JPH1016305A - Exposure apparatus and image-forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To switch and print multivalued print data and binary print data by a small image-forming apparatus. SOLUTION: A light-emitting element of a light-emitting part 2 emits light by energy corresponding to a multivalued print data DA. Accordingly, printing is realized in an energy gradation method. The light-emitting element is turned on and off in accordance with a binary print data DB. Printing in an area gradation method is thus realized. The light-emitting element is driven in accordance with either of the print data by switching the multivalued and binary print data DA, DB.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an exposure apparatus and an image forming apparatus for realizing halftone printing using multi-level and binary printing data.

[0002]

2. Description of the Related Art Generally, there are an energy gradation method and an area gradation method as halftone printing methods.

The energy gradation method is a method of expressing gradation by controlling the amount of energy according to a current value applied to a light emitting element and its time to change the size of a printing pixel.
For example, when expressing in 16 gradations, 4-bit print data is given to the light emitting element. In the case of controlling the current value, the number of constant current power supplies corresponding to the number of gradations is provided.

On the other hand, the area gradation method is a method in which one pixel is constituted by a plurality of printing dots and gradation is expressed by controlling the number of printing dots. Binary printing data is given to a light emitting element. . For example, when expressing in 16 gradations, 16-bit print data is required when a matrix of 4 main scanning directions × 4 sub-scanning directions is formed.

Further, as one type of such area gradation method, there is a method in which only the number of printing dots in the sub-scanning direction is changed to express gradation, and such a method is used to express a smooth curve. Case (hereinafter referred to as "smoothing")
Suitable for.

[0006]

As described above, in the energy gradation method and the area gradation method, the density of print dots,
In the case where the number of print data is different and printing is performed by switching the gradation system, two types of IC chips having different circuit configurations corresponding to each system must be provided.
The image forming apparatus becomes expensive and bulky.

An object of the present invention is to provide a small-sized exposure apparatus and a small-sized image forming apparatus capable of switching between printing using multi-valued printing data and printing using binary printing data.

[0008]

According to the present invention, there is provided a light emitting section comprising a plurality of light emitting elements which are arranged linearly and form printing pixels, and an IC which selectively controls light emission of the light emitting elements individually.
A multi-level modulation drive circuit having a plurality of stages of shift registers and a plurality of switching elements within said IC chip and controlling energy applied to light emitting elements in accordance with print data for energy gradation. When,
And a binary modulation driving circuit for turning on / off a light emitting element in accordance with print data for area gradation using a part of the shift register and the switching element of the multi-level modulation driving circuit. Device.

According to the present invention, the light emitting element of the light emitting section emits light with energy corresponding to the print data for energy gradation, whereby printing by the energy gradation method can be realized. Further, the light emitting element is turned on / off in accordance with the print data for the area gradation, whereby printing by the area gradation method can be realized. A drive circuit for controlling the energy applied to the element in accordance with such multi-valued print data for energy gradation and binary print data for area gradation is provided by one IC.
Since the exposure apparatus can be provided on a chip, the size of the exposure apparatus can be reduced.

Further, the present invention is characterized in that an input switching circuit for switching input print data to one of a multi-level modulation driving circuit and a binary modulation driving circuit is provided in the IC chip.

According to the present invention, one of the energy gray scale method and the area gray scale method can be realized by switching and supplying print data of a plurality of bits.

Further, according to the present invention, there is provided a photosensitive member having a photosensitive layer formed on a transparent substrate, a light emitting portion comprising a plurality of light emitting elements arranged linearly and forming printing pixels, and the light emitting elements are individually selected. A multi-valued IC that has a plurality of stages of shift registers and a plurality of switching elements, and controls the energy applied to the light emitting elements in accordance with the print data for energy gradation. A modulation drive circuit, and a binary modulation drive circuit that uses a part of the shift register and the switching element of the multi-level modulation drive circuit and turns on / off a light emitting element according to print data for area gradation. A first pixel column formed on the photosensitive layer by the first exposure device, and a photosensitive layer formed by the second exposure device. It is an image forming apparatus according to claim in which the second pixel row formed are respectively disposed on the surface side and the back side of the photoreceptor so as to overlap each other.

