JPH09243950A - Image forming device and method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of outputting an image by selecting a correct image or a mirror image by a simple control mechanism. SOLUTION: A laser beam L transmitted from a laser diode 3 is made incident on a polygon mirror 103 through a collimator lens 106 and scanned on a photoreceptor 107 by the polygon mirror 103. The polygon mirror 103 is rotatably driven by a motor 20. The rotating direction is changed over based on the input from a correct image/mirror image changeover button 33 in an operation panel 32 and thus the correct image or the mirror image is selected/ outputted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus and an image forming method, and more particularly to an image forming apparatus and an image forming method for forming an image by scanning with a polygon mirror.

[0002]

2. Description of the Related Art Image forming apparatuses that form an image with laser light are widely used in printers, facsimiles, copiers and the like. FIG. 3 is a diagram showing a configuration of a laser scanner which is an exposure unit of a laser beam printer. In the figure, 100 is a main body substrate of the laser scanner,
The scanner unit 101 is mounted on this substrate. The scanner unit 101 includes a laser unit 102, lens systems 104 to 106, beam detectors 109 and 110, and a polygon mirror 103. The laser unit 102 has a semiconductor laser and a collimator lens 106. Reference numerals 104 to 106 are lens systems for forming an image of the laser light L emitted from the semiconductor laser on the photoconductor 107 and for providing the f-θ characteristic.

Reference numeral 103 denotes a polygon mirror, which is rotationally driven in the direction A shown at a constant speed by a high-speed rotating motor (not shown) directly connected to the central axis of the polygon mirror. A magnet is attached to the rotor of this motor, and the number of rotations of the rotor is detected by a few Hall elements, and is controlled to a constant number of rotations. The laser beam L scanned by the polygon mirror 103 passes through the glass window 108 and the photoconductor 1
07.

Reference numerals 109 and 110 constitute a beam detector for detecting the write start position of the image in the main scanning direction. The laser beam L reflected by the reflection mirror 109 is directed to the starting end 110a of the glass fiber cable 110. It is guided and reaches the terminal end 110b of the glass fiber cable 110. A light receiving element (not shown) is attached to the end 110b of the glass fiber cable 110, which detects that a laser beam is received, and synchronizes with a detection signal (BD signal) to synchronize the head of the image in the main scanning direction. Delivering is done.

The image forming process will be specifically described below. The image information converted into an electrical signal from a host computer, an image scanner or the like (not shown) is input to the interface controller, signal-processed, and converted into a video signal. The laser drive circuit drives the semiconductor laser in the laser unit 102 based on the video signal. The laser light L emitted from the semiconductor laser is condensed by the collimator 106 and projected on the rotating polygon mirror 103, and then an optical system (not shown) for correcting the surface tilt of the fθ lens and the polygon mirror 103.
Then, the image is projected on the photoconductor 107 while scanning in the direction perpendicular to the rotation direction.

Before the irradiation of the laser beam L, the photoconductor 107
Are uniformly charged by the charging roller. Then, the portion on which the laser light L is applied attenuates the electric charge on the photoconductor 107, and the portion on which the laser light L is not applied is the photoconductor 1
The electric charge on 07 remains, which causes O of the semiconductor laser.
An electrostatic latent image is formed according to N and OFF.

Then, the electrostatic latent image is developed by the developing device, and a visible image corresponding to the electrostatic latent image is obtained on the photoconductor 107. The transfer material is taken out one by one by a paper feed roller (not shown), the timing is adjusted by a registration roller (not shown), and the photoconductor 10 is moved by a paper guide (not shown).
7 is contacted. In this state, the toner image is transferred onto the transfer material by the transfer roller to which a voltage having a polarity opposite to that of the toner (developing material) is applied. The transfer material onto which the toner image has been transferred is separated from the photoconductor 107 by its own weight and charge removal. After that, the transferred toner image is fixed on the transfer material by the fixing device and is discharged to a tray (not shown).

After the transfer process is completed, the residual toner on the photoconductor 107 is removed by the cleaner, and a series of image forming processes is completed.

