JP2010071698A - Monitoring apparatus, light source apparatus, optical scanning apparatus, and image formation apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a monitoring apparatus which can detect a change in the light amount of a light beam emitted from a light source stably and with high precision, a light source apparatus, an optical scanning apparatus, and an image formation apparatus using it. <P>SOLUTION: The light amount of the light beam emitted from the light source is monitored. The monitoring apparatus includes a separation optical element including an opening in which the part having the largest light intensity of the light beam emitted from the light source passes through its central part and reflecting a light beam incident in the vicinity of the opening as a monitoring light beam, and a light receiving element for receiving the monitoring light beam reflected by the separation optical element and detecting the light amount distribution of the monitoring light beam. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a monitor device, a light source device, an optical scanning device, and an image forming device, and more specifically, a monitor device that monitors the amount of light emitted from a light source, a light source device including the monitor device, and the light source device. And an image forming apparatus including the optical scanning device.

  In image recording by electrophotography, an image forming apparatus using a laser is widely used. An image forming apparatus using a laser generally includes an optical scanning device that scans the surface of a photosensitive member with a laser beam to form a latent image. The optical scanning device includes a laser light source, a deflector that deflects a light beam emitted from the laser light source, such as a polygon mirror, and a scanning imaging optical system that forms an image of the deflected light beam on the surface of the photoconductor. By moving the photosensitive member in a direction perpendicular to the main scanning direction (scanning direction is called “sub-scanning direction”). A latent image is formed on the surface of the body. The photoreceptor is generally drum-shaped, and the direction parallel to the central axis is the main scanning direction, and sub-scanning is performed by rotationally driving around the central axis.

  By the way, in the image forming apparatus, the amount of light of the scanning light beam changes with temperature change or change with time, and there is a possibility that density unevenness occurs in the formed image. Therefore, in order to suppress this, normally, in an optical scanning device, a part of the light beam emitted from the light source is received as a monitor light beam by a detector such as a photodiode, and the output level of the light source is determined based on the detection result by the detector. APC (Auto Power Control) is implemented to control the above.

  For example, in Patent Document 1, a light source, a separation member that separates a light beam emitted from the light source into a scanning light beam and a feedback light beam, and a scanning light beam separated by the separation member are deflected. A light deflector that scans the surface to be scanned; a second aperture that is disposed between the separating member and the light deflecting unit and has a second aperture that shapes the cross-sectional shape of the scanning light beam; and the separating member. An optical sensor that receives the separated feedback light beam and detects the light amount of the feedback light beam, a control unit that controls the amount of light emitted from the light source based on the light amount detected by the optical sensor, and the light source and the optical sensor And a first aperture having a first aperture larger than the second aperture, which is disposed between the first aperture and shapes the cross-sectional shape of the light beam.

  Further, Patent Document 2 includes a detection unit that detects the amount of light of an incident light beam and a light separation unit that separates a part of the light beam emitted from the light source, and the light beam separated by the light separation unit. An optical scanning device is disclosed that includes an optical system that partially enters a detection unit, and a light amount control unit that controls an output light amount of a light source so that a light amount detected by the detection unit is a predetermined light amount. Yes. In this optical scanning device, when the polarization direction of the light beam output from the light source changes, the variation rate of the light amount on the surface to be scanned and the variation rate of the light amount incident on the detection means are made to substantially coincide with each other. The characteristics of the optical system are defined.

  In Patent Document 3, a laser beam emitted from a surface emitting laser, shaped by an aperture, and collimated by a collimator lens is deflected by an optical deflector to scan and expose a surface to be scanned, and a part of the laser beam is also obtained. An optical scanning device that reflects light by a beam separation means and receives the reflected light by a light receiving element to detect the amount of light, wherein the light receiving element is provided on the same circuit board as the surface emitting laser is disclosed. Has been.

JP 2006-91157 A JP 2005-156933 A JP 2006-259098 A

  By the way, in the light source, the divergence angle of the emitted light beam may be different from the designed divergence angle due to manufacturing variations, temperature rise during driving, and the like. In this case, the change in the light amount of the scanning light beam that scans the surface to be scanned, that is, the surface of the photosensitive member, is not necessarily the same as the change in the light amount of the monitor light beam that is received by the detector. In the optical scanning device, the accuracy of APC may be lowered.

  The present invention has been made under such circumstances, and a first object thereof is to provide a monitor device that can stably and accurately detect a change in the amount of light emitted from a light source.

