CN1155104A - image forming device - Google Patents

Abstract

An image forming apparatus capable of controlling the overall image density without adhering toner to a white image even when the density becomes thick. Controlled by the control part 304, the tone level data read by the scanner is processed into a character mode or a photo mode and stored in the memory as a binary image value, based on the stored binary image data and the density change button. To change the density data, the image processing circuit of the laser printer uses the pulse width corresponding to the rising edge of 1 pixel corresponding to the text mode, or uses the pixel center of each pixel corresponding to the photo mode The pulse width centered on the part drives the semiconductor laser, and outputs a dark or light image on the printer.

Description

image forming device

The present invention relates to a kind of image data with tone level (gray scale) which is read in by a scanner, for example, after being converted into binary image data, it is temporarily stored in the memory, and the stored binary image An image forming device such as a digital copier that can change the overall image density when data is output by a laser printer.

In the past, image forming devices such as laser printers could not record halftones (halftones) in 1-dot (dot) recording, so image data without tone gradation such as characters and graphics were simply binary values. Ratio, imaging, and for images with tone equivalence such as photos, the group-type dithering method or the area tone level method is used as a method of maintaining tone level and binarization. imaging.

In addition, recently, in laser printers, it has been proposed (Japanese Patent Application No. 1-79571) to make the pulse width of the laser driving pulse variable to improve the repeatability of thin lines or to express the pulse width modulation method of the tone level. .

However, in a digital copying machine having a laser printer that stores binary image data in memory, after converting the tone level image read by the scanner into a binary image, it is temporarily stored in the memory, Then, when outputting the stored binary image with a laser printer, in the case of changing the density of the entire image with the density change button of the digital copier, the following method is used.

1. Concentration change is not performed (or cannot be changed).

2. Since the minimum white/black composition of a laser printer is a pixel unit, if you want to lighten the whole, you must remove the middle part of the melanin, and if you want to thicken it, add black pixels around the black pixels. Such image processing is performed by software on the memory.

3. Change the processing conditions so that the overall toner adhesion amount is increased or decreased to change the density.

However, the fact that the density cannot be changed is itself a disadvantage, and processing by software takes time, and when the overall density is increased, there is a disadvantage that the toner adheres to the white pixels in the background.

As mentioned above, in the case of changing the image density of the entire image in a digital copying machine that stores binary image data in memory, the density cannot be changed, or it takes time in software processing, or the overall There is a problem that the toner adheres to the white image of the background even when the density of the toner becomes thicker.

Therefore, it is an object of the present invention to provide an image forming apparatus capable of changing the overall image density without taking time for the process and without toner adhering to a white image when the density becomes darker.

The image forming apparatus of the present invention is composed of the following devices in an image forming apparatus that forms an image from a laser beam output from a semiconductor laser: a storage device that stores binary image data; Indicating means for the density when the binary image data forms an image; use the density data indicated by the indicating means and the binary image data stored in the above-mentioned storage means to generate multi-valued tone level data of one pixel A generating means; an image forming means for forming an image on a supplied image forming medium based on the multi-valued tone level data of one pixel generated by the generating means.

The image forming apparatus of the present invention, in the image forming apparatus that forms an image with a laser beam output from a semiconductor laser, is composed of the following devices: a storage device for storing binary image data; Indicating means for the density when the binary image data in the storage means forms an image; setting the density setting means for the density data indicated by the indicating means; from the density data and the density data set by the density setting means The binary image data stored in the above-mentioned memory device produces the generation device of the multi-valued tone level data of one pixel; According to the multi-value tone level data of one pixel produced by the generation device, one image of the above-mentioned semiconductor laser is controlled A control device for the irradiation time of the laser beam of the pixel; an image forming device for forming an image on the supplied image forming medium by controlling the irradiation time of one pixel of the above-mentioned semiconductor laser by the control device.

The image forming apparatus of the present invention is composed of the following devices in an image forming apparatus that forms an image from a laser beam output from a semiconductor laser: a storage device that stores binary image data; Indicating means for the density when the binary image data in the image is formed; the density setting means for setting the density data indicated by the indicating means; from the density data set by the density setting means and stored In the binary image data stored in the above-mentioned storage device, when the overall density is increased, the density of the white pixel adjacent to one black pixel is increased; The generation device of the multi-valued tone level data of 1 pixel whose concentration becomes lighter; control the laser beam irradiation time of 1 pixel of the above-mentioned semiconductor laser according to the multi-valued tone level data of 1 pixel produced by the generating device A control device; an image forming device for forming an image on a supplied image forming medium by controlling the laser beam irradiation time of one pixel of the semiconductor laser by the control device.

The image forming apparatus of the present invention is composed of the following devices in an image forming apparatus that forms an image on a supplied image forming medium with a slave semiconductor laser: a storage device for storing binary image data; means for indicating the density when forming an image from the binary image data stored in the storage means; means for setting the density of the density data indicated by the indicating means; The density data and the binary image data stored in the above-mentioned storage means are generated by making the density of a white pixel adjacent to one black pixel thicker when the overall density is darkened, and making a black pixel darker when it is lightened. A device for generating multi-valued tone level data for one pixel whose density becomes lighter; pulse width modulation for modulating a drive pulse for driving a semiconductor laser based on the multi-valued tone level data for one pixel generated by the generating device A device; a laser driving device for driving the above-mentioned semiconductor laser with a pulse width modulated by the pulse modulating device.

The image forming apparatus of the present invention is composed of the following devices in an image forming apparatus that forms an image on a supplied image forming medium with a laser beam output from a semiconductor laser: a storage device that stores binary image data Indicating means for indicating the density when forming an image from the binary image data stored in the storage means; setting the density setting means for the density data indicated by the density indicating means; The density data set by the device and the binary image data stored in the above-mentioned storage device generate darker white pixels adjacent to one black pixel when the overall density is darker, and darker white pixels when darker. , the generation device of the multi-valued tone level data of a pixel that makes a black pixel lighten itself; According to the multi-value tone level data of 1 pixel produced by the generation device, start from the rising edge of a pixel A pulse width modulating device for driving the driving pulse of the semiconductor laser by means of pulse width modulation; a laser driving device for driving the above-mentioned semiconductor laser with the pulse width modulated by the pulse modulating device.

The image forming apparatus of the present invention is composed of the following devices in an image forming apparatus that forms an image on a supplied image forming medium with a laser beam output from a semiconductor laser: a storage device that stores binary image data Indicating means for indicating the density when forming an image from the binary value stored in the storage means; setting the density setting means for the density data indicated by the indicating means; from the density setting means set In the case of making the overall density darker, the density of the adjacent white pixel of one black pixel is darkened, and the density of the adjacent white pixel of one black pixel is darkened. Under the light situation, then make the density of 1 black pixel itself lighten the generation device of the multi-valued tone level data of 1 pixel; The central part of each pixel is the pulse width of the center to modulate the width modulating device of the driving pulse driving the above-mentioned semiconductor laser; and the laser driving device for driving the above-mentioned semiconductor laser with the pulse width modulated by the pulse width modulating device.

