JPS6384377A - Image forming device - Google Patents

Abstract

PURPOSE:To easily and accurately add a mark for print positioning by providing a generating means which generates the pattern of the mark for print positioning. CONSTITUTION:A binarization circuit 88 performs the area gradation conversion, i.e. binarization of a color signal sent from a chrominance signal converting circuit 87 and sends the binarization signal to a positioning mark generator 97. The circuit 97 adds the pattern of the mark for print positioning to the binarization signal from the circuit 88 and sends the resulting signal to a thermal head temperature control part 93. Thus, the mark for positioning is added without area gradation conversion, so stuck a defect that the mark blurs in a dot shape owing to the area gradation conversion of the mark for positioning together with an image is eliminated, and the clear and proper mark is added.

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Application Field) The present invention relates to an image forming method for forming an image of a color-separated original document, which is required when creating a printing plate for offset printing, for example. Regarding equipment.

(Prior Art) Recently, plate making and printing technology has made great progress with the development of electronics, and electronic plate making has become mainstream today. This electronic plate making photoelectrically converts the shading of the original image,
By performing certain processing on the electrical signal, the intensity of the light is changed, exposing the film (photosensitive material), and developing it to create negative or positive film, which is the basis of the original printing plate. .

However, in such a method, the manufacturing process is very complicated, and the machine itself is large and therefore very expensive. In addition, conventional machines were dedicated to creating original plates and could not be used for other purposes.

Furthermore, in order to ensure reliable alignment with the film used to create printing master plates for each color, alignment marks (register marks) are pasted by hand onto each film used to create printing master plates. It was getting worse. For this reason, the operability was poor, and there was also a possibility that positional deviation would occur.

(Problems to be Solved by the Invention) As mentioned above, in the conventional method of creating a film for printing original plates, the manufacturing process is very complicated, and the machine itself is large, so it is very expensive. It has the disadvantage that it is not suitable for other purposes. Further, there are also disadvantages in that the marking of alignment marks on the film for producing the printing original plate is difficult to operate, and there is a possibility that misalignment may occur.

Therefore, the present invention eliminates the above-mentioned drawbacks, and makes it possible to create a film for printing original plate very easily without using the complicated production process as in the past, and also to realize it in a small size and at low cost. It is an object of the present invention to provide an image forming apparatus that can be used not only for producing films for printing original plates, but also as a color copying machine, and that can also easily, clearly and accurately apply marks for printing alignment. .

[Structure of the Invention (Means and Effects for Solving Problems)] The image forming apparatus of the present invention optically scans a document to read it as a plurality of color signals, and converts each obtained color signal into a plurality of color signals. The image forming signals are converted into image forming signals, each of these image forming signals is subjected to gradation, and a single color or It uses multi-color image forming media to form single-color or multi-color images on the image-forming medium.This makes it very easy to create films for printing original plates, and it is usually used for color copying, for example. It can also be used as a machine. In addition, images are formed on the image forming medium according to each one of the image forming signals of the plurality of colors and the pattern of the alignment marks, and this allows printing when creating a film for creating a printing original plate. Marks for alignment can be easily and accurately provided. Furthermore, since the print alignment mark is applied without gradation, it is possible to create a clear mark.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIGS. 2 and 3 show a thermal transfer color copying machine that is capable of selectively producing multicolor color copies and producing a printing original plate production film (block copy) as an example of the image forming apparatus according to the present invention. It is. That is, 1 is a main body of a copying machine, and an operation panel 2 is provided at the front of the upper surface of the main body 1. The left side of the main body 1 is a document scanning section 8 that scans and reads a document set on a document table 7, and the right side is an image forming section 9. Note that 10 is a document cover provided on the document table 7 so as to be openable and closable.

The document scanning section 8 is configured as shown in FIGS. 4 and 5, for example. That is, the document table 7 is fixed to the main body 1, and the document table 7 is placed under the document table 7 by reciprocating in the direction of arrow a in the figure along the lower surface of the document table 7.
A scanner 11 is provided which optically scans and reads the original O set on the second page. The scanner 11 includes an illumination lamp 12 that illuminates the original O, a photoelectric converter 13 that receives reflected light from the original O, an optical system 14 that guides the reflected light from the original O to the photoelectric converter 13, and supports these. Carriage 1
Consisting of 5. The photoelectric converter 13 photoelectrically converts the reflected light from the original O to convert the image of the original O into cyan, green, yellow (or red, green,
It separates and outputs the color signal of (blue) light, and is mainly composed of, for example, a CCD type image sensor. As shown in FIG. 5, the carriage 15 is guided by a guide rail 16 and a guide shaft 17 so as to be able to reciprocate in the direction of arrow a. A scanning motor (for example, a pulse motor) 1 that is capable of forward and reverse rotation is mounted on one end of the guide shaft 17.
A driving pulley 19 driven by a drive pulley 8 and a driven pulley 2° are provided at the other end thereof, and a timing belt 21 is stretched between these pulleys 19° and 20. One point of the timing belt 2 is fixed to the carriage 15 via a fixing member 22.

