JP2005234359A - Optical characteristic measuring apparatus of scanning optical system, method of calibrating optical characteristic measuring apparatus of scanning optical system, scanning optical system and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that such errors as pitching and yawing of a movable stage directly reduce measurement accuracy and the variation in temperature condition due to a time deviation caused by the movement of the stage reduces the measurement accuracy. <P>SOLUTION: In an optical characteristic measuring apparatus of scanning optical system, in which the position of a scanning line in a main scanning direction on an image plane with a light beam with a scanning optical system unit 6 with which at least either of writing-in or readout is performed by scanning the image plane with the light beam, is measured with photosensors 7 having a plurality of light receiving elements arranged in a subscanning direction or a photosensor which detects the position of the scanning line, the photosensors 7 are at least three or more fixed photosensors arranged in image height direction matching with the image plane. A plurality of subscanning positions on the image plane with the light beam are measured with the photosensors 7. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a scanning optical system optical characteristic measuring apparatus for measuring a scanning position of a scanning optical system, a scanning optical system optical characteristic measuring apparatus calibration method for calibrating the scanning optical system optical characteristic measuring apparatus, a scanning optical system, a laser printer, and a digital copy. The present invention relates to an image forming apparatus such as a printer.

  A scanning optical system that condenses a laser beam as a light spot on a surface to be scanned and scans the surface to be scanned is widely known for various image forming apparatuses such as a laser printer and a digital copying machine. In particular, in recent years, “higher density and multi-beam” scanning by a scanning optical system is intended, and “higher precision” is required for the scanning position by the light spot. The light spot moves on the surface to be scanned and scans the surface to be scanned. The ideal direction of movement of the light spot on the surface to be scanned is called the main scanning direction, and the direction perpendicular to the main scanning direction is called the main scanning direction. The term “sub-scanning direction” is well known. Further, the trajectory of the light spot is referred to as “main scanning line”.

  The “scanned surface” referred to here is a virtual plane, and is essentially a photosensitive surface of a photoconductive photoreceptor. Ideally, the main scanning line is an accurate straight line, but actually, the main scanning line is not an exact straight line due to various factors, and a slight bend occurs. When the laser beam is deflected by the rotating polygon mirror and the light spot is moved on the surface to be scanned, the main scanning line by the deflection of each deflecting reflecting surface of the rotating polygon mirror is the so-called "" of the rotating polygon mirror. It is conceivable that a minute distance fluctuates in the sub-scanning direction due to the influence of “surface tilt”. Such “curvature” and “minor distance fluctuation in the sub-scanning direction” of the main scanning line need to be within a predetermined allowable range. However, when the scanning density is increased or when scanning is performed with multiple beams. The tolerance of is quite narrow.

  To adjust the bending of the main scanning line and the fluctuation in the sub-scanning direction when actually assembling the scanning optical system or after the assembly, or to check whether these are within the allowable width as designed, It is necessary to measure the scanning position in the sub-scanning direction at a desired main scanning position on the surface to be scanned. In general, a CCD sensor is used to measure the scanning position of the scanning optical system. The CCD sensor is arranged so that the arrangement direction of the light receiving elements (optical element arrays) is in the sub-scanning direction on the measurement surface equivalent to the surface to be scanned. Arranged together.

  FIG. 6B is a diagram showing a light reception signal distribution (light intensity distribution) of the CCD sensor in the scanning position measurement by the measurement apparatus using the CCD sensor. In FIG. 6B, the horizontal axis represents the light receiving element address in the sub-scanning direction, and the vertical axis represents the light receiving signal level of the light receiving element of the CCD sensor. As shown in FIG. 6B, the distribution of the received light signal is generally peaked in the sub-scanning direction, and one peak appears in the received light signal by scanning one beam. Then, by counting the area center of the cross-sectional shape of this peak, it is possible to estimate the maximum value of the distribution of the received light signal and obtain the scanning position in the sub-scanning direction.

  FIG. 19 shows a conventional optical sensor moving type measuring machine. The semiconductor laser 2 is connected to the laser light source 1 and installed in the unit 6 of the scanning optical system. The laser beam emitted from the semiconductor laser 2 is focused on the mirror surface of the polygon mirror 4 by the collimator lens and the cylindrical lens 3. The laser beam focused on the polygon mirror 4 is reflected by the mirror surface of the polygon mirror 4, passes through the fθ lens 5, and forms an image as a light spot on the surface to be scanned (image plane), which is y in the main scanning direction. Scanned in the axial direction.

  The laser beam scanned by the polygon mirror 4 irradiates the CCD light receiving unit 8 of one optical sensor 7 that is arranged on the trajectory of the light spot on the surface to be scanned and is movably supported on the stage 28. The CCD light receiving unit 8 includes a light receiving element composed of an optical element array of 5000 pixels arranged in the sub-scanning direction (z-axis direction).

