroic color filter having a large transmittance is used in the green and blue spectral regions, the transmittance for the green and blue colors can be maximized. In addition, the sensitivity of the recording material to green and blue light is 20 to 50 times higher than that to red light, so the exposure time to the red component does not change the intensity or brightness of the image on the screen of the cathode line tube. It is possible to obtain exposure times for almost equal green and blue components. This can be obtained even if the green and blue radiant intensities of the luminescent material used according to the present invention are small, which cannot be recognized by a normal radiation curve. As long as the modulation of the cathode ray tube is constant, the sizes of the image points in the three primary colors can be made almost equal. This makes it possible to prevent the formation of colored rings formed around the center of the image point, which is an obstacle, especially in the gray area of the average density. Further, the color image printing apparatus according to the present invention has means for generating print light having high intensity in the red spectrum region and low intensity in the blue and green spectrum regions. This print light generating means is composed of, for example, a cathode ray tube having a screen coated with a luminescent substance that emits strong light in the red spectral region and weak light in the blue and green spectral regions. Further, the printing apparatus of the present invention includes an objective lens for directing the printing light to a predetermined optical path and means for filtering the printing light. This filter means is composed of, for example, a plurality of color filters that are sequentially inserted into the optical path. Further, the apparatus of the present invention is provided with a means for storing a photographic recording material such as a negative color recording material downstream of the filter means. Further, the apparatus of the present invention is provided with a signal source for generating three types of electronic image signals corresponding to the red, green, and blue components of the image, respectively. The print light generating means has a function of converting this image signal into optical information or data. The print light generating means can convert the electronic image signal into optical information along rows and columns, or point by point. The radiant intensity of the luminescent material in the blue and green spectral regions is preferably one-thirtieth or less of the radiant intensity in the blue spectral region. Emission peaks of luminescent material in such blue and green regions are not described in normal data. As the preferred luminescent substance, luminescent substances named P22R and P56 are used. The recording material used in the apparatus of the present invention has a relatively low sensitivity in the red spectral region, while the filter means has a large transmittance in the green and blue spectral regions. The filter means is a dichroic filter, which has a large transmittance in the green and blue regions, respectively.

[Example] Hereinafter, the present invention will be described in detail according to the examples shown in the drawings. The device that reproduces the primary colors by printing or copying illustrated in FIG. 1 has a signal source that generates a digital electronic image signal indicating the original image of the color to be duplicated. This signal source preferably comprises a digital memory 1 capable of storing an image signal. The image signals stored in the memory 1 are three types of signals, each of which corresponds to one component of the three primary colors of the image, that is, three types of signals corresponding to the red, green, and blue components of the image, respectively. In this embodiment, the image signal is obtained by scanning the original image electronically or optoelectronically into rows and columns. Further, the scanning device (scanner) used for scanning is configured so that the original image can be scanned for each series of individual points in each row and column, that is, each point of the original image can be scanned. Further, since each point of the original image is scanned for each of the three primary colors of red, green, and blue, three image signals corresponding to the components of red, green, and blue are formed for each point of the original image. Based on such a premise, each signal stored in the memory 1 becomes a predetermined point of the original image and a value related to the image. Such points will be referred to as image points below. The memory 1 is connected to the signal processing device 2, and the digital signal stored in the memory 1 is called from the memory 1 and sent to the signal processing device 2 at a rate suitable for the print speed. It is also possible to send the signal directly from the reading device to the signal processing device 2 via the electronic image processing unit. The signal processing device 2 converts each signal into a form suitable for exposure of the recording material. That is, the signal processing device 2 processes the signal so that the image points on the recording material to be reproduced accurately reproduce the appropriate color and density after development. The signal processing device 2 is connected to a printer or a central clock 3 that adjusts the timing of copy processing. The signal processing device 2 is further connected to a control unit 4 that controls the print filter unit 5. The filter unit 5 is composed of a filter disk 6 composed of three color filter portions 6a, 6b, and 6c each having an arc of 120 degrees. The filter part 6a constitutes a green filter, the filter part 6b constitutes a red filter, and the filter part 6c constitutes a blue filter. The filter disk 6 is coupled to a rotating shaft 6d driven by a motor 7. The motor 7 is controlled by the control unit 4, and when the recording material is exposed to light of a specific color, the filter of that color is controlled to be located