The image forming apparatus of the present invention is composed of the following devices in an image forming apparatus that forms an image on a supplied image forming medium with a laser beam output from a semiconductor laser: a storage device that stores binary image data Indicating means for indicating the density when forming an image from the binary image data stored in the storage means; setting the density setting means for the density data indicated by the indicating means; The fixed density data and the binary image data stored in the above-mentioned storage device are generated. In the case of making the overall density darker, the density of the white pixel adjacent to one black pixel is thickened, and in the case of lightening it Under the situation, then make the generation device of the multi-valued tone level data of 1 pixel that the density of a black pixel itself lightens; The first pulse width modulation device of the pulse width modulation driving the driving pulse of the laser at the beginning of the rising edge of the pixel; A second pulse width modulation device that modulates the driving pulse of the laser with the center part as the center; selects the second pulse width modulation device and the first pulse width modulation device; selects the first pulse width modulation device selected by the selection device A laser driving device for driving the semiconductor laser with the pulse width modulated by the first pulse width modulator or the second pulse width modulator.

The image forming apparatus of the present invention is composed of the following devices in an image forming apparatus that forms an image with a laser beam output from a semiconductor laser: a reading device that reads an image of an original document; Conversion means for converting incoming tone level image data into binary image data; storage means for storing binary data converted by the conversion means; instructing to form images from binary image data already stored in the storage means Indicating means for the density at the time of the image; setting the density setting means for the density data indicated by the indicating means; the density data set from the setting means and the binary image data stored in the above-mentioned storage means A generating device for generating multi-valued tone level data for one pixel; a control device for controlling the laser beam irradiation time of one pixel of the above-mentioned semiconductor laser according to the multi-valued tone level data for one pixel generated by the generating device; The control device controls the laser beam irradiation time of one pixel of the semiconductor laser to form an image on the supplied image forming medium.

The image forming apparatus of the present invention is composed of the following devices in the image forming apparatus for forming an image from a semiconductor laser: a receiving device connected to a public line and receiving binary image data sent by a facsimile machine; Storage means for storing the binary image data received by the receiving means; indicating means for indicating the concentration when forming an image from the binary image data stored in the storage means; setting the value indicated by the indicating means Density setting means for density data; Generating means for generating multi-valued tone level data of 1 pixel from the density data set by the setting means and the binary image data stored in the above-mentioned storage means; A control device for controlling the laser beam irradiation time of one pixel of the above-mentioned semiconductor laser by the multi-valued tone level data of one pixel generated by the generating device; using the control device to control the laser beam irradiation of one pixel of the above-mentioned semiconductor laser Time, an image forming device that forms an image on the supplied image forming medium.

The image forming apparatus of the present invention is composed of the following devices in the image forming apparatus that forms an image with a laser beam output from a semiconductor laser: a receiver that has been connected to the LAN line and receives the transmitted binary image data means; storage means for storing binary image data received by the receiving means; indicating means for indicating the density when forming an image from the binary image data stored in the storage means; setting the indicating means for Density setting means for the indicated density data; generating multi-valued tone level data of 1 pixel from the density data set by the density setting means and the binary image data stored in the above-mentioned storage means A generating device; a control device for controlling the laser beam irradiation time of one pixel of the above-mentioned semiconductor laser according to the multi-valued tone level data of one pixel generated by the generating device; one image of the above-mentioned semiconductor laser is controlled by the control device An image forming device that irradiates a pixel with a laser beam for an irradiation time and forms an image on a provided image forming medium.

The image forming apparatus of the present invention is composed of the following devices in an image forming apparatus that forms an image with a laser beam output from a semiconductor laser: a reading device that reads a document image; The color tone level data is transformed into the 1st conversion device of binary image data as character mode; The tone level image data read by above-mentioned reading device is converted into the 2nd conversion means of binary image data as photo mode; A first selection means for selecting the second conversion means and the first conversion means; storage means for storing binary image data converted by the first conversion means or the second conversion means selected by the selection means; instruction A first indicating means for the density when forming an image from the binary image data stored in the storage device; a density setting means for setting the density data indicated by the first indicating means; from the density setting The concentration data set by the device and the binary image data stored in the above-mentioned storage device generate the multi-valued tone level data generation device of 1 pixel; The first pulse width modulator of the driving pulse of driving the above-mentioned semiconductor laser with the pulse width modulation that starts from the rising edge of 1 pixel; The second pulse width driving device for driving the driving pulse of the semiconductor laser by pulse width modulation centered on the pixel center of each pixel; the second pulse width modulation device and the above-mentioned first pulse width modulation device are selected The second selection device; the laser driving device for driving the above-mentioned semiconductor laser with the pulse width modulated by the first pulse width modulation device or the second pulse width modulation device selected by the selection device; indicating the first selection device and the second Select the universal 2nd pointing device for the device.

The accompanying drawings are briefly described below.

Fig. 1 is a block diagram showing the overall configuration of a digital copying machine of an image forming apparatus of the present invention.

FIG. 2 schematically shows the overall configuration of a digital copying machine as an image forming apparatus.

Fig. 3 shows the density change key as part of the control panel.

FIG. 4 shows a schematic configuration of the inside of the laser printer.

Fig. 5 shows the configuration of a portion that converts binary image data into multi-valued image data, which is a part of the internal configuration of the image processing circuit.

Fig. 6 shows the signal conversion table in the decoder.

FIG. 7 shows changes in the pixel density of adjacent pixels when two black pixels are arranged in a row and the density is increased.

Fig. 8 shows conversion of laser on/off pulses from multivalued image data of 1 pixel by signal conversion from a decoder.

FIG. 9 shows a schematic configuration of a processing section of a laser printer used in the digital copying machine 1 .

Fig. 10 shows the relationship between the laser light emitting time and the printing state.

FIG. 11 shows the case where the laser irradiation time of the photosensitive drum is changed by pulse width modulation to change the density.

FIG. 12 shows the case where the laser irradiation time to the photosensitive drum is changed by pulse width modulation to change the density.

Fig. 13 shows the state of printing in one pixel unit of a halftone image by the error diffusion method.

Fig. 14 shows the printing state of one pixel unit of a halftone image by the error diffusion method.

Fig. 15 is a flowchart for explaining the operation of changing the density inside the laser printer.

Fig. 16 shows the overall configuration of a digital copying machine with a FAX board for storing binary image data in a memory.

Fig. 17 shows the overall configuration of a digital copying machine with LANI/F for storing binary image data in a memory.

Figure 18 shows the mode setting key as part of the control panel.

Fig. 19 shows a selection of image processing circuits inside the image processing section.