  An output signal as a light receiving signal level from the CCD light receiving unit 8 of the CCD camera 7 is taken into a personal computer (hereinafter referred to as a personal computer) 11 through an image input board 10. The image input board 10 measures the level of the received light signal from the CCD light receiving unit 8, particularly the distribution of the output signal of each optical element (light intensity distribution). The computing device of the personal computer 11 has software that can count the area center of the output cross-sectional shape, and calculates the area center of the output cross-sectional shape from the output signal distribution (light intensity distribution) of each optical element. This is processed as scanning position information in the sub-scanning direction.

  The arithmetic unit of the personal computer 11 performs the measurement of the scanning position at a plurality of points in the image height direction by each light reception signal taken from the CCD light receiving unit 8 of the CCD camera 7 through the image input board 10 and performs a plurality of sub scanning directions. The scanning position information is obtained, and the bending, inclination, pitch unevenness, pitch deviation, etc. of the scanning line are obtained based on the scanning position information.

  Patent Document 1 describes a light beam measuring apparatus that moves an optical sensor in a main scanning direction. Patent Document 2 describes a beam diameter measuring apparatus that measures the beam diameter of an intermittent irradiation beam. Patent Document 3 describes a measuring device for a scanning optical system related to a data acquisition range of an optical sensor in scanning position measurement. Patent Literature 4 describes an image reading apparatus having a line sensor.

JP-A-11-223551 JP 2001-221614 A JP 2000-121315 A Japanese Patent Laid-Open No. 8-139872

  By the way, the purpose of measuring the scanning position of the light beam in the sub-scanning direction is to obtain the curve and inclination of the scanning line from the sub-scanning position over the entire image height of the light beam, and to obtain the pitch deviation in the multi-beam. It is in. Particularly, since the sub-micron accuracy is required for the pitch deviation in the multi-beam, the measurement error due to the positional accuracy of the stage for moving the CCD sensor, temperature change, etc. cannot be ignored.

  The optical sensor used for measuring the scanning position is a line CCD sensor, and light receiving elements composed of a plurality of optical elements are arranged at a pitch of 7 μm between the optical elements. The output from each optical element changes linearly with respect to the light energy irradiated to the optical element, and becomes an output value in 256 stages by A / D conversion by the image input board. Then, the scanning position in the sub-scanning direction is calculated by calculating the position that becomes the center of gravity of the output value.

  Conventionally, a single CCD sensor is moved to a measurement position by a moving stage, and when the measurement at that position is completed, the operation of moving to the next position is repeated to perform measurement over the entire image height. In such a system, there has been a problem that errors such as pitching and yawing of the moving stage directly reduce the measurement accuracy. In addition, there is a problem that the temperature condition is changed due to the time shift due to the movement of the stage, resulting in a decrease in measurement accuracy.

An object of the present invention is to provide a scanning optical system optical characteristic measuring apparatus that can measure the scanning position of the light beam in the sub-scanning direction with high accuracy without the above-mentioned problems.
Another object of the present invention is to provide a scanning optical system optical property measuring device calibration method capable of causing the scanning optical system optical property measuring device to measure the absolute scanning position of the light beam in the sub-scanning direction.
Another object of the present invention is to provide a scanning optical system capable of adjusting the scanning position of the light beam in the sub-scanning direction with high accuracy.
Another object of the present invention is to provide an image forming apparatus capable of outputting an image with reduced color misregistration in the sub-scanning direction.

  In order to achieve the above object, the invention according to claim 1 is characterized in that the light beam is main-scanned on the image plane by a scanning optical system that scans the image plane with the light beam and performs at least one of writing and reading. In a scanning optical system optical characteristic measurement device that measures the position of a scanning line that scans in the direction by an optical sensor having a plurality of light receiving elements arranged in the sub-scanning direction, or an optical sensor that can detect the position of the scanning line, The optical sensors are fixed optical sensors arranged at least three in the image height direction according to the image plane, and the optical sensor measures the sub-scanning position of the light beam on the image plane at a plurality of positions. It is.

  According to a second aspect of the present invention, in the scanning optical system optical characteristic measuring apparatus according to the first aspect, an adjusting means for adjusting the position in the image plane direction is provided for each of the optical sensors.

  According to a third aspect of the present invention, in the scanning optical system optical characteristic measuring apparatus according to the first aspect, an adjusting means for adjusting a gain of sensitivity is provided for each of the optical sensors.

  According to a fourth aspect of the present invention, in the scanning optical system optical characteristic measuring apparatus according to the first aspect, there is provided mounting means for mounting an ND filter having a different transmittance for each of the optical sensors.

  According to a fifth aspect of the present invention, in the scanning optical system optical characteristic measuring device according to the first aspect, all the light sensors are connected to a single data input processing device via a sensor switching means, whereby The measurement values of the sensors are taken in order.

