JPH0387271A - Color image forming device - Google Patents

Abstract

PURPOSE:To enable color superposition in developing color to be accurately realized by a method wherein a deviated amount of a position of an image between in developing and in scanning for a previous other primary color is detected, and a position of a stored image for one primary color is corrected according to said deviated amount to reproduce the image. CONSTITUTION:Since an image stored in an image memory M0 is slightly deviated from a fixedly placed position in developing of a previous red color in prescanning with a portable copying machine 1, a prescanned image to the image memory M0 is slightly deviated from a previous developed image A. Then, verification of the image memory M1 to M0 is executed, and its deviated amount is calculated. When a deviated amount to the red image is obtained, a blue image data stored in an image memory M2 is taken out correcting its position according to the deviated amount, and a printing process for the blue image is performed by driving a thermal head 23 based on said corrected data. Thereafter, a deviated amount is calculated in the same way. An image data of an image memory M3 is taken out correcting it, and a printing process for an image of a yellow color data is executed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a color image forming apparatus, and particularly to a color image forming apparatus that takes into consideration obtaining beautiful reproduced images.

[Prior Art] Conventional color image forming devices such as color copying machines and color printing devices read a color image by separating it into three primary colors, and reproduce the color image by repeating a developing operation for each primary color image. It is excellent in that it can be done.

[Problem to be solved by the invention]

However, in the conventional color image forming apparatus, as a result of separating the color am into the three primary colors as described above, the developing operation must be performed three times for each primary color.

Therefore, as mentioned above, there is a problem in that unless the transfer sheet is accurately positioned with respect to the copying machine every three development operations, color misregistration will occur.

Especially with simple copying machines such as handheld copying machines, each time you perform a development operation, you have to lift the copying machine and replace it with a printing ribbon of a different color. The combination of these two factors will determine its feasibility.

Also, even in non-handheld color copying machines, registration rollers are used to align the transfer paper with the photoconductor, so it is difficult to always align the transfer paper perfectly with the photoconductor. Beautiful ri with good color overlap
Obtaining te was considered a difficult problem.

Therefore, it is an object of the present invention to accurately reproduce color overlap during color development using simple IJI rules. An object of the present invention is to provide a color image forming apparatus that can be used.

(Means for Solving the Problems ¥1) In order to achieve the above object, the present invention separates and reads a color image into 3i colors, stores each primary color image in a storage means, and stores each primary color image in a storage means. In a color image forming apparatus that reproduces a color image by repeating a development operation for each image, prior to the development operation for one primary color, the previous current alt! ! The image of the other primary colors obtained in the above process is scanned, the amount of deviation in the position of the image between the development operation for the above primary color and the time of the above scanning is detected, and the image position of the above one primary color is detected according to the deviation amount. This color image forming apparatus is characterized by correcting the position of a stored image and reproducing the image.

[Effect]

For example, suppose that a red image is first developed. Such a developing operation is performed in the same manner as in the prior art.

Next, when developing, for example, blue, in the present invention, the developed red image that has been developed first is scanned (prescanned), and the image position at the time of the red development operation is compared with the image position at the time of the above scanning. Based on the deviation, the difference in the mounting position of the machine between when the color is red and when it is blue is detected. Such an image shift in a two-dimensional plane can be precisely defined by, for example, parallel movement and rotation of the Ii image.

In the present invention, image formation is performed by correcting the position of the stored image to be developed in accordance with the deviation of the image obtained as described above.

Therefore, an image to be developed can be accurately color-superimposed on an image that has already been developed, and a beautiful color image can always be reproduced.

〔Example〕

Next, embodiments embodying the present invention will be described with reference to the accompanying drawings to provide an understanding of the present invention.

The first embodiment described below is intended for a portable copying machine.

Here, FIG. 1 is a side cross-sectional view showing a portable copying machine as an example of an image forming apparatus, FIG. 2 is a plan cross-sectional view of essential parts of the portable copying machine shown in FIG. 1, and FIG. is a conceptual diagram showing an enlarged view of the A arrow in FIG. 1, FIG. 4 is a block diagram of the image processing control section in the same portable copying machine, and FIG. 6 is a conceptual diagram showing the image reading procedure, FIG. 7 is a conceptual diagram showing the document writing procedure shown in FIG. 6, and FIG. 8 is a conceptual diagram showing the procedure for writing the document shown in FIG. 6. A conceptual diagram showing the overall configuration of a conventional color copying machine, FIGS.

In addition, the following example is only an example of embodying the present invention,
It is not intended to limit the technical scope of the present invention.