According to the present invention, it is possible to realize the printing by the energy gradation method by causing the light emitting element to emit light with the energy corresponding to the printing data for the energy gradation, and to make the light emitting element correspond to the printing data for the area gradation. The printing by the area gradation method can be realized by turning on / off. First and second exposure devices each including the element are disposed on the front side and the back side of the photoconductor, respectively, and the first exposure device forms a first pixel column formed on a scanning line of the photosensitive layer, and a second column. By arranging the second pixel row formed on the scanning line of the photosensitive layer by the exposure device so as to overlap each other, and preferably overlapping by half the pixel pitch, the light emitting element density is increased and the light emitting element density is increased. A small-sized image forming apparatus capable of performing high-quality printing can be realized.

[0014]

FIG. 1 is a block diagram showing an image forming apparatus 1 according to an embodiment of the present invention. The image forming apparatus 1 includes a light emitting unit 2, a driving circuit 3, a selection circuit 5, and an input switching circuit 11, and the overall operation is controlled by a control circuit 6 connected to the apparatus 1.

The light emitting section 2 is composed of a plurality of, for example, 40 light emitting diode (LED) arrays A1 to A40.
Each is composed of four LED elements. The LED elements are arranged in a straight line, and light emission is selectively controlled individually by an IC chip to form a print pixel.

The IC chip has a driving circuit 3 inside.
And an input switching circuit 11, and the driving circuit 3 includes a multi-value driving circuit and a binary driving circuit. The multi-value drive circuit controls and drives the energy applied to the LED elements in a single LED array based on the multi-level print data DA for energy gradation. The binary driving circuit drives the LED elements in a single LED array on / off based on binary print data DB for area gradation. Drive circuit 3
Specifically, the print data DA and DB provided from the control circuit 6 are temporarily stored in the storage unit 7, and the drive unit 8 stores the print data DA and D
B is supplied to the light emitting unit 2 at the timing of the strobe signal STB from the control circuit 6.

The input switching circuit 11 selects one of the print data DA and the print data DB and supplies it to the storage unit 7. The selection circuit 5 selects an LED array to be driven from the LED arrays A1 to A40 based on a selection signal SEL given in a time division manner from the control circuit 6. Therefore, dynamic driving for applying the print data DA and print data DB from the drive circuit 3 to the selected LED array can be realized.

FIG. 2 is a circuit diagram of the image forming apparatus 1.
In this case, five input terminals are provided for inputting print data, and one of the five input terminals is switched so that 2
Input value data. Although an example in which 5-bit print data is used as the multi-value print data DA will be described, the number of input terminals is not limited to five, and may be any number as long as it is two or more.

The LED arrays A1 to A4 of the light emitting section 2
Since 0 is composed of 64 LED elements L1 to L64, 2560 LED elements L1 to L64 are provided in total. Print data DA and DB are given to these LED elements L1 to L64, respectively.

The driving circuit 3 comprises 64 blocks BL1
To BL64, and each block BL1 to BLB
L64 is used to transfer 5-bit print data in parallel.
Stage shift register SA, latch circuits LA1 to LA5,
AND circuits AA1-AA5 and constant current sources RA1-RA
5 is included. Note that one bit of the shift register SA is also used for binary, and is denoted by reference numeral SB in FIG. In addition, a latch circuit L that is also used for binary
A5, an AND circuit AA5, and a constant current source RA5 are indicated by reference numerals LB, AB, and RB, respectively.

