JPS61193558A - Picture reading method - Google Patents

Abstract

PURPOSE:To speed up the reading of a picture by adjusting independently the charge storing time of a plural storing type image sensors according to an incident light and also changing a storing start. CONSTITUTION:When a storing start signal is outputted from a controller 52, an AND gate 73 is closed at the trailing edge of the first vertical synchronizing signal and after the lapse of a storing extension time set in advance, the AND gate 73 is opened and a master clock is transferred to a driver 33. Because a vertical synchronizing signal is inverted to 'H' after the normal storing time, a frame transfer is commenced and a storing is terminated. After the transfer of the frame and another rise of the vertical synchronizing signal, a blue color signal is started to take out and the taking out of this blue color signal is executed with slow speed by a long cycle master clock that is divided by a diver 79. So that the signal is taken out in rotation as the charge storing is terminated, it is possible to process a signal with high speed and is also possible to manage with only one signal processing circuit along with a drastic cost reduction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image reading method for reading an image with shading using a plurality of storage type image sensors.

[Conventional technology]

Color printers use an image reading device to scan the original color image (color negative film, etc.) before color printing.
The density at each point is measured, and color correction is performed according to the obtained three-color (blue, red, green) density. A conventional image reading device includes three types of storage image sensors that photoelectrically convert and store three color lights, three sets of signal processing circuits that process signals output from each storage image sensor, and Records i and a that store the output of each signal processing circuit
It is known that the structure consists of the following parts. In this device, a signal processing circuit is provided for each color, and an expensive signal processing circuit capable of high-speed processing is used so that signals can be captured in parallel, resulting in a complex structure and cost. There was a problem that it took a while.

[Problem that the invention seeks to solve]

SUMMARY OF THE INVENTION An object of the present invention is to provide an image reading method in which signals from each storage image sensor are sequentially extracted and signal processing can be performed by one set of signal processing circuits.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image reading method that makes it possible to obtain signals with less noise by extracting each signal in a manner that reduces the waiting time for signal extraction from each storage image sensor. It is something to do.

The present invention independently adjusts the charge accumulation time of each storage image sensor according to the incident light, widening the dynamic range, and driving each storage image sensor in parallel to achieve high-speed reading. The object of the present invention is to provide an image reading method that can be carried out in the following manner.

[Means for solving problems]

In order to achieve the above object, the present invention independently adjusts the charge Mla time of a plurality of accumulation type image sensors according to incident light, and also changes the start of accumulation of each accumulation type image sensor. Accumulation is performed in parallel, and signals are extracted in series so that the waiting time decreases in the order of charge accumulation.

The storage type image sensor is a CCD.

There are MOS type, CPD, etc., and the present invention can utilize either of them. In the case of a CCD, charge accumulation is completed by transferring signal charges from a photosensitive section that photoelectrically converts incident light and accumulates them to a transfer section, and the time from the start of accumulation to charge transfer is the charge accumulation time. This signal charge transfer may be performed using an interline method or a frame transfer method. In the case of the MOS type, since the signal is taken out by MOS transistors arranged in a matrix, the time when charge accumulation is completed and the time when the signal is taken out coincide.

If the charge accumulation in each accumulation type image sensor is performed in parallel and the signal output is carried out in series, then while the signal is being extracted from one accumulation type image sensor, the charge in another accumulation type image sensor is Once the accumulation is complete, it becomes necessary to postpone the retrieval of this signal. When a CCD is used as a storage type image sensor, noise is generated in the transfer section due to the influence of dark current while signal extraction is postponed, and this noise increases in proportion to time. Therefore, if the color signal extraction is started immediately after the signal charge is transferred from the photosensitive section to the transfer section without waiting for signal extraction, noise can be reduced. In addition, with the MOS type, it is necessary to use a shutter etc. to block the incident light when the charge accumulation is completed, so the structure of the photometry section can be simplified by doing it without delaying the signal extraction. There are advantages.

