JPH06960A - Image forming device - Google Patents

Abstract

(57) [Summary] [Purpose] To reduce power consumption and power supply cost. [Structure] An original image is read, and an image is recorded by driving a full line head in accordance with the read image data to eject ink.
Ink ejection signals corresponding to the read color image data are counted for each color, and the high density area of each color is detected according to the count value. Then, for an area where a high-density area exists for at least one color, the moving speed in the sub-scanning direction and the data reading speed are slowed to reduce the printing speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus having an ink jet type recording means.

[0002]

2. Description of the Related Art In the ink jet recording, by driving an energy generating means of a recording head on the basis of an image signal, flying ink droplets are ejected from a fine ejection port toward a recording material, and the flying ink droplet is formed on the recording material. To form an image consisting of a dot pattern. This system is suitable for color recording, and in the case of color, a plurality of recording heads are used corresponding to a plurality of ink colors (for example, yellow, cyan, magenta, black).

FIG. 6 is a longitudinal sectional view showing the structure of an ink jet type image forming apparatus having a width head having a plurality of recording elements corresponding to a length 10 in a width direction 10 which is a direction 8 at right angles to a recording material. is there. In the figure, width heads 1C, 1
M, 1Y and 1Bk have a length equivalent to the width of the largest recording paper that can be used in this machine, and each has approximately 5000 ink ejection nozzles, and each nozzle has an energy generating means (heater heater in this case). Is provided. Power supplies 6C, 6M, 6Y and 6Bk for supplying power to the energy generating means of the head are provided for each color. The heads are arranged side by side on the upper portion of the conveyor belt 2 for four colors. Therefore, the head moves in the main scanning direction (perpendicular to the paper feed direction) like the conventional serial scan type.
Unlike printing while moving to, printing in the main scanning direction can be done at one time. As a result, the leading edge of the recording paper fed from the cassettes 4 and 5 and sent from the transport belt 2 and the image on the original are fed from the original on the original glass 3 in one reading operation. Since the ink is ejected from the width head in the order of 1C, 1M, 1Y, 1Bk in accordance with the head, printing can be performed at a very high speed.

[0004]

However, in the above-mentioned conventional example, when high density printing is performed, many energy generating means are driven at a high speed at one time, resulting in considerable power consumption of each head. Head power supply 6
Since C, 6M, 6Y, and 6Bk must have sufficient capacity to supply electric power, there is a problem that the cost becomes high as a result.

Furthermore, since there are four colors of such power supplies, the power consumption of the entire apparatus becomes considerable.

The present invention has been made in view of the above points,
An object of the invention is to provide an image forming apparatus capable of suppressing power consumption and reducing power supply cost.

[0007]

That is, the present invention is an image forming apparatus having a recording means for forming an image on a recording material by ejecting ink in accordance with the image signal, and the recording means according to the image signal. A driving means for driving the driving means, a counting means for counting the ink ejection signals according to the image signal, and a control means for controlling the driving means according to the count value of the counting means, and the recording speed according to the image density. It is characterized by changing.

As a result, the recording speed control for the high density area is performed.

[0009]

Embodiments of the present invention will be described in detail below with reference to FIGS. FIG. 1 is a vertical cross-sectional view showing the structure of an ink jet type image forming apparatus having a wide head according to an embodiment of the present invention. In FIG. 1, 1 is a platen glass on which a document to be copied is placed, 2 is a document pressure plate for pressing the placed document, 3 is an operation unit, and a start switch 4, various display units 5, and the number of copies are input. It is composed of the numeric keypad 6 and the like. 7 is an exposure lamp for illuminating the original, 8 and 9
Reference numerals 10 and 10 are mirrors for forming an image of the reflected light from the original document irradiated by the exposure lamp 7 on the color image sensor 11, 12 is an imaging lens arranged in the optical system,
The image signal 3 is subjected to various corrections to the image signals color-separated by the color image sensor 11 so as to faithfully reproduce the colors of the original, and 14C for cyan, 14M for magenta, and 1 for yellow.
When an original is scanned and read in order to send out an ink ejection signal to the width heads of 4B for black and 14Bk for black and to detect a high density portion of the original, and there is a portion having a certain density or more. Is the printer control circuit 15
It is an image control circuit that performs various controls such as sending a signal for prompting speed control.