The multi-value drive circuit includes a 5-bit shift register SA, latch circuits LA1 to LA5, AND circuits AA1 to AA5 used as switching elements, and constant current sources RA1 to RA5. The shift register SA and the latch circuits LA1 to LA5 correspond to the storage unit 7, and the AND circuits AA1 to AA5 and the constant current source RA
1 to RA5 correspond to the drive unit 8. Constant current sources RA1 to R
The current value of A5 is selected to be different from each other.
A, 2 mA, 4 mA, 8 mA, and 16 mA are selected, and gradation printing of 5 bits = 32 gradations is realized.

The binary driving circuit includes a 1-bit shift register SB, a latch circuit LB, an AND circuit AB used as a switching element, and a constant current source RB. The current value of the constant current source RB is 16 mA.

The tristate buffer TB1 and the tristate buffer TB2 transfer the print data DA to the shift register SA of the multi-value drive circuit or the print data D.
B is an input switching circuit 11 for individually switching and supplying B to a shift register SB of a binary driving circuit. The tri-state buffer TB1 is provided for each input terminal, and the tri-state buffer TB2 includes first, seventeenth, thirty-third,
It is provided for each of the nine blocks BL1, BL17, BL33, and BL49.

When the print data DA is input, the buffer TB1 is turned on by the high-level switching signal S, and the buffer TB2 is turned off and becomes high impedance by the inverted low-level switching signal S. Therefore, the print data DA is sequentially stored in the shift register SA. When the print data DB is input, the buffer TB1 becomes high impedance and cut off by the low-level switching signal S, and the buffer TB2 becomes conductive by the inverted high-level switching signal S. Therefore, the print data DB is sequentially stored in the shift register SB.

The switching signal S is also supplied to the motor driver 1
2 given. The motor driver 12 outputs a switching signal S
The rotation speed of the photosensitive member according to the level of
Drive.

FIG. 3 is a timing chart for explaining the operation of the image forming apparatus 1. First, a description will be given of the case of energy gradation printing in which the high-level switching signal S shown in FIG. The 5-bit print data D1 to D5 as the print data DA are shown in FIGS.
At the timing shown in (7), the data is sequentially taken into the 5-bit shift register SA in synchronization with the clock signal CLK shown in FIG.
At the same time, are latched into the latch circuits LA1 to LA5 all at once.

The print data D1 to D5 fetched by the latch circuits LA1 to LA5 are applied to AND circuits AA1 to AA5, the output of which is opened and closed by a strobe signal STB shown in FIG. Sources RA1-R
A5, each LED array A in the first block BL1.
It is output to the anode terminals of the LED elements L1 to A40.

Similarly, in the second block BL2, the outputs from the constant current sources RA1 to RA5 are applied to the LED arrays A1 to A5.
The signal is output to the LED element L2 of A40, and the same is performed thereafter. In the 64th block BL64, the constant current sources RA1 to RA1
The output from RA5 is the LE of each of the LED arrays A1 to A40.
Output to the D element L64.

When the LED array A1 is activated by the selection signal SEL1 shown in FIG. 3 (9) and the other LED arrays A2 to A40 are deactivated, the latch circuits LA1 to LA5 of each of the blocks BL1 to BL64. The print data stored in the LED element L1 of the array A1
~ L64 only. When the LED array A2 is activated by the selection signal SEL2 shown in FIG. 3 (10) and the other LED arrays A1, A3 to A40 are deactivated, the latch circuits LA1 to LA1 of the blocks BL1 to BL64 are activated. The print data stored in LA5 is given only to the LED elements L1 to L64 of the array A2. After that, when the LED array A40 is activated and the other LED arrays A1 to A39 are deactivated by the selection signal SELn (n = 40) shown in FIG. The print data stored in the latch circuits LA1 to LA5 of the BL64 is supplied only to the LED elements L1 to L64 of the array A40.

Thus, the LED arrays A1 to A4
0 is time-divisionally selected and dynamically driven. The LED elements L1 to L64 are provided with multi-valued print data DA.
Light is emitted by the energy according to (D1 to D5), and thereby, it is possible to realize gradation printing by the energy gradation method in which the size of the printing pixel 14 is changed as shown in FIG.