First, the structure of a portable copying machine according to this embodiment will be explained with reference to FIGS. 1 to 4.

This portable copying machine 1 has a generally flat box shape, and one side has a scanning surface 3 on which a glass plate 2 is attached, and the other surfaces constitute a transfer surface 4.

This portable copying machine 1 has a scanning chamber 5 separated by a partition wall 5.
a and a control section storage chamber 5b.

Inside the scanning chamber 5a, there are a bearing 6 provided on the partition wall 5 and a bearing 8 provided on the partition wall 7 provided opposite to the partition wall 5.
A threaded rod 9 rotatably supported is housed in the housing.

A threaded portion 1O is screwed into the screw loft 9, and a mounting base 11 is fixed to this threaded portion 10.

At one end of the mounting base 11, an optical line sensor 12 such as a COD, which faces the glass plate 2, is mounted on the threaded rod 9.
It is arranged in a direction perpendicular to. Reference numeral 13 denotes a light emitting section comprising a group of LEDs and the like for providing reflected light from the original to the line sensor 12.

Further, a transfer device W14 is provided on the side of the mounting base 11 opposite to the mounting portion of the line sensor 12.

Details of the transfer device 14 are as shown in FIG. The running roller 15, which constitutes a part of the transfer device W14, is a rotatable roller that projects slightly outward from an opening formed in the transfer surface 4. A small gear 16 provided on this running roller 15 is connected to a fractional gear 18 via an idle gear 17. The winding gear 18 is connected to a winding roll 19, and the winding roll 19 scoops the transfer ribbon 21 unwound from the ribbon roll 20. The ribbon roll 20 is rotatably supported by a casing 22 of the transfer device 14 with some resistance.

In this embodiment, the above-mentioned steering gear 18. Idle gear 17.
II take roll 19. Ribbon roll 20 and transfer ribbon 2
1 is housed in a case (not shown) that is detachably attached to the casing 22, and can be replaced integrally as a ribbon cassette. Therefore, during color copying, three ribbon cassettes corresponding to the three primary colors are prepared, and color development is performed by sequentially exchanging these ribbon cassettes.

A thermal head 23 is in contact with the transfer ribbon 21 and performs thermal transfer on the transfer sheet P.

Further, one end of the casing 22 is provided with a pre-scan line sensor 24 parallel to the line sensor 12 and a pre-scan light emitting section 25 that irradiates the line sensor 24 with reflected light from the transferred image. .

On the other hand, the control unit storage chamber 5b includes a control device such as a micro combiator (not shown), a motor M connected to the threaded rod 9 and for rotationally driving the screw rod 9, and a motor M that protrudes from the control unit storage chamber 5b. two pistons 2
6a and 26b, the pistons 26a, 26b
The switch SW1 and SW2 are operated by the switch SW1 and SW2.

Furthermore, a display section D, a read key Kl, and a write key 2 shown in FIG. 4 are provided on the outside of the control section storage chamber 5b, respectively.

As shown in FIG. 4, the control section housed in the control section storage chamber 5b is equipped with a CPU that performs various arithmetic operations according to programs written in the ROM. This CPU
A RAM for temporary storage is connected to. This R.A.
M includes image memories Ml, M2 . M3 and a prescan image storage area Mo that temporarily stores image data read by prescanning. The RAM also stores the image obtained by the pre-scanning (stored in Mo) and the corresponding M1 to M3 as necessary.
The amount of deviation (xe,
It is provided with a shift storage memory Me that stores the data (ye, ee).

The reading area of the blue letter B (indicated by a broken line) and the letter C (-dotted line) is shown in FIG. 6 (al) by a broken line.

Here, SL, S2.・・・Hand) 11 (Step) Show the number.

The operator first places the scanning surface 3 of the portable copying machine 1 on the original G with the scanning surface 3 facing the original G (No. 61!1 (al)).

In this state, the operator first turns on the main switch MS shown in FIG. Then, the program according to the flowchart shown in FIG. 5fal is executed. The CPU first stores the three storage areas Ml, M2 . M3
, Mo and Me are cleared, flags Fl and F2 to be described later are reset to 0, and all display on the display section is erased, that is, initialization processing is executed.

Portable copy #! with the scanning surface 3 facing the original G as described above! When A1 is placed on the document G, the switch SWI of the three scanning surfaces comes into contact with Jj[G, so it is determined that the switch SWl is on in S2, and the process proceeds to S3.
Proceed to.

When the operator presses the reading key 1 in this state, the process proceeds to S4, where the motor M is started and the light emitting unit 1
3 is turned on.