[0009]

In the above conventional example, the processing for obtaining the mirror image output result (the output result in which the image on the transfer material is a mirror image) is complicated. FIG.
Shows a normal image of the character string "PRINTER", that is, a normal image, and FIG. 5 shows an image of the character string "PRINTER" seen from the back side, that is, a mirror image. As shown in FIG. 6, when a normal image is output on the transfer material P, the toner image formed on the photoconductor 107 is a mirror image. On the other hand, when a mirror image is output on the transfer material P as shown in FIG. 7, the toner image formed on the photoconductor 107 is a normal image.

In order to select and output a normal image and a mirror image,
The following two methods are possible. The first method is a normal image depending on whether the laser light L is reflected by an even number of mirrors and irradiated onto the photoconductor 107 or the laser light L is reflected by an odd number of mirrors and irradiated onto the photoconductor 107. And how to select a mirror image. In the second method, as shown in FIGS. 8 and 9, in the video controller in the interface controller, the scanning lines of the image drawn in the memory are read out in the direction (left or right in the illustrated example). This is a method of selecting a normal image and a mirror image by switching the direction).

However, the first method requires a mechanism for switching the number of mirrors for reflecting the laser beam to an even number or an odd number, which is not preferable from the viewpoint of cost increase and accuracy maintenance. Further, the second method requires a mechanism for switching the reading direction, which complicates the configuration.

An object of the present invention is to provide an image forming apparatus and an image forming method capable of selecting and outputting a normal image and a mirror image by a simple control mechanism.

[0013]

In order to solve the above problems, an image forming apparatus according to the present invention has the following features. That is, the image forming apparatus according to the present invention is an image forming apparatus that forms an image by scanning with a polygon mirror, and includes a selection means for selecting a rotation direction of the polygon mirror and a rotation for selecting the polygon mirror. Drive means for rotating in a direction, irradiation means for irradiating the rotated polygon mirror with an optical signal corresponding to image information, and image forming means for forming an image by the optical signal reflected by the polygon mirror.

The image forming apparatus according to the present invention preferably further has the following features. That is, in the image forming apparatus according to the present invention, it is preferable that the image forming unit forms an image on a recording medium.

Further, in the image forming apparatus according to the present invention, it is preferable that the selecting means selects a rotation direction of the polygon mirror based on an instruction from a user.

Further, the image forming apparatus according to the present invention further comprises a supplying means for supplying a recording medium to the image forming means, and a detecting means for detecting the transmittance of the recording medium supplied by the supplying means. It is preferable that the selecting unit selects the rotation direction of the polygon mirror based on the detected transmittance.

Further, in the image forming apparatus according to the present invention, when the transmittance of the recording medium is small, the selecting means selects the rotation direction in which the image formed by the constituting means becomes a normal image, and the recording is performed. If the medium has a high transmittance,
It is preferable to select a rotation direction in which the image formed by the above-mentioned constituting means becomes a mirror image.

In the image forming apparatus according to the present invention, it is preferable that the image forming means forms an image by an electrophotographic process.

In order to solve the above problems, the second image forming apparatus according to the present invention has the following features. That is, the second image forming apparatus according to the present invention is an image forming apparatus that forms an image by scanning with a polygon mirror, and includes a first polygon mirror that rotates in a first direction and a second direction. A second polygon mirror that rotates in a horizontal direction, an irradiation unit that irradiates the first and second polygon mirrors with an optical signal corresponding to image information, and the optical signal reflected by the first and second polygon mirrors. And an image composing means for composing an image.

The second image forming apparatus according to the present invention preferably further has the following features. That is, in the second image forming apparatus according to the present invention, it is preferable that the image forming unit forms an image on a recording medium.

In the second image forming apparatus according to the present invention, it is preferable that the image forming means forms an image by an electrophotographic process.