FIG. 20 shows a selection of pulse width modulation circuits inside the pulse width modulation circuit.

Fig. 21 shows a method of storing image processing pattern data in page units on the memory when image processing is performed on image data read by the scanner by the image processing section.

Example

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

Fig. 2 schematically shows the overall configuration of a digital copying machine as an image forming apparatus of the present invention. The digital copying machine 1 has a scanner 140 as a reading device and a laser printer 160 as an image forming device, and an automatic document feeder (ADF) 180 is installed on the upper part.

The scanner 140 consists of an exposure lamp 6 as a light source, a first carrier 7 on which a mirror 15 is installed, a second carrier 9 provided with reflectors 8a, 8b that bend the light path, a lens 10, and a light conversion part that receives reflected light. 11. The drive system (not shown) that changes the position of these parts, and the output of the photoelectric conversion part 11, that is, the A/D conversion part (not shown) that converts the image data from analog data to digital data. The above-mentioned first and second carriers 7, 9 are linked together by a synchronous conveyor belt (not shown). And it is comprised so that the 2nd carrier 9 may move in the same direction at 1/2 speed of the 1st carrier 7. As shown in FIG. In this way, it becomes possible to scan the optical path length before the lens 10 constant. The above-mentioned lens 10 is configured to have a fixed focal length and to move in the direction of the optical axis when changing magnification. The above-mentioned photoelectric conversion section 11 performs photoelectric conversion of reflected light from the document, and mainly constitutes, for example, a CCD type line image sensor or the like. In this case, one pixel of the original corresponds to one element of the CCD sensor. The output of the photoelectric conversion section 11 described above is output to the A/D conversion section. The movement of the above-mentioned first and second carriers 7, 9 and mirrors 8a, 8b are respectively carried out by stepping motors (not shown). Above-mentioned the 1st, the 2nd carrier 7,9 constitute as corresponding to the synchronous conveyer belt ( not shown) to move. The lens 10 uses a corresponding stepping motor (not shown) to rotate the helical axis of rotation. And with the help of this helical action, it moves to the direction of the optical axis.

60 is a semiconductor laser, and a collimating lens 62, a polygon mirror 64, a lens 66, mirrors 68, 70, and a lens 72 are disposed corresponding to the semiconductor laser 60, and is configured so that the laser beam is irradiated from the exposure device 52 to the photoreceptor. Drum 50 on.

The laser printer 160 combines, for example, a laser optical system and an electrophotographic method capable of forming an image on copy paper P as an image forming medium. That is, the laser printer 160 has a photosensitive drum 50 as an image carrier, which is rotatably supported on a substantially central part of the device, and around the photosensitive drum 50, an exposure device 52, a developing device 54, and a copy charger are sequentially arranged. 55. Light bulb 50, cleaning device 57 and charged charger 59 are removed. The photosensitive drum 50 is configured to be uniformly charged by a charging charger 59, and at the same time, a laser beam is output from a semiconductor laser 60 to form an image of a document on the photosensitive drum 50 to form an electrostatic latent image.

Next, the electrostatic latent image formed on the photosensitive drum 50 is developed with the developing device 54, and the copy paper is fed through the protective layer roller (register roller) 20 to the paper feeding cassette 30 used as the paper feeding device described later. The top side of P is copied with the copy charger 55, and then conveyed to the fuser 72 through the conveyance belt, and the copy paper P after melting and fixing the developed image by the fuser is discharged to the paper discharge tray by the paper discharge counter roller 073. 74 on. On the other hand, the photosensitive drum 50 after the developed image has been copied onto the above-mentioned copy paper P is decharged with the de-electric bulb 56, and the residual developer remaining on the photosensitive drum 50 that has not been copied is cleaned with a cleaner 57, so that it can be Proceed to the next copy operation.

In addition, 30 in the figure is a paper feeding cassette, and the upper and lower layers are detachably attached from the front side of the said apparatus main body. The sheet feeding cassette 30 is composed of a sheet feeding cassette box 31 which itself is a housing for storing the copy paper P, and the take-out end of the box body 31 is configured to be inclined in a direction in which the copy paper is taken out. In this way, the copy paper P stored in the box 31 of the paper feeding cassette 30 can be picked up by the pickup roller 81 from the uppermost layer and taken out. The copy paper P that is taken out by the pick-up roller 81 and sent into the side of the take-out end of the above-mentioned cassette case 31 is fed by the paper feed roller 84 arranged above the inside of the take-out end of the above-mentioned cassette case 31 . The copy paper separation part constituted by the separation roller (or separation table (pad)) 85 is separated into one piece at a time and sent to the laser printer 160,

FIG. 1 shows the overall configuration of a digital copier 1 as an image forming apparatus of the present invention. That is, the digital duplicating machine 1 is composed of a scanner 140 for reading in image data, an image processing section 301 for processing image data, a memory 303 as a storage device for storing processed image data, and a memory 303 for storing the processed image data. The laser printer 160 for printing processed image data on paper, the control panel 305 for operating the operation of the digital copying machine 1 from the outside, and the scanner 140, the image processing part 301, the laser printer 160, the memory 303, A control panel 305 constitutes a control section 304 for centralized control.

FIG. 3 shows a density change key 501 that is part of the control panel 305 . The concentration change button 501 as the pointing means has seven buttons, and the density is selected by pressing the buttons. There are LEDs on the buttons, and the LED of one of the selected 7 buttons lights up to inform the user of the selected density.

Usually the button 4 is optional. 4 This button represents the standard concentration. The smaller the number of the selected key is than 4, the density of the printed characters will be lighter than the standard density, and the larger the number of the selected key is than 4, the density of the printed characters will be darker than the standard density.

Usually, when copying, the control part 304 sends the multi-valued image data read by the scanner 140 to the image processing part 301 without processing, and in the image processing part 301, it is converted into a density change key 501 and The multi-value tone level data corresponding to the selected density is sent to the laser printer 160, and the laser printer 160 prints with the density corresponding to the multi-value tone level data.

In the case of temporarily storing image data in the memory 303, in order to store multiple pages of data in the memory 303, the image processing section 301 converts the image data into binary image data before storing in the memory 303.

In addition, when the binary image data is stored in the memory 303, when the image processing section 301 converts from multi-value to binary, it is darker or lighter than the constant density reference multi-value data. Binary image data of one pixel is converted into black data and white data. The density change button 501 is to be increased when the density reference multi-valued data is to be lightened during printing, and is to be decreased to be darker when printing.

In the past, when the binary image data temporarily stored in the memory 303 was printed by the laser printer 160, since one pixel was either black or white image value data, it was sent to the In the case of the laser printer 160, the density change button becomes invalid.