  A second object of the present invention is to provide a light source device capable of outputting a light beam having a stable light amount. A third object of the present invention is to provide an optical scanning device capable of performing optical scanning on a surface to be scanned with high accuracy and stability. A fourth object of the present invention is to provide an image forming apparatus capable of stably forming a high quality image.

  The present invention is a monitor device for monitoring the light amount of a light beam emitted from a light source, wherein the portion having the highest light intensity of the light beam emitted from the light source has an opening passing through a central portion and the periphery of the opening. A separation optical element that reflects the light beam incident on the monitor as a monitoring light beam, and a light receiving element that receives the monitoring light beam reflected by the separation optical element and detects a light quantity distribution of the monitoring light beam. Main features.

  The present invention is also a light source device comprising a light source and a monitor device that monitors the amount of light emitted from the light source, wherein the monitor device is the monitor device according to the present invention, and the monitor device The light beam that has passed through the opening of the separation optical element is output.

  The present invention is also an optical scanning device that scans a surface to be scanned with a light beam, the light source device according to the present invention, a deflector that deflects the light beam output from the light source device, and the light deflected by the deflector. And a scanning optical system for condensing the luminous flux on the surface to be scanned.

  The present invention is also an image forming apparatus comprising at least one image carrier and at least one optical scanning device that scans the at least one image carrier with a light beam including image information, wherein the optical scanning is performed. The apparatus is the optical scanning apparatus according to the present invention.

The monitor device of the present invention is suitable for stably and accurately detecting a change in the amount of light emitted from a light source.
The light source device of the present invention is suitable for outputting a stable light beam.
The optical scanning device of the present invention is suitable for optically scanning the surface to be scanned accurately and stably.
The image forming apparatus of the present invention is suitable for stably forming a high quality image.

Embodiments of a monitor device, a light source device, an optical scanning device, and an image forming apparatus according to the present invention will be described below with reference to the drawings.
FIG. 1 shows a schematic configuration of a laser printer 1000 as an image forming apparatus according to an embodiment of the present invention. The laser printer 1000 includes an optical scanning device 1010, a photosensitive drum 1030, a charging charger 1031, a developing roller 1032, a transfer charger 1033, a charge removal unit 1034, a cleaning blade 1035, a toner cartridge 1036, a paper feeding roller 1037, a paper feeding tray 1038, A registration roller pair 1039, a fixing roller 1041, a paper discharge roller 1042, a paper discharge tray 1043, a communication control device 1050, and a printer control device 1060 that comprehensively controls each of the above units are provided. These members are housed in predetermined positions in the printer housing 1044.

  The communication control device 1050 controls bi-directional communication with an external device such as a personal computer (personal computer) via a network or the like. The photosensitive drum 1030 is a cylindrical member, and a photosensitive layer is formed on the surface thereof. That is, the surface of the photosensitive drum 1030 is a surface to be scanned. The photosensitive drum 1030 rotates in the direction of the arrow in FIG. 1 with the central axis as the center of rotation.

  The charging charger 1031, the developing roller 1032, the transfer charger 1033, the charge removal unit 1034, and the cleaning blade 1035 are each arranged in the vicinity of the surface of the photosensitive drum 1030. Specifically, the charging charger 1031 → the developing roller 1032 → the transfer charger 1033 → the charge eliminating unit 1034 → the cleaning blade 1035 are arranged in this order along the rotation direction of the photosensitive drum 1030.

  The charging charger 1031 uniformly charges the surface of the photosensitive drum 1030. The optical scanning device 1010 irradiates the surface of the photosensitive drum 1030 charged by the charging charger 1031 with a light beam modulated based on image information from a host device (for example, a personal computer), and the light beam is irradiated to the photosensitive drum. Scan in the direction of the central axis 1030. Along with this main scanning, the photosensitive drum 1030 is rotationally driven to perform sub-scanning, whereby a latent image corresponding to image information is formed on the surface of the photosensitive drum 1030. The latent image formed in this way moves in the direction of the developing roller 1032 as the photosensitive drum 1030 rotates. The configuration of the optical scanning device 1010 will be described later.

  The toner cartridge 1036 stores toner, and the toner is supplied to the developing roller 1032. The developing roller 1032 causes the toner supplied from the toner cartridge 1036 to adhere to the latent image formed on the surface of the photosensitive drum 1030 to visualize the image information. The latent image to which the toner is attached (hereinafter also referred to as “toner image” for the sake of convenience) moves in the direction of the transfer charger 1033 as the photosensitive drum 1030 rotates.