Next, a description will be given of the case of smooth printing in which the low-level switching signal S shown in FIG. Smoothing printing, which is a type of area gradation, is intended to increase the number of sub-scanning lines to smoothly represent a curve such as a character, and print data increases by the amount of sub-scanning. The print data DB is divided into four parts,
The print data D1 to D4 are sequentially taken into the shift register SB at the timings shown in FIGS. 3 (3) to 3 (6) in synchronization with the clock signal CLK shown in FIG. 3 (2). Next, at the timing of the latch signal LATCH, the data is simultaneously taken into the latch circuit LB.

Print data D captured by latch circuit LB
1 to D4 are supplied to an AND circuit AB, the output of which is opened and closed by a strobe signal STB shown in FIG. 3 (8), and furthermore, via a constant current source RB, to the first block BL1.
Is output to the anode terminal of the LED element L1 of each of the LED arrays A1 to A40.

Similarly, in the second block BL2, the output from the constant current source RB is the L level of each of the LED arrays A1 to A40.
The signal is output to the ED element L2, and the same is performed thereafter.
In the four blocks BL64, the output from the constant current source RB is output to the LED elements L64 of each of the LED arrays A1 to A40.

When the LED array A1 is activated by the selection signal SEL1 shown in FIG. 3 (9) and the other LED arrays A2 to A40 are deactivated, they are stored in the latch circuits LB of the blocks BL1 to BL64. The given print data is given only to the LED elements L1 to L64 of the array A1. When the LED array A2 is activated by the selection signal SEL2 shown in FIG. 3 (10) and the other LED arrays A1, A3 to A40 are inactivated, the latch circuit LB of each of the blocks BL1 to BL64 is activated. The stored print data is the LED of the array A2.
Only applied to elements L1 to L64. And so on.
The selection signal SELn (n = 40) shown in FIG.
The LED array A40 is activated by another LED.
When the arrays A1 to A39 are inactivated, the print data stored in the latch circuits LB of the blocks BL1 to BL64 is stored in the LED elements L1 to L of the array A40.
64 only.

Thus, the LED arrays A1 to A4
0 is time-divisionally selected and dynamically driven. Further, the LED elements L1 to L64 are turned on / off in accordance with the binary print data DB, thereby performing gradation printing by the area gradation method in which the number of the printing pixels 14 is changed as shown in FIG. Can be realized.

As described above, according to the present embodiment, the LED elements L1 to L1 are changed according to the multi-valued and binary print data DA and DB.
A drive circuit for controlling the energy applied to L64
Since it can be mounted on a C chip, energy gray scale and area gray scale (smoothing) can be performed by a simple control method, a large amount of memory can be saved, and the image forming apparatus 1 can be reduced in size and cost. be able to. Further, it is possible to prevent a decrease in printing speed.

FIG. 5 is a sectional view showing the structure of the image forming apparatus 1. As shown in FIG. The image forming apparatus 1 includes a photoconductor 21 having a photosensitive layer 23 formed on a transparent base material 22, a first exposing device 2
4, a second exposure device 25, a developing device 26, a transfer device 27, a fixing device 28, a cleaner 29, and a charger 30. Each of the first and second exposure devices 24 and 25 includes the above-described light emitting unit 2 and the drive circuit 3 having the multi-value drive circuit and the binary drive circuit.
Is disposed on the front side of the photoconductor 21, and the second exposure device 25 is disposed on the rear side of the photoconductor 21.

The developing device 26 supplies toner to an electrostatic latent image corresponding to each pixel formed on the photosensitive member 21. The transfer device 27 transfers the toner adhered to the photoconductor 21 to recording paper. The fixing device 28 fixes the toner transferred to the recording paper. The cleaner 29 removes toner remaining on the photoconductor 21 at the time of transfer. The charger 30 applies a charge of a specific polarity to the photoconductor 21.