in the optical path of the printed light beam (hereinafter referred to as the optical path). That is, for example, the green filter is controlled so as to be arranged in the optical path when the recording material is exposed to the green light representing the green component of the image. The signal processing device 2 is connected to the input of the image generator that generates the print configuration. This image generator is realized by a normal type cathode ray tube 8. The cathode ray tube 8 has a screen 8a coated with a luminescent material (fluorescent or phosphorescent), as described in detail below. The light beam of the cathode ray tube 8 excites the luminescent material, which emits light to generate a printed light beam. The light generated by the luminescent material is used to expose the recording material to all three primary colors. The cathode ray tube 8 has a function of generating a printed ray and a function of converting an electronic image signal stored in the memory 1 into an optical image appearing on the screen 8a. The cathode ray tube 8 converts the image signal into an optical image row and column or point by row, similar to that obtained by scanning the original image at individual points along the rows and columns. The screen 8a of the cathode ray tube 8 and the optical image on the screen 8a are imaged by the objective lens 9 on the photographic recording material, that is, the copying material 12. The objective lens 9 serves as a means for directing the print light formed on the screen 8a by the luminescent substance to a predetermined optical path. The recording material 12 is, for example, a negative color recording material, and is stored in the holder 12a. Adjacent to the objective lens 9, a diaphragm or shutter 10 that functions as a means for adjusting the intensity of printed light rays in the optical path is provided. The shutter 10 may have various shapes, but for simplicity, a two-blade shutter having two blades 10a and 10b is used. The blades 10a and 10b are connected to the motor 11 via a shaft 10c, and the motor 11 has a function of moving the blades 10a and 10b to a position determined by the control unit 4. FIG. 2 shows the emission spectrum of the luminescent substance applied to the screen 8a of the cathode ray tube of FIG. The horizontal axis of Fig. 2 represents the emission wavelength of the luminescent substance, that is, the wavelength of the light emitted by the luminescent substance, which is indicated by a nanometer (nm) from 370 to 720 nm, while the vertical axis represents the luminescent substance as a percentage. The radiant intensity with respect to the strongest radiant intensity, that is, the relative intensity is shown in%. The luminescent material used in the cathode ray tube 8 is a rare earth luminescent material that emits strong light in the red spectrum region and weak light in the blue and green regions. Such luminescent substances are commercially available, for example, under the names P22R and P56. The radiant intensities in the blue and green spectral regions are at most one-thirtieth of the intensities in the red region, and the radiant peaks in the blue and green regions are not listed in regular data sheets. The maximum intensity of the luminescent material in Fig. 2 occurs at 620 nm, as shown by the radiation peak 13. The second emission peak 14 is located at 615 nm adjacent to the peak 13 and has a relative intensity of 70%. This emission peak 14 corresponds to the second magnitude of light of the luminescent material. The next highest radiant intensity is at 695 nm, as shown in 15. Near this peak 15, a slightly weaker emission peak 20 with a relative intensity of 20% appears. Furthermore, at 595 nm, a weaker peak 16 with a relative intensity of about 18% occurs. These peaks 13, 14, 15, 16 and 20 are located in the red spectral region. A very weak but peak 21 is observed in the green spectral region of about 538 nm. No emission peaks can be observed in the blue region below 480 nm. The luminescent substances shown in FIGS. 1 and 2 are the luminescent substances of P22R and P56, and do not contain other luminescent substances. FIG. 3 shows the characteristics of the diameter d of the image points appearing on the screen 8a of the cathode ray tube 8 having the brightness or intensity L of the image points as a function. As shown, the relationship between d and L is represented by a nearly parabolic function d = l (L), and the diameter d increases as the brightness L increases. Brightness or intensity is L₀In the range where the modulation up to is low, the diameter d of the image point increases relatively slowly as the brightness L increases, and the brightness L increases.₀In d₀Reach the value of. L₀From maximum strength L_maxUp to, the diameter d of the image point becomes significantly larger as the brightness L increases, and d_maxReach the value of. L₀And L_maxDuring that time, the rate of change of d with respect to L is more than linear. Since the size of the image point has an important effect on the sharpness of the image, increasing the brightness of the image point above a certain value causes a quantitative deterioration in the sharpness of the image. On the other hand, if the brightness of the image points is reduced, the printing time becomes longer, which reduces the capacity of the printing apparatus. FIG. 4 shows three sensitivity curves 17, 18 and 19 for the recording material 12. The horizontal axis of FIG. 4 represents the wavelength of the printed light in nanometers, while the vertical axis represents the relative spectral sensitivity based on the uniform energy spectrum. The vertical axis is the logarithm of the reciprocal of the amount of light required to obtain a constant density. Each of the sensitivity curves 17, 18 and 19 shows the value of the sensitivity to the predetermined wavelength light incident on the recording material 12. Curve 17 shows the sensitivity of recording material 12 to light rays in the red spectral region, curve 18 shows the sensitivity of recording material 12 to light rays in the green spectral region, and curve 19 shows the