JP5005438B2 - Optical scanning device and image forming apparatus - Google Patents

Description

  The present invention relates to an optical scanning apparatus and an image forming apparatus that can be used in laser printers, digital copying machines, plain paper fax machines, and the like.

In image recording in electrophotography, an image forming method using a laser is widely used as an image forming means for obtaining high-definition image quality. In the case of electrophotography, a method is generally used in which a latent image is formed by rotating a drum (sub-scanning) while scanning a laser (main scanning) using a polygon mirror in the axial direction of a photosensitive drum. In such an electrophotographic field, higher definition of images and higher speed of output are required. In order to increase the definition of an image, when the resolution of the image is doubled, twice the time is required for both main scanning and sub-scanning. Therefore, four times the time is required for image output. Therefore, in order to realize high definition of images, it is necessary to simultaneously achieve high speed image output.
As a method for realizing high-speed image output, it is conceivable to increase the output of the laser, increase the number of beams, increase the sensitivity of the photosensitive member, and the like. In particular, in a high-speed output machine, it is common to use a multi-beam writing light source. Compared to the case of using one laser, when n lasers are used at the same time, the latent image forming area is n times and the time required for image formation is 1 / n.
As such an example, a multi-beam semiconductor laser having a plurality of light-emitting light sources in one chip has been proposed (see, for example, Patent Document 1). These are configurations using edge-emitting semiconductor lasers, and are one-dimensionally arranged, and since multi-beams increase power consumption and require a cooling system, about 4 beams or 8 beams are required in terms of cost. It is a limit.

On the other hand, a surface emitting laser (vertical cavity surface emitting laser, VCSEL) is a semiconductor laser that emits light in a direction perpendicular to a substrate, and is easily two-dimensionally integrated. Further, the power consumption is about an order of magnitude smaller than that of the edge type laser, which is advantageous for integrating more light sources in two dimensions. As an example of this, there is an example of a writing optical system that scans using a polygon (see, for example, Patent Document 2).
Furthermore, in electrophotographic image forming apparatuses, the speed has been increased, and tandem-compatible image forming apparatuses having a plurality of (usually four) photoconductors have become widespread. However, in the case of the tandem method, the number of light sources increases, and accordingly, the number of parts increases, color shift due to a wavelength difference between a plurality of light sources, and cost increase. Further, the cause of the failure of the writing unit is the deterioration of the semiconductor laser. When the number of light sources is increased by the tandem method, the probability of failure increases and the recyclability deteriorates.
Therefore, as an example in which the number of light sources is not increased by the tandem method, a configuration using a pyramid mirror or a flat mirror having a single deflection reflection surface inclined by 45 degrees with respect to the rotation axis has been proposed (for example, Patent Document 3). reference.). Further, a configuration has been proposed in which the light beam emitted from the light source is divided into two beams by the beam splitting means, and the two polygon mirrors that are overlapped at different angles are incident on the upper and lower polygon mirrors of the deflection means that rotate coaxially. (For example, refer to Patent Document 4).

JP 11-340570 A JP 2005-274755 A JP-A-11-290442 JP 2006-284822 A

According to the conventional example, the light beam emitted from the light source is divided into two by the light beam splitting means, and is incident on the upper and lower polygon mirrors to scan on different photoconductors. In this case, out of the two divided by the light beam splitting means, only one light beam is scanned on the photoconductor, and one light beam is not deflected in the scanning direction on the photoconductor, so that it does not become stray light. A light shielding member is used. Therefore, if the light emitted from the surface emitting laser is halved by the light beam splitting means, for example, there is a loss of optical components on the way on the photosensitive member, and the light emitted from the surface emitting laser is reduced. A light intensity of 1/2 or less is used. This requires a higher output for the surface emitting laser, and as a result, there is a possibility that the deterioration of the surface emitting laser is accelerated.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to use a tandem high-speed electrophotographic image forming apparatus without dividing a light output of a surface emitting laser while using a light beam dividing means. For this purpose, the light output of the surface-emitting laser is effectively used without being divided by controlling the direction in which the light is split temporally by using the diffraction means arranged on the rotating plate as the light beam splitting means. In addition, a hologram capable of an arbitrary diffraction angle is used as the diffraction means. Furthermore, it uses also for condensing to a light quantity monitor using the lens action of a hologram.