Or, process the binary image stored in the memory 303 with software, and convert a part of the white pixels into black pixels when the selection of the density change button 501 is used to make it thicker, and when it is desired to make it lighter. Converting part of the black pixels to white pixels changes the overall printing density, but because it is processed by software, it takes time to process one page and slows down the printing speed.

In addition, the processing conditions of the laser printer 160 are changed by selecting the density change button 501, and the overall printing density is changed by increasing or decreasing the amount of toner adhered to the photosensitive drum 50. The disadvantage of making the white pixels of the background also adhere to the toner.

Therefore, in order to solve these disadvantages, the present invention sends the density data obtained by selecting the density change button 501 to the laser printer 160 as changed density data, so that the density change is performed inside the laser printer 160 .

Next, the configuration of the laser printer 160 of the present invention will be described.

FIG. 4 shows a schematic configuration inside the laser printer 160 .

First, the binary image data ID transmitted from the image processing section 301 is input to the interface (I/F) 100 in synchronization with the transmission clock ICLK. In the image I/F 100, the binary image data is sent to the image processing circuit 101 as the binary image data VD synchronized with the transfer clock VCLK inside the laser printer 160.

In the image processing circuit 101, the binary image data VD is converted into a pulse signal LD for turning on/off the semiconductor laser 60 by the laser driving circuit 102, and then output to the laser driving circuit 102. In the laser drive circuit 102, the semiconductor laser 60 is turned on/off at the on/off timing of the pulse signal LD. The laser beam output from the semiconductor laser 60 is scanned on the photosensitive drum 50 by the rotation of the polygon mirror 64 . A 2-dimensional electrostatic latent image formed with a laser beam is formed on the photosensitive drum 50 by the rotation of the photosensitive drum 50 . The electrostatic latent image formed on the photosensitive drum 50 forms a toner image on the copy paper P by a process to be described later.

Inside the semiconductor laser 60, there is a photodiode for monitoring the intensity of the laser beam. The intensity of the laser beam converted into an electrical signal by the photodiode of the monitor returns to the laser driving circuit 102, and is used as a feedback signal to maintain a stable output of the laser beam.

A drive circuit for a polygon motor that rotates the polygon mirror 64 is also provided inside the laser drive circuit 102 as a laser drive device.

The laser beam reflected by the polygon mirror 64 is input to the photodiode 106 to generate a horizontal synchronization signal HSYN. The horizontal synchronization signal HSYN forms a waveform in the laser drive circuit 102 and is output as a horizontal synchronization signal LHSYN to the image processing circuit 101, the image I/F 100 and the image processing section 301 as a horizontal synchronization signal for image data.

The vertical synchronous signal IVSYN is input from the image processing section 301 to the image I/F 100 and is input to the image processing circuit 101 and the control circuit 109 as the vertical synchronous signal VSYN used in the laser printer 160 . In the image processing section 301, the image data is sent to the image I/F 100 in the laser printer 160 in synchronization with the vertical synchronization signal IVSYN and the horizontal synchronization signal LHSYN.

Image data is sent from the image I/F 100 to the image processing circuit 101 in synchronization with the vertical synchronization signal VSYN and the horizontal synchronization signal LHSYN. The vertical synchronizing signal VSYN is input to the control circuit 109 and is used for timing alignment of paper conveyance.

The control circuit 109 controls the image I/F 100, the image processing circuit 101, and the laser drive circuit 102, especially for the image processing circuit 101 to transmit the concentration on the control panel 305 that has been transmitted from the control part 304 to the control circuit 109. Change the density data generated by the selection of the button 501, and set the binary image data inside the image processing circuit 101 as parameters for the setting value of the part that will be converted into multi-valued image data. .

The control circuit 109 detects the toner concentration on the photosensitive drum 50 by using the toner concentration sensor 108 to control the operation of the toner supply motor 110 . In addition, the control circuit 109 inputs a signal from the sensor 112 and generates control timing to control the on/off of the main motor 113 driving each part, the spiral tube 111, the fan motor 114 used for cooling, and the on/off of the light bulb 56, by controlling the high voltage The power drive circuit 116 controls the charging charger 59 , the copying charger 55 , on/off and output setting of the high voltage output of the developing bias voltage to the developing roller 119 . In addition, on/off of the heater bulb 115 in the fixing unit 72 is also controlled to keep the fixing temperature constant.

FIG. 5 shows the configuration of a portion that converts binary image data into multi-valued image data as part of the internal configuration of the image processing circuit 101. As shown in FIG.

The binary image data sent from the image processing section 301 is converted into a signal synchronized with the image clock VCLK (one cycle per pixel) inside the laser printer 160 and latched in the flip-flop 400 . It is also latched in flip-flop 402 .

The image data that has been latched in the flip-flop 400 and the flip-flop 402, if the image data of the flip-flop 400 is set as the nth image data, then what is latched in the flip-flop 402 is the n-1th No. image data.

No. n and No. n-1 image data, according to control circuit 109, the density change data D [2: 0] that the concentration change button 501 on the middle control panel 305 selects is set to the density change data D [2: 0] on the register 401 , and use the decoder 403 to transform into multi-valued image data. A flip-flop 404 is used to synchronize it with the video clock VLCK.

The multivalued image data is converted by the pulse width modulation circuit 405 into a laser driving on/off signal having a pulse width of 1 pixel unit. The laser driving circuit 102 generates a laser beam from the semiconductor laser 60 to be irradiated onto the photosensitive drum 50 using the laser on/off signal.

FIG. 6 shows a signal conversion table in the decoder 403. Binary image data "1" represents black, and "0" represents white. The changed density data in the horizontal axis direction in the image data of No. n and No. n-1, "4" represents the standard density (no density change), and the value of "3", "2" and "1" is higher A smaller value will make the density lighter, while a larger value like "5", "6", and "7" will make the density thicker.

The values converted by the decoder 403 and the values of the multi-valued image data "0" to "4" of one pixel. Here, the density of 1 pixel unit represents the value "0": 0/4*T, "1": 1/4*T, which divides the length T of laser irradiation time of 1 pixel into 5 steps. "2": 2/4*T, "3": 3/4*T, "4": 4/4*T. However, the divisions need not be at equal intervals, and the number of divisions need not be five steps.

Fig. 7 shows how the pixel density of adjacent pixels is changed when the density is to be increased when two black pixels are arranged in a row. (a) of FIG. 7 shows that before the change, the pixels (1) and (2) are black pixels, and the pixel (3) is a white pixel.

As shown in Figure 7(b), when the density of the pixel (1) is changed, a part of the adjacent pixel (2) becomes black, and as shown in Figure 7(c), when the density of the pixel (2) is changed , a portion of the adjacent pixel (3) becomes black.

As shown in Figure 7(c), the result of changing the density of pixels (1) and (2) is to make the two together, but since the pixel (2) is a black pixel from before the density change, the object The density change of the pixel (2) caused by the density change of the pixel (1) is negligible.