In order to solve the above problems, the image forming method according to the present invention has the following features. That is,
An image forming method according to the present invention is an image forming method in which an image is formed by scanning with a polygon mirror, and a rotation direction of the polygon mirror is selected depending on whether a normal image or a mirror image is formed. The polygon mirror is rotated in the rotation direction described above, an optical signal corresponding to image information is applied to the rotated polygon mirror, and an image is formed by the reflected optical signal.

In order to solve the above problem, the second image forming method according to the present invention has the following features. That is, a second image forming method according to the present invention is an image forming method of forming an image by scanning with a polygon mirror, wherein the rotation direction of the polygon mirror is determined based on the transmittance of a recording medium on which the image is formed. Is selected, the polygon mirror is rotated in the selected rotation direction, an optical signal corresponding to image information is applied to the rotated polygon mirror, and an image is formed by the reflected optical signal.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

<First Embodiment> FIG. 2 is a diagram showing a configuration example of a laser beam printer using an electrophotographic process. In the figure, 1 is an interface controller, 2 is a laser drive circuit, 3 is a laser diode, 103 is a polygon mirror, 5 is an fθ lens, and 106.
Is a collimator, 7 is a charging roller, 7A is a charging power source, 10
7 is a photoconductor, 9 is a developing device, 9A is a developing bias power source, 1
0 is a paper feed roller, 11 is a paper cassette, 12 is a register roller, 13 is a transfer roller, 14 is a transfer holder, 15 is a fixing device, 16 is a cleaner, 17 is an LED array, 18 is a transfer bias power supply, and 19 is a fixing entrance. guide,
Reference numeral 20 is a static elimination needle, and 21 is a static elimination bias power source.

The image information converted into an electric signal from a host computer (not shown), an image scanner (not shown), etc. is input to the interface controller 1 to be subjected to signal processing and converted into a video signal. The laser drive circuit 2 drives (light emission control) the laser diode 3 based on the video signal. Laser diode 3
The laser light L emitted from the laser beam is condensed by the collimator 106, projected on the rotating polygon mirror 103, and then passed through the fθ lens 5 and the optical system for correcting the surface tilt of the polygon mirror 103, and then the photosensitive drum 107. The upper part is projected while scanning in a direction perpendicular to the rotation direction of the photosensitive drum.

The polygon mirror 103 is rotationally driven by the motor 30. The motor control circuit 31 determines the rotation direction of the motor based on the information (normal image output or mirror image output switching instruction) input from the normal image / mirror image switching button 33 of the operation panel 32 or a host computer (not shown) or the like. It can be switched to clockwise or counterclockwise.

Prior to the irradiation of the laser beam L, the photosensitive drum 107 is uniformly charged by the charging roller 7 to which a voltage is applied by the charging power source 7A. Then, the portion on the photosensitive drum 107 where the laser light L is applied is attenuated, and the portion where the laser light L is not applied is on the photosensitive drum 1.
The electric charge on 07 remains, thereby forming an electrostatic latent image according to ON / OFF of the laser diode 3.

Then, the electrostatic latent image is developed by the developing device 9 to form a visible image corresponding to the electrostatic latent image on the photosensitive drum 1.
Obtained on 07. The transfer material P is the paper cassette 11
The sheet is picked up one by one by the paper feed roller 10, and the photosensitive drum 107 is picked up by the register roller 12 at a predetermined timing.
Be contacted with. The toner image is transferred to the transfer bias power source 18
Is transferred onto the transfer material P by the transfer roller 13 to which a predetermined voltage is applied.

The transfer material P on which the toner image has been transferred is separated from the photosensitive drum 107 by the dead weight of the transfer material, the waist, and the charge removal by the charge removal needle 20. After that, the transferred toner image is fixed on the transfer material P by the fixing device 15, and is discharged to a tray (not shown).

After the transfer process is completed, the cleaner 16 removes the residual toner from the photosensitive drum 107, and the LED array 17 uniformly exposes the photosensitive drum 107 to remove the residual charge, thus completing a series of image forming processes.