FIG. 6 shows a first pixel row formed by the first exposure device 24 on the scanning line of the photoconductor 21 and a second pixel row formed by the second exposure device 25 on the scanning line of the photoconductor 21. As shown, they are selected to overlap each other, and the arrangement of such LED elements 24a and 25a is selected. For example, by making the first pixel row and the second pixel row overlap by a half pitch, the LED element density is doubled, and high-quality printing can be realized with a small-sized image forming apparatus. .

[0040]

As described above, according to the present invention, gradation printing by energy corresponding to multi-valued printing data for energy gradation and turning on / off of an element corresponding to binary printing data for area gradation are performed. The gradation printing by turning off can be realized by a small-sized exposure apparatus, and the gradation printing can be performed by the energy gradation.
4, the number of input terminals can be increased even if the number of sub-scanning lines is increased, and a reduction in printing speed can be prevented.

Further, according to the present invention, a plurality of bits of print data can be switched and supplied to realize printing using one of multi-valued and binary data.

According to the present invention, the exposure devices are arranged on the front side and the back side of the photoreceptor, respectively, and the pixel rows formed by the exposure units are arranged so as to overlap each other.
The light-emitting element density is increased, and high-quality printing can be realized with a small-sized image forming apparatus.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an image forming apparatus 1 according to an embodiment of the present invention.

FIG. 2 is a circuit diagram of the image forming apparatus 1.

FIG. 3 is a timing chart for explaining the operation of the image forming apparatus 1.

FIG. 4A shows an example of gradation printing by an energy gradation method, and FIG. 4B shows an example of gradation printing by an area gradation method.

FIG. 5 is a cross-sectional view illustrating a configuration of the image forming apparatus 1.

FIG. 6 is a diagram showing an arrangement of LED elements 24a and 25a of first and second exposure devices 24 and 25.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 image forming apparatus 2 light emitting section 3 drive circuit 5 selection circuit 6 control circuit 11 input switching circuit 21 photoconductor 22 transparent substrate 23 photosensitive layer 24 first exposure device 25 second exposure device A1 to A40 LED array

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical indication G03G 15/04

Claims (3)

[Claims] 1. An exposure apparatus comprising: a light-emitting portion comprising a plurality of light-emitting elements arranged in a straight line to form a print pixel; and an IC chip for selectively controlling light emission of each of the light-emitting elements. A multi-level modulation drive circuit having a plurality of stages of shift registers and a plurality of switching elements, and controlling energy applied to the light-emitting elements in accordance with print data for energy gradation; and a shift register of the multi-level modulation drive circuit And a binary modulation drive circuit that uses a part of the switching element and turns on / off the light emitting element according to the print data for area gradation. 2. The IC chip according to claim 1, further comprising an input switching circuit for switching input print data to one of a multi-level modulation driving circuit and a binary modulation driving circuit. Exposure equipment. 3. A photoreceptor having a photosensitive layer formed on a transparent substrate, a light emitting portion comprising a plurality of light emitting elements arranged linearly and forming printing pixels, and selectively emitting light from the light emitting elements individually. And an IC chip to be controlled.
A multi-level modulation drive circuit having a plurality of stages of shift registers and a plurality of switching elements, and controlling energy applied to a light emitting element according to print data for energy gradation, and a shift register and a switching element of the multi-level modulation drive circuit A first and a second exposure device provided with a binary modulation drive circuit for turning on / off a light emitting element in accordance with print data for area gradation using a part of the first and second exposure devices. The exposure device according to (1), wherein the first pixel row formed on the photosensitive layer by the first exposure apparatus and the second pixel row formed on the photosensitive layer by the second exposure apparatus are superposed on each other. An image forming apparatus, wherein the image forming apparatus is arranged on a side and a back side.