According to the first aspect of the present invention, there is provided an optical scanning device that scans a surface to be scanned with a light beam, a light source unit that emits at least one light beam including image information, and at least light from the light source unit. It has a beam splitter for distributing the two directions, and deflection means for deflecting the light beam through the pre-Symbol beam splitting means, and a scanning optical system for converging the deflected light beam onto the surface to be scanned In the optical scanning device, the light beam splitting unit includes a rotating plate in which at least the diffraction unit region is partially arranged in the circumferential direction, and the beam splitting is performed by time division by the rotation of the rotating plate and is incident on the diffraction unit region. The direction of the light beam and the direction of the light beam that enters the outside of the diffraction means region are made different .

In the invention described in claim 2, in the optical scanning apparatus according to claim 1, wherein the rotary plate, said diffracting means area, the non-diffractive portion area and the circumferential direction to transmit without diffracting the light beam incident It is arranged so that it may line up alternately.
According to a third aspect of the present invention, in the optical scanning device according to the first aspect, the rotating plate is arranged such that two or more types of diffraction means regions having different diffraction angles are arranged in close contact with or spaced apart from each other in the circumferential direction. The diffractive means region is disposed outside the diffractive means region with respect to one type of diffractive means region .

The invention according to claim 4, in the optical scanning apparatus according to claim 3, having a light amount monitoring means, one of said plurality of types of diffraction unit region is diffracted by the one diffractive means area characterized in that the light beam is arranged to be incident on the light quantity monitor means.
According to a fifth aspect of the present invention, in the optical scanning device according to the fourth aspect, the diffraction means region for diffracting the light beam so as to be incident on the light amount monitor condenses the light beam on the light amount monitor. It is characterized by having a lens action.

According to a sixth aspect of the present invention, in the optical scanning device according to any one of the first to fifth aspects, the deflecting unit includes a polygon mirror, and the rotating plate is in relation to the one diffractive unit region. The polygon mirror is rotated so that one surface of the polygon mirror is synchronized.
According to a seventh aspect of the present invention, in the optical scanning device according to any one of the first to sixth aspects, the light source unit has a surface emitting laser element, and a plurality of light beams are emitted from the light source unit. It is characterized by being a light beam.

  According to an eighth aspect of the present invention, at least one image carrier, charging means for uniformly charging the surface of the image carrier, and optical scanning for forming an electrostatic latent image by exposing the charged image carrier. Image forming apparatus comprising: an apparatus; a developing unit that visualizes the electrostatic latent image; a transfer unit that transfers the visible image to a recording medium; and a fixing unit that fixes the visible image to the recording medium. In the apparatus, the optical scanning device is characterized by an image forming apparatus which is the optical scanning device according to any one of claims 1 to 7.

  According to the present invention, the light output of the surface emitting laser light source can be used without being divided. In addition, since the hologram as a diffracting means can be duplicated, it can be made inexpensively in large quantities.