When reading a color image, the types of storage image sensors are: a blue MHI image sensor that photoelectrically converts blue light, a green storage image sensor that photoelectrically converts green light, and a red storage image sensor that photoelectrically converts green light. A storage type image sensor for red color is used that photoelectrically converts the red color. In addition, there is a device that divides a color original into multiple areas, for example, the center and the periphery, and measures the white density of each area to determine whether the image was taken in front light or in backlight. , two partially light-shielded accumulation type image sensors are used to photometer each area.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

〔Example〕

FIG. 6 shows a color printer incorporating an image reading device embodying the present invention. The white light emitted from the light source 10 is passed through a yellow filter 11, a magenta filter 12 . The light passes through the cyan filter 13 one after another and reaches the diffuser plate 14 . The color original image 15 is illuminated by the light diffused by the diffuser plate 14, and the light transmitted therethrough passes through the lens 16 and then reaches the photographic paper 18 while the shutter 17 is open. The lens 16 changes its position depending on the enlargement magnification, and forms a color image recorded on the color original image 15 on the photographic paper 18.

A color original image 1 is placed at a position away from the optical path of the lens 16.
A blue photometry section 20 that measures the blue component of each pixel of No. 5, a green photometry section 21 that measures the green component, and a red photometry section 22 that measures the red component are provided. These photometric units 20 to 22 operate according to predetermined charge accumulation times so that signal extraction is performed without waiting time.
Accumulation start is shifted. During this charge accumulation time, the incident color light is photoelectrically converted and the obtained signal charges are accumulated. Then, the signals are serially read out in the order in which the charge accumulation (hereinafter simply referred to as accumulation) is completed and sent to the photographic image density information recording section 23.

The microcomputer 24 reads the three color densities of each pixel recorded in the photographic image density information recording section 23, integrates them, and calculates the average transmission density (LATD) for each of the three colors. Based on this average transmission density and the color tone (balance of blue density, green density, red density) of each pixel, etc., the color original image is classified into a standard scene, a scene with a color defect, and a scene with a density defect. Based on this classification result, for a scene with a color defect, the filter switching section 25 is controlled according to the color defect of the scene, and a desired yellow filter 11. Magenta filter 12. Select cyan filter 13. Then, for a scene with a density defect, the shutter control section 26 is controlled to adjust the opening time of the shutter 17. Note that for standard scenes, the well-known LAT
It is controlled by the D method.

FIG. 1 shows the configuration of an image reading device implementing the present invention. The blue photometry section 20 includes a lens 30;
A blue filter 31, an accumulation type image sensor 32,
A driver 3 that drives this storage type image sensor 32
3, the light passing through the blue filter 31 is incident on the accumulation type image sensor 32, where it is photoelectrically converted, and the obtained signal charges are collected. Note that this blue filter 31 is formed on the MH type image sensor 3 by vapor deposition or the like.
2 may be formed directly.

A CCD is used as the storage type image sensor 32, and a driver 33 performs storage and signal readout at a predetermined cycle, but normally an analog switch 34 is used.
is off, the read blue signal is not sent to the selector 35. While the storage type image sensor 32 is driven periodically, an effective M product is performed, and the obtained effective time-series color signal is taken out via the analog switch 34.

Generally, when measuring the density of photographic images, 1oooo
A dynamic range of about a step is required, but C
Storage type image sensors such as CDs have a narrow dynamic range and cannot perform highly accurate measurements.

By the way, if we look only at one color original image, a density level of about 100 steps is sufficient, so by changing the storage time of the storage type image sensor depending on the color original image, the dynamic range can be substantially increased. It can be spread out to perform highly accurate measurements.

In order to determine the storage time of the storage type image sensor 32, a prescan is performed before the main scan. The accumulation time in the main scan is determined according to the maximum value of the signal obtained in the pre-scan.

