JPH10217545A - Picture recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten a period of time for generating all of pulses by a method wherein timings for generating pulses in respective driving signals are made different for each printing head while a pulse width of a driving signals to be sent to at least one printing head is made different from the pulse width of another driving signal to be sent to at least one of the other printing heads. SOLUTION: Respective 8 pieces of pulses, having different pulse widths, are generated in strobe signals STB1-STB4 deviating from each other every time when respective pulses are generated in latch signals HD LD. Thus, a period of time necessary for generating all of pulses in respective strobe signals can be shortened and, further, the period of pulse, generated in the latch signals HD LD can be shortened whereby a printing speed can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image recording apparatus.

[0002]

2. Description of the Related Art Conventionally, in an image recording apparatus such as a color image recording apparatus, respective image forming portions for yellow, magenta, cyan and black are arranged along a carrier belt, and a recording medium is attracted to the carrier belt. The toner is conveyed in a direction perpendicular to the arrangement direction of the recording elements, and the toner images of the respective colors formed by the respective image forming units are transferred onto the recording medium in a superimposed manner to form a color image.

Each of the image forming units includes a print head formed by arranging a plurality of print elements in a line, and the print elements of each print head are selectively driven according to image data. It has become. By the way, in a print head using an LED element as a recording element, that is, an LED head, when each LED element of the LED head is driven at the same time, the power consumption increases and the power supply capacity needs to be increased. Therefore, in order to reduce the power supply capacity, each LED element of the LED head is divided into a plurality of blocks, a strobe signal as a drive signal is sent to each block, and a pulse is generated at a different timing for each strobe signal. Let L
The ED element is driven. Therefore, since the LED elements are driven at different timings for each block, the number of simultaneously driven LED elements is reduced, and the power supply capacity can be reduced accordingly.

However, in an image recording apparatus having a plurality of LED heads, if the strobe signals sent to the respective LED heads are generated in synchronization, continuous printing is performed and the respective image forming units are simultaneously operated. In such a case, LED elements are simultaneously driven between the LED heads, and the power consumption increases accordingly. Therefore,
In the strobe signal sent to each of the LED heads, the timing at which the pulse is generated is made different not only for each LED element block but also for each LED head.

[0005]

However, in the conventional image recording apparatus, resolution conversion is performed, an interpolation line is set between original lines, and an original image is formed on the original line and an interpolation image is formed on the interpolation line. The time required to generate all the pulses increases when the pulse width of the pulse generated in the strobe signal for forming the original image is long, especially when the image quality is improved by performing However, the printing speed is reduced accordingly.

FIG. 7 is a time chart showing the operation of the conventional image recording apparatus. In this case, the LED elements arranged in a line are divided into four blocks, and selectively emit light in accordance with the image data HD DATA of each color to expose the photosensitive drum. When the image data HD DATA of each color is sent to the shift register of each LED head, the latch signal HD LD
, A high-level pulse is generated, and the image data HD DATA in the shift register is latched by the latch circuit.

Next, strobe signals STB1 to STB4
, A low-level pulse is sequentially generated, and a driving current flows through the LED element in accordance with the latched image data HD DATA to cause the LED element to emit light. by the way,
In each of the strobe signals STB1 to STB4, the timing at which a pulse is generated differs for each block of the LED element and for each LED head. That is, the latch signal HD L sent to the LED head of each color
D, the pulses are generated in synchronization with each other, but the timing of the pulses generated by the strobe signals STB1 to STB4 is different for each of the strobe signals STB1 to STB4 and for each color. is there. Then, each of the strobe signals STB1 to STB4
The pulse width of the pulse is LED to form the original image
The light emission time when the element emits light is 25 [μS], and the light emission time when the LED element emits light to form an interpolated image is 12 [μS].

Therefore, in printing the first line, the strobe signals STB1 to STB4 for yellow are used.
After generating four pulses with a pulse width of 25 [μS] by shifting the timing, four pulses with a pulse width of 25 [μS] are shifted to the respective strobe signals STB1 to STB4 for magenta. generate. continue,
After shifting the timing to each of the strobe signals STB1 to STB4 for cyan to generate four pulses having a pulse width of 25 [μS], each of the strobe signals STB for black is generated.
The timing is shifted to B1 to STB4 so that the pulse width is 25.
Four pulses of [μS] are generated.