FIG. 1 is a schematic view of an embodiment of a beam splitting means used in the present invention. FIG. 4A is a diagram in which one type of hologram is formed, and FIG. 4B is a diagram showing an example in which a light shielding portion is provided in addition to the hologram.
In the figure, reference numeral 100 denotes a rotating plate, 101 denotes a hologram, 102 denotes a non-diffracting transmission portion, and 102 ′ denotes a light shielding portion.
The rotating plate 100 is made of a transparent member such as glass or plastic. There is a hole in the center so that it can rotate, and it can be rotated around the center of the rotating plate by a rotating means separately prepared. A plurality of holograms 101 are concentrically arranged on the rotating plate 100.
The hologram has a function of diffracting incident light at a certain angle, and can be diffracted at any angle by a structure formed in the hologram. However, in the hologram, when there is no change in the wavelength of the light source, light beams having the same incident angle always have the same diffraction angle, and there is no place dependency of the diffraction angle in one hologram. However, since the hologram of the present invention moves in an arc so as to cross the light beam at a fixed position as the disk rotates, the diffraction direction of the diffracted light beam is not changed by this movement. It has become.
The hologram can be directly formed on the rotating plate, or can be duplicated on the rotating plate by forming a separate mold. When forming directly on a rotating plate, a photosensitive resin is applied to the rotating plate and a hologram pattern is formed (exposure / development) at a position where a hologram is to be formed. The hologram pattern may be created by computer calculation and then optically drawn or formed by optical interference. In the case of forming with a mold, the production of the mold is the same as the production of the rotating plate directly, but using the completed mold, a photocurable resin is applied on the rotating plate and the mold is pressed to form a pattern and then cured. There is a method of manufacturing.
Next, the operation will be described with reference to FIG.

FIG. 2 is a diagram for explaining how light is divided by a hologram.
In the figure, reference numeral 103 denotes a light beam, 104 denotes a transmitted light beam, 105 denotes a diffracted light beam, and 106 denotes a mirror.
The light emitted from the surface emitting laser is converted into a weak convergent light beam, a parallel light beam, or a weak divergent light beam by a coupling lens (see FIG. 8 described later). The light beam 103 exiting the coupling lens passes through an aperture stop for stabilizing the beam diameter on the surface to be scanned and enters the hologram 101 of the rotating plate 100. Here, the light beam 103 becomes a diffracted light beam 105 and is further reflected by the mirror 106. Further, when the light beam 103 is incident on a transparent portion by rotating the rotating plate, the light beam 104 is transmitted as it is without being diffracted. In this way, the light beam is divided by time division. Note that the light beam incident on the rotating plate 100 is not divided because the light path itself is merely switched depending on whether or not the hologram 101 is present. The method is also called beam splitting.
Further, a region with a hologram is called a diffraction means region. Correspondingly, a region without a hologram is called a non-diffractive means region or simply a transmission region.
Depending on the beam diameter of the light beam at the boundary between the diffractive means region and the non-diffractive means region, the light beam may sometimes straddle both regions for a moment. When the diffracted light or transmitted light at this time becomes stray light that is not preferable for image formation, a light blocking portion 102 ′ that blocks the light beam may be provided at these boundaries.

FIG. 3 is a diagram showing another embodiment of the light beam splitting means.
In the figure, reference numeral 200 denotes a rotating plate, and 210 denotes a hologram.
The hologram 210 is composed of a plurality of two types of holograms having different characteristics, which are indicated by 210A and 210B, respectively.
The rotating plate is made of a transparent member such as glass or plastic. There is a hole in the center so that it can rotate, and it can be rotated around the center of the rotating plate by a rotating means separately prepared.
The holograms are arranged on the circumference, and adjacent holograms such as 210A and 210B have different diffraction directions. However, in the hologram, when there is no change in the wavelength of the light source, light beams having the same incident angle always have the same diffraction angle, and there is no place dependency of the diffraction angle in one hologram.
In the figure, two types of holograms are arranged in close contact with each other, but may be arranged apart from each other when there is a time zone in which no light beam is used. Furthermore, three optical paths can be switched by arranging three areas including the non-diffractive means area.
Next, the operation will be described with reference to FIG.

FIG. 4 is a diagram for explaining light beam splitting by the hologram shown in FIG.
In the figure, reference numeral 220 indicates a light beam, 230 and 240 indicate diffracted light beams, and 260 and 270 indicate mirrors, respectively.
The light emitted from the surface emitting laser is converted into a weak convergent light beam, a parallel light beam, or a weak divergent light beam by a coupling lens. The light beam 220 exiting the coupling lens is transmitted through an aperture stop for stabilizing the beam diameter on the surface to be scanned, and is incident on the hologram 210A of the rotating plate. Here, the light beam becomes a diffracted light beam 230 and further reflected by the mirror 260. When the light beam 220 is incident on the hologram 210B by rotating the rotating plate, the light beam 240 is diffracted at an angle different from that of the hologram 210A. Thereafter, the light is reflected by the mirror 270 in the same manner as the light diffracted by the hologram 210A. In this way, the light beam is divided by time division.