Therefore, effective storage and signal retrieval will occur twice. If the signal extraction from the storage image sensor 32 is slow, it is possible to use a slow and inexpensive signal processing circuit, which is advantageous in terms of cost. Therefore, in this embodiment, valid signals are retrieved more slowly than signal readout that is performed periodically.

Similarly, the green photometry section 2 is composed of a lens 37, a green filter 38, an accumulation type image sensor 39, and a driver 40. A signal is extracted. Further, the red photometry section 23 includes a lens 42,
A red filter 43, an accumulation type image sensor 44,
The signal is taken out via an analog switch 46.

A blue control circuit 48 is provided in order to cause the storage type image sensor 32 to perform prescanning and main scanning. This blue color control circuit 48 is connected to the driver 3
3 to cause accumulation to take place for a predetermined time, and then slowly take out the signal. Similarly, driver 40
The green control circuit 49 that controls the green color and the driver 45
A red color control circuit 50 is provided to control the red color. In this embodiment, each control circuit 48-50 is operated by an accumulation start signal and is operated by an accumulation start signal,
By blocking the passage of the basic clock signal of MH2, the accumulation time is changed independently for each color, and by dividing the basic clock signal, the readout speed is changed.

In other words, if the basic clock signal (master clock signal) is not input to the driver 33.40.45, photoelectric conversion will continue as it is, so the driver 33.40.4
The desired accumulation time can be set by determining the time difference (accumulation extension time) from the accumulation time when the controller 5 is operating normally, and stopping the basic clock signal for this time. Furthermore, since the signal is read out in synchronization with the master clock signal, if a master clock signal with a long period is input to the driver 33.40.degree. 45, the signal will be read out slowly.

The controller 52 sends an M-start signal to each of the control circuits 48 to 50 at a predetermined timing in the pre-scan and main scan so that each color signal is taken out without waiting time. The controller 52 instructs each of the control circuits 48 to 50 to extend the storage extension time before starting the N-time cycle, and also instructs the address counter 54 about the type of color signal being extracted, and switches the selector 35 to select the color signal to be extracted. The signal is sent to amplifier 55. This amplifier 55
In order to adjust the offset of the storage type image sensors 32, 39.degree. 44, an offset correction circuit 56 is provided which digitally converts the data written by the CPU 63 and outputs a voltage.

The time-series color signal amplified by the amplifier 55 is converted into an A/D
It is sent to converter 57. This A/D converter 57
samples the color signal using the sampling pulses output from the control circuits 48 to 50, converts it into an 8-bit digital signal, and sends it to the logarithmic conversion table 58. This logarithmic conversion table 58 has, for example, 15 tables, and by selecting the table corresponding to the base density of the color original image 15, that is, the storage time of the storage type image sensor, and referring to this table, the logarithm conversion is performed. Calculate the concentration value. Approximately 250 densities are written in each table, and if duplicates in each page are excluded, there are approximately 10,000 density steps in total.

The concentration signal output from the logarithmic conversion table 58 is
The image is sent to a look-up table 59 having three tables, and the table corresponding to the color specified by the controller 52 is referred to, and the sensitivity curves of the three colors of the photographic paper 18 are standardized so that they match.

This look amplifier table 59 is composed of a RAM, and the data of the ROM 60 is written in advance. The density data standardized by the look-up table 59 is sent to the RAM 62 via the pass line 61 and written directly to the memory address specified by the address counter 54. The address counter 54 is reset by the controller 52 at the start of taking out each color signal, counts sampling pulses, and specifies the address of the RAM 62 based on the count and the color signal.

The CPU 63 controls each section according to a program written in the ROM 60, and writes necessary data to each section. That is, it instructs the controller 52 to extend the accumulation time for each color, and also instructs the timing to start M product. Also, logarithmic conversion table 5
A page corresponding to the accumulation time is designated for the day, and data is written to the lookup table 59 and offset correction circuit 56. In addition, the I10 boat 64 has the following:
The filter switching section 25 and shutter control section 26 shown in FIG. 6 are connected.