This allows the carriage 15 to move linearly by rotating the scanning motor 18 in the forward or reverse direction.

The image forming section 9 is configured as shown in FIG. 6, for example. That is, a platen 30 is disposed approximately in the center of the image forming section 9, and a thermal head 31 is disposed on the left side facing the platen 30. Thermal head 3 ] is attached to a heat radiator 33 that is integrally formed on the rear end surface of the holder 32 .

A ribbon cassette 35 containing a thermal transfer ink ribbon 34 as an image forming medium is detachably attached via a holder 32, and the thermal transfer ink ribbon 34 is interposed between the thermal head 31 and the platen 30. It has become. As shown in FIG. 6, the ribbon cassette 35 has two parallel winding cores 36 and 37 around which both ends of the thermal transfer ink ribbon 34 are wound, and a midway portion of the thermal transfer ink ribbon 34 is wound around the cores 36 and 37. In order to be interposed between the platen 3o and the thermal head 31, it is covered with a case 38 with a part thereof exposed. When the ribbon cassette 35 is attached, the winding cores 36 and 37 are connected to a drive shaft of a motor (not shown) via a drive force transmission mechanism (not shown), and are rotated as necessary. Further, as shown in FIG. 2, the ribbon cassette 35 can be inserted into or removed from the holder 32 through an insertion/removal port 39 formed on the right side of the main body 1. Note that the insertion/removal port 39 is provided with a lid 40 that can be opened and closed.

A paper feed roller 41 is provided diagonally below the right side of the platen 30, and a paper (or plastic film) as an image forming medium housed in a paper feed cassette 42 is provided.
P is taken out one by one. Paper feed roller 41
The paper P taken out is sent to a registration roller 43 disposed diagonally to the right of the paper feed roller 4, and after its leading edge is aligned, it is directed toward the platen 30 by the registration roller 43. is transferred, and the pressing state is such that it is wrapped around the platen 30 by rollers 44 and 45 = 1
0 - This will send correctly. Here, the paper feed cassette 42
is removable from the front of the main body 1.

Note that 46 in FIG. 6 is a manual paper feeding device for manually feeding the paper P.

The thermal head 3 presses the paper P against the platen 30 via the thermal transfer ink ribbon 34, and heats and melts the ink 47 as a coloring agent on the thermal transfer ink ribbon 34 to print the paper P as shown in the seventh column. It is designed to be transferred to As shown in FIGS. 7 and 8, the thermal transfer ink ribbon 34 has a width approximately equal to that of the paper P and is yellow.

Magenta, cyan, and black ink portions 47Y.

47M, 47c, and 47B are sequentially stacked one on top of the other, and after transferring one color at a time, the paper P is returned to the transfer starting position, and the sheets are accurately stacked one after another. Note that the thermal transfer ink ribbon 34 may not have the black ink portion 47B, and in that case, approximately black can be produced by overlapping the three colors of yellow, magenta, and cyan.

In addition, in the case of color copying, each ink part 47Y, 47M of the thermal transfer ink ribbon 34 is used as described above.

Image formation is performed using 470.47B. On the other hand, when creating a film for printing original plates, a solid black thermal transfer ink ribbon, for example, is used as the thermal transfer ink ribbon 34 to form an image. In this case, it is not necessary to use a solid black thermal transfer ink ribbon, and the image may be formed using the black ink portion 47B of the thermal transfer ink ribbon 34.