Next, in the printing of the second line, four pulses having a pulse width of 12 [μS] are generated by shifting the timing to each of the strobe signals STB1 to STB4 for yellow, and then each of the strobe signals for magenta is generated. Strobe signal STB
The pulse width is 12 by shifting the timing from 1 to STB4.
Four pulses of [μS] are generated. Subsequently, the timing is shifted to each of the strobe signals STB1 to STB4 for cyan to generate four pulses having a pulse width of 12 [μS], and then each of the strobe signals STB1 to STB1 for black is generated.
The pulse width is 12 [μ] by shifting the timing to STB4.
S] are generated.

In this case, since one interpolation line is set for one original line, the fourth line is printed in the odd lines after the third line in the same manner as in the printing of the first line. Subsequent printing of even lines is
Strobe signals STB1 to STB as in the case of line printing
At 4 each pulse is generated. As described above, every time each pulse is generated in the latch signal HDLD, it is necessary to generate 16 pulses with a pulse width of 25 [μS] in the strobe signals STB1 to STB4 while shifting all the pulses. The time required to do so increases. Therefore, the printing speed decreases.

The present invention solves the problems of the conventional image recording apparatus, shortens the time required to generate all the pulses in the drive signal, and increases the printing speed. It is an object to provide an image recording device.

[0012]

For this purpose, in the image recording apparatus of the present invention, a plurality of printing heads formed by arranging a plurality of printing elements in a line, and a plurality of printing heads for each printing head are provided. Drive signal transmitting means for transmitting a drive signal. Then, the drive signal transmitting means varies the timing of generating a pulse in each drive signal for each print head, and transmits the drive signal to at least one print head and the drive signal to at least one other print head. Pulse width adjusting means for making the pulse width of the pulse different from that of the drive signal to be applied.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a first schematic diagram of an image recording apparatus according to an embodiment of the present invention, and FIG.
FIG. 3 is a second schematic diagram of an image recording apparatus according to an embodiment of the present invention, and FIG. 3 is a perspective view of a color image forming unit according to the embodiment of the present invention.

As shown in the figure, an image recording device, for example,
In the color image recording apparatus 11, the first to fourth printing mechanisms P1 to P4 move from the upstream side (insertion side) to the downstream side (discharge side) in the conveying direction of the recording medium 37 along the endless carrier belt 19. It is arranged in order. The first
The fourth to fourth printing mechanisms P1 to P4 have image forming sections 12 for yellow, magenta, cyan, and black, respectively. Then, the first to third printing mechanisms P1 to P3
The image forming units 12 are integrally formed and housed in the case 50a to form the color image forming unit 25. Further, the image forming unit 12 of the fourth printing mechanism P4 is the same as the image forming unit 12 of the first to third printing mechanisms P1 to P3.
And is housed in the case 50b.

The first to fourth printing mechanisms P1 to P
Reference numeral 4 includes an electrophotographic LED (light emitting diode) printing mechanism, and has the same structure. Therefore, only the first printing mechanism P1 will be described, and the second to fourth printing mechanisms P2 to P4 will be the first. The description is omitted by giving the same reference numerals as those of the printing mechanism P1. The first printing mechanism P1 includes an image forming unit 12, a print head that performs exposure according to image data, that is, an LED head 13, and a transfer roller that transfers a toner image formed in the image forming unit 12 to a recording medium 37. Consists of fourteen.

The image forming section 12 includes a photosensitive drum 16 which is rotated about an axis 15 in the direction of arrow a, a charging roller 17 for uniformly and uniformly charging the surface of the photosensitive drum 16, and a developing device. Consisting of a vessel 18. The developing device 18 includes a developing roller 18a, a developing blade 18b, and a sponge roller 18 for supplying an appropriate amount of toner (not shown) to the developing blade 18b.
c, and a toner tank 18d for storing toner. When the toner in the toner tank 18d runs out, the toner tank 18d is replaced.

The toner in the toner tank 18d is sent to a developing blade 18b via a sponge roller 18c, and thinned and adhered to the surface of the developing roller 18a. Is sent to the developing section formed between the two. When the toner is thinned, the developing roller 18a and the developing blade 1
8b are strongly rubbed (rubbed) and triboelectrically charged. In this embodiment, the toner is frictionally charged to a negative polarity.

