JP2009047551A - Instrument for measuring optical characteristic, scanning optical system unit, and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately measure a bend or a variation in a sub-scanning direction of a main scanning line of a beam spot which moves on a surface to be scanned. <P>SOLUTION: From the difference Δt between detection positions of both linear encoders 82A, 82B, and the interval L between both the linear encoders, an angular error displacement Δθ of a Y stage is found, and the position of a light receiving portion by a light receiver 71 at each image height is computed. Read head portions 80A, 80B are fixed to the undersurfaces of the end portions of the guide portion 73 of the Y stage. By the use of adjusting means which is arranged near the read head portions 80 and not shown by any drawings, the optimal positioning (azimuth adjustment) of the read head portions 80 with respect to scale portions 81 is performed. Thereby, excellent outputs of the read head portions 80 can be obtained over the whole moving range of the light receiver 71. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical characteristic measuring device that measures a beam spot position of a light beam scanned on a surface to be scanned, a scanning optical system unit in which optical characteristics are adjusted based on a measurement result of the optical characteristic measuring device, and the scanning The present invention relates to an image forming apparatus such as a copying machine having an optical system unit, a printer, a facsimile machine, a plotter, and a multifunction machine provided with at least one of them.

Conventionally, in various image forming apparatuses such as laser printers and digital copying machines, for example, a light spot formed by condensing a laser beam on a scanned surface of a photoreceptor is mainly used by deflecting the laser beam. A scanning optical system that moves in the scanning direction and scans the surface to be scanned is widely used.
In recent years, further improvement in scanning accuracy on the surface to be scanned has been demanded as the number of light sources is increased and the density of scanning lines is increased.
In this type of scanning optical system, the trajectory of the light spot on the surface to be scanned (hereinafter referred to as “main scanning line”) is ideally an accurate straight line. It is not a straight line, and a slight bend or inclination occurs.
Further, when the laser beam is deflected by, for example, a rotary polygon mirror having a plurality of deflecting reflecting surfaces, the main scanning line due to the deflecting for each deflecting reflecting surface is affected by the so-called surface tilt on the surface to be scanned. It is conceivable that a minute distance fluctuates in a direction orthogonal to the main scanning direction (hereinafter referred to as “sub-scanning direction”).

Such bends and inclinations of the main scanning line and minute distance fluctuations in the sub-scanning direction need to be within a predetermined allowable range. When the scanning lines are densified or when scanning is performed with multiple beams. The tolerance is considerably narrower. Therefore, when the scanning optical system is actually assembled or after the assembly, measurement and adjustment of the bending of the main scanning line and the fluctuation in the sub-scanning direction are performed.
For example, as disclosed in Patent Document 1, a measuring apparatus for measuring a scanning position in the sub-scanning direction at a desired position in the main scanning direction has been proposed.
The measurement apparatus described in Patent Document 1 moves one CCD camera to a desired position in the main scanning direction by a moving stage (X stage, Y stage), and sets the scanning position in the sub-scanning direction at that position. It is an optical characteristic measuring device to measure.

JP 2000-39573 A JP 2007-164205 A http: // www. weblio. jp / content / AGC

In this type of optical characteristic measuring apparatus, there is an error displacement in the moving stage, and accurate position measurement by the light receiving means may not be obtained.
In order to solve this problem, the present applicant provides an error displacement amount measuring means for measuring an error displacement amount that occurs during movement of the light receiving means on the stage, and corrects the light receiving position based on the measurement result. Proposed an optical property measurement device that accurately measures the beam spot position.
However, the output (measurement accuracy) of the error displacement amount measuring means is not constant over the entire movement range of the light receiving means, and there is a concern that a measurement error may occur depending on the position.

The present invention has been made in view of the circumstances as described above, and its first object is to accurately measure the bending of the main scanning line of the beam spot moving on the surface to be scanned and the fluctuation in the sub-scanning direction. It is an object of the present invention to provide an optical characteristic measuring apparatus capable of performing the above-mentioned.
A second object of the present invention is to provide a scanning optical system unit capable of improving scanning accuracy.
A third object of the present invention is to provide an image forming apparatus capable of forming a high quality image.