  Recording paper 1040 is stored in the paper feed tray 1038. A paper feed roller 1037 is arranged in the vicinity of the paper feed tray 1038. The paper feed roller 1037 takes out the recording paper 1040 one by one from the paper feed tray 1038 and conveys it to the position of the registration roller pair 1039. The registration roller pair 1039 temporarily holds the recording paper 1040 taken out by the paper supply roller 1037 and directs the recording paper 1040 toward the gap between the photosensitive drum 1030 and the transfer charger 1033 in accordance with the rotation of the photosensitive drum 1030. And send it out. A voltage having a polarity opposite to that of the toner is applied to the transfer charger 1033 in order to electrically attract the toner on the surface of the photosensitive drum 1030 to the recording paper 1040. With this voltage, the toner image on the surface of the photosensitive drum 1030 is transferred to the recording paper 1040. The transferred recording paper 1040 is sent to the fixing roller 1041.

  In the fixing roller 1041, heat and pressure are applied to the recording paper 1040, whereby the toner image is fixed on the recording paper 1040. The recording paper 1040 on which the toner image is fixed is sent to the paper discharge tray 1043 via the paper discharge roller 1042 and is sequentially stacked on the paper discharge tray 1043. The neutralization unit 1034 neutralizes the surface of the photosensitive drum 1030. The cleaning blade 1035 removes toner (residual toner) remaining on the surface of the photosensitive drum 1030. The removed residual toner is used again. The surface of the photosensitive drum 1030 from which the residual toner has been removed returns to the position of the charging charger 1031 again and is uniformly charged.

  Next, the configuration of the optical scanning device 1010 will be described. As shown in FIG. 2 as an example, the optical scanning device 1010 includes a light source 14, a coupling lens 15, an aperture plate 23 as a separation optical element, a cylindrical lens 17, a reflection mirror 18, a polygon mirror 13, and a deflector side scanning lens. 11a, an image plane side scanning lens 11b, a synchronization detection sensor 19a, a synchronization detection mirror 19b, a light receiving element 25, a scanning control device 20 (not shown in FIG. 2, refer to FIG. 15), and the like. These members are assembled at predetermined positions in the housing 30. The scanning lenses 11a and 11b constitute a scanning imaging lens. In this specification, in the XYZ three-dimensional orthogonal coordinate system, the direction along the longitudinal direction of the photosensitive drum 1030 is defined as the Y-axis direction, and the direction along the optical axis of each scanning lens (11a, 11b) is defined as the X-axis direction. explain.

  As shown in FIG. 3 as an example, the light source 14 includes a two-dimensional light emitting element array 100 in which 40 light emitting units are formed on one substrate. The M direction in FIG. 3 is a direction corresponding to the main scanning direction (here, the same as the Y axis direction), and the S direction is a direction corresponding to the sub scanning direction (here, the same as the Z axis direction). The T direction is a direction that forms an inclination angle α (0 ° <α <90 °) from the M direction toward the S direction. This two-dimensional light emitting element array 100 has four light emitting part rows in which ten light emitting parts are arranged at equal intervals along the T direction. These four light emitting unit rows are arranged at equal intervals in the S direction. That is, the 40 light emitting units are two-dimensionally arranged along the T direction and the S direction, respectively. Here, for the sake of convenience, each light emitting unit row is referred to as a first light emitting unit row, a second light emitting unit row, a third light emitting unit row, and a fourth light emitting unit row from top to bottom in FIG. In this specification, the “light emitting portion interval” refers to the distance between the centers of two light emitting portions.

  Further, in order to specify each light emitting unit, for the sake of convenience, the ten light emitting units constituting the first light emitting unit row are configured as v1 to v10 and the second light emitting unit row is configured from the upper left to the lower right in FIG. The ten light emitting units that constitute the third light emitting unit row are denoted by v11 to v30, and the ten light emitting units that constitute the fourth light emitting unit row are denoted by v31 to v40.

  Each of the light emitting units is a vertical cavity surface emitting laser (VCSEL) of a 780 nm band. That is, the two-dimensional light emitting element array 100 is a surface emitting laser array having 40 light emitting units. Here, the size in the M direction (longitudinal direction) of the two-dimensional light emitting element array 100 is 0.3 mm.

  Returning to FIG. 2, the coupling lens 15 converts the light beam emitted from the light source 14 into substantially parallel light. In this embodiment, the focal length of the coupling lens 15 is set to 27 mm. As shown in FIG. 4A as an example, the aperture plate 23 has a rectangular window hole-shaped aperture, and defines the beam diameter of the light beam through the coupling lens 15. The aperture plate 23 is arranged so that the portion with the highest light intensity of the light beam passes through the approximate center of the aperture. The periphery of the opening of the opening plate 23 is made of a reflective member.