Reference numeral 15 denotes a printer control circuit for controlling the operation of the printer unit, which controls a motor driver 31 for rotating the carry motor 27, a clutch (not shown), and a speed control signal from the image control circuit 13. I do. Further, a disc 28 having a long and narrow cutout is attached to the conveyance motor 27, and a photo interrupter 29 is attached so as to sandwich the disc 28. Therefore, according to the rotation of the conveyance motor 27, this photo is interrupted. The interrupter 29 outputs a waveform at regular intervals.
Reference numeral 16 is a pump for supplying ink to the width head of each color, 17C, 17M, 17Y and 17Bk are ink tanks of each color, and 18 is an adsorption charger, which is a recording material fed by the paper feeding means 22 to 25. Is electrostatically attracted to the transport belt 19 so that the recording material does not float or shift from the transport belt 19. 30C, 30M, 30Y, and 30Bk are power sources for supplying power to the energy generating means (heat generating heater) of each of the cyan, magenta, yellow, and black heads. Reference numeral 32 denotes a paper discharge roller for discharging the recorded recording material to the paper discharge tray 33. In this embodiment, each color head uses thermal energy to generate bubbles to cause the ink to change state and eject ink droplets from the ejection port.

FIG. 2 shows a circuit configuration example of such a control system.
In FIG. 2, the image control circuit 13 and the printer control circuit 1
Reference numeral 5 has microcomputers 201 and 202. The image control circuit 13 applies various corrections to the R, G, and B image signals color-separated by the color image sensor 11 and also performs a correction / color conversion circuit 203 for converting to Y, M, C, and Bk signals, and Y , M, C, Bk image width signals based on the width signals 14Y, 14M, 14C, 14Bk
Head drive circuit 204C, 2
04M, 204Y and 204Bk, main scanning data counting units 206C, 206M, 206Y and 206Bk that count data in the main scanning direction in synchronization with the clock from the main scanning data reading clock generating unit 205, and sub scanning data reading clock generating unit 207. Sub-scanning data counting units 208C, 208M, 208Y, 208 for counting data in the sub-scanning direction in synchronization with the clock signal from
Bk, selector 2 for switching the output destination of the ink ejection signal
09C, 209M, 209Y, 209Bk, and the output timing of the ink ejection signal in the sub-scanning direction is synchronized with the clock signal from the sub-scanning data read clock generation unit 207 or the signal from the photo interrupter 29. Selector 210 for switching between the main scanning data counting units 206C, 206M, 206Y and 206
Bk and sub-scanning data count units 208C, 208M,
Input ports 211 and 2 for sending respective outputs of 208Y and 208Bk to the microcomputer 201
12. A buffer memory 21 for holding the image signal output from the color image sensor 11 for a certain period of time
3. R that stores the program for the operation of this device
It has OM214 and the like.