  To achieve the above object, according to the first aspect of the present invention, a light beam emitted from a scanning optical system unit that scans a plurality of scanned surfaces is received by a light receiving means, and at least of the plurality of scanned surfaces. An optical characteristic measuring apparatus of the scanning optical system unit for measuring a beam spot position of the light beam in a plane including two scanned surfaces, wherein the light receiving means is configured to detect the scanning direction of the light beam and the scanning direction. In the optical characteristic measuring apparatus provided with the moving means for moving in the orthogonal direction and the error displacement measuring means for measuring the error displacement generated during the movement of the light receiving means, the output of the error displacement measuring means is: An adjusting means is provided for adjusting the light receiving means so that it can be satisfactorily obtained over the entire moving region.

According to a second aspect of the present invention, in the optical characteristic measuring apparatus according to the first aspect, the error displacement amount measuring unit is a diffraction interference method including a read head unit having a light source and a scale unit, and the adjusting unit is The positional relationship between the reading head unit and the scale unit is adjusted.
According to a third aspect of the present invention, in the optical characteristic measuring apparatus according to the second aspect, the adjustment means has a configuration of manual adjustment with an adjustment screw.

According to a fourth aspect of the present invention, in the optical characteristic measuring apparatus according to the second aspect, the adjusting means has a configuration in which adjustment is performed by an actuator that can be controlled from the outside.
According to a fifth aspect of the present invention, in the optical characteristic measuring apparatus according to any one of the second to fourth aspects, the output from the reading head unit is an auto gain.

According to a sixth aspect of the present invention, in the optical characteristic measuring apparatus according to any one of the second to fifth aspects, energization of the light source starts immediately before the movement of the light receiving means, and is de-energized after the movement is stopped. It was made to do.
According to a seventh aspect of the present invention, in the scanning optical system unit capable of adjusting the curvature of the scanning line formed on the surface to be scanned, the measurement result by the optical characteristic measuring device according to any one of the first to sixth aspects is used. Based on this, the curve of the scanning line is adjusted.
According to an eighth aspect of the present invention, an image forming apparatus includes the scanning optical system unit according to the seventh aspect.

  According to the present invention, it is easy to adjust the output of the error displacement amount measuring means, so that it is possible to accurately measure the bending of the main scanning line of the beam spot moving on the scanning surface and the variation in the sub-scanning direction. As a result, the scanning accuracy can be improved, and as a result, the image quality can be improved.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 shows a schematic configuration of a printer 10 as an image forming apparatus according to the present embodiment.
The printer 10 is a tandem type color printer that prints a multicolor image by superimposing and transferring, for example, black, yellow, magenta, and cyan toner images on plain paper (paper) using the Carlson process. is there.
As shown in FIG. 1, the printer 10 includes four optical scanning devices 100 as a scanning optical system unit in which optical properties such as inclination and bending of a scanning line are measured by an optical property measuring device described later. Photosensitive drums 30A, 30B, 30C, and 30D as scanning surfaces on an image carrier, a transfer belt 40, a misregistration detection device 45, a paper feed tray 60, a paper feed roller 54, a first registration roller pair 56, and a second registration roller A pair 52, a fixing roller 50, a paper discharge roller 58, and a substantially rectangular parallelepiped housing 12 that accommodates the above components are provided.

The housing 12 is formed with a paper discharge tray 12a on which the printed paper is discharged on the upper surface, and the optical scanning device 100 is disposed below the paper discharge tray 12a.
The optical scanning device 100 scans the photosensitive drum 30A with a light beam of a black image component modulated based on image information supplied from a host device (such as a personal computer), and cyan for the photosensitive drum 30B. The light beam of the image component is scanned, the light beam of the magenta image component is scanned on the photosensitive drum 30C, and the light beam of the yellow image component is scanned on the photosensitive drum 30D. The configuration of the optical scanning device 100 will be described later.
The four photosensitive drums 30A, 30B, 30C, and 30D are cylindrical members each having a photosensitive layer having a property that becomes conductive when irradiated with a light beam. Below the scanning device 100 are arranged at equal intervals along the X-axis direction.