  The aperture plate 23 is disposed so as to be inclined with respect to a virtual plane perpendicular to the traveling direction of the light beam via the coupling lens 15 in order to use the light beam reflected by the reflecting member around the opening as a monitor light beam. ing. In other words, the aperture plate 23 passes through the central portion with high light intensity among the light beams emitted from the light source 14, and reflects (separates) the outer peripheral portion with low light intensity as the monitoring light beam. Hereinafter, for the sake of convenience, the traveling direction of the monitoring light beam reflected by the aperture plate 23 is referred to as “Q direction”.

  In this embodiment, as shown in FIGS. 4A and 4B, the opening D of the aperture plate 23 has a length D2 in the direction corresponding to the sub-scanning direction (here, the Z-axis direction). It is 1.28 mm, and the length D1 in the direction corresponding to the main scanning direction (here, the Y-axis direction) is 5.8 mm. That is, D1> D2. FIG. 4B is an XY cross-sectional view passing through the center of the opening.

  Returning to FIG. 2, the cylindrical lens 17 converges the light beam that has passed through the opening of the aperture plate 23 only in the direction corresponding to the sub-scanning direction (here, the Z-axis direction), and passes through the reflection mirror 18 to form a polygon mirror. A line image in the main scanning direction is formed in the vicinity of 13 deflecting reflecting surfaces. The optical system arranged on the optical path between the light source 14 and the polygon mirror 13 is also called a pre-deflector optical system. In the present embodiment, the pre-deflector optical system includes a coupling lens 15, an aperture plate 23, a cylindrical lens 17, and a reflection mirror 18.

  A soundproof glass 21 is disposed between the reflection mirror 18 and the polygon mirror 13 and between the polygon mirror 13 and the deflector-side scanning lens 11a. For example, the polygon mirror 13 includes a four-sided mirror having an inscribed circle with a radius of 7 mm, and each mirror serves as a deflecting reflection surface. The polygon mirror 13 deflects the light beam from the reflection mirror 18 while rotating at a constant speed around an axis parallel to the direction corresponding to the sub-scanning direction (here, the Z-axis direction).

  The deflector-side scanning lens 11 a is disposed on the optical path of the light beam deflected by the polygon mirror 13. The image plane side scanning lens 11b is disposed on the optical path of the light beam via the deflector side scanning lens 11a. The optical system disposed on the optical path between the polygon mirror 13 and the photosensitive drum 1030 is also called a scanning optical system. In the present embodiment, the scanning optical system includes a deflector side scanning lens 11a and an image plane side scanning lens 11b.

  The light beam deflected by the polygon mirror 13 is condensed on the surface of the photosensitive drum 1030 by the scanning optical system. The light spot on the surface of the photosensitive drum 1030 moves in the Y-axis direction as the polygon mirror 13 rotates. Of the light beams deflected by the polygon mirror 13 and passed through the scanning optical system, a part of the light beams not involved in image formation is incident on the synchronization detection sensor 19a through the synchronization detection mirror 19b as a synchronization detection light beam. To do. The synchronization detection sensor 19a outputs a signal (photoelectric conversion signal) corresponding to the amount of received light. A dust-proof glass 22 (see FIG. 2) is disposed between the image-side scanning lens 11b and the photosensitive drum 1030.

The light receiving element 25 is arranged on the optical path of the monitoring light beam reflected by the aperture plate 23, and as shown in FIG. 11, as an example, is constituted by a CMOS sensor array having a very small area arranged two-dimensionally. For example, Figure 5 as (A), when the divergence angle of light flux F0 ₁ of A1 is outputted from the light source 14, as shown in FIG. 5 (B), the area Fs ₁ of the light flux F0 ₁ Passes through the opening of the first aperture plate 23, and the light flux in the region Fm ₁ is received by the light receiving portion of the light receiving element 25.

Further, for example, as shown in FIG. 6 (A), it has a light intensity distribution having a strong peak at the center than the light flux F0 _1, from the light beam F0 ₂ is a light source 14 of the divergence angle A2 (<A1) When output, as shown in FIG. 6B, the light beam in the region Fs ₂ of the light beam F 0 ₂ passes through the opening of the first aperture plate 23, and the light beam in the region Fm ₂ passes through the light receiving element 25. Light is received by the light receiving unit.