The LED head 13 includes an LED array composed of LED elements as recording elements (not shown), and a drive I (not shown) for driving the LED array.
C, a substrate 13a on which a register group (not shown) for holding image data is mounted, a rod lens array 13b for focusing light of the LED array, and the like. When image data is input from an interface unit to be described later, the LED head 13 causes each LED element of the LED array to emit light in accordance with the image data, exposes the photosensitive drum 16, exposes the photosensitive drum 16, An electrostatic latent image is formed on the surface of the C.16. Subsequently, the toner on the surface of the developing roller 18a is attached to the electrostatic latent image by electrostatic force, and the electrostatic latent image becomes a toner image.

The LED head 13 has a spring 13c.
Is pressed against the case 50a. Further, the carrier belt 19 includes first to fourth printing mechanisms P1 to P4.
Between the photosensitive drum 16 and the transfer roller 14. Incidentally, yellow toner is stored in the toner tank 18d of the developing device 18 in the first printing mechanism P1, magenta toner is stored in the toner tank 18d of the developing device 18 in the second printing mechanism P2, and the third toner is stored in the third printing mechanism P2. Cyan toner is stored in the toner tank 18d of the developing device 18 in the printing mechanism P3, and black toner is stored in the toner tank 18d of the developing device 18 in the fourth printing mechanism P4.

The LED head 13 of the first printing mechanism P1 has yellow image data of the color image data, and the LED head 13 of the second printing mechanism P2 has the magenta image data of the color image data. Data is input to the LED head 13 of the third printing mechanism P3, cyan image data of the color image data, and black image data is input to the LED head 13 of the fourth printing mechanism P4.

The carrier belt 19 is formed of a semiconductive plastic film having a high resistance value, and includes a driving roller 20, a driven roller 21, and a tension roller 22.
It is stretched between. In this case, the resistance value is such that the recording medium 37 can be attracted to the carrier belt 19 by electrostatic force, and when the recording medium 37 is separated from the carrier belt 19, It is set within a range where the remaining static electricity can be neutralized naturally.

The drive roller 20 and the driven roller 21
Is connected to a motor (not shown), and is rotated in the direction of arrow b by driving the motor. Further, the tension roller 22 is urged in the direction of arrow c by a spring (not shown) to apply tension to the carrier belt 19. The upper half 19a of the carrier belt 19 is
Each transfer section formed between each photoconductor drum 16 and each transfer roller 14 in the first to fourth printing mechanisms P1 to P4 can be run.

A cleaning blade 23 is provided to face the drive roller 20 with the carrier belt 19 interposed therebetween, and the tip of the cleaning blade 23 is pressed against the carrier belt 19. Therefore, as the carrier belt 19 travels, residual toner adhering to the surface of the carrier belt 19 is scraped off by the cleaning blade 23 and dropped into the waste toner tank 24. In addition, the cleaning blade 23 includes:
It is formed of a flexible rubber material, a plastic material, or the like.

On the lower right side of the color image recording apparatus 11 in FIG. The paper feed mechanism 30 includes a paper storage cassette 30A, a hopping mechanism 30
B, a transport roller 40, and first and second registration rollers 41 and 42 disposed to face the transport roller 40. The paper storage cassette 30A includes a recording medium storage box 31, a push-up plate 32, and a pressing unit 33, and the hopping mechanism 30B includes a discriminating unit 34, a spring 35, and a paper feed roller 36.

In the paper feed mechanism 30, first, the recording medium 37 stored in the recording medium storage box 31 is pressed against the paper feed roller 36 via the push-up plate 32 by the pressing means 33. In this state, when a motor (not shown) is driven to rotate the paper feed roller 36 in the direction of arrow e,
The recording medium 37 sandwiched between the paper feed roller 36 and the discriminating means 34 is guided by guides 38 and 39 and sent between the transport roller 40 and the first registration roller 41.

When the motor (not shown) is driven to rotate the transport roller 40 in the direction of arrow f, the recording medium 37 is transported by the transport roller 40 and the second registration roller 42.
Is transported in the direction of arrow d, guided by guides 81 and 82, and sent between the suction roller 83 and the carrier belt 19. The first and second registration rollers 41 and 42 are pressed against the conveyance roller 40.