The operation of this embodiment having the above configuration will be described with reference to the flow chart shown in FIG. 3 and the timing chart shown in FIG. The program according to the flowchart of FIG. 3 is stored in the ROM 214. First,
Place the original on the platen glass 1 and lower the original platen 2.
When the start switch 4 of the operation unit 3 is pressed (S1),
The output destination of the ink ejection signal is the main scanning data counting unit 20.
4C, 204M, 204Y, 204Bk and sub-scanning data count units 206C, 206M, 206Y, 206B
selectors 209C, 209M, 209Y,
A switching signal for switching the output of 209 Bk to B is output from the microcomputer 201. Further, a switching signal for switching the input of the selector 210 to A so that the output timing of the ink ejection signal in the sub-scanning direction is generated in synchronization with the clock signal from the sub-scanning data read clock generation unit 207 is a microcomputer 201.
(S3). Then, the first scanning is performed while irradiating the original document (not shown) with the exposure lamp 7. The reflected light at that time is imaged on the color image sensor 11 through the imaging lens 12 using the mirrors 8, 9 and 10 (S4). Next, the blue, green, and red image signals color-separated by the color image sensor 11 are the main scan data read clock from the main scan data read clock generator 205 and the sub scan data from the sub scan data read clock generator 207. It is input to the correction / color conversion unit 203 in synchronization with the read clock, and the main scanning data count units 206C, 206M, 20 are supplied from the correction / color conversion unit 203 as Y, M, C, and Bk ink ejection signals.
6Y, 206Bk and sub-scanning data counting unit 208
It is sent to C, 208M, 208Y, and 208Bk (S
5). Main scanning data counting unit 206C, 206M, 2
06Y, 206Bk and sub-scanning data counting unit 208
In C, 208M, 208Y, and 208Bk, counting of ink ejection signals from the correction / color conversion unit 203 is started in synchronization with the main scanning data read clock and the sub scanning data read clock, respectively (S6). These count values are sequentially input to the microcomputer 201 via the input ports 211 and 212, and the microcomputer 201 determines the continuity of the ink ejection signal according to the program. That is, the main scanning data counting units 206C, 20
6M, 206Y, and 206Bk are in the main scanning direction 1 for each color.
The number of discharge data for each line is counted. The microcomputer 201 determines for each line whether or not the count value of each main scanning data counting unit 206C, 206M, 206Y, 206Bk is a predetermined number or more, and if at least one count unit counts a predetermined number or more, the microcomputer 201 A high-density configuration determination counter provided in a RAM (not shown) in the computer 201 is incremented. The microcomputer 201 stores the count value and the color data of the sub-scanning data counting section for the line in which the number of data is equal to or more than the predetermined number in the predetermined area of the RAM as the leading edge address and the color data of the high density area. There is. Then, it is determined whether or not the count value of the high density region determination counter is equal to or greater than a predetermined number, and if the count value does not exceed the predetermined number, the same process is performed on the next line. Further, when there is a line in which the count values of all the main scanning data counting units do not exceed the predetermined number before the high density region determination counter counts a predetermined number, that is, when there is a low density line, the high density region determination counter and The leading edge address recording area is reset, and the above processing is repeated for the subsequent lines. Then, the main scanning data counters 206C, 206M, 206Y, 206B are again used.
When there is a line in which any of k counts a predetermined number or more, that is, a high density line, the high density region determination counter is incremented again, and the count value of the sub-scanning data count unit for this line is set to the leading end of the high density region. It is stored as an address.

When the count value of the high density area determination counter reaches a predetermined number, it is determined that there is a high density area. Then, the main scanning data counting units 206C, 206M, 206
The counting operation of the high-density area determination counter is continued until a line in which all the count values of Y and 206Bk do not exceed the predetermined number comes, and when there is a line in which the count values of all main scanning data counting units do not exceed the predetermined number. The counting operation of the high density area determination counter is interrupted, and the count value and the above-mentioned leading edge address data are stored in a predetermined area of the RAM as high density area data.

The above operation is performed for all areas of the original,
If there are a plurality of high density regions, the data for each high density region is stored in the RAM.

If there is a high density area, the input of the selector 210 is switched to B so as to receive the signal from the photo interrupter 29 as the sub-scanning synchronizing signal (S9). Next, selectors 209C, 209M, 209
The output of Y, 209Bk is switched to A, and the output destination of the ink ejection signal is set to the head drive circuit 204C, 204M, 204.
Y, 204 Bk (S10).