  According to a sixth aspect of the present invention, in the scanning optical system optical characteristic measuring device according to the first aspect, all the optical sensors are individually connected to separate data input processing devices, whereby the measured values of all the optical sensors are measured. Are taken at the same time.

  According to a seventh aspect of the present invention, in the scanning optical system optical characteristic measurement apparatus according to the first aspect, when the scanning optical system simultaneously scans a plurality of light beams, an algorithm that recognizes each of the light beams separately is used. Simultaneously, the scanning position is measured by a plurality of the light beams.

  The invention according to claim 8 is the scanning optical system optical characteristic measurement device according to claim 7, wherein the differential value of the raw data of the optical sensor is calculated, and each light beam is separated from the plurality of light beams from the result. To recognize.

  The invention according to claim 9 is the scanning optical system optical characteristic measuring apparatus according to claim 1, further comprising beam splitting means for splitting the light beam in a plurality of scanning directions, and the light beam split by the beam splitting means is By scanning a sensor capable of detecting the main scanning position of the scanning line, the sub-scanning position and the main scanning position of the scanning line are simultaneously measured.

  A tenth aspect of the present invention is a scanning optical system optical characteristic measuring device calibration method for calibrating the scanning optical system optical characteristic measuring device according to the first aspect, wherein a plurality of light receiving elements constituting each of the optical sensors. Measuring the relative positional relationship of the same address in the sub-scanning direction to obtain a correction value of the relative positional relationship of each optical sensor in the sub-scanning direction, and correcting the measurement result of the light beam sub-scanning position with this correction value, The absolute position of the light beam sub-scanning position is calculated.

  According to an eleventh aspect of the present invention, in the scanning optical system optical property measuring apparatus calibration method according to the tenth aspect, the measurement of the relative positional relationship in the sub-scanning direction between the optical sensors is applied from a parallel light emitting unit. The reference parallel light is subjected to parallel scanning or rotation with respect to the scanning optical system optical characteristic measuring apparatus in which all the optical sensors are installed, thereby measuring the sub-scanning position of the reference parallel light, and sub-scanning of each optical sensor. A correction value for calculating the relative positional relationship in the scanning direction is calculated.

  According to a twelfth aspect of the present invention, in the scanning optical system optical characteristic measuring device calibration method according to the tenth aspect, the relative positional relationship between the optical sensors in the sub-scanning direction is measured from a fixed parallel light emitting unit. By moving the scanning optical system optical characteristic measuring apparatus in which all the optical sensors are installed in parallel with the irradiated reference parallel light, the relative positional relationship correction value for each optical sensor is calculated. It is characterized by that.

  According to a thirteenth aspect of the present invention, in the scanning optical system optical property measuring apparatus calibration method according to the tenth aspect, the measurement of the relative positional relationship between the optical sensors in the sub-scanning direction is performed by installing a microscope for all the sensors. The scanning optical system optical characteristic measuring device is translated or rotated in parallel to measure the position of the light receiving element of the actual optical sensor, thereby correcting the relative positional relationship correction value of each optical sensor in the sub-scanning direction. Is calculated.

  The invention according to claim 14 is the scanning optical system optical property measuring apparatus calibration method according to claim 10, wherein the relative positional relationship in the sub-scanning direction between the optical sensors is measured with respect to a fixed microscope. By moving the scanning optical system optical characteristic measuring apparatus in which all the optical sensors are installed, the actual light receiving element position of the optical sensor is measured, and the relative positional relationship correction value of each optical sensor is measured. Is calculated.

  According to a fifteenth aspect of the present invention, in the scanning optical system optical characteristic measuring apparatus according to the first aspect, the support on which the photosensor is mounted is an integral unit structure integrated with the photosensor, and all the photosensors are removed integrally. It is possible.

According to a sixteenth aspect of the present invention, in the scanning optical system optical property measuring apparatus according to the fifteenth aspect, the support on which the optical sensor is mounted is made of a material having a thermal expansion coefficient of 5 × 10 ⁻⁶ / ° C. or less.

  The invention according to claim 17 is provided with means capable of being attached in a measurable state with respect to the scanning optical system optical characteristic measuring device according to any one of claims 1 to 10, 15, and 16. is there.

  The invention according to claim 18 is an image carrier, a scanning optical system according to claim 17, a developing device for developing an electrostatic latent image written on the image carrier, and a developed image on the image carrier. And a fixing device for fixing the transferred image transferred onto the transfer paper.

According to the present invention, it is possible to measure the scanning position of the light beam in the sub-scanning direction with high accuracy without being affected by the moving stage.
According to the present invention, there is no positional variation for each optical sensor, and there is an effect that the scanning position of the light beam in the sub-scanning direction can be measured with high accuracy.
According to the present invention, it is possible to correct the light amount difference due to the image height, and it is possible to measure the scanning position of the light beam in the sub-scanning direction with high accuracy regardless of the light amount difference due to the image height.