The photosensitive drum 30A is disposed at the −X side end inside the housing 12 with the Y-axis direction as the longitudinal direction, and is rotated clockwise in FIG. 1 (the direction indicated by the arrow in FIG. 1) by a rotation mechanism (not shown). It is like that.
In the vicinity thereof, a charging charger 32A is arranged at the 12 o'clock (upper) position in FIG. 1, a toner cartridge 33A is arranged at the 2 o'clock position, and a cleaning case 31A is arranged at the 10 o'clock position. .
The photosensitive drum 30B is arranged at a predetermined interval on the + X side of the photosensitive drum 30A, and is rotated clockwise (in the direction indicated by the arrow) in FIG. 1 by a rotating mechanism (not shown). A charging charger 32B, a toner cartridge 33B, and a cleaning case 31B are arranged around the photosensitive drum 30A in the same positional relationship as the above-described photosensitive drum 30A.

The photosensitive drum 30C is arranged at a predetermined interval on the + X side of the photosensitive drum 30B, and is rotated clockwise (in the direction indicated by the arrow) in FIG. 1 via a rotation mechanism (not shown). Around the periphery, a charging charger 32C, a toner cartridge 33C, and a cleaning case 31C are arranged in the same positional relationship as the photosensitive drum 30A.
The photosensitive drum 30D is arranged at a predetermined interval on the + X side of the photosensitive drum 30C, and is rotated clockwise (in the direction indicated by the arrow) in FIG. 1 by a rotating mechanism (not shown). Around the periphery, a charging charger 32D, a toner cartridge 33D, and a cleaning case 31D are arranged in the same positional relationship as the above-described photosensitive drum 30A.

Hereinafter, the photosensitive drum 30A, the charging charger 32A, the toner cartridge 33A, and the cleaning case 31A are collectively referred to as a first station, and the photosensitive drum 30B, the charging charger 32B, the toner cartridge 33B, and the cleaning case 31B are collectively referred to as a second station, The photosensitive drum 30C, the charging charger 32C, the toner cartridge 33C, and the cleaning case 31C are collectively referred to as a third station, and the photosensitive drum 30D, the charging charger 32D, the toner cartridge 33D, and the cleaning case 31D are collectively referred to as a fourth station. .
The transfer belt 40 is an endless annular member, a driven roller 40a disposed below the photosensitive drum 30A, a driven roller 40c disposed below the photosensitive drum 30D, and a position slightly lower than these driven rollers 40a and 40c. The upper end surface is wound around the driving roller 40b disposed in the contact roller 40b so as to be in contact with the lower end surfaces of the photosensitive drums 30A, 30B, 30C, and 30D.
When the drive roller 40b rotates counterclockwise in FIG. 1, the drive roller 40b rotates counterclockwise (in the direction indicated by the arrow in FIG. 1). A transfer charger 48 to which a voltage having a polarity opposite to that of the above-described charging chargers 32A, 32B, 32C, and 32D is applied is disposed near the + X side end of the transfer belt 40.

The paper feed tray 60 is disposed below the transfer belt 40. The paper feed tray 60 is a substantially rectangular parallelepiped tray, and a plurality of sheets 61 to be printed are stacked and stored therein.
A rectangular paper feed port is formed in the vicinity of the + X side end of the upper surface of the paper feed tray 60.
The paper feed roller 54 takes out the paper 61 one by one from the paper feed tray 60 and leads it to a gap formed by the transfer belt 40 and the transfer charger 41 via a registration roller 56 composed of a pair of rotating rollers.
The fixing roller 50 is composed of a pair of rotating rollers. The fixing roller 50 heats and presses the paper 61 and guides it to the paper discharge roller 58 via the registration roller 52.
The paper discharge roller 58 includes a pair of rotating rollers, and sequentially stacks the derived paper 61 on the paper discharge tray 12a.

Next, the configuration of the optical scanning device 100 will be described. FIG. 2 is an optical layout diagram of the optical scanning device 100. As shown in FIG. 2, the optical scanning device 100 includes a light source 130, a condensing optical system including a coupling lens 146, a first cylinder lens 102, and a second cylinder lens 103, and, for example, six deflection surfaces. A scanning optical system including a polygon mirror 104, an fθ lens 105, four reflection mirrors 106A, 106B, 106C, 106D, four toroidal lenses 107A, 107B, 107C, 107D, and four reflection mirrors 108A, 108B, 108C. ing.
The light source 130 is a surface emitting semiconductor laser array having a plurality of light emitting points. Each light emitting point is divided into four light emitting points G1 to G4 corresponding to the first to fourth stations, and a light beam directed toward the polygon mirror 104 is emitted from each light emitting point.
The coupling lens 146, the first cylinder lens 102, and the second cylinder lens 103 are arranged in order from the side closer to the light source 130 on the path of the light beam emitted from the light source 130.
The coupling lens 146 shapes the light beam emitted from the light beam 143 so as to be condensed once on the incident side of the first cylinder lens 102.