sensitivity of recording material 12 to light rays in the blue spectral region. Shows the sensitivity of. From this figure, it can be seen that the recording material 12 is sensitive to the light in the portion corresponding to the spectral region of the light rays passing through the filters 6a, 6b, and 6c. Since the vertical axis of FIG. 4 is a logarithmic memory, the sensitivity of the recording material 12 shown in curve 17 to red light is about 1/30 of the sensitivity to blue light shown in curve 19. You can see that there is. The sensitivity of the recording material 12 shown by the curve 18 to the green light is about one sixth of the sensitivity to the blue light. In this way, the sensitivity of the recording material 12 to light in the red spectrum region becomes considerably low. The recording material 12 is preferably CN4, type 7 or 8 sold by Agfa-Gevaert of Germany. FIG. 5 shows the transmission characteristic curves of the filters 6a, 6b, and 6c in Fig. 1. The horizontal axis of FIG. 5 shows the wavelength of the print light with a nanometer, while the vertical axis shows the transmittance of the filter. The transmission curve rises sharply, and the transmission curves of the red and green filters 6b and 6a are adjacent to each other as well as the transmission curves of the green and blue filters 6a and 6c. In addition, the transmission curves of the red and green filters 6b and 6a or the transmission curves of the green and blue filters 6a and 6b have slight overlaps, respectively. It can be seen that the green filter 6a has a large transmittance in the green spectrum region, and the blue filter 6c has a large transmittance in the blue spectrum region. The filters 6a, 6b, and 6c are dichroic filters, respectively, and each filter transmits light in a spectral portion corresponding to one of the spectral regions to which the recording material 12 is exposed. Dichroic filters are made by depositing multiple thin λ-1 / 4 (quarter) layers on a glass substrate. Depending on the thickness of the obtained filter layer, light having a predetermined wavelength may be reflected or transmitted by an interference effect. As a result, a portion having a rising edge perpendicular to the transmission curve is obtained. In order to reproduce the predetermined color component of the image point on the recording material 12, the intensity of the image point on the screen 8a as seen through the transmittance of each color filter 6a, 6b, 6c is reduced by the density of the filter, and then The sensitivity of the recording material 12 to a predetermined wavelength must be applied. According to the present invention, rare earth luminescent materials that emit only weak light in the green and blue spectral regions are combined with a filter having the highest transmittance in the green and blue regions. Since this combination and the sensitivity of the recording material 12 differ greatly in the red, green, and blue spectral regions, the exposure time for the three primary color components and the intensity on the screen 8a of the three primary color cathode ray tubes 8 are in the neutral color image region. It will be almost equal. When the recording material 12 is exposed to a predetermined color component of a predetermined exposure time image point, the exposure time is divided into a plurality of discrete time intervals or print cycles instead of continuous exposure, and then the exposure time is divided into a plurality of discrete time intervals or print cycles. When the recording material 12 is repeatedly exposed to the color components over a predetermined time interval or cycle, the control of the cathode ray tube 8 becomes simple. As an example, the recording material 12 can be exposed according to a television technique in which the exposure time for each color component is divided into discrete time intervals of 0.04 seconds. It can be seen that the maximum print speed is obtained when the entire color image is printed using a single time interval or print cycle for each color component. However, this cannot be done given the current sensitivity of recording materials and the strength of cathode ray tubes at television frequencies. The number of print cycles for each of the three primary colors in the image is between 5 and 10. Basically, the amount of print light of each of the three primary colors can be adjusted based on the size of the predetermined maximum image point determined by the intensity and the cathode voltage through the curve of FIG. Set the number of print cycles for the color component with the longest exposure time and change the screen intensity, i.e. the intensity of the cathode ray tube 8 on screen 8a, to obtain the next number of time-consuming print cycles (integer). .. Also, the screen intensity is adjusted so that the print cycle for the shorter exposure time of each of the remaining two color components is an integer. In this case, care must be taken not to exceed the screen strength corresponding to the diameter of the maximum permissible image point in any case. If the cathode ray tube 8 is controlled as described above, the size of the image points of different color components changes. This tendency is more likely to occur as the number of print cycles is reduced. Such an effect appears as the formation of colored circular rings in the image points, especially in the gray areas of the image. Depending on the size of the image points, such a ring becomes an obstacle. Such colored circular rings can be removed by finely adjusting the amount of print light by using an appropriate means of reducing the amount of print light instead of reducing the intensity of the image points on the screen 8a. .. The shutter 10 illustrated in FIG. 1 functions as a control means for reducing the intensity of the print light in the optical path. Instead of this shutter 10, it has a different gray gradation and can be replaced with a transparent disc or other member that is automatically driven by the control unit 4 by an appropriate motor. When adjusting the amount of print light, the control unit 4 calculates how much the intensity for a given