The attraction roller 83 is pressed against the driven roller 21, charges the recording medium 37 sent by the paper feed mechanism 30, and attracts the recording medium 37 to the carrier belt 19 by electrostatic force. Therefore, the suction roller 83 is formed of a semiconductive rubber material having a high resistance value. A photo sensor 70 for detecting the front end of the recording medium 37 is provided between the suction roller 83 and the first printing mechanism P1 in the transport direction of the recording medium 37.
Is arranged.

Reference numeral 84 denotes a manual feed tray. The operator can manually insert the recording medium 37 along the manual feed tray 84 and the guide 85. Reference numeral 86 denotes a photo sensor for detecting the front end of the recording medium 37 inserted by hand. In this case, the recording medium 37 inserted manually is transported by the transport roller 40 and the second
Of the guide 81,
It is guided by 82 and fed between the suction roller 83 and the carrier belt 19.

A static eliminator 43 is provided so as to face the upper half 19a of the carrier belt 19 on the drive roller 20 side. The static eliminator 43 neutralizes the recording medium 37 adsorbed and conveyed by the carrier belt 19, cancels the attracted state, and facilitates separation of the recording medium 37 from the carrier belt 19. A photo sensor 71 for detecting the rear end of the recording medium 37, a guide 44, and a fixing device 45 are disposed on the left side of the static eliminator 43 in FIG. The fixing device 45 fixes the color toner image on the recording medium 37 on which the toner images of each color are transferred by the carrier belt 19 and the color toner images are formed. To this end, the fixing device 45 has a heat roller 46 for heating the toner on the recording medium 37 and a pressure roller 47 for pressing the recording medium 37 together with the heat roller 46.

Further, a discharge port 48 is provided on the left side of the fixing device 45 in the drawing, and the discharge stacker 4 is provided outside the discharge port 48.
The recording medium 37 on which printing has been completed is discharged to the discharge stacker 49. 4 is a block diagram of a control circuit according to the embodiment of the present invention, FIG. 5 is a circuit diagram of an LED head according to the embodiment of the present invention, and FIG. 6 is a time chart showing the operation of the image recording apparatus according to the embodiment of the present invention. It is a chart. Note that the reference characters Y, M, C, and K in parentheses indicate yellow, magenta, cyan, and black image forming units 12.
(FIGS. 1 and 2) or first to fourth printing mechanisms P1 to P4
It belongs to.

In FIG. 1, reference numeral 91 denotes a control circuit, which comprises a microprocessor or the like (not shown) and controls the entire color image recording apparatus 11. Also,
The control circuit 91 includes an SP bias power source (not shown) for applying a voltage to each sponge roller 18c,
a bias power source (not shown) for applying a voltage to a, a charging power source (not shown) for applying a voltage to each charging roller 17,
A transfer power supply (not shown) for applying a voltage to each transfer roller 14 and a suction power supply (not shown) for applying a charging voltage to the suction roller 83 are connected to each other.
The P bias power source, the DB bias power source, the charging power source, the transfer power source, and the attraction charging power source are controlled to be turned on / off according to an instruction from the control circuit 91.

Further, the control circuit 91 is connected to print control circuits 98Y, 98M, 98C, 98K as drive signal transmitting means corresponding to the respective image forming sections 12. Each of the print control circuits 98Y, 98M, 98C, 98K
Are stored in the memories 99Y and 99Y according to an instruction from the control circuit 91.
Image data of each color is read from 9M, 99C, and 99K, sent to each LED head 13, and controls the exposure time of each LED element (not shown) to form an electrostatic latent image on the surface of the photosensitive drum 16.

Reference numeral 100 denotes an interface unit.
The interface unit 100 includes the external device, for example,
The color image data sent from the host computer is separated for each color to generate image data for forming an original image on an original line, and an interpolation line is set between each of the original lines. The image data for forming an interpolation image is generated in the memory 99Y, the yellow image data is stored in the memory 99Y, and the magenta image data is stored in the memory 99M.
Then, the cyan image data is stored in the memory 99C, and the black image data is stored in the memory 99K.