The first cylinder lens 102 shapes the light beam emitted from the light source 130 into a predetermined shape, and the second cylinder lens 103 condenses the light beam that has passed through the first cylinder lens onto the deflection surface of the polygon mirror 104. To do.
The polygon mirror 104 is formed of a regular hexagonal columnar member having a low height, and six deflection surfaces are formed on the side surface. And it rotates at a fixed angular velocity by a rotation mechanism (not shown) around an axis parallel to the Z axis.
As a result, the light beam emitted from the light source 130 and condensed on the deflection surface of the polygon mirror 104 via the first cylinder lens 102 and the second cylinder lens 103 is fixed by the rotation of the polygon mirror 104. Is deflected along the Y-axis at an angular velocity of.
The fθ lens 105 has an image height proportional to the incident angle of the light beam, and moves the image surface of the light beam deflected at a constant angular velocity by the polygon mirror 104 at a constant speed with respect to the Y axis.
The reflection mirrors 106A, 106B, 106C, and 106D have the longitudinal direction as the Y-axis direction, fold back the light beam that has passed through the fθ lens, and guide the light beams to the toroidal lenses 107A, 107B, 107C, and 107D, respectively.
The toroidal lens 107 </ b> A is stably supported by a support plate 110 </ b> A whose longitudinal direction is the Y-axis direction and whose both ends are fixed to the housing 12.
Then, the light beam folded back by the reflection mirror 106A is imaged on the surface of the photosensitive drum 30A via the reflection mirror 108A whose longitudinal direction is the Y-axis direction.

The toroidal lenses 107B, 107C, and 107D have a longitudinal direction as the Y-axis direction, one end (+ Y side) is fixed to the housing 12, and the other end (−Y side) is, for example, a drive mechanism including a rotary motor and a feed screw mechanism. It is stably supported by support plates 112B, 112C, and 112D supported by 112B, 112C, and 112D. Then, the light beams folded back by the reflection mirrors 106B, 106C, and 106D are respectively connected to the surfaces of the photosensitive drums 30B, 30C, and 30D via the reflection mirrors 108B, 108C, and 108D having the Y-axis direction as the longitudinal direction. Image.
In the optical scanning device 100 configured as described above, the plurality of light beams from each of the light emitting point groups G1, G2, G3, and G4 are temporarily intersected by the coupling lens 146, and are sub-scanned by the first cylinder lens 102. Is expanded and enters the second cylinder lens 103. The second cylinder lens 103 condenses the light beams emitted from the incident light emission point groups G 1, G 2, G 3 and G 4 in the vicinity of the deflection surface of the polygon mirror 104.
The light beams deflected by the polygon mirror 104 enter the fθ lens 105 while widening the interval between the light beams.
The light beam from the light emitting point G1 incident on the fθ lens 105 is reflected by the reflection mirror 106D and enters the toroidal lens 107D. Then, the light is condensed on the surface of the photosensitive drum 30D by the toroidal lens 107D.

Similarly, light beams from the light emitting points G2, G3, and G4 that have entered the fθ lens 105 are reflected by the reflection mirrors 106A, 106B, and 106C and enter the toroidal lenses 107A, 107B, and 107C.
Then, the light is condensed on the surfaces of the photosensitive drums 30A, 30B, and 30C by the toroidal lenses 107A, 107B, and 107C via the reflection mirrors 108A, 108B, and 108C.
The condensing points of the light beams from the light emitting point groups G1, G2, G3, and G4 formed on the photosensitive drums 30A, 30B, 30C, and 30D in this way are rotated on the Y axis by the polygon mirror 104 rotating. It is moved (scanned) collectively in the direction.
On the other hand, the photosensitive layer on the surface of each of the photosensitive drums 30A, 30B, 30C, and 30D is charged with a predetermined voltage by the charging chargers 32A, 33B, 33C, and 32D, so that charges are distributed at a constant charge density. . As described above, when each of the photosensitive drums 30A, 30B, 30C, and 30D is scanned, the photosensitive layer where the light beam is condensed becomes conductive, and charge transfer occurs in that portion, and the potential is increased. Becomes zero.

