JPH02293155A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent a change in image density by correcting the density value of digital image data to be transmitted to a head part on the basis of accumulation data obtained by successively adding the digital image data per thermal recording element. CONSTITUTION:Accumulation data is determined by successively adding digital image data for every thermal recording element C by an addition means A. Based on the accumulation data, a correction means B finds correction data by an operation using a predetermined operation formula including the accumulation data as a variable, thereby correcting the density value of the digital image data to be transmitted to the head part and controlling an electric conduction to each of the thermal recording elements C. Alternatively, for example, a look-up table may be used as the correcting means B in accordance with the accumulation data as a read address, whereby the pulse width of an image signal is changed, or a dither pattern may be varied. In this manner, a density change caused by the temperature increase of the thermal recording elements can be corrected, and a uniform image density can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming apparatus that forms an image using a recording element that uses thermal energy.

[Prior Art] Conventionally, bubble jet type devices and thermal transfer type devices are known as devices of this type. Bubble jet type devices have a heating section (heater) installed in the ink liquid path of the head section, and when the heating section is energized, thermal energy is given to the ink to generate steam bubbles. Ink droplets are ejected using bubbles. The size of the heating part of this device is much smaller than that of a piezoelectric element, making it possible to create a high-density multi-nozzle system and making it more compact. Full color. It has features such as being able to achieve high speed. On the other hand, thermal transfer devices melt ink on an ink ribbon and transfer the ink onto a recording material (generally paper) by applying electricity to a heating element. This device has features such as a simple structure, relatively low noise, and clear printing at a reasonable price.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional bubble jet device, the temperature of the heating section increases due to heating due to electricity supply, so the ink jet 1 differs between the beginning and the end of writing, and the image density decreases. The downside is that it changes.

Further, in the thermal transfer type device, as described above, the temperature of the heating element increases when energized, so the amount of ink transferred differs between the beginning and end of writing, resulting in a change in image density.

The object of the invention is to provide an image forming apparatus that eliminates the above-mentioned drawbacks and prevents changes in image density. [Means for Solving the Problems] In order to achieve the above object, the present invention provides an image forming apparatus that performs image formation by energizing a plurality of heating recording elements of a head portion according to digital image data.
Equipped with an addition means for sequentially adding digital image data for each heating type recording element, and a correction means for correcting the 7 degree value of the digital image data sent to the head section based on the cumulative data obtained by the addition means. It is characterized by

[Function] According to the present invention, the density of image data is corrected in a time-division manner using the accumulated data values of the entire image data in response to the temperature rise of the heating type recording element of the recording head section. Since the heating amount of the recording head section is controlled by doing this, it is possible to control the image density.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings. FIG. 1 shows the basic configuration of an embodiment of the present invention. In this figure, A is an addition means that sequentially adds digital image data to each heating type recording element C. Reference numeral B denotes a correction means for correcting the density value of the digital image data sent to the head section based on the accumulated data obtained by the addition means A.

As correction step B, for example, data conversion may be performed using a look-up table to change the pulse width of image A2 using accumulated data as a read address, or a dither pattern may be changed using accumulated data as a read address. This can be achieved by Further, the correction data can also be obtained by providing a calculation means as the correction means B and performing calculations using a predetermined calculation formula using the above-mentioned cumulative data as a variable.

FIG. 2 shows the circuit configuration of the electric circuit system of a color copying machine according to an embodiment of the present invention, and FIG.
Figure CB) shows the printer section. Further, FIG. 3 shows a structural cross section of the color copying machine of this embodiment.

Hereinafter, each component unit and its contents will be explained in order.

In FIG. 2 (8), 1 is a synchronization signal processing section,
Paper leading edge detector 22 of printer unit 2000 in FIG. 2(B)
Based on the signal from 20, various timing signals are generated in synchronization with the horizontal synchronization signal 22 output from the synchronization control circuit 2l60. Reference numeral 2 denotes a close-contact type CCD sensor block, which reads the document and converts the image signal into an electrical signal 5 and outputs it using the soda horizontal synchronization signal (R}ISYNC) generated by the synchronization signal processing unit l and the drive signal 4. do. 3
is a signal processing section that performs waveform shaping processing to prevent the high frequency components of the electrical signal 5 from attenuating. Reference numeral 6 denotes an image processing block which manually inputs the output signal of the signal processing section 3, and is composed of an analog processing section 7, a connection memory 8, and an image processing unit (IPII) 9.