When the motor M shown in FIG.
Start moving in the direction shown by arrow X in the figure, and line sensor 1
2 starts scanning. Motor M
is rotated in the forward direction until the line sensor 12 reaches the rightmost position of the scanning surface 3 shown in FIG. 1, and stops at the rightmost position. The output signal from the line sensor 12 is divided into three signals corresponding to the three primary colors by passing through a well-known frequency analysis filter, and is sent to the Ii image memories Ml, M2 corresponding to the three primary colors.

An image based on three primary colors is stored in M3. A line sensor 24, which will be described later, is similarly connected to a filter that analyzes the three primary colors.

Image memory M1 is the image with red A drawn (6th box))
, M2 is the image with the blue letter B (Fig. 6 (C)),
Also, M3 stores the drawn images of the student C (Fig. 6 + dl).

When the operator notices that the image has been read by means of a flashing lamp on the display or a comment display, the operator then lifts up the portable copying machine, inserts, for example, a red ribbon cassette, and then presses the corresponding button. The portable copying machine 1 is turned over and placed on the transfer paper so that the transfer surface 4 faces the transfer paper.

Then, the switch SWI is turned off, and the switch SW2 is turned on instead. Therefore, the process moves from S2 to 35, and the switch SW2 is turned on, so the judgment in 56 is made. Here, when the operator turns on 2 to the write key, the process further proceeds to S7 (Fig. 5). .

In the above S7, it is determined that the flag F1 is O, but
Here, it is set to F-0 by default, so S
8 print processing is executed.

That is, in S8, the motor M is driven while the thermal head 23 is driven in accordance with the image data of the image memory M1 that stores the red image data, and the transfer device 14 is moved so that only the red image A is placed on the transfer paper. Figure 7 Te
It is transferred as shown in 1.

When the red image transfer is completed, the flag F1 is set to 1 in S9.

At this point, the operator opens the portable copy wA1 again, replaces the ribbon cassette with a blue one, and places l1 on the transfer paper.
iH. At this time, the copying machine should be placed at the position where the transfer surface 4 (indicated by the broken line) is approximately exposed to light (red A>) as shown in FIG. 7 (bl).

Here, when the operator presses the write key 2 again, the process proceeds to S2. S5.36. The process proceeds to S7, and a negative determination is made in S7, leading to S10.

At 510, it is determined whether the flag F2 is 0, and since it is set to F-0 by default here, the process proceeds to Sll.

In the Sll, the light emitting unit 25 is turned on and the motor M is driven to scan the line sensor 24 along the red developed image (prescan), and the read data of the red image is stored in the image memory MO.
Store in.

Here, the image stored in the image memory MO is slightly shifted from the placement position when the portable copying machine 1 was developing the red image during the pre-scanning as described above, so the image stored in the image memory MO is The pre-scanned image is the 7th [! 110
), as shown by the solid line A, the previously developed image A (Fig. 7 tc
(indicated by a dashed line).

Next, in step 312, the image memories Ml and MO (broken line A and solid line A in FIG. 7 tel) are compared, and the amount of deviation is calculated. Calculation of such a shift amount is well known, so a description thereof will be omitted here.

Normally, the displacement (movement) li of the congruent figures 2111 in a two-dimensional plane as described above is equivalent to the parallel displacement (Xe and y
e) and rotation (ee).

The same holds true here, and the deviation amounts xe, ye, and ee are stored in the memory Me.

When the amount of deviation with respect to the red image is obtained as described above, the blue image data stored in the image memory M2 is taken out while its position is corrected according to the amount of deviation, and the thermal head 23 is driven based on this correction data in step S8. The printing process for the blue image is performed in the same manner as (S13).

In this embodiment, the data is corrected based on the amount of deviation in parallel with the data retrieval from the image memory M2, that is, in parallel with the printing process of the blue image. The corrected data may be obtained and stored in another memory, and then the stored corrected data may be used to perform print processing.

When the printing process of blue image data is completed, the flag F2 is set.
is set to 1 (S14).

The last yellow image data (stored in the image memory M3) is subjected to the same operations and processing as the blue image data, and after the SIO judgment is no, 315 to
The process of S17 is executed.

That is, first, a pre-scan is performed (315), and red image data or blue image data is stored in the memory MO. Thereafter, the image data stored in the memory M1 or M2 is compared with the image data in the memo IJMO according to the color of the image data, and the amount of deviation is calculated (516). Based on the amount of deviation, the image data in the image memory M3 is While correcting the image, take it out and print the yellow data image (3
1B) When the printing process for all three primary colors is thus completed, the flags F1 and F2 are reset to O in 318, and the process returns to 82.