FIG. 2 shows the timing of pre-scan and main scan. When the color original image 15 is positioned at the measurement position, a detection signal from a sensor (not shown) is sent to the CPU 6.
3, and the storage type image sensors 32, 39.44, which are operated at a predetermined cycle, sequentially start a pre-scan and a main scan. When starting this pre-scan, the CPU 53 first instructs the controller 52 about the accumulation extension time and the timing to start accumulation.

The controller 52 sends a red accumulation start signal to the red control circuit 50 at time t1 to prevent the master clock signal from being input to the driver 45. In this case, the driver 45 is in a stopped state, and charge accumulation progresses during that time. Then, when a predetermined accumulation extension time has elapsed, the basic clock signal starts to be stopped, and the master clock signal obtained from this is sent to the driver 45. As a result, the driver 45 starts normal operation, so that storage continues for the normal storage time.

Note that during this accumulation, the readout of the signal charge that was previously photoelectrically converted and stored in the transfer section is performed at the same time, but since the analog switch 46 is in the OFF state, the readout red color The signal will be dropped.

When the accumulation end time t2 is reached, the accumulated signal charges are transferred to the transfer section, and the accumulation ends. Therefore, the storage time is (t2-tl), which is the normal storage time plus the extra time.

Note that this transfer time is omitted in the drawings.

When the controller 52 receives the end signal from the red control circuit 50, it sends a color designation signal indicating the type of color to start taking out to the selector 35, and connects the storage type image sensor 44 to the amplifier 55. do. Further, this color designation signal is sent to a lookup table 59 to select a table for red. Furthermore, this color designation signal is sent to the address counter 54 and used as the upper two bits of the address. The controller 52 also sends a reset signal to the address counter 54 to reset it.

The red control circuit 50 turns on the analog switch 46 and sends the frequency-divided basic clock signal to the driver 45 as a master clock signal. This driver 45 is driven by a master clock signal with a long period, sends the signal charge stored in the transfer section to the output section, converts it into a voltage, and outputs it as a red signal. The time-series red signal output from this output section is output from the analog switch 4.
6 to an amplifier 55, where it is amplified and then sent to an A/D converter 57. The A/D converter 57 samples and holds the red signal using a sampling pulse synchronized with the reading of the red signal, and converts the sampled and held red signal into a digital signal. On the 5th day of the logarithmic conversion table, the digital signal is logarithmically converted with reference to the page selected according to the accumulation time to determine the red density. This red color density is normalized using the lookup table 59 and then written to the address of the RAM 62 designated by the address counter 54.

This red signal is taken out between time t2 and t4.

This signal extraction time is determined by the period of the master crotter signal and the number of pixels, and is the same for each storage type image sensor 32, 39, and 44. When time t3 is reached during the extraction of the red signal, the controller 52 sends the green accumulation start signal to the green control circuit 4.
9 to start green charge accumulation i. The timing of the start of this accumulation is the time required for red charge accumulation and signal extraction (t4 - tl) minus the time required for green charge accumulation (t4 - t3), at the start of red charge accumulation. This is when it is delayed from t1.

When time t4 is reached, the extraction of the red signal and the accumulation of green charges are completed. When the extraction of this red signal is completed,
Since the controller 52 receives the extraction end signal from the red control circuit 50, it switches the switch of the selector 35 and changes the logarithmic conversion table 58 and look amplifier table 59.
page selection. At the same time, the address counter 54 is set and the analog switch 41 is turned on. Then, in the same procedure as the red signal described above, the green signal is extracted, processed, and then stored in the RAM 62.
write to.

The green signal is taken out until time t6, and during this time, blue charge accumulation starts from time t5, and at time L6, when the green signal extraction ends, the blue charge accumulation ends, and this blue signal Removal is from time t6 to t
It is carried out until l.