Therefore, by scanning the photosensitive drums 30A, 30B, 30C, and 30D rotating in the directions of the arrows in FIG. 1 with the light beams modulated based on the image information, the respective photosensitive drums 30A, 30B, and 30C are scanned. , 30D can form an electrostatic latent image defined by the charge distribution.
When electrostatic latent images are formed on the surfaces of the photosensitive drums 30A, 30B, 30C, and 30D, the developing rollers of the toner cartridges 33A, 33B, 33C, and 33D shown in FIG. Toner is supplied to each surface of 30D. At this time, since the developing rollers of the toner cartridges 33A, 33B, 33C, and 33D are charged by voltages having a polarity opposite to that of the photosensitive drums 30A, 30B, 30C, and 30D, the toner adhering to the developing rollers is the photosensitive drums 30A, 30B, and 30D. It is charged with the same polarity as 30C and 30D.
Therefore, the toner does not adhere to the portions of the surfaces of the photosensitive drums 30A, 30B, 30C, and 30D where the electric charges are distributed, and the toner adheres only to the scanned portions, whereby the photosensitive drums 30A, 30B, and 30C. , A toner image in which the electrostatic latent image is visualized is formed on the surface of 30D.
These toner images are transferred onto the transfer belt 40 in a superimposed manner, and are transferred by a transfer charger 41 to a sheet 61 taken out from a paper feed tray 60 and fixed by a fixing roller 50 as shown in FIG. To form an image.

Next, an optical property measuring device 70 that receives the light beams emitted from the optical scanning device 100 to the photosensitive drums 30A, 30B, 30C, and 30D and measures the optical properties of the optical scanning device 100 will be described.
FIG. 3 is a perspective view of the optical characteristic measuring apparatus 70. As shown in FIG. 3, the optical characteristic measuring device 70 includes a rectangular plate-like base 77 whose longitudinal direction is the X-axis direction, a light receiving device 71 as a light receiving means for receiving the light beam, and a light receiving device 71 as Y. Y stage YST driven (moved) in the axial direction, X stage XST for driving the light receiving device 71 in the X axis direction together with the Y stage YST, and a main controller 90 (see FIG. 4) for comprehensively controlling each of the above parts It has.
The Y stage YST has a rail-shaped guide portion 73 and a movable stage 72, and the light receiving device 71 is provided on the movable stage 72. The movable stage 72 is driven (moved) by an X stage drive source 89 (see FIG. 4).
The X stage XST has a rail-shaped guide part 75 and a movable stage 74, and a guide part 73 for the Y stage YST is provided on the movable stage 74. The movable stage 74 is driven (moved) by a Y stage drive source 88 (see FIG. 4).
The Y stage YST and the X stage XST constitute moving means.
The light receiving device 71 includes an area CCD (Charge Coupled Device Image Sensor) housed in a cubic casing, and a rectangular incident surface 71a on which a light beam is incident is formed on the upper (+ Z side) surface. Has been.
When receiving the light beam, the light receiving device 71 outputs information related to the beam spot position of the light beam to the main control device 90.

The X stage XST drives the X stage surface by, for example, a guide member, a feed screw mechanism, and a stepping motor.
The Y stage YST is fixed on the stage surface of the X stage XST so as to be orthogonal to the X stage. For example, the Y stage surface is driven by a guide member, a feed screw mechanism, and a stepping motor.