FIG. 5 is a diagram showing another embodiment of the light beam splitting means.
In the figure, reference numeral 300 denotes a rotating plate, 310 and 320 denote holograms, and 330 denotes a transmission portion that is not diffracted.
The rotating plate 300 is made of a transparent member such as glass or plastic. There is a hole in the center so that it can rotate, and it can be rotated around the center of the rotating plate by a rotating means separately prepared. A plurality of two types of holograms 310 and 320 are arranged on the rotating plate 300.
The holograms are arranged on the circumference, and the hologram 310 is a hologram that diffracts at a certain angle, and the hologram 320 has a function of diffracting and further converting into a convergent light beam. However, in the hologram, when there is no change in the wavelength of the light source, light beams having the same incident angle always have the same diffraction angle, and there is no place dependency of the diffraction angle in one hologram.

FIG. 6 is a diagram for explaining the operation of the hologram shown in FIG.
In the figure, reference numeral 340 denotes a light beam, 350 denotes a diffracted light beam, 360 denotes a diffracted and convergent light beam, 370 denotes a transmitted light beam, and 380 denotes a mirror.
The light emitted from the surface emitting laser light is converted into a weak convergent light beam, a parallel light beam, or a weak divergent light beam by a coupling lens. The light beam 340 exiting the coupling lens passes through an aperture stop for stabilizing the beam diameter on the surface to be scanned, and enters the hologram 310 of the rotating plate. Here, the light beam becomes a diffracted light beam 350 and further reflected by the mirror 380. When the light beam 340 exiting the coupling lens is incident on the hologram 320 due to the rotation of the rotating plate, the light beam 340 is diffracted at a different angle from the hologram 310 and becomes a converged light beam 360. Further, when the rotating plate rotates and the light beam 340 enters the transmission part 330, it is transmitted as it is as transmitted light 370. In this way, the light beam is divided by time division. Incidentally, the light beam 360 that is diffracted and converged by the monitoring hologram 320 is then incident on the light intensity monitoring means (usually a photodiode) to monitor the light output.
In the above embodiment, the monitor hologram is added to the configuration shown in FIG. 1, but a monitor hologram can be added to the configuration shown in FIG.
In the above embodiment, the rotating plate is transparent and the hologram is a transmission type. However, the rotating plate may be a reflective material and the hologram may be a reflection type. Further, the hologram is designed so that almost no zero-order light is generated, or is processed so that the generated zero-order light does not become ghost light.

FIG. 7 is a diagram showing a schematic configuration of a laser printer as an image forming apparatus according to an embodiment of the present invention.
In the figure, reference numeral 500 is a laser printer, 900 is an optical scanning device, 901 is a photosensitive drum, 902 is a charging charger, 903 is a developing roller, 904 is a toner cartridge, 905 is a cleaning blade, 906 is a paper feed tray, and 907 is a paper supply. Reference numeral 908 denotes a registration roller pair, 909 denotes a fixing roller, 910 denotes a paper discharge tray, 911 denotes a transfer charger, 912 denotes a paper discharge roller, 913 denotes a recording paper, and 914 denotes a static elimination unit.
The charging charger 902, the developing roller 903, the transfer charger 911, the charge removal unit 914, and the cleaning blade 905 are each disposed in the vicinity of the surface of the photosensitive drum 901. Then, with respect to the rotation direction of the photosensitive drum 901, the charging charger 902, the developing roller 903, the transfer charger 911, the static elimination unit 914, and the cleaning blade 905 are arranged in this order.