A pre-scan is performed between time t1 and time t7, and when the pre-scan ends, the controller 52 outputs a reset signal to reset each part. The CPU 63 determines the brightest part (minimum density) of the color original image,
The accumulation extension time in the main scan is determined for each color so that when photometering this part, the output is close to the saturation value of the accumulation type image sensor. The obtained storage extension time for each color is sent to the controller 52, and the page of the logarithmic conversion table 58 is designated according to this storage extension time.

The controller 52 instructs each of the control circuits 48 to 50 to extend the accumulation time, and then starts the main scan. This main scan starts at time t8, and first, charge accumulation for red color, which has the shortest accumulation time, is started. This red charge accumulation is carried out until time t11, and then at time tll
The red signal is read out between time t12 and time t12.

The green charge accumulation with the second shortest accumulation time starts at time t9, and the blue charge accumulation with the longest accumulation time starts at time e.
It starts from lo. Then, the extraction of the green signal is started from the time tit when the extraction of the red signal ends. From the time t13 when the green signal extraction ends, the blue signal extraction starts, and the blue signal extraction ends at the time t13.
It will be held until 14.

After the main scan is completed, the controller 52
Since the reset signal is output to reset each part, the basic clock signal is not divided by the frequency divider 79 and is directly used as a master clock signal for each driver 33, 40.
．． 45, each storage type image sensor 32, 3
9 and 44 perform storage and readout in a normal cycle. However, in this case, each analog switch 34, 41.46
is OFF, the read color signal is essentially washed away.

In the embodiment described above, the accumulation is started from the one with the shortest accumulation time, but for example, if the accumulation time for green is longer than the sum of the accumulation time for red and the signal extraction time, the accumulation for green is started first. After that, the shortest red charge accumulation of M81 time is started.

Note that although the overall image reading time is somewhat longer, if the accumulation is started in order from the one with the longest accumulation time, such an order error will not occur. In addition, for example, the extraction of the green signal is started immediately after the extraction of the red signal is completed, but for the purpose of ensuring sequence control of the system, it is necessary to wait a little while after the extraction of the red signal is completed. The green charge start timing may be set so that the green charge M@ is completed and the signal can be taken out.

If the pre-scan accumulation time is the same as the accumulation time when the driver is operating normally, the pre-scan accumulation can be omitted.

In this case, it is sufficient to start extracting the color signals immediately when pre-scanning is started. In addition, in this pre-scan, the digitized color signal is not logarithmically converted or normalized (a dedicated page is provided for use in the pre-scan, and this page has the same address and data), and is directly stored in the RAM 62. May be stored. In this case, the accumulation time in the main scan is determined so that the maximum value of the color signal is close to the saturation value of the M-type image sensor.

FIG. 3 shows an example of a control circuit for blue color which performs frame transfer. The controller 52 sets the data of the accumulation extension time determined by the pre-scan in the timer 70, and then outputs the accumulation start signal to the AND gate 7.
Send to 1. This AND gate 71 has a vertical synchronization signal (
V-sync) is input, so when the vertical synchronization signal goes to low level (hereinafter referred to as rLJ), its output inverts to high level (hereinafter referred to as rHJ), and at this rising timing, the flip-flop 72 to the set state. When this flip-flop 72 is set, its output terminal page is inverted from rHJ to rLJ, so that the AND gate 73 is closed. When this AND gate 73 is closed, as shown in FIG. 4, the passage of the basic clock signal is stopped, so the operation of the driver 33 is temporarily stopped as described above, but the driver 33 is kept in the driving state. Because of this, storage type image sensors
The accumulation of 32 continues as it is.