In this case, for the yellow image data and the cyan image data, the image data for the interpolation line is first put, and for the magenta image data and the black image data, the image data for the original line is put first in each memory. 9
9Y, 99M, 99C, and 99K. The fixing device driver 101 controls the heat roller 4 in the fixing device 45.
The heater (not shown) in the heat roller 46 is driven so as to keep the temperature of No. 6 constant. The motor drive circuit 10
The motor 103 drives each of the motors 103 to 105, the motor 103 feeds the paper feed roller 36, and the motor 104 drives the photosensitive drum 16, the charging roller 17, the developing roller 18 a and the sponge roller 18 c of the fourth printing mechanism P 4, The transfer roller 14, the drive roller 20, the transport roller 40, and the heat roller 4 of the fourth printing mechanisms P1 to P4.
6, the first to third printing mechanisms P1
To P3, each charging roller 17, each developing roller 18a, and each sponge roller 18c are rotated. Each member rotated by the motor 104 and each member rotated by the motor 105 are connected by a gear or a belt (not shown).

When the motors 104 and 105 are driven, the peripheral speed of each photosensitive drum 16, the traveling speed of the carrier belt 19, and the conveying speed of the recording medium 37 are set to be equal to each other. . Then, the sensor receiver driver 106 controls each of the photo sensors 70, 71, 8
6 is operated to receive the output waveforms of the photosensors 70, 71, 86 and send them to the control circuit 91.

Next, the LED head 13 will be described. In this case, each L of the first to fourth printing mechanisms P1 to P4
Since the ED heads 13 have the same structure, only the LED head 13 of the first printing mechanism P1 will be described, and the LED heads 1 of the second to fourth printing mechanisms P2 to P4 will be described.
Description of 3 is omitted. 5, reference numeral 130 denotes 40 driver ICs arranged in a line, 131 denotes a 64-bit shift register connected to each driver IC 130, and 132 denotes a shift register corresponding to the shift register 131. A latch circuit 133 for temporarily storing the bit data of each bit is an output signal of the latch circuit 132 and strobe signals STB1 to STB1 as drive signals.
A gate circuit 134 operated in response to the STB 4 is provided with output signals OUT1 to OUT2 from the gate circuit 133.
The driver transistors 135 that are turned on / off in response to 560 are 2560 LED elements that emit light by receiving the drive current of the driver transistor 134. The LED elements 135 are arranged in a line and divided into four blocks, and the yellow image data HD DA
The photosensitive drum 16 is exposed to light by selectively emitting light corresponding to the TA. Then, the strobe signal ST
B1 to STB4 are set for each block, and sent to the LED head 13 independently.

Reference numeral 98Y denotes a print control circuit for outputting various signals to each driver IC 130. The yellow image data HD output from the print control circuit 98Y
DATA moves in the shift register 131 in synchronization with the transfer clock HDCLK, and is output to the adjacent shift register 131 after moving by 64 bits. All the shift registers 131 store yellow image data HD.
When DATA is sent, a high-level pulse is generated in the latch signal HD LD input to the latch circuit 132, and the yellow image data HD DATA in the shift register 131 is latched by the latch circuit 132.

Next, the strobe signals STB1 to STB4
Are sequentially generated, and the latched yellow image data HD DATA and the strobe signals STB1 to STB4 are calculated in the gate circuit 133. Then, the strobe signals STB1 to STB
4, when the pulse is generated, the output signal O is output in accordance with the latched yellow image data HD DATA.
UT1 to OUT2560 become high level, the driver transistor 134 is turned on, and the LED element 13
5, a drive current flows to drive the LED element 135 to emit light. The driving time at this time is determined by the pulse width of each pulse generated in the strobe signals STB1 to STB4.

Meanwhile, in the color image recording apparatus 11 having the above-described configuration, the LED heads 13 are provided for each of the first to fourth printing mechanisms P1 to P4.
, The strobe signals STB1 to STB4 are sent. The timing at which a pulse is generated in each of the strobe signals STB1 to STB4 is determined by the LED element 135.
Is different not only for each block, but also for each LED head 13.

