JPS61252759A - Image forming device - Google Patents

Abstract

PURPOSE:To copy sharply an original image not having much density difference by storing a non-image forming signal to a level being a prescribed input level or below of a density correction signal stored in a random access memory and changing the copy density in response to the content of the random access memory. CONSTITUTION:Plural different density correction signals Y2, Y3 are stored in a ROM141, the content of the ROM141 is read in response to the operation of a density designation key 45 on an operation panel 4 and the content of a RAM131 is rewritten. That is, in operating the density designation key 45, a read address signal S0 of the ROM141 in response to,e.g., the operation number of times is generated by a main control section 100. The density correction signal of the ROM141 is read in response to the read address signal S0, written in the RAM140 and the picture forming density is changed over. Further, the forming density of the image corresponding to dirt of the original picture is changed over by operating a threshold designation key 46 on the operation panel 4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an image forming apparatus applied to, for example, a thermal transfer type color copying machine.

[Technical background of the invention and its problems]

Conventionally, in this type of image forming apparatus, only the image density can be changed, and the image density has been adjusted to handle colored originals and thin originals. For example, when copying a document with a dirty base, such as an old newspaper, the image density is lowered to make the entire image lighter and the dirt on the base is removed.

For this reason, there is a problem that the original image also becomes thin.

[Purpose of the invention]

This invention was made based on the above circumstances.
The purpose is to provide an image forming apparatus that can clearly copy an original image with a dirty background and no difference in density.

[Summary of the invention]

The present invention stores, for example, a density correction signal for setting copy density in a random access memory, and also stores a non-image forming signal below a predetermined input level of this density correction signal. The copy density can be changed depending on the content of the image.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1(d) shows the external appearance of the image forming apparatus.
An image information reading device 2 is detachably provided on the upper surface of the device main body 1. The image information reading device 2 is provided with a document cover 3 that can be opened and closed freely, and a document table (not shown) made of transparent glass on which a document is placed is provided under the cover 3. There is. This image information reading device 2 optically scans a document set on a document table by reciprocating a scanner section (details will be described later) consisting of an exposure optical system along the lower surface of the document table. This optical information is photoelectrically converted, and an operating panel 4 is provided on the upper surface. The signal converted by this image information reading device 2 is supplied to an image forming section 5 which is detachably provided on the right side of the device main body 1, and in this image forming section 5, a transfer material is transferred according to the converted signal. An image is formed on the paper. There is an operation button J? A flannel 6 is provided. This operation panel 6 includes an online scanner key 7 for selecting the image information reading device 2 connected to the main body 1, and an online scanner key 7 to be operated when taking out the thermal transfer reden as a transfer agent through a door 8 provided on the side. An eject key 9 and a display 10 are provided. In addition, a guide section 1 for manually feeding paper is provided at the front of the image forming section 5.
1 is provided so as to be openable and closable, and a paper discharge tray 12 is provided on the upper surface of the paper tray 12 from which the paper after the transfer is discharged.

Furthermore, a paper feed cassette 13 for storing paper is provided in the main body 1 of the apparatus located below the image forming section 5 so as to be freely accessible and removable.

On the other hand, FIG. 2 shows the configuration of the image information reading device. Two light sources 23 are arranged in parallel on a carrier and a jig 22 constituting the scanner section 21, and two lenses 24 are arranged in an inverted V shape between the light sources 23. . A photoelectric converter 25 consisting of a color CCD is provided at the lower end of this lens 24. the carriage 22
One end is slidably inserted into the guide shaft 26, and is attached to a so-called timing belt (toothed belt) 27 stretched along the guide shaft 26. This timing belt 27 is driven by a wrist motor 28.

In other words, the timing belt 27 is stretched between the motor pulley P8 provided on the rotating shaft of the pulse generator 28 and the idle boob 923.
The scanner section 21 is moved in the directions of arrows A and B in the figure in accordance with the operation.

Note that 29 is an A/D converter that converts the output signal of the photoelectric converter 25 into a digital signal, and 30 is an inverter 3.
1 is a flat cable that supplies the output power to the light source 23 and also supplies the output signal of the A/D converter 29 to the image forming section 5.