Further, as shown in FIG. 7 (A), has a light intensity distribution spread gently from the center than the light flux F0 _1, the divergence angle of the light beam F0 ₃ of A3 (> A1) is outputted from the light source 7B, the light beam in the region Fs ₃ of the light beam F0 ₃ passes through the opening of the first aperture plate 23, and the light beam in the region Fm ₃ is received by the light receiving unit of the light receiving element 25. Is done. By the way, when the divergence angle of the light beam output from the light source 14 (referred to as light beam F0) increases, as shown in FIG. 8 as an example, the light beam passing through the opening of the first aperture plate 23 (referred to as light beam Fs). The amount of light decreases. Here, it is assumed that the light amount of the light beam F0 is constant even if the divergence angle changes.

  Therefore, in order to make the light amount of the light beam Fs constant, as can be seen from the graph shown in FIG. 9 as an example, when the divergence angle of the light beam F0 is larger than the design value (here, A1), When the light amount is increased and the divergence angle of the light beam F0 is smaller than the design value, it is necessary to reduce the light amount of the light beam F0.

  As shown in FIG. 10 as an example, the amount of light reflected from the periphery of the aperture of the aperture plate 23 increases as the divergence angle of the light flux F0 increases. Assume that all the light beams (F0-Fs) are received by a single light receiving element (for example, a photodiode). In this case, when APC is performed in the same manner as in the prior art, for example, when the divergence angle of the light beam F0 is A3, the light amount of the light beam F0 is controlled to be further reduced. In some cases, the amount of light of the light beam F0 is controlled to be further increased. As a result, the light quantity of the light flux Fs deviates from the fixed value. That is, the accuracy of APC is reduced.

In the present embodiment, a two-dimensional light receiving element is used as the light receiving element 25. FIG. 11 shows an embodiment using a CMOS sensor as a light receiving element. The entire monitor light beam is received, and the amount of light passing through the aperture plate 23 is calculated from the detected light amount distribution. An example of the distribution of the detected light quantity is shown in FIG. As shown in FIG. 12, when it is close to a Gaussian function, the optimum a, k, m is obtained from the equation (1) representing the Gaussian curve, and the equation (1) is integrated with y and z and passed through the aperture plate 23. The amount of light Fs is obtained. F (y, z) = a × exp (− (k × y ² + m × z ² ) (1) Note that the detected light quantity distribution need not be limited to a Gaussian function, for example, a quadratic function or 4 Fitting with a polynomial function such as a quadratic function is performed, and the integrated light quantity of the light beam that has passed through the aperture plate 23 may be calculated based on the function.

  FIG. 16 shows an example of a circuit for controlling the CMOS sensor. In the CMOS sensor array of 1024 rows and 1280 columns (not shown in FIG. 16), the exposure is reset by the sensor reset signal and the next exposure is started. The exposure is terminated by the transfer start signal, and the transfer of the received light data outside the sensor is started. The light reception data in the row designated by the row address is sampled and held for each column, converted into 10-bit digital data by an ADC (analog / digital converter), and temporarily stored in an ADC register (SRAM). The stored ADC data is transferred to the output register by the Shift signal of the SRAM read control circuit, and is output by the signal of the column decoder. The two-dimensional light receiving element is not limited to a CMOS sensor, and may be a CCD (charge coupled device) sensor, a PD (photodiode) array, or the like.

  Furthermore, when the monitoring light beam enters the light receiving surface of the light receiving element 25 perpendicularly, the reflected light from the light receiving surface may return to the light source 14 through an optical path opposite to the incident light. Therefore, in the present embodiment, as shown in FIG. 13 as an example, the light receiving element 25 is such that the normal direction of the light receiving surface at the light receiving position of the monitor light beam is inclined with respect to all incident directions of incident light. The reflected light from the light receiving surface is prevented from returning to the light source 14. Specifically, the incident angle is 10 °.

  In this embodiment, as shown in FIG. 13 as an example, the light source 14 and the photodiode 25 are mounted on the same substrate 28. Since the light receiving element 25 has different detection sensitivity depending on the temperature, it is desirable to dispose the light receiving element 25 away from the heat source. FIG. 14 shows the relationship between the distance from the center position of the light source 14 and the temperature rise due to light emission of the light source at that position. According to this, a temperature increase of about 50 ° C. is observed at the center position of the light source 14, but when the distance from the light source 14 is 1 mm, there is almost no effect, and when the distance is 2 mm or more, the light source 14 is not affected at all. I understand. In the present embodiment, the distance between the centers of the light source 14 and the CMOS sensor 25 (symbol W in FIG. 13) is 7 mm because of the relationship with the layout of the optical system.