During color copying, the paper P is reciprocated by the number of colors by the rotation of the platen 30, but the path of the paper P at this time is the lower surface of the paper output tray 48 that is provided at an angle and protrudes from the main body 1-h. The 1st. 2nd guide board 49.5
Leads to 0. This includes the platen 30 and the first. The first guide plates 49 and 50 respectively provided between
．． This is done by the second distribution gates 51, 52. That is, the paper P taken out from the paper feed cassette 42 is
It is transferred through the registration rollers 43 and the first distribution gate 51, and its tip end is wrapped around the platen 30. Next, the platen 30 is rotated in the forward direction by a pulse motor (not shown) to transport the paper P at a constant speed, and the heating elements of the thermal head 31 arranged in a line tread along the axial direction of the platen 30 (not shown) generates heat in response to the print signal, and thereby the ink 47 of the thermal transfer ink ribbon 34 is transferred onto the paper P. Then, the paper P that has passed through the platen 30
At this time, the tip of the second distribution gate 5 is located at the solid line position.
2, the paper is sent to a first guide plate 49'2 provided along the lower surface of the paper discharge tray 48. In this way, when the transfer of ink 47 of one color is completed, the platen 30 is rotated in the opposite direction, so that the paper P is reversely transported and returned to the transfer starting position. At this time, the trailing edge of the paper P is sent to the second guide plate 50' provided along the lower surface of the four first guide plates by the first distribution gate 51 which is rotated to the position indicated by the two-dot chain line. . In this way, a plurality of colors are transferred by moving the paper P back and forth a plurality of times. Finally, the paper P on which the transfer of ink 47 of all colors has been completed
At this time, the second sorting gate 52, which is rotated to the position indicated by the two-dot chain line, guides the paper to the paper discharge roller 53, and the paper discharge roller 53 discharges the paper onto the paper discharge tray 48.

Note that when forming an image using a solid black thermal transfer ink ribbon, that is, when creating a film for creating a printing plate, the transfer is performed only once, and the paper P is not moved back and forth, and the paper after the transfer is completed. P is discharged onto the paper discharge tray 48 as it is.

FIG. 9 shows the operation panel 2, in which a mode key 61 is used to select between normal mode (color copying mode) and monochrome mode (film production mode for producing printing master plates).
, a color selection key 62 for specifying the color in single color mode, a numeric keypad 63 for setting the number of copies, etc., a clear key 64 for clearing the set number of copies, etc., a copy key 65 for starting the copying operation, and a numeric display for displaying the number of copies, etc. A status display section 67 for displaying a device 66, an operating state, etc. is provided. The color selection keys 62 include, for example, a Y key 68 for specifying yellow (Y), an M key 69 for specifying magenta (M),
It is composed of a C key 70 for specifying cyan (C), a B key 71 for specifying black (B), and a batch print key 72 for specifying sequential output of each of the above colors.

FIG. 1 schematically shows the overall control system, which includes a main control section 81, a first sub-control section 82, and a second sub-control section 83. The main control unit 81 includes the operation panel 2, a correction circuit 84, a luminance/color difference separation circuit 85, an image quality improvement circuit 86,
A color signal conversion circuit 87, a binarization circuit 88 as an area gradation means that performs area gradation using a dither method, etc., an alignment mark (register mark) generation circuit 97, and a first sub-control unit 8.
2 and a second sub-control unit 83, respectively, and controls these units. The first sub-control unit 82 includes a light source control unit 89,
It is connected to the motor drive section 90, the photoelectric converter 13, the A/D converter 91, and the resolution conversion section 92, respectively, and controls these. The light amount control section 89 controls the illumination lamp 1.
2 and controls the amount of light. Motor drive section 9
0 is connected to the scanning motor 18 and drives it. The second sub-control section 83 is connected to a thermal head temperature control section 93, the thermal helad 31, various detection switches 94, and a drive section 95, and controls these. The drive unit 95 is connected to a drive system 96 such as a motor and a solenoid, and drives the drive system 96 .

The main control unit 81 operates using a mode key 61 in the operation panel 2.
Therefore, when the single color mode is selected, a mark adding signal (“1” signal) is output to the alignment mark generation circuit 97.

The flow of signals in FIG. 1 in such a configuration will be explained. The reflected light emitted from the illumination lamp 2 onto the original forms an image on the photoelectric converter 13. Photoelectric converter 13
This light is cyan (C).