FIG. 8 shows the conversion from the multivalued image data output of 1 pixel to the laser on/off pulse by signal conversion from the decoder 403 in the pulse width modulation circuit 405. Fig. 8(a) shows the video clock VCLK, and Fig. 8(b) shows video data synchronized with the video clock VCLK.

A pulse width modulation circuit 405 as modulating means generates a laser on/off signal for the values of multivalued image data "0" to "4" of one pixel converted by the decoder 403. In Figure 8(c), the value of "0" has no laser pulse on time, as the value of the data increases from "1" to "4", the laser conduction time con increases, and turns on 1 at "4". The pixel illumination time is so long. As the length of the on time of the laser increases, the black part of the screen will continue to increase in the n-pixel printing state.

FIG. 9 shows a schematic configuration of a processing section of the laser printer 160 used in the digital copier 1 .

The photosensitive drum 50 is configured to rotate at a constant speed in the direction of the arrow a in the figure. A charging charger 59 , a laser beam 203 as an exposure tool, a developing device 54 , a copying charger 55 , a neutralizing bulb 56 and a cleaner 57 are sequentially disposed on the peripheral portion of the photosensitive drum 50 along its rotational direction a.

When forming an image, the surface of the photosensitive drum 50 is uniformly charged while being rotated and passed through the charging charger 59 . On the charged photosensitive drum 50, a laser beam 203 is irradiated and exposed according to image data. The surface potential of the photosensitive drum 50 irradiated by the laser beam is changed to form a latent image corresponding to the image data. When the latent image passes through the developing device 54, toner is supplied to become a developed visible image.

In addition, when the copy paper P is supplied from the paper feeding section (not shown) and conveyed to the copy charger 55, the visible image (toner image) on the photosensitive drum 50 developed by the developing device 54 ) is copied on the copy paper P with the copy charger 55. The copy paper P on which the visible image has been copied is conveyed to the above-mentioned fixing unit 72, and the toner image on the copy paper P is heated and pressurized to be fixed on the copy paper P.

The photosensitive drum 50 is neutralized by a neutralizing bulb 56 after copying. The toner remaining on the photosensitive drum 50 without being copied is removed by the cleaner 57 , and the photosensitive drum 50 reaches the charging charger 59 again.

The laser printer 160 performs continuous printing by repeatedly repeating the above-mentioned process.

Fig. 10 shows the relationship between the laser light emitting time and the printing state. That is, in the binary image data on the memory 303 as shown in FIG. The comparison between laser emission time and printing state shows the laser emission time and printing state when the density is increased, and the laser emission time and printing state when the density is lightened.

As shown in FIG. 10( b ), when the density is not changed, the laser emits light only during the time that the laser scans the black pixels. In the processing of the laser printer 160, only the place where the laser beam has been irradiated on the photosensitive drum 50 is made to adhere to the toner and become black. In this way, as long as the processing conditions are appropriate, an area equivalent to 1 pixel will become black. In the drawing, a black pixel is schematically represented as a square of one pixel.

As shown in Figure 10 (c), in the case where the concentration is to be made thicker, the adjacent pixel, in this case, scans only one image with the laser light for the next pixel to be scanned by the laser along the main scanning direction. Half the time of the amount of prime. In this way, only half the area of a pixel adjacent to a white pixel is printed black.

As shown in Fig. 10(d), in the case of lightening the density, the area of the printed black characters is reduced by half by reducing the time of laser irradiation on the black pixel portion by half.

As described above, in the case of making the density thicker, the time for irradiating the adjacent pixels with laser light is reduced to half of the time for one pixel, and in the case of lightening the density, the laser light is irradiated to the black pixel portion. The time is reduced to half of the irradiation time of one pixel, but in this embodiment, the laser irradiation time is changed stepwise by the degree of density change to change the black printing area.

11 and 12 show the case where the laser irradiation time to the photosensitive drum 50 is changed by pulse width modulation in order to change the density. In the case of performing normal copying, black pixels are irradiated for an irradiation time corresponding to one pixel.

In the case of lightening it, the irradiation time is changed in 3 steps. To make it lighter, the pulse irradiation time should be shortened to minimize the toner adhesion.

In the case of making it darker, the laser irradiation time of a black pixel is also for one pixel, and the laser irradiation time of adjacent pixels is changed in three steps. To make it thicker, it is necessary to lengthen the laser irradiation time and increase the amount of toner attached to adjacent pixels.

Fig. 11 shows a method for increasing the black portion from the left end portion of one pixel. This is effective when maintaining the sharpness of the edge portion such as a character image, and since the black portion is added adjacent to the black pixel, the edge will not be blurred.

Note that changing the density data is expressed as 1 to 7 levels. Level 4 is a criterion not to change the density. The smaller the number set from level 4 to 1, the lighter it is, and the larger the number set from level 4 to 7, the darker it is. For example, when the level 1 of the density data is changed, the laser pulse becomes the minimum, and the printing state also fills the left side of the figure and becomes the minimum (lightest). On the contrary, when the level 7 of the density data is changed, the laser pulse becomes the largest, and the printing state also fills the left side of the figure to become the largest (the darkest).

Fig. 12 shows a method of increasing the black portion from the center. It is effective in the case of dot processing such as photographic images. Since the black pixels are not concentrated, but the embedded pixels are scattered in the part connected to the adjacent image, it is half tone as a whole. image.

Changing the concentration data Figs. 1 to 7 show that level 4 is the standard for not changing the concentration. From level 4 to 1, the smaller the number is set, the lighter it becomes, and from level 4 to 7, the larger the number is set, the thicker it becomes. For example, when the level 1 of the density data is changed, the laser pulse becomes the minimum at the center of the pixel, and the printing state also becomes the minimum (lightest) at the center of the pixel. On the contrary, in the case of changing the level of the density data to 7, the laser pulse makes the center of the pixel and the adjacent pixel combined into the maximum, and the printing state also combines the center of the pixel and the adjacent pixel. rise to become the largest (most concentrated).

13 and 14 show the state of printing in units of one pixel of a halftone image obtained by the error diffusion method.

Figure 13(a) and Figure 14(a) show the printing status under the standard (level), because black and white are exactly half the image density each, so the printing is black and white with 1 pixel unit interactively.

When it is subjected to density change using pulse width modulation, a larger value is set to the pulse width for the adjacent image in accordance with the density change level to make it darker. (b) and (c) of FIG. 13 and FIG. 14 show that the areas of white and black are changed in the printing state where the density data is changed, and halftones are expressed.

FIG. 13 shows the method of increasing the black portion from the left end portion of the pixel in 1 as already shown in FIG. 11. That is, with the standard shown in FIG. 13 (a) as level 4, FIG. 13 (b) shows the situation of fading, and the order of changing the levels 1, 2, and 3 of the density data is gradually fading, and FIG. 13 (c) shows the case of becoming richer, and the level 5, 6, and 7 of the density data are changed to become darker in order.