A photosensitive layer is formed on the surface of the photosensitive drum 901. Here, the photosensitive drum 901 is rotated clockwise (in the direction of the arrow) within the plane in FIG.
The charging charger 902 uniformly charges the surface of the photosensitive drum 901.
The optical scanning device 900 irradiates the surface of the photosensitive drum 901 charged by the charging charger 902 with light modulated based on image information from a host device (for example, a personal computer). As a result, a latent image corresponding to the image information is formed on the surface of the photosensitive drum 901 on the surface of the photosensitive drum 901. The latent image formed here moves in the direction of the developing roller 903 as the photosensitive drum 901 rotates. The configuration of the optical scanning device 900 will be described later.
The toner cartridge 904 stores toner, and the toner is supplied to the developing roller 903.
The developing roller 903 causes the toner supplied from the toner cartridge 904 to adhere to the latent image formed on the surface of the photosensitive drum 901 to visualize the image information. Here, the latent image to which the toner is attached moves in the direction of the transfer charger 911 as the photosensitive drum 901 rotates.

Recording paper 913 is stored in the paper feed tray 906. A paper feed roller 907 is disposed in the vicinity of the paper feed tray 906, and the paper feed roller 907 takes out the recording paper 913 one by one from the paper feed tray 906 and conveys it to the registration roller pair 908. The registration roller pair 908 is disposed in the vicinity of the transfer roller 911, temporarily holds the recording paper 913 taken out by the paper feed roller 907, and the recording paper 913 is synchronized with the rotation of the photosensitive drum 901. It is sent out toward the gap between 901 and the transfer charger 911.
A voltage having a polarity opposite to that of the toner is applied to the transfer charger 911 in order to electrically attract the toner on the surface of the photosensitive drum 901 to the recording paper 913. With this voltage, the latent image on the surface of the photosensitive drum 901 is transferred to the recording paper 913. The recording sheet 913 transferred here is sent to the fixing roller 909.

In the fixing roller 909, heat and pressure are applied to the recording paper 913, whereby the toner is fixed on the recording paper 913. The recording paper 913 fixed here is sent to the paper discharge tray 910 via the paper discharge roller 912 and sequentially stacked on the paper discharge tray 910.
The neutralization unit 914 neutralizes the surface of the photosensitive drum 901.
The cleaning blade 905 removes toner remaining on the surface of the photosensitive drum 901 (residual toner). The removed residual toner is used again. The surface of the photosensitive drum 901 from which the residual toner has been removed returns to the position of the charging charger 902 again.

FIG. 8 is a diagram for explaining the configuration and operation of the optical scanning device.
In the figure, reference numeral 1 is a surface emitting laser array as a light source, 2 is a surface emitting laser base, 3 is a coupling lens, 4a is a rotating plate as light beam dividing means, 4b is a mirror as light beam dividing means, 5 and 5 '. Is a cylindrical lens, 6 is a soundproof glass, 7 is a polygon mirror as a deflecting means, 8 is a first scanning lens, 9 is a mirror, 10 is a second scanning lens, 11 is a photoreceptor as a surface to be scanned, and 12 is an aperture stop. , 13 indicate light quantity monitoring sensors, respectively.
The divergent light beam emitted from the surface emitting laser 1 including image information is converted into a weak convergent light beam, a parallel light beam, or a weak divergent light beam by the coupling lens 3. The beam exiting the coupling lens 3 passes through the aperture stop 12 for stabilizing the beam diameter on the surface to be scanned, enters the hologram on the rotating plate 4a, and passes through the diffraction or non-hologram region. The diffracted light beam for image information is reflected by the mirror 4b, or the light beam that has been transmitted without being diffracted remains as it is and enters the cylindrical lens 5 as a single light beam. Here, it is converted into a line image that is long in the main scanning direction in the vicinity of the deflecting reflection surface. Here, in the deflecting means 7, single polygon mirrors 7a and 7b are concentrically arranged on the upper and lower stages, respectively, and the rotation direction angles are shifted from each other.
When there is diffracted light for monitoring the light quantity, the light is condensed on the sensor 13 for monitoring the light quantity, and its output is used not only for adjusting the light quantity but also for timing signals for synchronization.