That is, as shown in FIG.
Pulses are generated in the latch signal HD LD sent to the D head 13 in synchronization with each other, but the timing of the pulses generated in the strobe signals STB1 to STB4 is the same as the strobe signals STB1 to STB4.
It is different for each STB 4 and for each color. The pulse width of the pulse of each of the strobe signals STB1 to STB4 corresponds to the LED element 1 belonging to each LED head 13.
35, the LED elements 135 belonging to each LED head 13 have the same light quantity, but when the LED elements 135 are the same, the LED elements 13 are used to form the original image.
The emission time when emitting 5 is 25 [μS], and the emission time when emitting the LED element 135 to form an interpolated image is 12 [μS]. Note that even if the light emission time for forming the interpolation image is shorter than the light emission time for forming the original image, the image quality is not affected.

Therefore, each of the print control circuits 98Y, 98
The M, 98C, and 98K pulse width adjusting means (not shown) shift four timings to the yellow strobe signals STB1 to STB4 to print four pulses having a pulse width of 12 [μS] in the printing of the first line. After the generation, each of the magenta strobe signals STB1 to STB4
Then, four pulses having a pulse width of 25 [μS] are generated by shifting the timing. Subsequently, the timing is shifted to each of the strobe signals STB1 to STB4 for cyan to generate four pulses having a pulse width of 12 [μS], and then the pulses are shifted to each of the strobe signals STB1 to STB4 for black. Four pulses having a width of 25 [μS] are generated.

Next, in the printing of the second line, four pulses having a pulse width of 25 [μS] are generated by shifting the timing to each of the strobe signals STB1 to STB4 for yellow, and then each of the strobe signals for magenta is generated. Strobe signal STB
The pulse width is 12 by shifting the timing from 1 to STB4.
Four pulses of [μS] are generated. Subsequently, four pulses having a pulse width of 25 [μS] are generated by shifting the timing to the strobe signals STB1 to STB4 for cyan, and then the strobe signals STB1 to STB1 for black are generated.
The pulse width is 12 [μ] by shifting the timing to STB4.
S] are generated.

In this embodiment, since one interpolation line is set for one original line, printing of odd lines after the third line is performed in the same manner as printing of the first line. In the printing of the even-numbered lines after the fourth line, similarly to the printing of the second line, the strobe signal ST is output.
Each pulse is generated in B1 to STB4. Therefore, when a pulse having a pulse width of 12 [μS] is generated in the previous line, the pulse width is 25 [μS] in the next line.
Are generated, and a pulse having a pulse width of 12 [μS] and a pulse having a pulse width of 25 [μS] are generated alternately.

As described above, in the strobe signals STB1 to STB4 sent to each LED head 13, an original image is formed by a pulse having a long pulse width, and an interpolation image is formed by a pulse having a short pulse width.
Each time a pulse is generated in synchronization with the latch signal HD LT sent to the ED head 13, the interpolated image is converted by the at least one LED head 13 into the remaining L signals.
Since the original image is formed by the ED head 13, every time each pulse is generated in the latch signal HDLD, the strobe signals STB1 to STB4 include eight pulses having a pulse width of 25 [μS] and a pulse width of 25 pulses. Is 12
Eight pulses of [μS] are generated by being shifted from each other.

Therefore, the time required for generating all the pulses in the strobe signals STB1 to STB4 sent to each LED head 13 can be shortened.
As a result, power consumption can be reduced, and power supply capacity can be reduced. Also, the latch signal HD
Since the period of the pulse generated in the LD can be shortened, the printing speed can be increased.

Next, the operation of the control circuit 91 having the above configuration will be described. First, the control circuit 91 receives the color image data transmitted from the host computer via the interface unit 100, and
0 and instructions to the memories 99Y, 99M, 99C, and 99K. In the interface unit 100, the color image data is separated for each color to generate original line image data, and an interpolation line is set. The image data for the interpolation line is generated, and the image data for the original line and the image data for the interpolation line are stored in the memories 99Y and 99Y.
Store in 9M, 99C, 99K. In this manner, each of the memories 99Y, 99M, 99C, and 99K stores the image data of each color of one page to be printed on the recording medium 37.

Next, the control circuit 91 drives the motor 103 via the motor drive circuit 102,
6 is rotated in the direction of arrow e. The recording medium 37 in the recording medium storage box 31 is separated by the rotation of the paper feed roller 36, and only one sheet is sent to the guides 38 and 39, and the recording medium 37 is separated.
Reaches between the transport roller 40 and the first registration roller 41.