FIG. 14 shows the case where the method of increasing the black portion from the center of one pixel is used as shown in FIG. 12 . That is, with the standard shown in FIG. 14 (a) as level 4, FIG. 14 (b) shows the situation of fading, and it becomes light in the order of levels 1, 2, and 3 of changing density data, and FIG. 14 (c ) shows the case of becoming richer, and becomes darker in order of levels 5, 6, and 7 of the changed density data.

Next, in such a configuration, using the digital copying machine 1 composed of the laser printer 160, when printing the binary image data temporarily stored in the memory 303 with the laser printer 160, press the density change button 501 to The selected density data is sent to the laser printer 160 as changed density data, and the operation of changing the density inside the laser printer 160 will be described with reference to the flow chart in FIG. 15 .

First, the density change data desired by the user through the selection (ST1) of the density change button 501 on the control panel 305 is sent to the control section 304, and then sent from the control section 304 to the laser printer 160 (ST2).

Inside the laser printer 160 , the control circuit 109 receives the changed density data, and the control circuit 109 forwards it to the image processing circuit 101 . Inside the image processing circuit 101, the changed density data is sent to the register 401 to be latched and input to the decoder 403 as density changed data D[2:0] (ST3).

The binary image data n, n-1 input to the decoder 403 is to latch the binary image data VD transmitted from the memory 303 via the image processing part 301 with the flip-flop 400, which is latched with the flip-flop 402. Binary image data to be latched.

These two data are changed from the binary image data n, n-1 and the density data D (2:0). The decoder 403 as generating means is caused to generate multi-valued image data of one pixel (ST4).

Multivalued image data for one pixel is latched in flip-flop 404 and input to pulse width modulation circuit 405 . The pulse width modulation circuit 405 divides the laser on time of one pixel into five levels by using the input multivalued image value of one pixel, and outputs the obtained laser on time with five levels of density. The /off signal LD is output to the laser drive circuit 102 (ST5).

The laser drive circuit 102 drives the semiconductor laser 60 according to the input laser on/off signal (ST6), irradiates the laser beam from the semiconductor laser 60 onto the photosensitive drum 50, and by means of the electrophotographic process, it can be obtained on the copy paper. The toner density image corresponding to the laser ON time (ST7).

According to the above action, the control section 304 uses the image processing section 301 to process the tone level image data read from the scanner 140 and stores it in the memory 303 as binary image data. Binary image data can be output as a dark or light image from the laser printer 160 by operating the density change button 501 on the control panel 305 .

FIG. 16 shows the overall configuration of a digital copier with FAX board 200 for storing binary image data in memory. That is, it is a configuration of a digital copier in which a FAX board is connected instead of the scanner 140 in the digital copier 1 shown in FIG. 1 . In addition, the same components as those of the digital copying machine 1 already shown in FIG. 1 are given the same reference numerals, and description thereof will be omitted.

The digital copying machine 200 is provided with a FAX board 600 for receiving binary image data sent through a public line.

The control unit 304 can obtain dark or light image output from the laser printer 160 by operating the density change button 501 on the control panel 305 using the binary image data stored in the memory 303 in this way.

FIG. 17 shows the overall configuration of a digital copier with LANI/F 300 for storing binary image data in memory. That is, instead of the scanner 140 in the copier 1 shown in FIG. 1, a LAN interface (I/F) is connected. In addition, the same reference numerals are assigned to the same components as those of the digital copying machine 1 shown in FIG. 1, and description thereof will be omitted.

The digital copier 300 is provided with a LAN interface (I/F) 700 for receiving binary image data transmitted through the LAN line, and the control unit 304 transmits the binary image data transmitted from the LAN I/F 700 to the memory 303 and stores them.

The control unit 304 can obtain dark or light image output from the laser printer 160 by operating the density change button 501 on the control panel 305 using the binary image data stored in the memory 303 in this way.

FIG. 18 shows the mode setting key 920 as part of the control panel 305 . Inside the image processing part 301, since the processing method is different depending on whether the document is a text image or a photo image, the user presses the mode setting button 920 to select the text mode or the photo mode.

The mode setting button 920 as a selection means has an LED built in, and is configured to light up the LED of the selected button so that the user can determine which mode is selected. The initial value is the text mode, when the photo mode is selected, the LED in the text mode turns off, and the LED in the photo mode turns on. Conversely, if the text mode is selected when the photo mode LED is already on, the photo mode LED is turned off, and the text mode LED is turned on.

FIG. 19 shows a selection of image processing circuits inside the image processing section 301. As shown in FIG. The data of the mode selected by the mode setting button 920 is read by the control section 304 and latched in the flip-flop 913 as image processing circuit selection data. The latch data as a selection signal 914 controls a selector 912 for selecting binary image values from the image processing circuit 910 in the text mode and the image processing circuit 911 in the photo mode. When the signal is "0", the selection signal 914 selects the output of the text mode image processing circuit 910, and when the signal is "1", the output of the photo mode image processing circuit 911 is selected.

The character mode image processing circuit 910 as the first conversion means converts the multi-valued image data from the scanner 104 into binary image data in the character mode.

The photo mode image processing circuit 911 as the second conversion means converts the multi-valued image data from the scanner 104 into binary image data as a photo mode.

The selected binary image data is transferred to the memory 303 .

FIG. 20 shows a selection of pulse width modulation circuits inside the pulse width modulation circuit 405 . The data of the mode selected by the mode setting button 920 is read by the control part 304 and sent to the control circuit 109 in the laser printer 160, and then the control circuit 109 latches it in the flip-flop 903 as modulation circuit selection data.

The latch data as a selection signal 904 controls a selector 902 for selecting pulse signals from the pulse width modulation circuit 900 and the pulse width modulation circuit 901 . The selection signal 904 selects the output of the pulse width modulation circuit 900 when the signal is "0", and selects the output of the pulse width modulation circuit 901 when the signal is "1".

The pulse width modulation circuit 900 as the first pulse width adjustment means is a pulse width adjustment circuit for modulating the driving pulse for driving the semiconductor laser 60 with the pulse width from the rising edge of one pixel. The pulse width modulation circuit 901 as the second pulse width modulation means is a pulse width modulation circuit that modulates the driving pulse for driving the semiconductor laser 60 with a pulse width centered on the center of each pixel. The selected pulse signal LD is sent to the laser driving circuit 102 .

When the user uses the laser printer 160 to print the binary image data stored in the memory 303, he can select the pulse width modulation circuit. That is, the pulse width modulation circuit 900 can be selected for the data that converts images with many characters into binary image data and has been stored in the memory 303, and converts images with many halftones into binary images. The data stored in the memory 303 can select the pulse width modulation circuit 901 .