FIG. 15 shows an example of the scanning control device 20. In FIG. 15, the scanning control device 20 includes a main control unit 20A and a drive control unit 20B. The main control unit 20A includes a CPU 210, a flash memory 211, a RAM 212, an IF (interface) 214, and the like. The drive control unit 20B includes a pixel clock generation circuit 215, an image processing circuit 216, a frame memory 217, line buffers 218 _{1 to} 218 ₄₀ , a write control circuit 219, and the like. The drive controller 20B is provided on a substrate 28 on which the light source 14 and the light receiving element 25 are mounted. Note that the arrows in FIG. 15 indicate the flow of typical signals and information, and do not represent the entire connection relationship of each block.

  The pixel clock generation circuit 215 generates a pixel clock signal. The frame memory 217 temporarily stores image data rasterized by the CPU 210 (hereinafter abbreviated as “raster data” for convenience).

The image processing circuit 216 reads raster data stored in the frame memory 217, performs predetermined halftone processing, etc., and then creates dot data for each light emitting unit, and a line buffer 218 ₁ corresponding to each light emitting unit. To 218 ₄₀ .

The writing control circuit 219 obtains the scanning start timing based on the output signal of the synchronization detection sensor 19a. Then, in accordance with the scanning start timing, the dot data of each light emitting unit is read from the line buffers 218 _{1 to} 218 ₄₀ and superimposed on the pixel clock signal from the pixel clock generation circuit 215, and independent modulation is performed for each light emitting unit. Generate data. The write control circuit 219 calculates the light amount of the light beam passing through the opening of the aperture plate 23 based on the output signal of the light receiving element (CMOS sensor) 25 at a predetermined timing, and the light amount becomes constant. As described above, the drive current of each light emitting unit is corrected. That is, APC (Auto Power Control) is performed.

  The light source driving circuit 221 drives each light emitting unit of the two-dimensional array 100 according to the modulation data from the writing control circuit 219.

  The flash memory 211 stores various programs written in codes readable by the CPU 210 and various data used in the programs. The RAM 212 is a working memory. The CPU 210 operates according to a program stored in the flash memory 211 and controls the entire optical scanning device 1010. An IF (interface) 214 is a communication interface that controls bidirectional communication with the printer control apparatus 1060. Image data from the host device is supplied via an IF (interface) 214.

  As is clear from the above description, in the optical scanning device 1010 according to the present embodiment, a monitor device is configured by the aperture plate 23 and the light receiving element (CMOS sensor) 25. The light source 14, the coupling lens 15, and the monitor device constitute a light source device. The light flux Fs that has passed through the opening of the aperture plate 23 is a light flux output from the light source device. Further, at least a part of signal processing by the CPU 210 according to the program may be configured by hardware, or all may be configured by hardware.

  As described above, according to the monitor device according to the present embodiment, an opening is arranged on the optical path of the light beam emitted from the two-dimensional array 100, and the portion with the highest light intensity of the light beam passes through the substantially center. An aperture plate 23 (separation optical element) that reflects the light beam incident on the periphery of the aperture as a monitor beam; and is disposed on the optical path of the monitor beam reflected by the aperture plate 23; And a light receiving element 25 for receiving light. Then, the light amount of the light beam Fs that has passed through the aperture plate 23 is estimated from the light amount distribution of the light receiving element 25. Thereby, the light quantity of the light flux Fs can be accurately detected at any divergence angle.

  Therefore, it is possible to stably and accurately detect a change in the amount of light emitted from the two-dimensional array 100. In addition, the light source device according to the present embodiment has a monitor device that can stably and accurately detect a change in the amount of light emitted from the two-dimensional array 100, and thus outputs a stable light beam. It becomes possible.

  Further, according to the optical scanning device 1010 according to the present embodiment, since the light source device that can output a stable light beam is provided, the surface of the photosensitive drum 1030 can be optically scanned with high accuracy and stability. It becomes possible.

  In addition, the laser printer 1000 according to the present embodiment includes the optical scanning device 1010 that can accurately and stably optically scan the surface of the photosensitive drum 1030. As a result, a high-quality image can be obtained. It becomes possible to form stably.

  In the above embodiment, the case where the light source 14 has 40 light emitting units has been described, but the present invention is not limited to this. In the above embodiment, instead of the two-dimensional array 100, a one-dimensional array in which a plurality of light emitting units are arranged one-dimensionally may be used.

  In the above embodiment, the case of the laser printer 1000 as the image forming apparatus has been described. However, the present invention is not limited to this. In short, if the image forming apparatus includes the optical scanning device 1010, a high-quality image can be stably formed as a result. For example, an image forming apparatus that directly irradiates laser light onto a medium (for example, paper) that develops color with laser light may be used.