Next, the control circuit 91 controls the motor drive circuit 1
, Motors 104 and 105 are driven through the photoconductor drums 16, the charging rollers 17, the developing rollers 18a, and the sponge rollers 1 of the first to fourth printing mechanisms P1 to P4.
8c, each of the transfer roller 14, the drive roller 20, the transport roller 40, and the heat roller 46 of the fixing device 45 are rotated. At the same time, the control circuit 91 turns on the suction charging power supply and applies a charging voltage to the suction roller 83.

At this time, since the transport roller 40 is rotated in the direction of arrow f, the recording medium 37 is guided and transported by the first and second registration rollers 41 and 42 and the guides 81 and 82, and is transported. Reaches between the suction roller 83 and the carrier belt 19. At this point, the front end of the recording medium 37 is moved by the electrostatic force between the suction roller 83 and the driven roller 21 to the carrier belt 19.
Is adsorbed.

Further, the transport roller 40 further moves in the direction of arrow f.
When rotated in the direction, the recording medium 37 is conveyed in the direction of arrow d while being attracted to the carrier belt 19. On the other hand, the charging roller 1 of the first to fourth printing mechanisms P1 to P4
7. In order to apply a voltage to the developing roller 18a and the sponge roller 18c, the control circuit 91 turns on the charging power source, the DB bias power source, and the SP bias power source. The surfaces of the respective photosensitive drums 16 of the first to fourth printing mechanisms P1 to P4 are uniformly and uniformly charged by the respective charging rollers 17, and the first to fourth printing mechanisms P1 to P4 are used. The sponge roller 18c and the developing roller 18a are charged to a predetermined high voltage.

Next, the control circuit 91 issues an instruction to the memory 99Y storing the yellow image data, reads out one line of yellow image data from the memory 99Y, and sends it to the print control circuit 98Y. The print control circuit 98
Y is stored in the memory 99Y in accordance with an instruction from the control circuit 91.
The image data sent from the LED head 13
And sent to the LED head 13. The LED head 13 causes the LED element 135 corresponding to the transmitted image data to output a strobe signal S
The photosensitive drum 16 is driven for a time corresponding to the pulse width of the pulse generated in TB1 to STB4 to form one line of an electrostatic latent image corresponding to the image data on the surface of the charged photosensitive drum 16. In this way, an electrostatic latent image is formed line by line on the surface of the photosensitive drum 16 by the yellow image data sent from the memory 99Y line by line, and the image data of each line in the sub-scanning direction is obtained. When the electrostatic latent image is formed, the exposure ends.

Subsequently, yellow toner is made to adhere to the electrostatic latent image formed on the surface of the photosensitive drum 16 by the developing roller 18a, and the electrostatic latent image becomes yellow as the photosensitive drum 16 rotates. It becomes a toner image. Then, when the front end of the recording medium 37 reaches the transfer section, the control circuit 91 turns on the yellow transfer power supply and applies a voltage to the transfer roller 14. Thereby, the photosensitive drum 1
6 is transferred to the recording medium 37 by the transfer roller 14.
Is transferred to Further, with the rotation of the photosensitive drum 16, the toner images are sequentially transferred to the recording medium, and when the one-page toner image is transferred to the recording medium 37, the transfer of the yellow toner image ends.

During this time, the carrier belt 19 continues to run, and the recording medium 37 is moved to the first printing mechanism P1.
To the second printing mechanism P2. In the second printing mechanism P2, a magenta toner image is formed by the image forming unit 12, and the toner image is transferred to the recording medium 37 and superimposed on the yellow toner image. . Similarly, in the third printing mechanism P3, the formation of the cyan toner image by the image forming unit 12 and the transfer of the toner image to the recording medium 37 are performed by the image forming unit 12 in the fourth printing mechanism P4. Is formed, and the transfer of the toner image to the recording medium 37 is performed. The toner images of the respective colors are superimposed, and a color toner image is formed on the recording medium 37.

Thereafter, the recording medium 37 is conveyed to the static eliminator 43 by the carrier belt 19, and at this time, the control circuit 91 turns on the power supply for static elimination (not shown) to turn the recording medium 3 on.
7 is neutralized. As a result, the recording medium 37 is easily separated from the carrier belt 19, separated from the carrier belt 19 above the driving roller 20, guided by the guide 44, and sent to the fixing device 45. Then, when the recording medium 37 is separated from the static eliminator 43, the control circuit 91 turns off the static elimination power supply.