In one embodiment, the photosensitive drum 10
7 has a length of 346 mm coated with a photoconductive substance made of an organic material and an outer diameter of 30 mm, for example. Further, in forming the toner image, for example, the surface of the photosensitive drum 107 is uniformly charged with a negative polarity by the charging roller 7, and then the portion corresponding to the black pixel of the image is irradiated with the laser beam L to be charged. A method of attenuating the electric charge and adsorbing the negative polarity toner to the part (so-called “image exposure, reversal development”) can be applied.

FIG. 1 is an external view showing the structure of the exposure unit of the laser beam printer according to this embodiment. In the figure, reference numeral 100 is a main body substrate, on which a scanner unit 101 is attached. The scanner unit 101 has a laser unit 102, beam detectors 109, 110, 115 and 116, a polygon mirror 103 and the like. The laser unit 102 has a laser diode 3 and a collimator lens 106.
104 to 106 form an image of the laser light L emitted from the laser diode 3 on the photoconductor 107 and f
It is a lens system for giving -θ characteristic.

The polingon mirror 103 is rotated at a constant speed in the A or B direction shown by the motor 30 directly connected to the central axis thereof. The rotation direction A or B is switched depending on whether the normal image or the mirror image is output as described above. A magnet is attached to the rotor of the motor 30, and the number of rotations is detected by using two to three Hall elements, and the number of rotations is controlled to be constant. The laser light L scanned by the polingon mirror 103 passes through the glass window 108 and is applied to the photoconductor 107.

Reference numerals 109 and 110 designate a polygon mirror 1
When 03 rotates in the A direction (when outputting a normal image),
The reflection mirror 109 constitutes a beam detector for detecting the writing position of the image in the main scanning direction.
The laser light L reflected by is guided to the start end 110a of the glass fiber cable 110 and reaches the end 110b of the glass fiber cable 110. A light receiving element (not shown) is attached to the terminal end 110b of the glass fiber cable 110, and it is detected that the laser beam L is received, and in synchronization with the detection signal (BD signal), an image in the main scanning direction is displayed. Cue is performed.

Reference numerals 115 and 116 denote the polingon mirror 1.
When 03 rotates in the B direction (when outputting a mirror image),
The reflection mirror 115 constitutes a beam detector for detecting the write start position of the image in the main scanning direction.
The laser light L reflected by is guided to the starting end 116 a of the glass fiber cable 116 and reaches the ending end 116 b of the glass fiber cable 116. A light receiving element (not shown) is attached to the terminal end 116b of the glass fiber cable 116, which detects that the laser beam L is received and synchronizes with the detection signal (BD signal) in the main scanning direction. Is cued.

FIG. 8 is a schematic view showing the state of the laser beam printer when the polygon mirror 103 rotates in the A direction (when a normal image is output). FIG. 10 is a schematic diagram showing a state of the laser beam printer when the polygon mirror 103 rotates in the B direction (at the time of mirror image output).

As described above, by switching the rotation direction of the polygon mirror 103 (motor 30) between the case of outputting the normal image and the case of outputting the mirror image, the output of the normal image and the mirror image is switched. Can be easily realized.

One of the advantages of outputting a mirror image is the case where a mirror image output image and a diazo photosensitive paper are superposed and a copy is made by a diazo copying machine. FIG. 11 shows a normal image output image (second image).
FIG. 3 is a diagram schematically showing a state in which copying is performed by a diazo copying machine using an original drawing). On the other hand, FIG. 12 is a diagram schematically showing how a diazo copying machine performs copying using a mirror image output image (second original drawing). As shown in the figure, when copying is performed by a diazo copying machine, a toner image T is brought into close contact with the diazo photosensitive paper by using a mirror image, so that a sharp copied image can be obtained.

Another advantage of outputting a mirror image is that
This is a case where an output image is projected by a reflection type OHP (overhead projector) as shown in FIGS. 13 and 14.
In the reflection type OHP, an OHT (overhead transparency) which is an output image of the laser beam printer is placed on the reflection type mirror Fresnel lens 204.