  Further, an image forming apparatus using a silver salt film as an image carrier may be used. In this case, a latent image is formed on the silver salt film by optical scanning, and this latent image can be visualized by a process equivalent to a developing process in a normal silver salt photographic process. Then, it can be transferred to photographic paper by a process equivalent to a printing process in a normal silver salt photographic process. Such an image forming apparatus can be implemented as an optical plate making apparatus or an optical drawing apparatus that draws a CT scan image or the like.

  Even in an image forming apparatus that forms a multicolor image, a high-quality color image can be formed at high speed by using an optical scanning device corresponding to the color image. For example, as shown in FIG. 17, a tandem color machine 1500 corresponding to a color image and including a plurality of photosensitive drums may be used.

  The tandem color machine 1500 includes a black (K) photosensitive drum K1, a charger K2, a developing device K4, a cleaning unit K5, a transfer charging unit K6, a cyan (C) photosensitive drum C1, and a charging unit. A developing unit C2, a developing unit C4, a cleaning unit C5, a transfer charging unit C6, a magenta (M) photosensitive drum M1, a charging unit M2, a developing unit M4, a cleaning unit M5, and a transfer charging unit M6; It includes a yellow (Y) photosensitive drum Y1, a charger Y2, a developing device Y4, a cleaning unit Y5, a transfer charging unit Y6, an optical scanning device 1010A, a transfer belt 1580, a fixing unit 1530, and the like. .

  Each photosensitive drum rotates in the direction of the arrow in FIG. 17, and a charger, a developing device, a transfer charging unit, and a cleaning unit are arranged in the rotation direction. Each charger uniformly charges the surface of the corresponding photosensitive drum. The surface of the photosensitive drum charged by the charger is irradiated with a light beam modulated by the image signal of the corresponding light color component by the optical scanning device 1010A, and an electrostatic latent image is formed on the photosensitive drum. Then, a toner image of a color corresponding to the surface of the photosensitive drum is formed by the corresponding developing device. Further, the toner images of the respective colors are transferred onto the recording paper by the corresponding transfer charging means, and finally the image is fixed on the recording paper by the fixing means 1530.

  The optical scanning device 1010A includes a light source device for black, a cylindrical lens, a scanning optical system and a synchronization detection sensor, a light source device for cyan, a cylindrical lens, a scanning optical system and a synchronization detection sensor, a light source device for magenta, a cylindrical lens, and scanning. It has an optical system and a synchronization detection sensor, a light source device for yellow, a cylindrical lens, a scanning optical system and a synchronization detection sensor, a polygon mirror, and the like.

  Each light source device is a light source device equivalent to the light source device in the above embodiment, and has a monitor device equivalent to the monitor device. The light beam output from each light source device is deflected by a polygon mirror via a corresponding cylindrical lens, and then condensed on the surface of the corresponding photosensitive drum via a corresponding scanning optical system. Further, a part of the light beam that is deflected by the polygon mirror 13 and does not participate in image formation out of the light beam that passes through the corresponding scanning optical system enters the corresponding synchronization detection sensor.

  Since each light source device is a light source device equivalent to the light source device in the above embodiment, each light source device can output a stable light beam. As a result, the optical scanning device 1010A can stably and stably perform optical scanning on the surface of each photosensitive drum. The tandem color machine 1500 can stably form a high-quality image. In a tandem color machine, color misregistration of each color may occur due to machine accuracy or the like, but the correction accuracy of color misregistration of each color can be increased by selecting a light emitting unit to be lit. In this tandem color machine 1500, instead of the optical scanning device 1010A, a black optical scanning device, a cyan optical scanning device, a magenta optical scanning device, and a yellow optical scanning device may be used. In short, each optical scanning device only needs to have a light source device equivalent to the light source device in the above embodiment.

  As described above, the monitor device according to the present invention is suitable for stably and accurately detecting a change in the amount of light emitted from the light source. The light source device of the present invention is suitable for outputting a stable light beam. Further, the optical scanning device of the present invention is suitable for optically scanning the surface to be scanned with high accuracy and stability. The image forming apparatus of the present invention is suitable for stably forming a high quality image.