The signal is separated into green (G) and yellow (Y) analog color signals and sent to the A/D converter 91. The A/D converter 91 converts each analog color signal into a digital signal and sends it to the resolution converter 92. The resolution conversion unit 92
Resolution conversion is performed to match the resolution of the photoelectric converter 13 and that of the thermal head 3, and the result is sent to the correction circuit 84. The correction circuit 84 includes a resolution converter 92
A correction process is performed on each of the C, G, and Y color signals sent from the photoelectric converter 13 to correct for variations in the photoelectric converter 13.
The result is sent to the luminance/color difference separation circuit 85. The luminance color difference separation circuit 85 receives the C, G, and Y signals sent from the correction circuit 84.
Various calculation processes are performed on each color signal of the luminance signal (I
), color difference signal 1 (C1), and color difference signal 2 (C2), and send them to the image quality improvement circuit 86. Image quality improvement circuit 8
6 analyzes the luminance signal, color difference signal 1, and color difference signal 2 sent from the luminance color difference separation circuit 85, performs image improvement processing such as edge emphasis and character identification, and converts the luminance signal to the color signal conversion circuit 87.
send to The color signal conversion circuit 87 performs color conversion based on the luminance signal, color difference signal 1, and color difference signal 2, which have been subjected to image quality improvement processing, to produce yellow (Y).

It is converted into a color signal of one of magenta (M), cyan (C), and black (B) [the three primary colors (Y, M, C) plus B during printing] and sent to the binarization circuit 88. Binarization circuit 8
8 is a color signal (Y
. The alignment mark generation circuit 97 adds print alignment marks A to the binarized signal sent from the binarization circuit 88 in response to the mark adding signal (“]” signal) from the main control unit 81. Either the pattern is given and sent to the thermal head temperature control unit 93, or the binary signal sent from the binarization circuit 88 is sent as it is to the thermal head temperature control unit without the pattern of print alignment mark A being given. Send to 93. The thermal head temperature control section 93 sends a print signal to the thermal head 31 based on the binary signal sent from the 1st alignment mark generation circuit 97. The thermal head 31 performs printing (that is, image formation) according to this print signal.

Here, the color signal conversion circuit 87 will be explained in more detail with reference to FIG. The luminance signal (I), color difference signal 1, (C1), and color difference signal 2 (C2) sent from the image quality improvement circuit 86 are sent to the color signal conversion circuit 87, where Y, M, and Y.

A binarization circuit 88 converts one of the color signals of C and B.
I am sending them to Y, M, and C.

The selection of the B color signal is performed by the main control section 81.

That is, as shown in the table below, the main control section 81 receives the signal a.
, b are sent to the binarization circuit 88 by the combination of Y, M
, C, and B color signals are selected. Note that the -2 color signals are automatically selected sequentially in the normal color copying mode (for example, in the order of Y-+M-+C-4-B), and in the single-color mode, the selection of the color selection key 62 is performed automatically. The corresponding color signal is selected according to the operation.

=19- Also, the alignment mark generation circuit 97 will be explained in more detail with reference to FIG. That is, a horizontal counter 100 counts up in response to a data synchronization signal (DCLK) from the main control section 8 and clears it in response to a line synchronization signal (H8YNC);
A vertical counter 1o1 counts up in response to a single line synchronization signal (H8YNC) and clears in response to a page synchronization signal (PSYNC), and the horizontal counter 100
The address signal corresponding to the count value from ROM 103 and the pattern selection signal from the output terminal 103a of the ROM 103 is output to the output terminals 102a (HDI) and 102b (HD2).
The ROM 102 outputs a signal of the address corresponding to the count value from the vertical counter 100 to the output terminal 10.
3 a (VD 1.),], ROM 1.03 output from 03b (VD2), AND the horizontal mark signal supplied from the output end 102a and the vertical mark signal supplied from the output end 103b. Take and circuit 10
4. Marking signal (MCO) from the symbol main control unit 81
An AND circuit 105 which takes the AND between M) and the output of the AND circuit 104 in 1. Only when the output from the AND circuit]05 is not supplied via the inverter circuit 106, the output from the binarization circuit 88 is Valued signal (image data,
RD A'r) in the thermal head temperature control section 9.
3, and the AND circuit 1
Only when the output of 05 is supplied, the above ROM]
, 02 from the output end 102b (alignment mark data) to the thermal head temperature control section 93.

The pattern of print position alignment mark A is set in the above ROM 102 and 103, and the relationship between each output and the data output to the thermal head temperature control section 93 is as shown in the table below. .

Therefore, as shown in FIG. 12(a), a pattern of print alignment marks A is output corresponding to the four corners, and other than that, the image data from the binarization circuit 88 is used as it is to control the temperature of the thermal head. It is output to section 93. As a result, as shown in FIG. 12(b), print position alignment marks A are printed at the four corners, and images are printed at the other corners.