color component can be reduced to reduce the amount of light for this color and maximize the number of next print cycles. For example, if the amount of red component of the print light seems to be equal to the integer print cycle + 1/2 print cycle in terms of exposure time, the control unit 4 reduces the intensity of the red component and the amount of red light is 1/2 print. Control to decrease by an amount equal to the cycle. When reducing the intensity of the color component, the control unit 4 calculates the optimum intensity or the size of the optimum image point with respect to the cathode ray tube 8. In this case, the calculation is performed in consideration of the sharpness of the image, the printing speed, the characteristics of the cathode ray tube 8, and the like. The intensity of the color component is then reduced to the optimum intensity as needed, followed by the print cycle of the next largest integer. An unexposed recording material 12 is placed in the holder 12a and one of the filters 6a, 6b, 6c is inserted into the optical path to print the color image stored in the memory 1. Now suppose that the blue filter 6c is placed in the optical path. The image signal corresponding to the blue image component is supplied from the memory 1 to the signal processing device 2. At the same time, the print cycle is calculated according to the size of the maximum image point that can be tolerated for the blue image component based on the contrast and maximum value in memory 1. The reduction in blue intensity required to reach this number is translated into a command to the motor 11, which moves the shutter 10 into place. When the shutter 10 is adjusted in this way, a signal indicating a blue image component appears on the screen 8a of the cathode ray tube 8, is converted into a series of blue images, and is printed in the recording material 12. The conversion of the signal to a blue image and the printing of that image are regulated by clock 3. When the exposure to the blue image component is complete, the filter disk 6 is rotated 120 degrees and the next filter, eg, the red filter 6b, is inserted into the optical path. After that, the shutter 10 is adjusted, and the red component of the image is printed on the recording paper 12 through the screen 8a of the cathode ray tube 8 using a predetermined number of print cycles. When the printing of the red component is completed, the filter disk 6 is rotated by the motor 7 again, the green filter 6a is inserted into the optical path, and the green image component is printed using a predetermined number of print cycles. The number of print cycles for each color component is an integer, which is somewhat larger than the minimum number of print cycles for that color component. The minimum possible number of print cycles is generally not an integer and corresponds to the number of print cycles at maximum screen intensity and image point size. In this way, the optimum balance between print output and image quality is obtained. In other words, even if the print speed is increased, even if the size of the image points exceeds the size of the predetermined maximum image points, the size of the image points for each of the three primary colors is different, resulting in a gray area. Even if a colored ring is generated, the sharpness of the image is not significantly deteriorated. The present invention is not limited to the examples described above, and various modifications and improvements can be made without departing from the essence of the present invention, and all such examples are included.

[Effect of the invention] As described above, in the present invention, a luminescent material having a radiant intensity in the blue and green spectral regions of about 1/30 of the radiant intensity in the red spectral region is used as the luminescent material, and a red luminescent material is used as the recording material. Red that exposes the recording material through a dichroic filter using a recording material that is about one-thirtieth the sensitivity to blue light and about one-sixth the sensitivity to blue light to green light. Since the exposure time of the print light corresponding to the green and blue image signals is almost the same, each color can be exposed with almost the same exposure time, which simplifies the control of the exposure amount and the total working time. Has the advantage of being shortened. Further, in the present invention, since the radiant intensity of each color of the luminescent material and the sensitivity of each color of the recording material are matched, the image intensity or brightness on the screen is changed in order to obtain the same exposure time for each color. It is not necessary, and therefore the size of the image points of each color can be made almost equal, and it is possible to prevent the formation of a colored ring around the center of the image points in the gray region of the average density. An excellent effect can be obtained. Further, the recording material used in the present invention has the sensitivity characteristics of ordinary commercially available negative color photographic recording materials, and has an advantage that it can be obtained at low cost.

[Simple explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a main part of the apparatus of the present invention, FIG. 2 is a diagram showing an emission spectrum of a firefly phosphorescent body used in the apparatus of FIG. 1, and FIG. 3 is an apparatus of FIG. A characteristic diagram showing the relationship between the intensity of image points on the cathode ray tube and the size of the image points, Fig. 4 is a characteristic diagram showing the photosensitive characteristics of the recording material used in Fig. 1, and Fig. 5 is Fig. 1. It is a characteristic diagram which shows the transmittance of the color filter used for a figure | apparatus. 1 ...... Memory, 2 ...... Signal processing device 3 ...... clock, 4 ...... control unit 5 ...... Filter unit 6 ...... Filter disk 7 ...... Motor, 8 ...... Cathode ray tube 9 ...... Objective lens, 10 ...... Shutter 12 ...... Recording material