According to the present invention, it is possible to measure the scanning position of the light beam in the sub-scanning direction with a small hardware configuration, and to easily cope with an increase in the number of optical sensors.
According to the present invention, it is possible to perform measurement by all optical sensors in a short time, and it is possible to measure the scanning position of the light beam in the sub-scanning direction with high accuracy without being affected by disturbance such as temperature change. There is an effect of becoming.
According to the present invention, it is possible to perform measurement in a short time without the need to switch the light beam, and to measure the scanning position of the light beam in the sub-scanning direction with high accuracy without being affected by disturbance such as a temperature change. There is an effect that becomes possible.

According to the present invention, it is possible to measure the scanning position of the scanning line in the sub-scanning direction and the scanning position in the main scanning direction under the same conditions.
According to the present invention, there is an effect that the absolute position of the scanning position of the light beam in the sub-scanning direction can be measured.
According to the present invention, there is an effect that movement and replacement are possible while maintaining the positional relationship between the optical sensors whose positions have been adjusted.
According to the present invention, there is an effect that the scanning position of the light beam in the sub-scanning direction can be measured with high accuracy without being affected by heat.
According to the present invention, it is possible to adjust the scanning position of the light beam in the sub-scanning direction with high accuracy.
According to the present invention, it is possible to output an image with reduced color shift in the sub-scanning direction.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a first embodiment of the invention will be described with reference to the drawings.
FIG. 1 shows a scanning optical system optical characteristic measuring apparatus and a scanning optical system according to the first embodiment. The semiconductor laser 2 is connected to the laser light source 1 and installed in the unit 6 of the scanning optical system. A laser beam as a light beam emitted from the semiconductor laser 2 is condensed by the collimator lens and the cylindrical lens 3 onto the mirror surface of the polygon mirror 4 that is a rotating polygon mirror. The laser beam focused on the polygon mirror 4 is reflected by the mirror surface of the polygon mirror 4, passes through the fθ lens 5, and forms an image as a light spot on the surface to be scanned (image plane), which is y in the main scanning direction. Scanned in the axial direction.

  Here, the surface to be scanned is the photosensitive surface of the photoconductive photoconductor of the image forming apparatus. The image forming apparatus includes the scanning optical system unit 6, a photoconductor as an image carrier, a charger for uniformly charging the photoconductor, and development for developing an electrostatic latent image written on the photoconductor. A transfer unit that transfers the developed image on the photosensitive member to a transfer sheet, and a fixing unit that fixes the transfer image transferred to the transfer sheet. The photosensitive member is rotationally driven by a driving unit to move the photosensitive surface as the surface to be scanned, and is scanned in the main scanning direction by the laser beam from the fθ lens 5 by the scanning optical system unit 6 and the photosensitive member itself. Is scanned in the sub-scanning direction. The semiconductor laser 2 is driven by an image signal by a drive circuit, and the photosensitive member is exposed with a laser beam from the fθ lens 5 to form an electrostatic latent image. The electrostatic latent image on the photoconductor is developed by a developing device to become a toner image. The toner image on the photoconductor is transferred onto a transfer paper by a transfer device and then fixed on the transfer paper by a fixing device. The scanned surface may be a scanned surface (image surface) that reads an image by scanning with a light beam in a scanning optical system unit in the image forming apparatus.

  The laser beam scanned by the polygon mirror 4 is emitted from three or more fixed photosensors such as CCD cameras 7 (7 (1), 7 (2), 7) arranged on the trajectory of the light spot on the surface to be scanned. (3) ... 7 (7)) CCD light receiving section 8 (8 (1), 8 (2), 8 (3) ... 8 (7)) is irradiated. The CCD light receiving unit 8 includes a light receiving element composed of an optical element array of 5000 pixels arranged in the sub-scanning direction (z-axis direction). The pitch of this optical element array is 7 μm.

  In addition, a plurality of CCD cameras 7 (seven in the first embodiment) are fixedly arranged in the main scanning region where the laser beam is scanned in the main scanning direction by the polygon mirror 4. CCD light receiving portions 8 (8 (1), 8 (2), 8 (3) ... 8 (7) of all CCD cameras 7 (7 (1), 7 (2), 7 (3) ... 7 (7)) The output signal as the received light signal level from)) is taken into the personal computer 11 through the switching box 9 as switching means such as a relay and the image input board 10 as measuring means. The image input board 10 measures the level of the received light signal from the CCD light receiving unit 8, particularly the distribution of the output signal of each optical element (light intensity distribution). The computing device of the personal computer 11 has software that can count the area center of the output cross-sectional shape, and calculates the area center of the output cross-sectional shape from the output signal distribution (light intensity distribution) of each optical element. This is processed as scanning position information in the sub-scanning direction.