Then, a second scanning is performed (S1
1) The recording material is fed from the cassette 20 or 21 at a predetermined timing, the recording material is sent to the conveyor belt 19 by the conveyor roller 24 or 25 and the registration roller 26 at a predetermined timing, and the conveyor belt 19 is used for cyan. The print is sent to the bottom of the head 14C, and the print permission signal from the correction / color conversion unit 20 becomes active to enable printing (S1).
2). If there is a continuous ink ejection signal of a certain value or more (S13), the color and location of the ink ejection signal are already known. Therefore, the portion is stored in the RAM until it comes under any head. The transport motor 27 is operated at a normal speed until the required number of main scanning data read clocks and the required number of sub scanning data read clocks are counted.
Is turned (S14 to S15). After counting the required clocks, the rotation speed of the carry motor 27 is reduced as much as necessary. Then, according to the rotation, the disc 28
Rotate, and as a result, pulses are generated from the photo interrupter 29 at a cycle longer than that at the normal speed. This pulse serves as a sub-scanning data read clock, and printing is performed according to the movement of the conveyor belt 19 (S1).
6). After that, the same control is performed each time the high density area stored in the RAM reaches the recording area, and when passing a place where there are continuous ink ejection signals, the carry motor 27 rotates again at the normal speed (S17 to S18). ), The sub-scanning data is read out in accordance therewith, printing is performed, and the recording paper is ejected onto the ejection tray 33 by the ejection roller 32 (S19), and the operation ends.

(Other Embodiments) In the above embodiment, the disk 28 attached to the conveying roller 27 and the photo interrupter 20 are used.
Although the printing speed is reduced by changing the cycle of the sub-scanning data read clock, the circuit configured by the line memory 501, the counter 502, and the count value setting unit 503 performs the same function as shown in FIG. Is also good. That is, by connecting the ripple carry terminal of the counter 502 to the read reset terminal of the line memory, the ripple carry terminal becomes active and the data written in the line memory 501 is read out after counting the value set by the count value setting unit. The cycle of the sub-scanning data read clock becomes longer. The circuit speed of the carry motor 27 may be slowed down accordingly.

Although the circuits of the above-described embodiment are composed of general-purpose ICs, if these are combined for each color or one into a custom IC, it becomes more advantageous in terms of the size and cost of the substrate.

[0019]

As described above, according to the present invention,
Since the recording speed is changed according to the image density, the power consumption can be suppressed and the power supply cost can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of an inkjet type image forming apparatus to which the present invention is applied.

FIG. 2 is a block diagram showing a control system of the image forming apparatus shown in FIG.

FIG. 3 is a flowchart showing a control flow according to the present invention.

FIG. 4 is a diagram showing various signals in the control system block diagram shown in FIG. 2.

FIG. 5 is a block diagram showing a control system of another embodiment of the present invention.

FIG. 6 is a diagram showing a schematic configuration of a conventional inkjet type image forming apparatus.

[Explanation of symbols]

 4 Start Switch 13 Image Control Circuit 15 Printer Control Circuit 27 Conveyor Motor 28 Disc 29 Photointerrupter 201, 202 Microcomputer 203 Complementary Color / Color Converter

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location B41J 29/20 8804-2C 9012-2C B41J 3/04 103 X

Claims (3)

[Claims] 1. An image forming apparatus comprising a recording means for forming an image on a recording material by ejecting ink in accordance with an image signal, a drive means for driving the recording means according to the image signal, and an image signal. A count means for counting the ink ejection signals according to the above, and a control means for controlling the drive means according to the count value of the count means,
An image forming apparatus characterized in that a recording speed is changed according to image density. 2. The image according to claim 1, wherein the control unit controls the driving unit to slow down the driving speed of the recording unit when the count value of the counting unit exceeds a certain value. Forming equipment. 3. The image forming apparatus according to claim 1, wherein the recording unit ejects an ink droplet by causing a state change in the ink by using thermal energy.