Therefore, in the case of maintaining the sharpness of the edge portion of a text image, it is possible to select the pulse width modulation circuit 900 that modulates the pulse width from the rising edge of one pixel to perform halftone processing such as a photo image. In this case, a pulse width modulation circuit 901 is used which modulates the pulse width centered on the pixel center of each pixel so as not to concentrate black pixels and prevent Moire from being generated.

FIG. 21 shows a method of storing image processing pattern data in units of pages in the memory 303 when the image data read by the scanner 140 is image-processed by the image processing section 301.

Data with a storage sequence number of "0" or "1" in units of pages in the memory is stored as image processing mode data in the memory. "0" means text mode, "1" means photo mode. When the image data is converted into binary image data by the image processing section 301 via the scanner 140 and stored in the memory 303, a page unit management number is assigned in units of one page, and the image processing section 301 performs The image processing pattern for image processing is collectively stored in the memory 303 as an on-memory image processing pattern.

By pressing the start button (not shown) on the control panel 305, the original document reading with the scanner 140 starts, but before this, the control part 304 reads the state of the mode setting button 920 earlier, It is stored in the memory 303 as on-memory image processing mode data indicating whether it is a text mode or a photo mode, together with a page unit storage number.

When the page unit storage number has been stored in the memory 303, a different number is assigned to each page unit of the image. Cleared in case of a read failure. In addition, when the binary image data is deleted from the memory 303, it is also deleted at the same time.

After using the image processing part 301 to change the image data read by the scanner 140 into binary image data and store it in the memory 303, in the case of printing with the laser printer 160, the image processing circuit of the laser printer 160 The selection signal 904 for selection by the pulse width modulation circuit 900 and the pulse width modulation circuit 901 in the pulse width modulation circuit 405 in 101 is generated from the memory image processing mode data stored in the memory 303 .

When printing with the laser printer 160, the control section 304 obtains the stored image processing number stored in the memory 303 from the memory page unit storage number of the image data to be printed immediately before printing in 1 page unit. The mode data is sent to the control circuit 109 in the laser printer 160.

The control circuit 109 latches the image processing mode data on the memory to the flip-flop 903 as modulation circuit selection data. The latch data as a selection signal 904 controls a selector 902 for selecting pulse signals from the pulse width modulation circuit 900 and the pulse width modulation circuit 901 . The selection signal 904 selects the output of the pulse width modulation circuit 900 when the signal is "0", and selects the output of the pulse width modulation circuit 901 when the signal is "1".

By using the image processing mode data processed in the image processing part of the image data read by the scanner 140 to select the pulse width modulation circuit of the laser printer 160, it is possible to automatically set the The mode when image data is read by the scanner 140 does not need to be changed by the user by the mode setting button 920 page by page. At this time, when the mode setting button 20 of the control panel 305 has already been pressed by the user, the setting by the mode setting button 920 may be ignored.

As explained above, if the embodiment of the above invention is adopted, since it does not perform software processing like the prior art, high-speed printing is possible, and since the processing conditions are not changed, the density can be changed stably, preventing the prior art from Such a phenomenon in which toner is added to a white image portion to turn it into a black portion.

As described in detail above, according to the present invention, it is possible to provide a process that does not take a lot of time. An image forming apparatus that can change the image density of the entire process without attaching toner to a white image when the density is increased.

Claims (11)