  The arithmetic unit of the personal computer 11 measures the scanning position by measuring the CCD light receiving unit 8 (8 (1), 8) of the CCD camera 7 (7 (1), 7 (2), 7 (3)... 7 (7)). (2), 8 (3)... 8 (7)) through the switching box 9 and the image input board 10 are performed at a plurality of points in the image height direction by the respective received light signals, and a plurality of scanning position information in the sub-scanning direction. Based on these scanning position information, the bending, inclination, pitch unevenness, pitch deviation, etc. of the scanning line are obtained. Although it is desirable that each CCD light receiving portion 8 (8 (1), 8 (2), 8 (3)... 8 (7)) exactly coincides with the image plane position, in reality, the CCD camera 7 (7 (1), 7 (2), 7 (3)... 7 (7)), and there are subtle individual differences due to variations in the CCD elements themselves. Therefore, for example, the distance from the front surface of the CCD camera alone to the CCD element is measured in advance with a microscope, and each CCD light receiving unit 8 (8 (1), 8 (2), 8 (3)... 8 (7) ) Are arranged on the same plane, each CCD light is received by position adjusting means 12 (12 (1), 12 (2), 12 (3)... 12 (7)) such as the micro head shown in FIG. Each of the portions 8 (8 (1), 8 (2), 8 (3)... 8 (7)) is exactly matched with the position of the image plane.

  In general, the amount of laser beam on the surface to be scanned is strongest in the vicinity of the central image height and weakened in the peripheral image height. For example, as shown in FIG. 3, when the scanning position is measured by adjusting the output light amount of the semiconductor laser 2 so that the maximum output value of the CCD camera 7 (4) having the center image height becomes 200 gradations, The maximum output value of the CCD cameras 7 (1) and 7 (7) is about 80 gradations. Although the measurement of the scanning position can be performed with this, the measurement accuracy is also reduced because the resolution of the scanning position measurement based on the output values of the peripheral CCD cameras 7 (1) and 7 (7) is lowered.

  Therefore, in the first embodiment, gain adjusting means capable of adjusting sensitivity (gain) such as a variable resistor is provided for each optical sensor, and the peripheral CCD cameras 7 (1), 7 ( The maximum output value of 7), the maximum output value of the central CCD camera 7 (4), and the maximum output value of the other CCD cameras 7 (2), 7 (3), 7 (5), 7 (6) are comparable. By adjusting the sensitivity (gain) of each optical sensor so that the following results are obtained, the same measurement accuracy can be obtained over the entire scanning width.

  Even when the CCD camera 7 (7 (1), 7 (2), 7 (3)... 7 (7)) does not have gain adjusting means, as shown in FIG. 7 (2), 7 (3)... 7 (7)) so that the ND filter 13 is inserted in the input optical path of each CCD camera 7 (7 (1), 7 (2), 7 (3). If an ND filter mounting portion 13a capable of mounting the ND filter 13 is provided in 7)), the ND filter mounting portion of each CCD camera 7 (7 (1), 7 (2), 7 (3)... 7 (7)) By attaching ND filters 13 having different transmittances to 13a so that the maximum output values of the CCD cameras 7 (7 (1), 7 (2), 7 (3)... 7 (7)) are approximately the same. Similarly, the same measurement accuracy can be obtained over the entire scanning width. In this case, it is necessary to prepare ND filters with various transmittances, and it is necessary to readjust the image plane position according to the thickness of the ND filter. When light exceeding the limit light quantity is incident on the CCD camera, the output is saturated even if there is gain adjusting means. Since the ND filter can reduce the absolute input light amount of the CCD camera, it can also cope with a strong scanning beam.

  As shown in FIG. 1, all optical sensors 7 (7 (1), 7 (2), 7 (3)... 7 (7)) are connected through a switching box 9 which is a sensor switching means such as a relay. By connecting to the image input board 10 which is a data input processing device, the measured values of the optical sensors 7 (7 (1), 7 (2), 7 (3)... 7 (7)) are sequentially transmitted to the personal computer 11. Can be imported. The personal computer 11 obtains the bending, inclination, pitch unevenness, pitch deviation, etc. of the scanning line from all the data thus acquired.

According to the first embodiment, the optical sensor 7 is a fixed optical sensor arranged at least three in the image height direction according to the image plane, and the optical sensor 7 determines the sub-scanning position on the image plane of the light beam. Since measurement is performed at a plurality of locations, there is an effect that the sub-scanning position of the light beam can be measured with high accuracy without being affected by the stage.
According to the first embodiment, since the adjusting means for adjusting the position in the image plane direction is provided for each optical sensor 7, there is no positional variation for each sensor, and the sub-scanning position of the light beam can be measured with high accuracy. There is an effect that it becomes possible.

According to the first embodiment, since the adjustment means for adjusting the gain of sensitivity is provided for each optical sensor 7, the light amount difference due to the image height of the light beam can be corrected, and high accuracy can be achieved regardless of the light amount difference due to the image height. In addition, it is possible to measure the sub-scanning position of the light beam.
According to the first embodiment, since the mounting means 13a for mounting the ND filter 13 having a different transmittance is provided for each optical sensor 7, the light amount difference due to the image height of the light beam can be corrected, and the light beam image height can be corrected. There is an effect that the sub-scanning position of the light beam can be measured with high accuracy regardless of the light amount difference.