Next, the operation will be explained with reference to the flowcharts shown in FIGS. 13(a) and 13(b). First, in step S1-, it is determined whether or not the monochrome mode is selected. If the monochrome mode is not selected, it is the normal color copying mode, and the process proceeds to step S2. In step S2, a "0" signal as a reset signal is output to the AND circuit 105 in the alignment mark generation circuit 97, and the process proceeds to step S3.

In step S3, it is determined whether or not the copy key 65 is turned on. If it is not turned on, the process returns to step S. If it is turned on, the process goes to step S4.

In step S4, an image forming operation is performed. That is, in this case, since the mode is color copying, color copying (image formation) is performed using the thermal transfer ink ribbons 34 of a plurality of colors by the above-described operation.

In step S1, if the single color mode is selected, this is the mode for producing a film for producing a printing original plate, so the process advances to step S5. In step S5, the main control unit 81
outputs a 1'' signal as a mark I'' group signal to the AND circuit 105 in the alignment mark generation circuit 97, and the process proceeds to step S6.

In step S6, the -batch printing flag is reset, and the process proceeds to step S7. In step S7, as an initial setting, the color signal conversion circuit 87 is commanded to convert the yellow (Y) color signal into a color signal, and the process proceeds to step S8.

In step S8, it is determined whether the -bulk print key 72 has been turned on, and if it has not been turned on, the process advances to step S10. Further, if it is determined that the batch print key 72 is turned on in step 8 of "2," the - batch print flag is set, and the process proceeds to step S10. In step S], 0, it is determined whether the color selection key 62 has been turned on, and if it has not been turned on, the process proceeds to step Sll. In step S11, it is determined whether or not the single color mode has been cleared by pressing the mode key 61. If it is determined that the mode has been cleared, the process returns to step 1; if it has not been cleared, step S12 is determined.
Proceed to. In step S12, it is determined whether or not the copy key 65 is turned on, and if it is not turned on, step S8
Returns to step S21, and if it is turned on, the process advances to step S21.

=24=If the color selection key 62 is turned on in step S10, the process advances to step S813. In step S13, the batch printing flag is reset, and the process proceeds to step S14.

In step 81.4, it is determined whether or not the Y key 68 has been turned on. If the Y key 68 has been turned on, the process proceeds to step S5.

In step S15, the color signal conversion circuit 87
Y) to a color signal, and the process returns to step S8.

In step S14, if the Y key 68 is not turned on, the process advances to step S16. In step S16,
Determine whether 6 M keys are turned on or not, and press M key 69.
If it is turned on, the process advances to step S17. In step S17, the color signal conversion circuit 87 is commanded to convert hemagenta (M) into a color signal, and the process returns to step S8.

In step S16, if the M key 69 is not turned on, the process advances to step S18. In step S18,
It is determined whether or not the C key 70 is turned on, and the C key 70 is turned on.
If it is turned on, proceed to step S1.9. In step S19, the color signal conversion circuit 87
Then, the process returns to step S8.

In step 818, if the C key 70 is not turned on, the process advances to step S20. In step S20,
It is determined that the B key 71 has been turned on, and the color signal conversion circuit 87 is commanded to convert the black (B) color signal, and the process returns to step S8.

In step 21, it is determined whether the batch printing flag is set, and if it is not set, step 22
Proceed to.

In step S22, an image forming operation is performed for a single color component. That is, since this is the mode for producing a film for producing a printing original plate, monochrome copying (image formation) using a monochrome thermal transfer ink ribbon is performed by the above-described operation.

In this case, when the color signal conversion circuit 87 is instructing to convert the yellow (Y) color signal into a color signal, image formation is performed for the yellow component of the image of the document, and the color signal of the color signal conversion circuit 87 is hemagenta (M). When commanding conversion to , image formation is performed on the magenta component of the original image,
When the color signal conversion circuit 87 is commanded to convert Hessian (C) to a color signal, image formation is performed on the cyan component of the image of the original, and the color signal conversion circuit 87 Hessian (B)
When instructing the conversion into a color signal, image formation is performed for the black component of the original image. In this case, it is assumed that a solid black thermal transfer ink ribbon is set in advance, and as the paper P, for example, a plastic film is set in advance.

As a result, different films for producing printing original plates can be obtained for the yellow component, magenta component, cyan component, or black component of the original image.