1 is a front view schematically showing an example of an image forming apparatus according to the present invention. It is a top view which shows the Example of the optical scanning device based on this invention which can be used for the said image forming apparatus. It is an enlarged front view which shows typically the Example of the light source device which concerns on this invention which can be used for the said optical scanning device. (A) which shows the example of the separation optical element in the said optical scanning device is a perspective view, (b) is a longitudinal cross-sectional view. It is a graph which shows an example of light quantity distribution in the cross section of the light beam output from a light source, and the example of distribution of the light beam which permeate | transmits the opening part of the said separation optical element, and the light beam reflected in the periphery of the said opening part. It is a graph which shows another example of light quantity distribution in the cross section of the light beam output from a light source, and the example of distribution of the light beam which permeate | transmits the opening part of the said separation optical element, and the light beam reflected in the periphery of the said opening part. It is a graph which shows another example of light quantity distribution in the cross section of the light beam output from a light source, and the example of distribution of the light beam which permeate | transmits the opening part of the said separation optical element, and the light beam reflected in the periphery of the said opening part. It is a graph which shows the relationship between the divergence angle of the light beam inject | emitted from a light source, and the light quantity which permeate | transmits a separation optical element. It is a graph which shows the relationship with the light quantity of the light source with respect to the divergence angle of a light beam required in order to make constant the light quantity which permeate | transmits a separation optical element. It is a graph which shows the relationship between the divergence angle of a light beam, and the light quantity of the light beam reflected by a separation optical element. It is a front view which shows a mode that the light beam reflected by the example of the light receiving element comprised by the CMOS sensor array of the micro area arranged in two dimensions applicable to this invention and the isolation | separation optical element is received. It is a three-dimensional graph which shows an example of light quantity distribution of the light beam which permeate | transmitted the separation optical element. It is an optical arrangement | positioning figure which shows the relationship between the incident optical path to the said isolation | separation optical element, a reflected light path, and the light receiving element on a reflected light path. It is a graph which shows the relationship between the distance from the center position of a light source, and the temperature rise by light emission of the light source in the position. It is a block diagram which shows the example of the scanning control apparatus applicable to the optical scanning device of this invention. It is a block diagram which shows the example of the CMOS sensor control circuit applicable to this invention. 1 is a front view schematically showing an embodiment of an image forming apparatus according to the present invention.

Explanation of symbols

13 Polygon mirror 14 Light source 15 Coupling lens 23 Separation optical element 25 Light receiving element 100 Two-dimensional light emitting element array 1000 Laser printer 1030 Photosensitive drum

Claims (12)

A monitor device for monitoring the light quantity of a light beam emitted from a light source, wherein a portion having the highest light intensity of the light beam emitted from the light source has an opening passing through a central portion and enters the periphery of the opening. And a light receiving element that receives the monitoring light beam reflected from the separation optical element and detects a light amount distribution of the monitoring light beam. The monitor device according to claim 1, wherein the amount of light that has passed through the opening of the separation optical element is calculated from a light amount distribution of a light beam detected by the light receiving element. The monitor device according to claim 1, wherein the light receiving element has a normal direction of a light receiving surface at a light receiving position of the monitor light beam inclined with respect to all incident directions of incident light. A light source device comprising: a light source; and a monitor device that monitors the amount of light emitted from the light source, wherein the monitor device is the monitor device according to any one of claims 1 to 3. A light source device that outputs a light beam that has passed through an opening of a separation optical element of the device. 5. A coupling lens is further provided between the light source and the monitor device, and the separation optical element of the monitor device is optically disposed in the vicinity of a focal position of the coupling lens. Light source device. The light source device according to claim 4, wherein the light source includes a plurality of light emitting units. The light source device according to claim 4, wherein the light source includes a vertical cavity surface emitting laser. An optical scanning device that scans a surface to be scanned with a light beam, wherein the light source device according to any one of claims 4 to 7, a deflector that deflects the light beam output from the light source device, and deflection by the deflector And a scanning optical system for condensing the emitted light beam on the surface to be scanned. An image forming apparatus comprising: at least one image carrier; and at least one optical scanning device that scans the at least one image carrier with a light beam including image information. An image forming apparatus which is the optical scanning apparatus described. The image forming apparatus according to claim 9, wherein the image information is multicolor image information.   Image carriers are arranged corresponding to the number of colors corresponding to multicolor image information, and the optical scanning device scans each image carrier with a light beam modulated by the image information of the color shared by each image carrier. The image forming apparatus according to claim 9. An image carrier arranged in the number corresponding to the number of colors corresponding to multicolor image information, and an electrophotographic process unit arranged to execute an electrophotographic process corresponding to each image carrier, The exposure unit of the electrophotographic process unit is an optical scanning device according to claim 8, wherein the optical scanning device scans each image carrier with a light beam modulated by image information of a color shared by each image carrier. A color-compatible image forming apparatus configured to develop a latent image formed on each image carrier with toner of a color corresponding to each image carrier, and to transfer the toner images in a superimposed manner.

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