FIG. 3 shows the operating armpit 4 of the image information reading device 2. As shown in FIG. This operation arm panel 4 includes a print key 41 for instructing to start printing, a numeric keypad 42 for specifying the number of prints, a clear/stop key 43 for canceling the number of prints or instructing to stop printing, and a number display for displaying the number of prints, etc. 44, density specification key 45 for specifying print density;
Threshold specification key 46, density specification key 45, threshold specification key 46 for setting the density threshold for removing dirt etc. from the base
It consists of a display 47 that displays that the is being operated, and a display 48 that displays various displays. This indicator 48 includes a jam display section 481 that lights up when a paper jam occurs in the main body 1 of the apparatus, and indicates various conditions such as no adhesive for the reden cassette installed in the main body 11fC of the apparatus, or a cassette itself not installed. A paper display section 483 that displays the installed state of the paper feed cassette 8 or the presence or absence of paper, and a scanner display section 4B that displays the operating state of the scanner section 11. Mode key 45
, and a concentration display section 486 that selectively displays the setting and threshold value set by operating the threshold value designation key 46.

Further, the image forming section 5 has a configuration as shown in FIG. 4. That is, a grating 50 is installed approximately in the center of the image forming section 5, and a grating 15 is installed.
In front of the recording head 0 (leftward in the state of FIG. 4), a thermal recording head 51 is arranged so as to be movable toward and away from the platen 50.

Furthermore, to the above-mentioned thermometer, Do 51 is a reden case,) R
A thermal transfer ring 52 is placed between the thermal transfer plate 51 and the platen 50.

Then, the paper P is pressed against the platen 50 in a good state with the thermal transfer member 52f interposed therebetween, and in this state, the heating element (not shown) formed in the shape of a T-shape is transferred to the thermal thermal transfer platen 51, and the image information is transferred to the thermal transfer member 52f. The ink on the thermal transfer den 52 is heated and melted by generating heat in response to the heat transfer, and is transferred onto the paper P.

Further, a paper feed roller 53 is provided in the apparatus main body 1 diagonally below the platen 50, and the paper feed roller 53 is configured to sequentially take out the paper Pt as a transfer material stored in the paper feed cassette and the tonneau 3 one by one. It has become.

The taken out paper P passes through a paper guide path 54'ft and is guided to a registration roller 55 disposed diagonally above the paper feed roller 53, and its leading edge is aligned by the registration roller 55.

Thereafter, it is transferred toward the platen 50 and the pressing roller 56
．． 57, it is accurately fed into a state where it is wrapped around the platen 50.

On the other hand, the thermal head 51 presses the paper PT platen 50 through the thermal transfer gun 52t, and as shown in FIG. It is designed to be transcribed.

Further, the thermal transfer redden 52 is yellow (2), approximately the same size as the paper P, as shown by range A in FIG. 6, for example.
(Mazen), cyan (C), each ink section 60m,
60b, 60at - Yellow (2) provided side by side or as indicated by range opening.

Magenta (goods), cyan (C), and black (B) ink portions 60a.

sb, 1 with 60b, 60e, and 60d arranged side by side.
After transferring the colors one by one, the paper Pt is returned to its original state and overlapped one after another accurately.

Further, the side edges corresponding to the respective ink portions 60a to 60d of the thermal transfer reden 52 are provided with the necessary information to identify each ink portion 60a to 60tlt and to control the leading edge of each ink portion 60&~60tl to coincide with the leading edge of the paper. A barcode BC is provided. This number code BC is read by a bar code sensor (indicated by 78 in FIG. 8) which will be described later.

If the thermal transfer resin includes a black ink portion 61)d, this black ink portion 60d is used when it is desired to produce black clearly. Even if it does not have the black ink portion 60dt, approximately black can be produced by overlapping three colors.

In this way, the paper P is reciprocated by the number of colors by the rotation of the platen 50, but the path of the paper P at this time is the first one, which is sequentially arranged along the lower surface of the paper ejection tray 12. It will be guided onto the second guide 61.62.

That is, the explanation will be made with reference to FIGS. 7(a) to 7).

First, the paper P supplied from the paper feed cassette 13 passes through the registration roller 55 and the arrangement portion of the first vibrator 63 and is wound around the platen 50 . (See FIG. 7(A)) Next, the platen 50 rotates using a nockle smoke (not shown) as a driving source to transport the paper P at a predetermined speed and form a line tod shape along the axial direction of the platen 50. The heating element of the thermal head 51 (
(not shown) generates heat according to the image information, and the thermal transfer 5
The second ink 60 is transferred onto the paper P.