If it is determined in step 21 that the batch printing flag is set, the process proceeds to step 23.

In step 23, the color signal conversion circuit 87
) to a color signal, and the process proceeds to step 24. In step 24, image formation for the yellow component of the original image is performed on the first sheet of plastic film or paper, and the process proceeds to step 25.

In step 25, the color signal conversion circuit 87
) to a color signal, and the process proceeds to step 26. In step 26, image formation for the magenta component of the original image is performed on a second sheet of plastic film or paper, and the process proceeds to step 27.

In step 27, the color signal conversion circuit 87 converts the Hessian (C)
Then, the process proceeds to step 28. In step 28, image formation for the cyan component of the original image is performed on the third sheet of plastic film or paper, and the process advances to step 29.

In step 2, the color signal conversion circuit 87
) to a color signal, and the process proceeds to step 30. In step 30, image formation for the black component of the original image is performed on a fourth sheet of plastic film or paper.

The provision of print alignment marks A when performing an image forming operation for a single color component as described above will be described.

That is, in the 111 color mode, a mark addition signal, that is, a "1" signal from the main control section 81 is supplied to the AND circuit 105, and the gate of the AND circuit 105 is opened.

In this state, the image signal of one component of the original is supplied bit by bit from the binarization circuit 88 to the buffer 107 and stored. At this time, the data synchronization signal (DCLK) and line synchronization signal (H8YNC
) is supplied to the counter 100, and the line synchronization signal (H8
YNC) and a page synchronization signal (PSYNC) are supplied to the counter 101.

As a result, when the image signal of the first column of the first line is supplied to the buffer 107, the counters 100 and 101 each count up.

According to the count value of the counter 101, the output end 103a of the ROM 103 outputs a "1" signal as a pattern selection signal, and the output end 103b outputs a "1" signal as a vertical mark signal. Also, the counter 100
R according to the count value of R and the signal from the output terminal 103a.
The output end 102a of the OM 102 outputs a "1" signal as a horizontal mark signal, and the output end 102b outputs a "0" signal as register mark data.

This registration mark data is stored in buffer 108.

A "1" signal is output from the AND circuit 104 based on the vertical mark signal from the output terminal 03b and the horizontal mark signal from the output terminal 102a. The output of this AND circuit 104 is sent to the buffer 1 via an AND circuit 105.
08 and is also supplied to a buffer 107 via an AND circuit 105 and an inverter circuit 106.

Therefore, the registration mark data "O" signal stored in the buffer 108 is transmitted to the alignment mark generation circuit 9.
7 is supplied to the thermal head temperature control section 93. At this time, the buffer 107 is prohibited from outputting its stored data.

Thereafter, similarly to the above, registration mark data is output to the four corners of the image.

Therefore, when image formation is performed for one color component of a document image in monochrome mode, a pattern of print alignment marks A is output corresponding to the four corners, as shown in FIG. 12(a). Otherwise, the image data for one color component from the binarization circuit 88 is output as is to the thermal head temperature control section 93. As a result, Figure 12 (
As shown in b), print alignment marks A are printed at the four corners, and an image for one color component is printed in addition to these marks.

In this way, the original is optically scanned to produce cyan.

It is read as three types of color signals, green and yellow, and these three types of color signals are read as yellow and magenta.

It converts into four-color image forming signals of cyan and black, and prints a single-black thermal transfer ink ribbon according to one of these four-color image forming signals or four sequentially output image forming signals. It is used to form images on plastic film or paper. As a result, it is possible to create a film for printing original plates very easily, with a relatively simple structure, without using conventional complicated production processes such as exposure and development, and it is also small and inexpensive. can. Furthermore, by switching modes, images are formed on paper using thermal transfer ink ribbons of a plurality of colors in accordance with the image forming signals of the four colors. As a result, it can be used not only for producing films for printing original plates, but also as a color copying machine, which is very convenient.

In addition, marks for print alignment can be easily and accurately applied to the film (base plate) for producing a printing original plate.

Furthermore, since the marks for print alignment are applied without area gradation, there is a drawback that area gradation is applied along with the image, making the marks blurred and difficult to see. First, clear and appropriate print alignment marks can be provided.

−32= In the above embodiment, the case where the print alignment marks are provided at the four corners has been described, but the present invention is not limited to this.
There may be one, or two or more. If there are two or more, reliable alignment is possible.

In addition, although a mode key is provided on the operation panel and the mode is switched using this mode key, the present invention is not limited to this. The mode may be switched by.