The light beam deflected in the main scanning direction by the deflecting means 7 is collected by the scanning optical system including the first scanning lens 8, the plurality of mirrors 9, and the second scanning lens 10 so that the surface to be scanned is substantially focused. Lighted.
The movement of the light beam in the main scanning direction by the deflecting unit and the direction switching of the light beam by the beam splitting unit are synchronized. That is, when the upper beam from the light beam splitting means is scanning the photoconductor 11a which is the surface to be scanned, the light beam from the light source is transmitted through one of the transmission regions without the hologram of the light beam splitting means 4a. When the lower beam from the beam splitting means scans the photoconductor 11b different from the upper stage, the beam from the light source is diffracted by one hologram region of the beam splitting means 4a and reflected by the mirror 4b. . Further, when the modulation drive is shifted in the upper stage and the lower stage and the photoconductor 11a corresponding to the upper stage is scanned, the modulation driving of the light source is performed based on the image information of the color (for example, black) corresponding to the upper stage, When scanning the photoreceptor 11b corresponding to the lower stage, the light source is modulated based on image information of a color (for example, magenta) corresponding to the lower stage. For this reason, a main controller (not shown) that controls the above-described units in an integrated manner is provided.
When the rotating plate 200 having the configuration shown in FIG. 3 is used, the moving distance of the light beam in the main scanning direction is set to be longer than the actually required main scanning length, and synchronization is detected at the end. A conventionally used method of providing a sensor can be employed.

FIG. 9 is a schematic view of a light emitting surface of a surface emitting laser array (VCSEL) used in the present invention.
In the figure, reference numerals d1 and d2 denote pitches of light emitting points in the sub-scanning direction, and LA denotes a laser array.
When the LA as shown in the figure is used for the optical scanning device having the above configuration, in the surface emitting laser array, a perpendicular line (in the right direction in the figure) extends from the center of each surface emitting laser element (VCSEL) to the direction corresponding to the sub-scanning direction. ), The positional relationship between the surface emitting laser elements in the direction corresponding to the sub-scanning direction is equal (interval d2). Therefore, by adjusting the lighting timing, the position on the photosensitive drum 11a or 11b is adjusted. Then, it can be considered that the configuration is the same as the case where the light sources are arranged at equal intervals in the sub-scanning direction. For example, if the pitch d1 of the surface emitting laser elements in the direction corresponding to the sub-scanning direction is 26.5 μm, the interval d2 is 2.65 μm. If the magnification of the optical system is doubled, writing dots can be formed on the photosensitive drum 901 at intervals of 5.3 μm in the sub-scanning direction. This corresponds to 4800 dpi (dots / inch). That is, high-density writing of 4800 dpi (dot / inch) can be performed. Of course, higher density can be achieved by increasing the number of surface emitting lasers in the direction corresponding to the main scanning direction, making the array arrangement in which the pitch d1 is reduced and the interval d2 is further reduced, or the magnification of the optical system is reduced. And higher quality printing becomes possible. Note that the writing interval in the main scanning direction can be easily controlled by the lighting timing of the light source.
In this case, the laser printer 500 can perform printing without decreasing the printing speed even if the writing dot density increases. Further, when the writing dot density is the same, the printing speed can be further increased.

In the surface emitting laser array, since the heat dissipation of each surface emitting laser element is improved as compared with the prior art, even if the pitch d1 = 26.5 μm and the interval d2 = 2.65 μm, high output from each surface emitting laser element. It is possible to emit light beams respectively. Even if a plurality of surface emitting laser elements are operated simultaneously, the laser printer 500 can form a high-definition image at high speed because there is little variation in the light output characteristics of each surface emitting laser element.
As described above, according to the optical scanning device 900 according to the present embodiment, the light source is the surface-emitting laser array, and therefore can operate at a higher output than the conventional one. As a result, the photosensitive drums 11a and 11b It is possible to scan the surface at high speed.

Since the laser printer 500 according to the present embodiment includes the optical scanning device 900 including the surface emitting laser array, a high-definition image can be formed at high speed.
In the above embodiment, the laser printer 500 is described as the image forming apparatus. However, the present invention is not limited to this. In short, an image forming apparatus having any one of the light beam dividing means 100 to 300 can form a high-definition image at high speed.