Although the above embodiment has been described with reference to the portable copying machine 1, the present invention is also applicable to ordinary color copying machines or color printers.

FIG. 8 shows an outline of a conventional color copying machine as an example of such a color image forming apparatus.

In such a color copying machine 30, the document feeder ADF
A document is supplied, and the document image is separated into three primary colors by a color sensor unit C8 having three color sensors and stored.

The image processing unit (IPU) forms an electrostatic latent image on the surface of the photoreceptor 31 according to the stored image data of each primary color.

A developing device 32 contains red, blue, yellow, and black developers, and allows color development processing by switching between these developers.

When performing color copying processing, for example, when developing in the order of red, blue, and yellow, the developing device 32 has a developing tank containing a red developer facing the photoreceptor 31, and in this state, the I
The photoreceptor 31 is exposed to red image data by the PU, and in synchronization with this, 33a, 33b, 3
The transfer paper is sent out from one of the paper feed cassettes 3c,
It reaches the registration roller 35 via the feed roller 34.

A light emitting section 36 and a line sensor 37 are provided between the registration roller 35 and the photoreceptor 31, as shown in FIG. 9 (M1).

The transfer paper that has passed through the registration roller 35 is further transferred to the light emitting section 36. The line sensor 37 is attached through a position where the red toner image formed on the photoreceptor 31 is transferred.

Thereafter, the transfer sheet passes through the fixing section 38, has its conveyance direction changed by a switching guide 39, and is returned from the feed roller 34 to the registration roller 35 through a lower return path 40.

In conventional color copying machines, when the transfer paper passes through the registration rollers 35 again after this, the transfer paper is misaligned compared to the first pass, so the color overlap with the second transfer image (blue image) does not match accurately. There was an inconvenience in not doing so.

In this regard, in the copying machine according to this embodiment, before bringing the transfer paper close to the photoreceptor 31 for the next blue development operation, the registration roller 35 is rotated slightly, For example, the red image is scanned (prescanned) by the light emitting unit 36 and the line sensor 37, and as in the first embodiment, the positional deviation of the image between the red image operation and the prescanning is detected. The amount of deviation is detected, the stored data for the previous image is corrected according to the amount of deviation, and the blue image is developed and reproduced.

Prior to such a developing operation for one primary color, the images for the other primary colors obtained in the previous developing operation are scanned, and the images at the time of the developing operation for the above primary color and at the time of the above scanning are compared. The processing procedure of detecting the amount of positional deviation, correcting the position of the stored image for the one primary color according to the amount of deviation, and reproducing the image is as follows. Since this is the same as that in the first embodiment described above except that the line sensor 37 is used, the explanation will be omitted here.

〔Effect of the invention〕

Since the present invention is configured as described above, it is possible to accurately superimpose colors during development and reproduce beautiful color images.

[Brief explanation of drawings]

FIG. 1 is a side sectional view showing a portable copying machine as an example of an image forming apparatus, FIG. 2 is a plan sectional view of main parts of the portable copying machine shown in FIG. 1, and FIG. 4 is a block diagram of the image processing control section in the portable copying machine, and FIG. 5 is a flowchart showing the processing procedure of the image processing control, respectively. FIG. 6 is a conceptual diagram showing an image reading procedure, FIG. 7 is a conceptual diagram showing a document writing procedure shown in FIG. 6, and FIG. 8 is an overall diagram of an ordinary color copying machine according to the second embodiment. Conceptual diagram showing the configuration, FIG. 9 (al and bl are respectively schematic side views showing the main parts of the apparatus shown in FIG. 8. [Explanation of symbols] 1... Portable copying machine 3... - Scanning surface 4... Transfer surface 12... Line sensor 13... Light emitting part 14... Transfer device 23... Thermal head 24... Line sensor 25... Light emitting part
30... Copying machine 31... Photoreceptor 3
2...Developing device 35...Registration roller 36...
・Light emitting part 37...Line sensor D...1 in the display part...Reading key K2...Writing key MI A
-M3...Image memory Me, MO...Memory

Claims (1)

[Claims] (1) A color image forming apparatus that separates and reads a color image into three primary colors, stores each primary color image in a storage means, and reproduces the color image by repeating a developing operation for each primary color image, Prior to the development operation for one primary color, scan the image for the other primary color obtained in the previous development operation, and calculate the amount of positional deviation of the image between the development operation for the other primary color and the above scanning. A color image forming apparatus characterized in that the position of the stored image for the one primary color is corrected according to the amount of deviation, and the image is reproduced.