When the flip-flop 72 is set, the output terminal Q becomes rHJ, so as shown in FIG.
The clock signal obtained by frequency division is input to the timer 70. This timer 70 counts the input clock signals, and when the content matches the accumulation extension time, the output terminal O is set to rHJ, the gate is closed, and the counting of the clock signals is stopped. When the output terminal O of the timer 70 becomes rHJ, the flip-flop 72 is reset, so the AND gate 73 is opened, allowing the basic clock signal to pass, and causing the driver 33 to operate normally. Furthermore, since the output signal of the timer 70 is input to the AND gate 71, even if the vertical synchronization signal is reversed to rLJ again during the - scan, the flip-flop 72
is never set.

When the AND gate 73 opens after the accumulation extension time to allow the basic clock signal to pass, driver 33 begins to operate and continues charge accumulation for the normal accumulation time.

Then, when the vertical synchronization signal is inverted to "H", frame transfer is started and storage is completed. When this frame transfer is completed, the vertical synchronization signal is inverted to rLJ, so the AND gate 76 which calculates the AND of the output signal of the timer 70 and the vertical synchronization signal is inverted to rHJ, and the flip-flop 77 is set.

A frequency divider 79 and an AND gate 80 are provided to slowly extract the blue signal. AN
A D gate 81 is provided, and AND gates 80 and 81 are selectively opened by the flip-flop 77. That is, during storage and transfer, the flip-flop 77 is in the reset state, so the output terminal Q is rLJ.
Therefore, the AND gate 80 is closed. On the other hand, the signal inverted by the inverter 83 is A
Since it is input to ND gate 81, this opens and sends the basic clock signal to OR gate 84. While the flip-flop 82 is set and the signal is being taken out, the AND gate 80 is open and the AND gate 81 is closed. Said AN
When the D gate 80 is open, the basic clock signal is divided and a clock signal with long synchronization is sent to the OR gate 84.

The driver 33 generates a plurality of clock signals with different phases based on the master clock signal output from the OR gate 84, and generates a plurality of clock signals having different phases.
to drive. This accumulation type image sensor 32 includes a photosensitive section 32a that photoelectrically converts incident light and accumulates it, and a photosensitive section 32a that photoelectrically converts incident light and accumulates it.
a transfer section 32b that receives and stores the signal charge from the transfer section 32b; and an output section that transfers the signal charge vertically transferred from the transfer section 32b in the horizontal direction, converts the signal charge into voltage, and outputs it as a blue signal. It is composed of 32C.

When the photosensitive section 32a photoelectrically converts incident light,
The transfer section 32b transfers the signal charges that have been previously photoelectrically converted and frame transferred to the output section 32c, and each cell must be emptied before frame transfer of new signal charges from the photosensitive section 32a.

The driver 33 outputs a vertical synchronization signal and a horizontal synchronization signal (H
-sync) and sampling pulse (SP). This vertical synchronization signal is sent to an AND gate 86, where it is ANDed with the accumulation start signal. This AN
The output of the D gate 86 is counted by a counter 87,
Its contents are sent to decoder 88. The counter 87
In this case, the vertical synchronization signal goes from rLJ to “H” after the accumulation starts.
The decoder 88 counts the number of times the data has been reversed, and when the value is "1", the decoder 88 sends an accumulation completion signal to the controller 52. When the content of the counter 87 is "2", the decoder 8
8 sends an extraction end signal to the controller 52 to instruct that the next color signal can be extracted.

Since the storage type image sensor 32 operates periodically, it outputs a blue signal from the output section 32c even in times other than pre-scanning and main scanning.

However, since this blue signal is unnecessary, it flows without activating the processing circuit. This can be achieved by not inputting the sampling pulse to the A/D converter 57, since the A/D converter 57 operates in synchronization with the sampling pulse. For this purpose, a flip-flop 89 is set by the output signal from the flip-flop 77, which is set at the start of signal extraction, and is reset by the extraction end signal, and an analog switch 90 connected to the output terminal Q of this flip-flop 89. It is provided.

Note that when this analog switch 90 is used, the analog switch 34 shown in FIG. 1 becomes unnecessary. Also,
This sampling pulse, horizontal synchronization signal, and vertical synchronization signal are input to an AND gate 91, and the sampling pulse is sent to the address counter 54 only during signal extraction in pre-scan and main scan.