At this time, as shown in FIG.
A sharper projected image can be obtained when a mirror image OHT is placed as shown in FIG. 16 than when T is placed on the mirror Fresnel lens 204.

<Second Embodiment> In this embodiment, O
In consideration of the effect of forming a mirror image on a transparent transfer material such as HT, when a transfer material having a high transmittance is used, the polygon mirror 103 (motor 30) is rotated so as to automatically output the mirror image. The direction is switched.

FIG. 17 and FIG. 18 are views showing an example of the structure in the vicinity of the transfer material guide 118 shown in FIG. In this embodiment, the upper guide 118a of the transfer material guide 118 is used.
The lower guide 118b and the lower guide 118b are provided with windows 170a and 170b, respectively. The window 170a side is provided with a phototransistor 180 which is an optical sensor, and the window 170b side is provided with a light emitting element 181. The phototransistor 180 outputs a signal (detection signal) indicating the transmittance of the transfer material to the motor control circuit 3 shown in FIG.
Feed to 1.

The motor control circuit 31 determines the rotation direction of the motor 30 based on the input detection signal. That is, when the transfer material P has a high transmissivity such as OHT, the motor control circuit 31 rotates the motor 30 in the B direction (direction in which a mirror image is output) so that the transfer material P is normally transferred. When the sheet has low transparency like paper, the motor 30 is rotated in the A direction (direction to output a normal image).

Therefore, in the present embodiment, a mirror image is formed when an image is formed on a transfer material having high transmittance, and a normal image is formed when an image is formed on a transfer material having low transparency. become. Whether or not to use the function of automatically selecting the rotation direction of the motor 30 (polygon mirror 103) as described above is determined by, for example, the automatic selection button 3 in the operation panel 32.
It may be made selectable by operating 4.

<Third Embodiment> FIG. 19 is a view showing the arrangement of the exposure unit of the laser beam printer according to this embodiment. In this embodiment, two polingon mirrors 10 are used.
3 and 103 'and two motors 30 and 30' for driving them are provided. The motors 30 and 3
0'is controlled by the motor control circuit 31, the polygon mirror 103 is rotated in the A direction, and the polygon mirror 10
3'is rotated in the B direction.

FIG. 20 is a diagram showing an example in which a normal image and a mirror image are formed on one OHT by the laser beam printer according to this embodiment. For example, when only a mirror image is formed on an OHT or the like (especially when an image of only a figure is formed),
It is difficult to distinguish the front side from the back side, and filing cannot be performed efficiently. However, according to the present embodiment, since a normal image and a mirror image can be formed on one transfer material, for example, By outputting the page number and the like as a normal image, such a problem can be solved.

The area (line) for outputting the normal image and the area for outputting the mirror image are selected by the operation panel 32 or the like. In the area for outputting the normal image, the laser beam L1 (incident on the polygon mirror 30) is selected. The laser beam L2 (the laser beam incident on the polygon mirror 30 ′) only needs to be output in the region where the mirror image is to be output.

Even when the present invention is applied to a system composed of a plurality of devices (eg, host computer, interface device, reader, printer, etc.), a device composed of one device (eg, copier, (For example, a facsimile machine).

As described above, according to the present invention,
An image forming apparatus and an image forming method capable of selecting and outputting a normal image and a mirror image with a simple control mechanism can be provided.

[0050]

[Brief description of drawings]

FIG. 1 is an external view showing a configuration of an exposure unit of a laser beam printer.

FIG. 2 is a diagram showing a configuration example of a laser beam printer using an electrophotographic process.

FIG. 3 is a diagram showing a configuration of a laser scanner which is an exposure unit of a laser beam printer.

FIG. 4 is a diagram showing a normal image of a character string “PRINTER”.

FIG. 5 is a diagram showing a mirror image of a character string “PRINTER”.

FIG. 6 is a diagram showing an example in which a normal image of a character string “PRINTER” is output.

FIG. 7 is a diagram showing an example in which a mirror image of a character string “PRINTER” is output.