In addition, even an image forming apparatus that forms a color image can form a high-definition image at high speed by using an optical scanning device corresponding to the color image.
The image forming apparatus corresponds to a color image. For example, a photosensitive drum for black (K), a photosensitive drum for cyan (C), a photosensitive drum for magenta (M), and a photosensitive drum for yellow (Y). A tandem color machine including a plurality of photosensitive drums such as a photosensitive drum may be used.

It is a general-view figure of one Example of the light beam splitting means used for this invention of this invention. It is a figure for demonstrating the mode of the division | segmentation of the light by a hologram. It is a figure which shows the other Example of a light beam splitting means. It is a figure for demonstrating the light beam division | segmentation by the hologram shown in FIG. It is a figure which shows the other Example of a light beam splitting means. It is a figure for demonstrating the effect | action of the hologram shown in FIG. 1 is a diagram illustrating a schematic configuration of a laser printer as an image forming apparatus according to an embodiment of the present invention. It is a figure for demonstrating the structure and effect | action of an optical scanning device. It is a schematic diagram of the light emission surface of the surface emitting laser array (VCSEL) used for this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Surface emitting laser array 100 Rotating plate 101 Hologram 102 Transmission part 103 Light beam 105 Diffracted light beam 106 Mirror 200 Rotating plate 210 Hologram 220 Light beam 230 Diffracted light beam 240 Diffracted light beam 260 Mirror 270 Mirror 300 Rotating plate 310 Hologram 320 Hologram 330 transmissive portion 340 light beam 350 diffracted light beam 380 mirror 360 diffracted and converged light beam

Claims (8)

An optical scanning device for scanning a surface to be scanned by the light beam, a light source unit for emitting at least one light beam containing image information, a light beam splitting means for distributing light from the light source unit to at least two directions in the optical scanning device having a deflecting means for deflecting the light beam having passed through the pre-Symbol beam splitting means, and a scanning optical system for converging the deflected light beam onto the surface to be scanned,
The beam splitting means includes a rotating plate in which at least a diffraction means region is partially arranged in the circumferential direction, and the beam splitting is performed by time division by rotation of the rotating plate, and the beam incident on the diffraction means region and the diffraction An optical scanning device characterized in that the direction of a light beam incident outside the means region is varied . The optical scanning device according to claim 1,
Said rotary plate, said diffracting means region, the optical scanning device, characterized in that a non-diffracting means regions are alternately arranged in a circumferential direction to transmit without diffracting the light beams incident. The optical scanning device according to claim 1,
The rotating plate is arranged such that two or more types of diffraction means regions having different diffraction angles are arranged in close contact with or spaced apart from each other in the circumferential direction, and one type of diffraction means region is another type of diffraction means region. Is outside the diffractive means region . The optical scanning device according to claim 3.
It has a light quantity monitor means, wherein one of the plurality of types of diffraction unit area, characterized in that the light beam diffracted by the one diffractive means regions are arranged to be incident on the light quantity monitor means An optical scanning device. The optical scanning device according to claim 4.
The optical scanning device according to claim 1, wherein the diffraction means region for diffracting the light beam so as to enter the light amount monitor has a lens function for condensing the light beam on the light amount monitor. The optical scanning device according to any one of claims 1 to 5,
The deflecting means comprises a polygon mirror, and the rotating plate rotates with respect to one diffraction means region so that one surface of the polygon mirror is synchronized. In the optical scanning device according to any one of claims 1 to 6,
The light source unit includes a surface emitting laser element, and the light beam emitted from the light source unit is a plurality of light beams. At least one image carrier, charging means for uniformly charging the surface of the image carrier, an optical scanning device for exposing the charged image carrier to form an electrostatic latent image, and the electrostatic latent image In an image forming apparatus comprising: a developing unit that converts a visible image; a transfer unit that transfers the visible image to a recording medium; and a fixing unit that fixes the visible image to the recording medium.
The image forming apparatus according to claim 1, wherein the optical scanning device is the optical scanning device according to claim 1.

Images