Next, a method for measuring the optical characteristics of the optical scanning apparatus 100 described above using the optical characteristic measuring apparatus 70 will be described. As a premise, as shown in FIG. 5 as an example, the optical scanning device 100 is supported above the optical characteristic measuring device 70 by a support member (not shown), and the incident surfaces 71a of the optical scanning device 100 and the light receiving device 71 move. It is assumed that the distance to the moving surface is set to be equal to the distance between the optical scanning device 100 and the scanned surfaces of the photosensitive drums 30A to 30D in the first to fourth stations.
In order to adjust this distance, a Z stage ZST (not shown) is fixed on the stage surface of the Y stage.
The light beam emitted from the optical scanning device 100 and incident on the first station is LB1, the light beam incident on the second station is LB2, the light beam incident on the third station is LB3, and the light beam incident on the fourth station is LB4. It is defined as
The main controller 90 of the optical characteristic measuring device 70 drives the X stage XST, and first moves the light receiving device 71 to a position where the light beam LB1 can be detected. In this state, the Y stage YST is driven, and the light receiving device 71 is moved to a plurality of image height positions set as measurement points in advance.
In FIG. 3, reference numeral 82 denotes a linear encoder which will be described later, and 85 denotes a reference block serving as a reference for measuring the straightness of the stage.

When the light receiving device 71 is a line CCD, the continuously emitted light beam is detected as shown in FIG. 5, and the position of the center of gravity is obtained, and the light beam position in the sub-scanning direction becomes clear. When a line CCD is used, the Z stage ZST can be dispensed with.
In the case where the light receiving device 71 is an area CCD, by performing pulsed light emission at the timing at each measurement point and detecting by the light receiving device 71, it is detected as shown in FIG. The light beam position in both directions is revealed.

The stage is preferably driven straight, but error displacement and angular error displacement as shown in FIG. 8 occur due to the bending of the guide portion, the gap, the accuracy of the feed screw, and the like.
As shown in FIG. 8, two linear encoders 82 as error displacement measuring means are provided at two symmetrical positions parallel to the moving direction of the stage. By doing so, it becomes possible to determine the angular displacement error of the stage.
As shown in FIG. 3, each linear encoder 82A, 82B has a scale portion 81 extending in the Y-axis direction and a read head portion 80 provided on the lower surface of the end portion of the guide portion 73 of the Y stage YST.
FIG. 8 shows a principle diagram. The angle error displacement Δθ of the Y stage is obtained from the difference Δt between the detection positions of the two linear encoders and the distance L between the two linear encoders, and the position of the light receiving unit at each image height is calculated.
The linear encoder can be measured with high accuracy by a diffraction grating scale as a scale unit 81 and a head as a reading head unit 80 using a semiconductor laser as a light source, such as a BL-57 made by SONY shown in FIG. Things can be used.

The positional relationship between the head 80 and the scale 81 needs to be adjusted very accurately. Conventionally, adjustment (azimuth adjustment) is performed manually while viewing the output waveform with an oscilloscope.
However, in order to adjust to a position where it can be measured satisfactorily over the entire scanning area (the entire movable area of the light receiving device 71), it is necessary to repeat the adjustment many times.
Therefore, in the present embodiment, as shown in FIG. 9, the azimuth adjustment of the head 80 provided on the support member 86 fixed to the lower surface of the end portion of the guide portion 73 of the Y stage YST so as to be rotatable about the fulcrum 86a. These are finely adjusted by adjusting means 87 provided on the support member 86. This makes it possible to easily set the optimum position.
As the adjusting means 87, a finely adjustable screw can be employed. If an externally controllable actuator is used instead of a screw, adjustment can be made without changing the environment even when installed in a thermostatic chamber.

In the case of SONY BL-57, it is necessary to adjust the azimuth so that the output signal from the head 80 becomes 0.7V to 1.4V. When the output is out of this range, a reading error occurs. However, when the temperature is shaken in a thermostatic chamber or the like, the output may be out of this range due to the extension or deformation of the scale 81.
Since it is desirable to avoid skipping even if the measurement accuracy is somewhat lowered, as shown in FIGS. 10 and 11, the auto gain is set so that the output always falls within the proper range during the measurement.
The gain is adjusted by automatically adjusting an amplifier in the circuit, and this can be achieved by using a general auto gain circuit (see Non-Patent Document 1).
In the case of measurement in a high temperature range, the output may decrease due to a decrease in the light amount of the light source of the head 80, and a reading error may occur. In order to prevent this, it is necessary to suppress heat generation due to energization to a minimum, and therefore it is necessary to stop energization of the light source until immediately before the start of measurement (immediately before the movement of the light receiving device 71 or just before the movement of the moving means is started). is there.