Furthermore, the leading edge of the paper P that has passed through the platen 50 is
The first paper provided along the lower surface of the paper discharge tray 12 is sent onto the ID 61 by the distribution gate 64 . (See FIG. 7(B)) In this way, the paper P onto which the ink 60 of one color has been transferred is transported backwards by reversing the platen 50, and then passes through the first sorting gate K. The 630 rotational displacement action drives the first onto a second guide 62 provided along the lower surface of the id 6. (See FIG. 7(c)) In this way, by reciprocating the paper P a plurality of times, a plurality of colors are transferred.

Finally, all the colors of ink 60 are transferred to the nine paper P.
The paper is guided by the second sorting dart 64 to a pair of paper discharge rollers 65 and discharged onto the paper discharge tray 12 . (See Fig. 7)) In Fig. 4, roller pairs 66 and 67 are for conveying manually fed paper, and these roller pairs 66 and 6
The paper conveyed by the resistor 7 is guided to the resist μm 55 via the guide path 68.

Next, the configuration of the image forming section 5 will be further explained. In FIGS. 8 to 10, the printer block 71 has almost the same external shape as the ribbon cassette Rc, and this block 71 supports the thermal head 51 from the rear side. Head holder 7
2. A member 73 integrally attached to the head holder 72; a rod 25 with one end attached to the head holder 22 and the other end connected to the drive link 74; a pivot shaft 76 of the link 74; The coil spring 77 rotates the link 74 in one direction and moves the thermal head 51 toward the platen 50 through the opening and the door 5t, and detects the bar code attached to the thermal transfer (ink) printer 752. A barcode detector 78 consisting of a light emitting element and a light receiving element is provided.

The platen 50 is attached to a frame 29 attached to both sides of the printer 71, and this frame 79 is provided with pressure rollers 56, 57O, support shafts 81 for pressing the paper against the platen 50. ing.

The pressure rollers 56, 51 are driven by a solenoid (not shown). Further, a paper guide 82 is provided between the pressure roller 56 and the platen 500. Further, the frame 79 is provided with a motor 83 for driving the thermal head 51 and a motor frame 84, as shown in FIG. The motor 8
A cam is provided on the rotation shaft (not shown) of 3, and the lever 85 provided on the rotation support shaft 76 is rotated by this cam, so that the thermal head 51 resists the biasing force of the coil spring 77. It is a trap to be driven. The motor frame 84 also includes a platen drive motor 86 and a thermal transfer (ink) cartridge housed in the ribbon cassette R. N52
In-drive motors 89 and 90 are provided to drive the winding cores sv and ss (shown in FIG. 8). These motors 8
6, 89.90 is connected to the platen 50 via gears (not shown);
The winding cores 8'i and 88 are driven, and among these, the winding core 87.88t - the rotation center of the gear to be driven is the first
As shown in FIG. 0, the engaging protrusion 91. ．． 91□ is provided. By controlling these motors 89 and 90,
Heat transfer? The engine 52 can run in both forward and reverse directions.

Also, the ribbon cassette R is! It is said that it can be attached to and detached from the printer holder 71. That is, IJ, j? As shown in FIG. 11, the ribbon cassette Re has a holder 2 between the exposed back side of the thermal transfer ribbon 52 and the ribbon cassette Rc.
, member 73, and thermal head 51, the cross section is formed into a substantially U-shape. In addition, the ribbon cassette Rc has a core storage section 931.
.

93, and the fitting part 7 of the printer block 71 (
(shown in FIGS. 9 and 10) is fitted into the slit 93.
is formed along the length direction. This slit 93
m and the length t of the fitting portion 711 are approximately equal, and this length t is set to be more than half the width dimension of the thermal transfer retin 52. Therefore, by moving the ribbon cassette R with respect to the printer 21 in its length direction,
The reden cassette Rc can be attached to or removed from the printer block 71. Further, the core storage portions 932, 93. The winding core 81 stored inside is on the side part of the
．． Engagement recess 941.94 attached to 88! Is there a setting? Connector cassette Rc is printer Glock 71
1IC installed, this engagement recess 94. ．．
94. and the engaging protrusion 91. ．． 91° are engaged with each other. vinegar? When the thermal head 51 is driven in the direction of the platen 5o with the printer block 7 mounted with the printer cassette Rc, the thermal transfer plate 52 moves to the eighth position.
As shown in the figure, it is brought into contact with the platen 5° by a member 73. A sheet of paper (not shown) is interposed between the platen 5o and the thermal transfer zone 752, and the thermal head 5 generates heat according to the image information, thereby causing thermal transfer. N5
The ink No. 2 is heated and melted and transferred onto the paper.