  According to the first embodiment, since all the photosensors are connected to a single data input processing device via the sensor switching means, the measurement values of the photosensors are sequentially fetched. With the hardware configuration, it is possible to measure the sub-scanning position of the light beam and to cope with the increase in the number of optical sensors.

  In the second embodiment of the present invention, as shown in FIG. 5, a plurality of optical sensors 7 (7 (1), 7 (2), 7 (3)... By connecting to a plurality of image input boards 10 (10 (1), 10 (2), 10 (3)... 10 (7)) without using a switching box, each optical sensor 7 (7 (1 ), 7 (2), 7 (3)... 7 (7)) are simultaneously acquired. In this case, the personal computer 11 can perform parallel processing of data, and the measurement speed is higher than that in the first embodiment.

  When the scanning optical system unit 6 measures the scanning position where the scanning surface is scanned with a single beam (one light beam), the output signal of the optical sensor 7 has one peak as shown in FIG. . However, as shown in FIG. 7, when the scanning optical system unit 6 measures the scanning position where the surface to be scanned is scanned with a multi-beam (a plurality of light beams), the tandem optical system scans the surface to be scanned with a light beam. When measuring each scanning position, the output signal of the optical sensor 7 has a plurality of peaks.

  When measuring each scanning position scanned with multiple light beams, each scanning position scanned with a single light beam may be measured sequentially, but if each scanning position can be measured at the same time, the measurement is efficient and close to the actual machine state. It becomes. In this case, if measurement is performed normally, the vicinity of the intermediate position between the two light beams is recognized as one beam that becomes the scanning position (sub-scanning position) in the sub-scanning direction. Therefore, when measuring the sub-scanning positions of a plurality of light beams at the same time, the personal computer 11 uses an algorithm that recognizes each light beam separately. For example, to separate two light beams, FIG. As shown in FIG. 4, the raw data as measured values from the respective optical sensors 7 are differentiated to obtain absolute values thereof, and the absolute values are binarized at a predetermined threshold level, whereby each light beam (beam 1, beam 1) is obtained. 2) is recognized separately, and from each result, the bending, inclination, pitch unevenness, pitch deviation, etc. of the scanning line by each light beam are obtained.

According to the second embodiment, since all the optical sensors are individually connected to separate data input processing devices, the measurement values of all the optical sensors are simultaneously acquired. Measurement can be performed, and there is an effect that the sub-scanning position of the light beam can be measured with high accuracy without being affected by disturbance such as temperature change.
According to the second embodiment, when the scanning optical system simultaneously scans a plurality of light beams, the scanning position measurement by the plurality of light beams is simultaneously performed by an algorithm that recognizes each light beam separately. There is no need to switch between and the measurement can be performed in a short time, and the sub-scanning position of the beam can be measured with high accuracy without being affected by disturbance such as a temperature change.

  According to the second embodiment, the differential value of the raw data of the optical sensor is calculated, and each light beam is separated and recognized from the result, so there is no need to switch the light beam, and the time is short. Thus, it is possible to measure the sub-scanning position of the light beam with high accuracy without being affected by disturbance such as a temperature change.

  In the third embodiment of the present invention, in the first embodiment (or the second embodiment), a half mirror, a prism or the like is provided in the optical path between the fθ lens 5 and the CCD camera 7 as shown in FIG. The beam splitting unit 14 is arranged, and the light beam from the fθ lens 5 is separated by the beam splitting unit 14 into a plurality of (for example, two) scanning directions. One of the two separated light beams scans the optical sensor 7 capable of detecting the sub-scanning position of the scanning line as described above, and the other of the two separated light beams is the scanning direction in the main direction of the scanning line. The sensor 15 capable of detecting (main scanning position) is scanned.

  The sensor 15 capable of detecting the main scanning position has a structure as shown in FIG. 10, and a plurality of slits 17 whose intervals are accurately determined by etching on one surface of the transparent substrate 16 with little elongation such as glass. Is formed. A plurality of optical sensors 18 are installed at positions corresponding to the plurality of slits 17..., And each optical sensor 18 is connected to a time interval analyzer that can accurately measure the time when light is detected. When the light beam from the beam splitting unit 14 scans the sensor 15, the fluctuation of the main scanning time over the entire image height becomes clear, and the main scanning position shift can be calculated. The personal computer 11 takes in the measured value of the time interval analyzer through the switching box 9 and the image input board 10, and measures the main scanning position from the measured value of the time interval analyzer to calculate the main scanning position deviation. As a result, the sub-scanning position and the main scanning position of the scanning line can be measured simultaneously.