Furthermore, instead of the mode key, a separately provided print alignment mark designation switch may be used to designate the marking.

Further, although the gradation means is an area gradation, other gradations such as density gradation may be used.

[Effects of the Invention] As detailed above, according to the present invention, a film for producing a printing plate can be produced very easily without using the complicated production process as in the past, and it can be realized in a small size and at a low cost. Besides, it can also be used as a color copying machine in addition to creating films for printing master plates, and marks for print alignment can be easily and clearly and accurately added to films for creating printing master plates. An image forming apparatus can be provided.

[Brief explanation of the drawing]

The drawings are for explaining one embodiment of the present invention.
The figure is a block diagram schematically showing the overall control system.
The figure is a schematic perspective view with a part cut away to show the overall structure, FIG. 3 is an external perspective view schematically showing the overall structure, and FIG. 4 is a side view schematically showing the structure of the document scanning section. 5 is a perspective view showing the scanner moving mechanism of the document scanning section, FIG. 6 is a vertical side view schematically showing the structure of the image forming section, and FIG. 7 is a perspective view for explaining the transfer operation state. 8 is a plan view showing the configuration of the thermal transfer ink ribbon, FIG. 9 is a plan view of the operation panel, FIG. 10 is a block diagram for explaining the color signal conversion circuit in detail, and FIG. 11 is a positioning diagram. 12(a) is a diagram showing the relationship between image data and the pattern of print alignment marks; FIG.
FIG. 13B is a diagram showing the printing state of the image and the print alignment mark, and FIG. 13 is a flowchart for explaining the operation. 0...Original, P...Paper (image forming medium), 2...Operation panel, 8...Original scanning unit, 9... Image forming section, 11...Scanner, 31...Thermal head, 34...
...Thermal transfer ink ribbon (image forming medium), 61...
...Mode key (mode changeover switch), 62...
...Color selection key, 63...Numeric keypad, 72.
...-Pattern printing key, 81...Main control section, 82°8
3... Sub-control unit, 87... Color signal conversion circuit, 88... Binarization circuit (area gradation means), 93...
... Thermal head temperature control section, 97 ... Alignment mark generation circuit (generation means), 100 ... Horizontal counter, 101 ... Vertical counter, 102.103
...ROM. 104.105...AND circuit, 106...Inverter circuit, 107.108...Buffer. Applicant's agent Patent attorney Takehiko Suzu Figure 4 Figure 5

Claims (11)

[Claims] (1) A scanning means for optically scanning a document and reading it as multiple types of color signals; a color conversion means for converting each color signal obtained by the scanning means into image forming signals of multiple colors; A gradation means that performs gradation on each of the obtained image forming signals of a plurality of colors, and a single color or multi-color image depending on the one or more image forming signals to which gradation is performed by the gradation means. an image forming means for forming a single-color or multi-color image on an image forming medium using a forming medium; a generating means for generating a pattern of print alignment marks; and when forming an image with the image forming means. An image forming apparatus comprising: means for forming an image by applying a pattern of print alignment marks from the generating means without going through the gradation means. (2) The image forming apparatus according to claim 1, wherein the gradation means performs area gradation. (3) The image forming apparatus according to claim 1, further comprising a specifying means for specifying the provision of print alignment marks. (4) The image forming apparatus according to claim 3, wherein the designation means is a print alignment mark designation switch provided on the operation panel. (5) The image forming apparatus according to claim 1, wherein the plurality of types of color signals are cyan, green, and yellow, or three types of red, green, and blue. (6) Image forming signals of multiple colors include yellow, magenta,
Claim 1 characterized in that the four colors are cyan and black, or the three colors are yellow, magenta and cyan.
The image forming apparatus described in . (7) The single-color image forming medium is characterized by consisting of one color, black, and the multi-color image forming medium is characterized by consisting of four colors, yellow, magenta, cyan, and black, or three colors, yellow, magenta, and cyan. An image forming apparatus according to claim 1. (8) The image forming apparatus according to any one of claims 1 and 7, wherein the image forming medium is a thermal transfer ink ribbon. (9) The image forming apparatus according to claim 1, wherein the image forming medium is paper or a plastic film. (10) The image forming apparatus according to claim 1, wherein the image formed on the image forming medium is used for creating an original plate for offset printing. (11) The image forming apparatus according to claim 10, wherein the printing alignment mark is generated only when creating an original plate for offset printing.