FIG. 12 schematically shows the overall control system.

Main control unit 100. 1st. Second. Third-control unit 101,1
02 and 103 are each constituted by, for example, a microcomputer. The main control section 100 controls the entire image forming apparatus. Second. The third sub-control units 101, 102, and 103 are the main control unit 10, respectively.
Controlled by 0. Here, the first sub-control unit 101 mainly controls the image information reading device 2. That is, the light source 23 is connected to the first sub-control section 101 via a light source control section 104t, and the pulse motor 28 for driving the carriage 22 is connected via a motor drive section 105. Furthermore, this first sub-control unit 101 includes the photoelectric converter 25 provided with a filter consisting of R, G, and B, for example, an A/D converter 29, and a resolution converter 106.
is connected.

This resolution converter 106 converts the resolution of the photoelectric converter 25 to the resolution of the thermal head 51.

Further, a mode changeover switch 107 for adjusting the wavelength distribution of the light source 230, switching the overall hue, etc. is connected to the main control section 100, and the operation panel 4
and online scanner key 7 provided in 6,
Eject key9. Print key 41. Part 108 of operation keys consisting of numeric keypad 42° clearst, key 43, etc.
A display section 109 consisting of a display section 10.48 is connected. Furthermore, this main control section 100 includes a correction circuit 1.
10. Luminance color difference separation circuit 111, image quality improvement circuit 112,
A color signal conversion circuit 113 and a binarization circuit 114 are connected. The correction circuit 110 is a circuit that performs so-called shading correction on the signal output from the resolution conversion section 106. The luminance/chrominance separation circuit 111 separates the shading-corrected signal into a luminance signal and a chrominance signal. Further, the image quality improvement circuit 112 performs edge enhancement and density correction (r correction) on the output signal of the luminance and color difference separation circuit 111. Color signal conversion circuit 113
represents the color signal of the light output from the image quality improvement circuit 112 as Y,
It is intended to convert into an ink color signal consisting of M, C, and B. Furthermore, the binarization circuit 114 is a well-known Didema) +
This is to binarize the input signal using a J-box.

Further, the third sub-control unit 103 controls writing and reading of the memory 115. The memory 115 stores the transfer data output from the binarization circuit 114 for each ink color signal.

Further, the second sub-control section 102 mainly controls the image forming section 5, and 1) a detection switch group 116 for detecting the operating state of each section is connected to the second sub-control section 1θ2. , the drive motor 86 of the platen 50 via the drive unit 117, and the thermal transfer motor 86. Motor 8 that drives 752
9.90, a drive system 118 consisting of a motor that drives the paper feed roller 53, registration roller 55, paper discharge roller 65, etc., a lensoid (not shown) that drives the first and second sorting darts 63, 641, etc. is connected. moreover,
A thermal head 51 and a thermal head temperature control section 119 are connected to the second sub-control section 102 . This sumal head temperature control section 119 is connected to the binarization circuit 11.
4 or the transfer data supplied from the memory 115 to the thermal head 51, and controls the driving pulse width of the thermal head 51 according to a signal supplied from the temperature side portion of the thermal head 51 (not shown); This is to control the temperature of the thermal head 51 to an appropriate value.

Next, the main parts of this invention will be further explained. In the present invention, it is possible to make a copy at any density while removing dirt and the like existing in the original image at any density. This image density adjustment is performed by the image quality improvement circuit 112 described above.

FIG. 1(a) shows the image quality improvement circuit 112.

The image quality improvement circuit 112 includes an image enhancement circuit 130 and a density correction circuit 131. The output signal of the luminance and color difference separation circuit 111 is first sent to the edge stiffening circuit 13.
0, and the contours of the luminance signal and color difference signal are corrected. This signal with the enhanced contour is supplied to a density correction circuit (γ correction circuit) 131. This density correction circuit 131 is a RAM (random access
140 (memory) 140 and ROM (read only memory) 141.