The image signal from the signal processing section 3 is first input manually to the analog processing section 7. In the analog processing section 7, the signal 5 from the contact type CCO sensor block 2 is converted into cyan (C) for each pixel.
．． Green (G). Since the configuration is such that the yellow (Y) signal is sequentially output, the signals are first separated for each color of C, G, and Y. next,
In the analog processing section 7, each developing device of the printer section 2000 is colored yellow (Y). Magenta (M). Since it supports cyan (C), the above C. For now, change the G and Y image signals to red (R). Convert to green (G) and blue (8) signals. This conversion process is performed by arithmetic processing according to the formulas C-G-B and Y-G-n. In addition, these Il. Since the output voltage of the signals divided into G and B changes linearly with respect to the concentration, the A/D (analog-digital) converter provided in the analog processing section 7 converts the signals into 8-bit concentration signals. is converted to The above processing is executed by the analog processing section 7.

The image signals for each color of R, G, and B digitized by the analog processing section 7 are divided into five channels, but since the video signals of each channel are not synchronized,
The linking memory 8 combines the images into one image data. Combined by link memory 8, and R, G
, B signals to Y, M, C signals are sent to the image processing unit (IPt1) in synchronization for each color.
Sent to 9th. In IPtl9, shading processing for correcting light distribution and control unit 1 of reader unit 100
0, the desired color signal is selected, and the 8-bit image data 1l that has been subjected to predetermined color conversion processing is sent to the printer unit 20.
00.

On the other hand, apart from controlling the image data 11, the control unit 10 drives a motor driver l3 for manipulating the original, controls the rotation of the motor l2, and also controls the power supply unit (C.V.) for lighting the exposure lamp l4. l1) 15, a copy start key (copy disclosure key), and an operation unit 16 having various keys for performing other operations.

On the other hand, in FIG. 2(B), the control unit 2500 on the printer unit 2000 side controls the selector of the binarization circuit, which will be described later, to C.
Controlled by signals from Pro (central processing unit) 2110.

Now, Y, M output from IPU9 of league part 100
, C, Bk (black) image data 11 is input to the synchronization control circuit 2160 of the printer section 2000. Since the speeds of the image clock of the reader section 100 and the image clock of the printer section 2000 are different, the synchronization control circuit 2160 has a function to synchronize them and the image data 1l.
It has a function to match the color reproduction density of the printer section 2000. The output data from the synchronous control circuit 216o is inputted to the inkjet driver 2200 to drive the inkjet recording head 2223 to form an image.

The control unit 2500 of the printer unit 2000 sends and receives signals via the control unit 1G of the soda unit 100 and the communication control unit 24.
controls each control element of the printer unit 2000.

For example, the control unit 2500 controls the drive motor 2285 for conveying the transfer material, and the paper leading edge detector 2 2 0 0
An actuator 2298 that drives the registration roller is controlled by signals such as h% and the like. Note that 25o2 is the CPU
ROM (read only memory) that stores the control procedure executed by 2110, 2503 is a ^/D converter that converts analog data to digital data, 25o4 is CPII
2110 is a RAM (random access memory) used as a work area.

As shown in FIG. 3, the copying apparatus 80 is composed of a reader section 100 and a printer section 200θ.

In FIG. 3, reference numeral 83 denotes a document scanning unit, which performs vertical scanning in the direction of arrow 8 in order to read the image of the document 84 on the document table. At this time, the exposure lamp l4 in the document scanning unit 83 is Light. The reflected light from the original 84 is guided to a focusing lens array 86 and focused on a contact type color CCO sensor 87 . The close-contact color CCO sensor 87 has 5 chips each with 1024 pixels arranged in a staggered manner, with each pixel being 62.5μa+ (1/16mm), and each pixel is 15.5μ1×62.5μ×3.
It is divided into parts, and color filters of (:, G, and Y are pasted on each part).