  According to the third embodiment, the light beam splitting means for separating the light beam in a plurality of scanning directions is provided, and the light beam separated by the beam splitting means scans the sensor capable of detecting the main scanning position of the scanning line. Therefore, the sub-scanning position and the main scanning position of the scanning line can be measured simultaneously, so that the sub-scanning position and the main scanning position of the scanning line can be measured simultaneously. There is an effect that becomes possible.

  The positions of the optical sensors 7 (7 (1), 7 (2), 7 (3)... 7 (7)) in the CCD sub-scanning direction are not completely matched due to assembly errors and component variations. As shown in FIG. 11, when the pixels of the same address in the optical sensor 7 (1) and the optical sensor 7 (2) are relatively shifted by L in the sub-scanning direction, the initial scanning line curve or inclination is changed. This value L is added to the value. Therefore, in the fourth embodiment of the present invention, as shown in FIG. 12, in the third embodiment, the scanning optical system optical property measuring apparatus of the fourth embodiment is fixed on a flat surface plate. The parallel light emitting means 19 such as HE-NE is installed so as to emit light in parallel with the installation surface, and the parallel light emitting means 19 is connected to the scanning optical system optical characteristic measuring apparatus in which all the sensors 7 are installed. Or move parallel to the scanning optical system optical characteristic measuring apparatus as shown in FIG. The personal computer 11 takes in the measured value of the sensor 15 through the switching box 9 and the image input board 10 and measures the main scanning position of the reference parallel light from the parallel light emitting means 19 from the light receiving signal of the sensor 15 to each light. Deviation of the center of gravity of the sensor 7 (7 (1), 7 (2), 7 (3) ... 7 (7)) (each optical sensor 7 (7 (1), 7 (2), 7 (3) ... 7 (7)) of the plurality of light receiving elements constituting the same address are calculated. The personal computer 11 uses the deviation of the center of gravity of each optical sensor 7 (7 (1), 7 (2), 7 (3)... 7 (7)) obtained as a correction value, and performs sub-scanning as described above. The scanning position in the direction is calculated, and this is corrected by the correction value to obtain an accurate sub-scanning position (absolute position of the scanning position of the light beam in the sub-scanning direction). The parallel light emitting means 19 may be fixed and the scanning optical system optical characteristic measuring apparatus of the fourth embodiment may be moved as shown in FIG.

  According to the fourth embodiment, the relative positional relationship in the sub-scanning direction of each optical sensor is measured by measuring the relative positional relationship in the sub-scanning direction between the same addresses of the plurality of light receiving elements constituting each optical sensor. Since the value is obtained and the measurement result of the light beam sub-scanning position is corrected by this correction value and the absolute position of the light beam sub-scanning position is calculated, the absolute position of the light beam sub-scanning position can be measured.

  According to the fourth embodiment, the measurement of the relative positional relationship between the optical sensors in the sub-scanning direction is performed by using the reference parallel light emitted from the parallel light emitting means and the optical characteristics of the scanning optical system in which all the optical sensors are installed. By measuring the sub-scanning position of the reference parallel light and calculating the relative position correction value in the sub-scanning direction of each optical sensor by moving the measurement device in parallel or rotating, the result of the light beam sub-scanning position measurement Thus, the absolute position of the light beam sub-scanning position can be measured.

  According to the fourth embodiment, the measurement of the relative positional relationship between the optical sensors in the sub-scanning direction is performed by setting all the optical sensors with respect to the reference parallel light emitted from the fixed parallel light emitting means. The relative position relationship correction value of each optical sensor is calculated by moving the scanning optical system optical characteristic measuring device in parallel. Therefore, the optical beam sub-scanning position measurement result is corrected, and the absolute position of the beam sub-scanning position is corrected. There is an effect that measurement becomes possible.

  In the fifth embodiment of the present invention, a microscope 20 is used instead of the parallel light emitting means 19 in the fourth embodiment as shown in FIG. (7 (1), 7 (2), 7 (3)... 7 (7)) are moved in parallel, and each optical sensor 7 (7 (1), 7 (2), 7 (3) )... 7 (7)) pixel position is read. However, in this case, it is difficult to determine the number of pixels in the vicinity of the central address of each photosensor 7 (7 (1), 7 (2), 7 (3)... 7 (7)). It is necessary to read the pixels.

As shown in FIG. 16, the support 21 on which the optical sensors 7 (7 (1), 7 (2), 7 (3)... 7 (7)) are mounted has a unit structure in which all the optical sensors 7 are fixed integrally. All of the optical sensors 7 (7 (1), 7 (2), 7 (3)... 7 (7)) can be integrally removed. In this way, each optical sensor 7 (7 (1), 7 (2), 7 (3)... 7 (7)) is unitized so that the adjusted positional relationship can be obtained even when measuring the scanning position of another scanning optical system. And measurement without resetting the correction coefficient. Moreover, the measurement error due to the temperature change can be kept low by using the material of the support 21 as a material having a thermal expansion coefficient of 5 × 10 ⁻⁶ / ° C. or less like Super Invar. For example, when the thickness of the support 21 is 30 mm, the support 21 is elongated by 0.15 μm with a change of 1 ° C. Therefore, if measurement is performed in a thermostatic bath, the measurement error can be suppressed sufficiently small.