This RAM 146 stores density correction signals as shown by the solid line γ in FIG. This is the read address signal. Therefore, the luminance signal and color difference signal are corrected according to their signal levels. Here, stains on the original image can be avoided by setting a threshold value Th1, for example, in the read address signal, and making the output signal corresponding to the address signal below this threshold value Th□ a non-image forming signal (0'' level signal). Appropriate density can be achieved during image formation.

The ROM 141 also has γ2. γ3
Different m! A plurality of correction signals are stored, and the contents of this ROM 141 are read out in response to the operation of the density designation key 45 on the operation panel 4 described above, and are stored in the RAM.
The contents of 131 can be rewritten. That is,
When the density designation key 45 is operated, the main control unit ioo generates, for example, a read address signal S0 of the ROM 141 according to the number of operations. The density correction signal from the ROM 141 is read out in response to the read address signal S0 and written into the RAM 140. In this way, the image forming density can be switched.

Further, the forming density of an image corresponding to the stain equal pressure of the original image can be changed by operating the threshold designation key 46 of the operation/main panel 4. That is, when the threshold value specification key 46 is operated, R
A glance address signal Sa of the AM 140 is generated, and a write data signal S of, for example, a '0'' level is supplied to the RAM 140 together with this signal S1.
The threshold value in RAM J 40 is as shown in FIG.
Th.

Th, and so on.

According to the embodiment described above, a threshold value is set for the density correction signal, and input signals below the threshold value during this period are treated as non-image forming signals. Therefore, it is possible to set the overall copying density while eliminating some of the dirt on the original image, so it is possible to copy clearly even originals with very little difference in density from the dirty background, for example. be.

In addition, since the overall copying density and the threshold value can be changed, it is possible to perform copying while erasing stains at an arbitrary density, which is convenient in practice.

Note that this invention is not limited to the above embodiments,
Of course, various modifications can be made without departing from the gist.

〔Effect of the invention〕

As described in detail above, according to the present invention, it is possible to provide an image forming apparatus capable of clearly copying an original image with a dirty background and an S-reverse difference.

[Brief explanation of the drawing]

The drawings show one embodiment of the invention.6. D. Figure 1 (,) is a configuration diagram showing an example of an image quality improvement circuit, Figure 1 (b)
2 is a block diagram showing an example of a density correction circuit, (cl is shown to explain the density correction signal, FIG. 2D is a perspective view showing an overview of the image forming apparatus, and FIG. 2 is a diagram of an image information reading device. FIG. 3 is a plan view showing the structure of the operation panel, FIG. 4 is a side sectional view showing the structure of the image forming section,
Fig. 5 is a perspective view shown to explain the transfer operation state, Fig. 6 is a plan view showing the ink application state during thermal transfer, and Fig. 7 (a) to 7) are during multicolor transfer. The explanatory diagrams shown for explaining the movement of the paper, FIGS. 8 to 10, respectively show the main parts of the image forming section. FIG. 8 is a side sectional view, FIG. 9 is a perspective view, and FIG. Is the diagram in Figure 8? FIG. 11 is a side sectional view showing the state in which the link cassette is removed, FIG. 11 is a perspective view showing the structure of the link cassette, and FIG. 12 is a block diagram showing the structure of the control system. 1... Apparatus body, 2... Image information reading device, 5...
・Image forming unit, 45...Density specification key, 46...Threshold value specification key, 5...Thermal head, 52...Thermal transfer IJ fn, 100...Main control unit, 101-10
3... 1st. Second. Third sub-control unit, 112... Image quality improvement circuit, 131... Density correction circuit, 140...R
A.M. 141...ROM. Applicant's representative Patent attorney Takehiko Suzue Figure 1 (a), 112 Figure 1 Figure 1 Figure 1 (d) Figure 5 Figure 6 A To E3 BC Figure 7 Figure 7 Figure 8 ○琺

Claims (1)

[Scope of Claims] 1) Optical scanning means that optically scans an original image and outputs an electrical signal corresponding to the original image, and image formation that forms an image on a transfer material according to the electrical signal obtained by this means. The image forming apparatus includes a density correction means for setting a density correction signal and a non-image forming signal for the original image, correcting an output signal of the optical scanning means using these signals, and supplying the signal to the image forming means. An image forming apparatus characterized by: 2) The density correction means includes a random access memory in which a density correction signal and a non-image forming signal are stored, and a read memory in which a plurality of different density correction signals for changing the stored contents of the random access memory are stored. 2. The image forming apparatus according to claim 1, further comprising an only memory.