The optical image focused on this contact type color CCD sensor 87 is converted into an electrical signal for each color. These electrical signals are subjected to the predetermined processing described above in FIG. 1(A) by the image processing block 88. The color separated image electrical signals formed by image processing block 88 are sent to printer 2000.
is sent to and printed.

Now, the color image data from the league unit 100 is subjected to temperature processing and the like, and finally drives an ink jet recording head (hereinafter referred to as an ink head) 2223.

The drive signal modulated according to the image data is sent to a heating section (not shown) in the inkjet 2223, and ejects dots corresponding to the image.

One horizontal scan of this dot ejection corresponds to one horizontal scan of an image, and in this example, the width is 1716 mm.

The four colors of the ink heads 2223 are arranged in a predetermined color order according to the paper conveyance direction, the distance of each head is stored in the buffer memory in the synchronous control circuit 2160, and the image signal is sent from the synchronous control circuit 2160. The signal is transmitted to the inkjet driver 2200, and the ink head 2
223 performs image recording (printing). When forming an image, when the operator places the document 84 on the document table of the reader section 1O in advance and presses the copy start key from the operation section 16, the reader section 100 performs a prescan once to print the image. In order to process the contents, the synchronization control circuit 2160 performs predetermined arithmetic processing.

Next, referring to FIG. 4, the above-mentioned synchronous control circuit 2160
will be explained in more detail.

In the above pre-scan, Y. M. C, Bk color data (video signal) 11
is the image control circuit 31 in the synchronous control circuit 2160
, 34. :17.40, and by the processing operation described later in FIG. 5, the addition data of each color data is stored in the RAM 32,
35, 38, and 4l. RAM32, 35, 3
The data stored in 8.41 is subjected to a predetermined calculation with the manually input video signal 11 in the next copying sequence, and the calculation result is stored as a video signal in the buffer memories 33.36, 39.42 corresponding to each color position. The distance between the heads is corrected. 43 is a synchronization circuit for the correction process. The synchronization circuit 43 generates an internal clock (CLκ) and an internal horizontal synchronization signal in synchronization with the paper leading edge detection signal of the paper leading edge detector 2220. Furthermore, the control unit 2500 controls the image control circuits 31, 34, 37, 38, 40. It sends out a predetermined timing signal to control each gate.The image control circuits 31, 34, 37.40 and RAMs 32, 35, 38.41 each have the same circuit configuration, so the representative As an example, the operations of the image control circuit 3l and the RAM 32 that process the Y signal will be explained in more detail with reference to FIG.
When the video signal 1l is manually input from the video signal 9 to the image control circuit 31, the selector 5l first selects and outputs the video signal 11 in the direction controlled by the control unit 2500. That is, in the copying sequence, the video signal 11 is transmitted to the control unit 250.
Since the control signal 60 of 0 is passed through, it is outputted to the next stage selector 59 through the selector 5l, and outputted as it is to the buffer memory 33 as a video signal. On the other hand, the video signal input to the latch circuit 54 during pre-scanning is sent to the latch circuit 53 in a predetermined adder (^DD) 55.
After being added to the output signal of , it is input to FIFO (flip-flop circuit) 52.

The signal that entered the PIFO 52 is an RC (read control) for synchronization control sent out from the synchronization circuit 43.
signal and the WC (write control) signal.
The data is outputted from the latch circuit 53 as line-delayed data, and added to the output data of the latch circuit 54 by an adder 55. In this way, the added data and the video signal are cumulatively calculated, and the added data of the horizontal line is sent to the controller 2500.
The data is stored in the RAM 32 via the gate circuit 56 at a predetermined timing according to the timing signal 62 from the synchronization circuit 43 in synchronization with the WC signal sent from the synchronization circuit 43. Next, in the copying sequence, the data in the RAM 32 is output from the gate circuit 56 in response to the signals 65 and 62 and sent to the arithmetic unit 58, where it is combined with the current video signal from the next stage selector 5l and a predetermined arithmetic operation. It is calculated based on the formula and output from the selector 59 to the buffer memory 33.