As shown in FIG. 12, when a certain time elapses after energization, the temperature at which a reading error occurs due to heat generation is exceeded. Therefore, the control method is such that power is supplied immediately before the stage movement is started.
As shown in FIG. 13, scanning is performed as shown in FIG. 14 by adjusting the inclination of the scanning line by adjusting the inclination of the scanning lens (toroidal lens 107) or by pressing and deforming the vicinity of the center of the scanning lens. A scanning optical system unit can be obtained in which line bending can be reduced and color misregistration is small.
In the present embodiment, a pressurizing unit that pressurizes the vicinity of the center of the scanning lens is omitted, but the one described in Patent Document 2, for example, can be employed.

1 is a schematic configuration diagram of a printer as an image forming apparatus according to an embodiment of the present invention. It is an optical layout figure of the optical scanning device as a scanning optical system unit. It is a perspective view of an optical characteristic measuring device. It is a control block diagram. It is a figure which shows the positional relationship of an optical scanning device and an optical characteristic measuring apparatus. It is a figure which shows the signal strength at the time of using line CCD for a light-receiving means. It is a figure which shows the signal strength at the time of using area CCD for a light-receiving means. It is a top view which shows the principle which calculates | requires the error displacement in a moving means. It is a figure which shows the relationship between an error displacement amount measurement means and an adjustment means. It is a schematic diagram which shows the change of the output of the error displacement amount measurement means at the time of auto gain. It is a flowchart which shows auto gain control. It is a timing chart which shows the relationship between head temperature and electricity supply to a light source. It is a figure which shows the action state of the adjustment force which adjusts the scanning line curve of a scanning lens. It is a figure which shows the state change after adjustment of a scanning line bend based on the measurement result by the optical characteristic measuring apparatus before adjustment of a scanning line bend.

Explanation of symbols

30A, 30B, 30C, 30D Photosensitive drum as scanning surface 71 Light receiving device as light receiving means 70 Optical characteristic measuring device 80 Reading head portion 81 Scale portion 82 Linear encoder as error displacement amount measuring means 87 Adjustment means 100 Scanning optical system Optical scanning device as unit YST Y stage as moving means XST X stage as moving means

Claims (8)

A light beam emitted from a scanning optical system unit that scans a plurality of scanned surfaces is received by a light receiving means, and the beam of the light beam in a plane including at least two scanned surfaces among the plurality of scanned surfaces An apparatus for measuring optical characteristics of the scanning optical system unit for measuring a spot position,
An optical system provided with a moving means for moving the light receiving means in the scanning direction of the light beam and a direction perpendicular to the scanning direction, and an error displacement measuring means for measuring an error displacement amount generated during the movement of the light receiving means. In the characteristic measuring device,
An optical characteristic measuring apparatus comprising adjusting means for adjusting so that the output of the error displacement measuring means can be obtained satisfactorily over the entire moving region of the light receiving means. In the optical characteristic measuring device according to claim 1,
The error displacement measuring means is a diffraction interference method including a reading head unit having a light source and a scale unit, and the adjusting unit adjusts a positional relationship between the reading head unit and the scale unit. Optical characteristic measuring device. In the optical characteristic measuring device according to claim 2,
The optical characteristic measuring apparatus according to claim 1, wherein the adjusting means has a configuration for manual adjustment with an adjusting screw. In the optical characteristic measuring device according to claim 2,
The optical characteristic measuring apparatus according to claim 1, wherein the adjusting means is configured to be adjusted by an actuator controllable from outside. In the optical characteristic measuring device according to any one of claims 2 to 4,
An optical characteristic measuring apparatus characterized in that an output from the reading head unit is an auto gain. In the optical characteristic measuring device according to any one of claims 2 to 5,
The optical characteristic measuring apparatus is characterized in that energization of the light source is started immediately before the movement of the light receiving means and is de-energized after the movement is stopped.   The curve of the scanning line formed on the surface to be scanned can be adjusted, and the curve of the scanning line is adjusted based on the measurement result by the optical characteristic measuring device according to any one of claims 1 to 6. Characteristic scanning optical system unit.   An image forming apparatus comprising the scanning optical system unit according to claim 7.

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