When the pre-scan or main scan ends, the controller 52 outputs a reset signal to start the timer 70. The flip-flop 77 and counter 87 are reset. After this, the NM type image sensor 32 performs accumulation and reading at a normal cycle, and outputs the read blue signal.

FIG. 5 shows the timing of accumulation and extraction in the main scan. The accumulation start signal is from controller 5.
2, the AND gate 73 closes at the timing of the first fall of the vertical synchronization signal. Then, when the preset N product extension time has elapsed, the AND gate 73 opens and sends the master clock signal to the driver 33. Then, when the normal M-time period has elapsed, the vertical synchronization signal is inverted to rHJ, so frame transfer is started and storage is completed. After this frame transfer is completed and the vertical synchronization signal falls again, extraction of the blue signal is started. This blue signal is taken out slowly using a master clock signal whose frequency is divided by the frequency divider 79 and has a long period.

Although the frame transfer method was explained in the above embodiment,
This may be an interline method. Even in the case of this interline method, the accumulation time can be adjusted by stopping the basic clock signal and delaying the generation of the shift signal.

〔Effect of the invention〕

The present invention uses a plurality of storage image sensors, and independently controls their charge storage time and take-out start time, thereby driving each storage image sensor in parallel during charge accumulation, and Since signals are taken out in order from the ones that have been stored, it is possible to process signals at high speed, and since only one signal processing circuit is required, costs can be significantly reduced. Furthermore, since the charge accumulation time is changed depending on the incident light, the dynamic range is widened and accurate reading can be performed.

If charge accumulation in another storage image sensor ends while a signal is being taken out from one storage image sensor, it is necessary to delay the extraction of this signal. Noise occurs due to the influence of In the present invention, since the signal is taken out immediately when the charge immersion is finished, a good signal with less noise can be obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of a device implementing the present invention. FIG. 2 is an explanatory diagram showing the image reading method of the present invention. FIG. 3 is a circuit diagram showing an embodiment of the control circuit for blue color shown in FIG. 1. FIG. 4 is a timing chart showing the operation of the timer. FIG. 5 is a timing chart showing the state of l-scan. FIG. 6 is a schematic diagram showing a color printer using an image reading device embodying the present invention. 15...Color original image 17...Shutter 18...Photographic paper 20...Photometering section for blue 21...Photometering section for green 22...Photometering section for red 31...Blue filter 32.39.44...Storage type image Sensor 38...
Green filter 43...Red filter 34.41.46
...Analog switch 70, ...Timer. Procedural amendment March 15, 1985

Claims (5)

[Claims] (1) In an image reading method in which an image is read by a plurality of storage image sensors that photoelectrically convert and store incident light, the charge accumulation time of each storage image sensor is set independently according to the incident light, and In order to reduce the waiting time for signal extraction from each accumulation type image sensor, the accumulation start of each accumulation type image sensor is staggered, charge accumulation is performed in parallel, and signal extraction is performed in series. image reading method. (2) The image reading method according to claim 1, wherein the accumulation type image sensor starts accumulation in order of charge accumulation time. (3) The image reading method according to claim 1, wherein in the storage type image sensor, storage is started in order of charge storage time starting from the one with the shortest charge storage time. (4) A patent characterized in that the storage type image sensor is a CCD, and the charge storage time is extended by a predetermined period of time by blocking a master clock signal from being input to a driver that drives the CCD during charge storage. An image reading method according to claim 1. (5) The plurality of storage image sensors include a blue storage image sensor that photoelectrically converts blue light and stores it, a green storage image sensor that photoelectrically converts green light and stores it, and a green storage image sensor that photoelectrically converts and stores red light. 2. The method for reading both images according to claim 1, wherein the image sensor is an accumulation type image sensor for red color that converts and accumulates.