The selector 59 selects and outputs video data calculated based on the accumulated data in the RAM 32, since it is necessary to heat the image data with a large amount of black data in advance. Therefore,
The control unit 2500 reads the data in the RAM 32 and controls the selector 59, and also divides one scan into n parts during pre-scanning and sequentially writes the cumulatively calculated data to the R8M 32 which has n tables.
By reading out the corresponding table data from the RAM 32 every n divisions of one scan and performing calculations, the amount of video data added by the calculator 58 can be made variable sequentially in accordance with the temperature change of the heating section (heater) of the ink head 2223. can.

The arithmetic unit 58 described above does not have to be a logical arithmetic circuit, but may be configured as a look-up table using memory. At this time, the arithmetic unit 58 corrects the human data 11 in such a way that the concentration decreases as the cumulative amount of data sent from the RΔM 32 through the gate 56 increases. Thereby, the image density can be made uniform during one scan. As a method for correcting this data, a known halftone expression technique can be applied. For example, the inkjet driver 2200 modulates the density by changing the pulse width according to the value of the video data, or the arithmetic unit 58 modulates the density according to the accumulated data. It is preferable to modulate the density by changing the pattern. On the other hand, making the level of the voltage applied to the ink head 2223 variable has the problem that the circuit configuration of the inkjet driver 2220 becomes complicated and stable control is difficult.

M. The other three color signals of C and Bk are also processed in the same way as the above-mentioned YfX signal, and are stored in the respective buffer memories 36 and 39.
．． 42.

Other Embodiments Also, in this embodiment described above, the ink head 2223
If the sum of the cumulative degrees for each discharge port varies around the 8i end, by inputting the averaged data read from the RAM 32 into the calculator 58, the heat of only the predetermined discharge port can be reduced to the surrounding area. This will avoid problems that could cause problems. In addition, in the embodiment of the present invention described above, density correction is performed using the cumulative value of image data obtained by pre-scanning, but the cumulative value is obtained during the copying cycle without pre-scanning, and the cumulative value is Density correction may be performed using change data.

Further, in the above-mentioned embodiment, a bubble inkjet recording type copying machine has been described, but it goes without saying that the present invention can be similarly applied to a thermal transfer type apparatus.

In addition, in the above-described embodiment, the league section was exemplified as the source of image data, but the source is not limited to this, but may include word processors, etc. Personal computer, facsimile machine. Other image data generation devices such as magneto-optical disk devices can be applied.

[Effects of the Invention] As explained above, according to the present invention, image data is recorded in a time-division manner using the accumulated data values of the entire image data in response to the temperature rise of the heating type recording element of the recording head. Since the amount of heating of the recording head section is controlled by correcting the density, uniformity of image density can be achieved.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the basic configuration of an embodiment of the present invention, FIG. 2(A) is a block diagram showing the circuit configuration of a reader section in an embodiment of the present invention, and FIG. 2(B) is a block diagram showing the circuit configuration of a reader section in an embodiment of the present invention. A block diagram of the printer section in one embodiment; FIG. 3 is a sectional view showing a schematic cross-sectional configuration of a copying machine in one embodiment of the present invention; FIG. 4 is a detailed circuit of the synchronous control circuit in FIG. 2(B). Block Diagram Showing Configuration FIG. 5 is a block diagram showing the detailed circuit configuration of the image control circuit shown in FIG. 4. 2... CCD sensor block, 3... Signal processing unit, 9... Image processing unit (IPt1), 31,:
14, 37. 40... image control circuit, 32,
35, 38.41...RAM, 33.36.39.
42... Buffer memory, 55... Adding circuit, 58... Arithmetic unit, 80... Copying machine, 83... Original scanning unit, 84... Hara ■ High, 87... CCD sensor , 88... Image processing block, 100... League section, 2000... Printer section, 2l60... Synchronous control circuit, 2200... Inkjet driver, 2223...
- Inkjet recording head, 2500...control unit. Figure 1 Figure 2 (B) 2160 area cram school #I Naw 8 pay

Claims (1)

[Scope of Claims] 1) In an image forming apparatus that forms an image by energizing a plurality of heating type recording elements of a head portion according to digital image data, the digital image data is transmitted to each of the heating type recording elements. An image forming apparatus comprising: an adding means for sequentially adding; and a correcting means for correcting a density value of digital image data sent to the head section based on cumulative data obtained by the adding means.