1. An image forming device, which forms an image with a laser beam output by a semiconductor laser, is characterized in that it has the following devices: A storage device for storing binary image data; indicating means for indicating the density when an image is formed from the binary image data stored in the storage means; generating means for generating multi-value tone level data for 1 pixel from the density data indicated by the above-mentioned indicating means and the binary image data stored in the above-mentioned storage means; An image forming means for forming an image on the supplied image forming medium based on the multi-valued tone level data for one pixel generated by the generating means. 2. An image forming device, in the image forming device for forming an image with a laser beam output from a semiconductor laser, it is characterized in that it has the following devices: A storage device for storing binary image data; indicating means for indicating the density when forming an image from the binary image data stored in the above-mentioned storage means; Concentration setting means for setting the concentration data indicated by the above-mentioned indicating means; generating means for generating multi-valued tone level data for one pixel from the density data set by the density setting means and the binary image data stored in the storage means; a control device for controlling the laser beam irradiation time of one pixel of the above-mentioned semiconductor laser according to the multi-valued tone level data of one pixel generated by the above-mentioned generating device; An image forming apparatus for controlling the laser beam irradiation time of one pixel of the semiconductor laser by the control means and forming an image on the supplied image forming medium. 3. An image forming device, in the image forming device for forming an image with a laser beam output from a semiconductor laser, it is characterized in that the following devices are provided: A storage device for storing binary image data; indicating means for indicating the density when an image is formed from the binary image data stored in the above-mentioned storage means; Concentration setting means for setting the concentration data indicated by the above-mentioned indicating means; generating means for generating a black pixel adjacent to one black pixel when making the overall density darker from the density data set by the density setting means and the binary image data stored in the storage means. The density of the white pixel is thickened, and in the case of lightening it, the multi-valued tone level data of 1 pixel that makes the density of 1 black pixel itself light; a control device for controlling the laser beam irradiation time of 1 pixel of the above-mentioned semiconductor laser according to the multi-valued tone level data of 1 pixel generated by the above-mentioned generating device; image forming device. An image is formed on the supplied image forming medium by controlling the laser beam irradiation time of one pixel of the semiconductor laser by the control means. 4. An image forming device, in the image forming device for forming an image on a supplied image forming medium with a laser beam output from a semiconductor laser, it is characterized in that the following devices are provided: A storage device for storing binary image data; indicating means for indicating the density when an image is formed from the binary image data stored in the above-mentioned storage means; Concentration setting device for setting the concentration indicated by the above-mentioned indicating device; Generating means for generating from the density data set by the above-mentioned density setting means and the binary image data stored in the above-mentioned storage means, in the case of making the overall density darker, a black pixel Multi-valued tone level data of 1 pixel that darkens the density of adjacent white pixels, or lightens one black pixel itself; Pulse width modulation means for modulating the pulse width of the driving pulse driving the semiconductor laser according to the multi-valued tone level data of 1 pixel generated by the above-mentioned generating means; A laser driving device for driving the semiconductor laser with the pulse width modulated by the pulse width modulation device. 5. An image forming device, in an image forming device for forming an image on a supplied image forming medium with a laser beam output from a semiconductor laser, it is characterized by having the following devices: A storage device for storing binary image data; indicating means for indicating the density when an image is formed from the binary image data stored in the above-mentioned storage means; Concentration setting means for setting the concentration data indicated by the above-mentioned indicating means; generating means for generating the density data corresponding to one black pixel in the case of making the overall density darker from the density data set by the density setting means and the binary image data stored in the storage means. Multi-valued tone level data of 1 pixel that darkens the density of adjacent white pixels and lightens the density of 1 black pixel itself; Pulse width modulating means for driving the driving pulse of the above-mentioned semiconductor laser with pulse width modulation starting from the rising edge of one pixel according to the multi-valued tone level data of one pixel generated by the above-mentioned generating means; A laser driving device for driving the semiconductor laser with the pulse width modulated by the pulse width modulation device. 6. An image forming device, in an image forming device for forming an image on a supplied image forming medium with a laser beam output from a semiconductor laser, it is characterized by having the following devices: A storage device for storing binary image data; indicating means for indicating the density when an image is formed from the binary image data stored in the above-mentioned storage means; Concentration setting means for setting the concentration data indicated by the above-mentioned indicating means; generating means for generating the density data corresponding to one black pixel in the case of making the overall density darker from the density data set by the density setting means and the binary image data stored in the storage means. The density of the adjacent white pixel is thickened, and in the case of making it light, the multi-valued tone level data of 1 pixel that makes the density of 1 black pixel itself light; A pulse width modulation device for driving the driving pulse of the above-mentioned semiconductor laser with pulse width modulation centered on the pixel center of each pixel according to the multi-valued tone level data of one pixel generated by the above-mentioned generating device; A laser driving device for driving the semiconductor laser with the pulse width modulated by the pulse width modulation device. 7. An image forming device, in an image forming device for forming an image on a supplied image forming medium with a laser beam output from a semiconductor laser, it is characterized by having the following devices: A storage device for storing binary image data; indicating means for indicating the density when an image is formed from the binary image data stored in the above-mentioned storage means; Concentration setting means for setting the concentration data indicated by the above-mentioned indicating means; generating means for generating from the density data set by the above-mentioned density setting means and the binary image data stored in the above-mentioned storage means, in the case of making the entire density darker, a black pixel Multi-valued tone level data of 1 pixel that darkens the density of adjacent white pixels and lightens the density of 1 black pixel itself; The 1st pulse width modulating means is used to drive the driving pulse of the above-mentioned semiconductor laser with the pulse width modulation starting from the rising edge of 1 pixel according to the multi-valued tone level data of 1 pixel generated by the above-mentioned generating means; The second pulse width modulation means is used to drive the above-mentioned semiconductor laser with pulse width modulation centering on the pixel center of each pixel based on the multi-valued tone level data of one pixel generated by the above-mentioned generating means. driving pulse; selection means for selecting the second pulse width modulation means and the first pulse width modulation means; A laser driving device for driving the semiconductor laser with the pulse width modulated by the first pulse width modulation device or the second pulse width modulation device selected by the selection device. 8. An image forming device, in the image forming device for forming an image with a laser beam output from a semiconductor laser, it is characterized by having the following devices: A reading device for reading the image of the original; conversion means for converting the tone level image data read from the above-mentioned reading means into binary image data; Storage means for storing the binary image data transformed by the above-mentioned transformation means; indicating means for indicating the density when an image is formed from the binary image data stored in the above-mentioned storage means; Concentration setting means for setting the concentration data indicated by the above-mentioned indicating means; generating means for generating multi-valued tone level data for 1 pixel using the density data set from the above-mentioned density setting means and the binary image data stored in the above-mentioned storage means; a control device for controlling the laser beam irradiation time of 1 pixel of the above-mentioned semiconductor laser according to the multi-valued tone level data of 1 pixel generated by the above-mentioned generating device; An image forming apparatus for forming an image on the supplied image forming medium by controlling the laser beam irradiation time of one pixel of the semiconductor laser by the control means. 9. An image forming device, in the image forming device for forming an image with a laser beam output from a semiconductor laser, it is characterized by having the following devices: The receiving device has been connected to the public line and receives the binary image data sent by the facsimile machine; storage means for storing the binary image data received by the receiving means; indicating means for indicating the density when an image is formed from the binary image data stored in the above-mentioned storage means; Concentration setting means for setting the concentration data indicated by the above-mentioned indicating means; generating means for generating multi-valued tone level data of 1 pixel from the density data set by the above-mentioned density setting means and the binary image data stored in the above-mentioned storage means; A control device for controlling the laser beam irradiation time of 1 pixel of the above-mentioned semiconductor laser according to the multi-valued tone level data of 1 pixel generated by the above-mentioned generating device; An image forming apparatus for forming an image on the supplied image forming medium by controlling the laser beam irradiation time of one pixel of the semiconductor laser by the control means. 10. An image forming device, in the image forming device for forming an image with a laser beam output from a semiconductor laser, it is characterized by having the following devices: The receiving device has been connected to the LAN line and receives the transmitted binary image data; storage means for storing the binary image data received by the receiving means; indicating means for indicating the density when an image is formed from the binary image data stored in the above-mentioned storage means; Concentration setting means for setting the concentration data indicated by the above-mentioned indicating means; generating means for generating multi-valued tone level data of 1 pixel from the density data set by the above-mentioned density setting means and the binary image data stored in the above-mentioned storage means; A control device for controlling the laser beam irradiation time of one pixel of the above-mentioned semiconductor laser according to the multi-valued tone level data of one pixel generated by the above-mentioned generating device; An image forming apparatus for forming an image on the supplied image forming medium by controlling the laser beam irradiation time of the semiconductor laser for one pixel by the control means. 11. An image forming device, in an image forming device for forming an image with a laser beam output from a semiconductor laser, characterized in that it has the following devices: A reading device for reading the image of the original; The 1st converting means is used for converting the tone level image data read from the above-mentioned reading means into binary image data as a character pattern; The 2nd conversion means is used for converting the tone level image data read from the above-mentioned reading means into binary image data as a photo mode; a first selection means for selecting the second conversion means and the first conversion means; Storage means for storing the binary image data converted by the first conversion means or the second conversion means selected by the first selection means; 1st indicating means for indicating the density when forming an image from the binary image data stored in the storage means; Concentration setting means for setting the concentration data indicated by the above-mentioned first indicating means; generating means for generating multi-valued tone level data of 1 pixel from the density data set by the above-mentioned density setting means and the binary image data stored in the above-mentioned storage means; The 1st pulse width modulating means is used to modulate the drive pulse of the above-mentioned semiconductor laser with the pulse width starting from the rising edge of 1 pixel according to the multi-valued tone level data of 1 pixel generated by the above-mentioned generating means; The second pulse width modulation means is used to drive the above-mentioned semiconductor laser with pulse width modulation centering on the pixel center of each pixel based on the multi-valued tone level data of one pixel generated by the above-mentioned generating means. driving pulse; a second selection means for selecting between the second pulse width modulation means and the first pulse width modulation means; A laser driving device for driving the semiconductor laser with the pulse width modulated by the first pulse width modulation device or the second pulse width modulation device selected by the second selection device; The shared second indicating means is used to indicate the above-mentioned first selecting means and the second selecting means.

Images