FIG. 8 is a schematic diagram showing a state of the laser beam printer when the polygon mirror 103 rotates in the A direction (when a normal image is output).

FIG. 9 is a schematic diagram showing a state of a laser beam printer when outputting a mirror image by reversing the reading direction of an image drawn in a memory.

FIG. 10 is a schematic diagram showing a state of the laser beam printer when the polygon mirror 103 rotates in the B direction (at the time of mirror image output).

FIG. 11 is a diagram schematically showing how a diazo copying machine copies an output image of a normal image (second original drawing).

FIG. 12 is a diagram schematically showing how a diazo copying machine performs copying using a mirror image output image (second original drawing).

FIG. 13 is a diagram showing an example of a reflective OHP.

FIG. 14 is a diagram showing an example of a reflective OHP.

FIG. 15 shows a mirror Fresnel lens 204 for a normal image OHT.
It is a figure which shows the mode mounted on the top.

FIG. 16 is a mirror Fresnel lens 204 for a mirror image OHT.
It is a figure which shows the mode mounted on the top.

FIG. 17 is a perspective view showing a configuration example near a transfer material guide 118.

FIG. 18 is a cross-sectional view showing a configuration example near a transfer material guide 118.

FIG. 19 is a diagram showing a configuration of an exposure unit of a laser beam printer.

FIG. 20 is a diagram showing an example in which a normal image and a mirror image are formed on one sheet of OHT.

Claims (11)

[Claims] 1. An image forming apparatus for forming an image by scanning with a polygon mirror, comprising: selecting means for selecting a rotation direction of the polygon mirror; and driving means for rotating the polygon mirror in the selected rotation direction. And an irradiation unit that irradiates the rotated polygon mirror with an optical signal corresponding to image information, and an image forming unit that forms an image by the optical signal reflected by the polygon mirror. Forming equipment. 2. The image forming apparatus according to claim 1, wherein the image forming unit forms an image on a recording medium. 3. The image forming apparatus according to claim 1, wherein the selection unit selects a rotation direction of the polygon mirror based on an instruction from a user. 4. A supply unit for supplying a recording medium to the image forming unit, and a detection unit for detecting the transmittance of the recording medium supplied by the supply unit, wherein the selection unit detects the detected transmittance. The image forming apparatus according to claim 2, wherein the rotation direction of the polygon mirror is selected based on the above. 5. The selecting means selects a rotation direction in which the image formed by the constituting means is a normal image when the transmittance of the recording medium is low, and when the transmittance of the recording medium is high, the selecting means selects the rotation direction. The image forming apparatus according to claim 4, wherein the rotation direction in which the image formed by the constituting unit becomes a mirror image is selected. 6. The image forming apparatus according to claim 2, wherein the image forming unit forms an image by an electrophotographic process. 7. An image forming apparatus for forming an image by scanning with a polygon mirror, comprising a first polygon mirror rotating in a first direction and a second polygon mirror rotating in a second direction. Irradiating means for irradiating the first and second polygon mirrors with an optical signal corresponding to image information, and an image forming means for forming an image with the optical signals reflected by the first and second polygon mirrors An image forming apparatus comprising: 8. The image forming apparatus according to claim 7, wherein the image forming unit forms an image on a recording medium. 9. The image forming apparatus according to claim 8, wherein the image forming unit forms an image by an electrophotographic process. 10. An image forming method for forming an image by scanning with a polygon mirror, wherein a rotation direction of the polygon mirror is selected depending on whether a normal image or a mirror image is formed, and the rotation direction is selected in the selected rotation direction. An image forming method comprising rotating the polygon mirror, irradiating the rotated polygon mirror with an optical signal corresponding to image information, and forming an image by the reflected optical signal. 11. An image forming method for forming an image by scanning with a polygon mirror, wherein the rotation direction of the polygon mirror is selected based on the transmittance of a recording medium on which the image is formed. An image forming method comprising rotating the polygon mirror, irradiating the rotated polygon mirror with an optical signal corresponding to image information, and forming an image by the reflected optical signal.