In the fixing device 45, the color toner image is fixed on the recording medium 37 by the heat roller 46 which has already reached the fixing temperature and the pressure roller 47 pressed against the heat roller 46. Recording medium 3
7, a color image is formed. When the fixing is completed, the recording medium 37 is discharged to the discharge stacker 49. When the photo sensor 71 detects the rear end of the recording medium 37, the control circuit 91 knows that the recording medium 37 has been discharged to the discharge stacker 49.

Subsequently, the control circuit 91 stops the motors 104 and 105 via the motor drive circuit 102. In the first to fourth printing mechanisms P1 to P4, when the transfer of each toner image is completed, the charging power supply, the SP bias power supply, the DB bias power supply, and the transfer power supply are turned off. When forming only a black image, the case 50a is lifted and separated from the carrier belt 19. However, when forming a color image, black is used as inking by under color removal (UCR) or the like. There is no need to lift case 50b.

In the present embodiment, the photosensitive drum 1
LED as print head to form electrostatic latent image on
Although the head 13 is used, a laser generator can be used instead of the LED head 13. Also, the first
Each of the fourth to fourth printing mechanisms P1 to P4 has an electrophotographic printing mechanism, but an ink jet printing mechanism, a thermal transfer printing mechanism, or the like can also be used.

Furthermore, in the present embodiment, the pulse width of the pulse generated in the strobe signals STB1 to STB4 is changed for each line, but may be changed for each dot. Also, it can be changed for each of a plurality of dots. In this embodiment, the pulse width for the interpolation line is changed. However, the pulse width for the original line can be changed.

Further, in the present embodiment, first to
Although the fourth printing mechanisms P1 to P4 are provided, the number of printing mechanisms can be changed. It should be noted that the present invention is not limited to the above embodiment, and various modifications can be made based on the gist of the present invention.
They are not excluded from the scope of the invention.

[0060]

As described in detail above, according to the present invention, in an image recording apparatus, a plurality of printing heads formed by arranging a plurality of printing elements in a line, and each of the printing heads And a driving signal transmitting means for transmitting a plurality of driving signals for each. Then, the drive signal transmitting means varies the timing of generating a pulse in each drive signal for each print head, and transmits the drive signal to at least one print head and the drive signal to at least one other print head. Pulse width adjusting means for making the pulse width of the pulse different from that of the drive signal to be applied.

In this case, the timing at which a pulse is generated in each drive signal differs for each print head, and the drive signal sent to at least one print head and the drive signal sent to at least one other print head And the pulse width of the pulse is different. Therefore,
Since the time required to generate all the pulses in the drive signal sent to each print head can be shortened,
The power consumption can be reduced, the power supply capacity can be reduced, and the printing speed can be increased.

[Brief description of the drawings]

FIG. 1 is a first schematic diagram of an image recording apparatus according to an embodiment of the present invention.

FIG. 2 is a second schematic diagram of the image recording apparatus according to the embodiment of the present invention.

FIG. 3 is a perspective view of the image recording apparatus according to the embodiment of the present invention.

FIG. 4 is a block diagram of a control circuit according to the embodiment of the present invention.

FIG. 5 is a circuit diagram of the LED head according to the embodiment of the present invention.

FIG. 6 is a time chart illustrating an operation of the image recording apparatus according to the embodiment of the present invention.

FIG. 7 is a time chart showing an operation of a conventional image recording apparatus.

[Explanation of symbols]

 11 Color Image Recording Device 13 LED Head 98Y, 98M, 98C, 98K Print Control Circuit 135 LED Element STB1-STB4 Strobe Signal

Claims (3)

[Claims] (A) a plurality of print heads formed by arranging a plurality of recording elements in a line;
(B) driving signal transmitting means for transmitting a plurality of driving signals for each of the print heads, and (c) the driving signal transmitting means sets a timing at which a pulse is generated for each of the driving signals for each print head. And a pulse width adjusting means for making the pulse width of the pulse different between a drive signal sent to at least one print head and a drive signal sent to another at least one print head. Image recording device. 2. The image recording apparatus according to claim 1, wherein the pulse width adjusting unit changes the pulse width for each line. 3. The image recording apparatus according to claim 1, wherein the pulse width adjusting unit changes the pulse width in dot units.