  According to the fifth embodiment, the measurement of the relative positional relationship between the optical sensors in the sub-scanning direction is performed by moving the microscope in parallel or rotating with respect to the scanning optical system optical property measuring apparatus in which all the sensors are installed. As a result, the light receiving element position of the actual optical sensor is measured and the relative positional relationship correction value of each optical sensor is calculated. Therefore, the measurement result of the optical beam sub-scanning position is corrected, and the absolute position of the beam sub-scanning position is corrected. There is an effect that position measurement becomes possible.

  According to the fifth embodiment, the relative positional relationship between the optical sensors in the sub-scanning direction is measured by translating the scanning optical system optical characteristic measuring apparatus in which all the optical sensors are installed with respect to the fixed microscope. As a result, the position of the light receiving element of the actual optical sensor is measured and the relative positional relationship correction value of each optical sensor is calculated. Therefore, the measurement result of the optical beam sub-scanning position is corrected, and the position of the beam sub-scanning position is corrected. There is an effect that absolute position measurement is possible.

  According to the fifth embodiment, the support on which the photosensors are mounted has an integrated unit structure, and all the photosensors can be removed as a single unit. There is an effect that becomes possible.

According to the fifth embodiment, since the support on which the optical sensor is mounted is made of a material having a thermal expansion coefficient of 5 × 10 ⁻⁶ / ° C. or less, the sub-scanning position measurement of the light beam can be performed with high accuracy without being affected by heat. There is an effect that it becomes possible.

  In the second embodiment, the scanning optical system optical property measuring apparatus 23 according to the sixth embodiment of the present invention is such that the quadruple tandem scanning optical system 22 is detachable by a fixing member 24 as shown in FIG. Fixed. The scanning optical system optical characteristic measuring device 23 can fix the quadruple tandem scanning optical system 22 in this way, thereby directly measuring and adjusting the scanning position of the actual scanning optical system. In addition, when the space | interval of a light beam is wide like this 6th Embodiment, you may use the elongate optical sensor 7, or may use it combining a some optical sensor.

  Further, the optical sensor is not a type composed of a plurality of light receiving elements arranged in the sub-scanning direction as in the CCD described above, but two light receiving elements arranged non-parallel as shown in FIG. An element 25 composed of the elements 26 and 27 may be used. The optical sensor 25 includes a light receiving element 26 disposed perpendicular to the main scanning direction and a light receiving element 27 disposed non-parallel to the light receiving element 26. Each of the light receiving elements 26 and 27 is connected to a time interval analyzer that can accurately measure the time when the light is detected. The measuring means (not shown) detects the time interval t1 when the beam 1 is detected by the light receiving elements 26 and 27 and the beam 2 when the beam 1 moves in the sub-scanning direction from the measured values of the time interval analyzer. The amount of movement in the sub-scanning direction is obtained by comparing the time intervals t2.

  Here, the quadruple tandem scanning optical system 22 is used in a color image forming apparatus. This color image forming apparatus has a plurality of image forming units, and in each of the plurality of image forming units, the photosensitive member is driven to rotate by a driving unit, and a photosensitive surface as a surface to be scanned moves, and a plurality of image forming units move. The scanning optical system unit 6 scans in the main scanning direction with the laser beam from the fθ lens 5 and scans in the sub scanning direction by the movement of the photosensitive member itself. When the semiconductor laser 2 is driven by the image signal of each color by the drive circuit, the photosensitive member is exposed with the laser beam from the fθ lens 5 to form an electrostatic latent image. The electrostatic latent image on each photoconductor is developed by each color developer to become a toner image of each color, and the toner image of each color on each photoconductor is transferred by being superimposed on a transfer sheet conveyed by a transfer belt. After that, the image is fixed on the transfer paper by a fixing device.

  According to the sixth embodiment, since the scanning optical system optical characteristic measuring device is provided with means that can be mounted in a measurable state, the scanning optical system can adjust the light beam sub-scanning position with high accuracy. There is an effect.

  According to the image forming apparatus of the sixth embodiment, the image carrier, the scanning optical system, the developing device for developing the electrostatic latent image written on the image carrier, and the developed image on the image carrier are transferred to the transfer paper. And a fixing device for fixing the transferred image transferred onto the transfer paper, an image output with reduced color misregistration in the sub-scanning direction can be achieved.

1 is a schematic cross-sectional view illustrating a scanning optical system optical characteristic measurement apparatus and a scanning optical system according to a first embodiment of the present invention. It is a section schematic diagram expanding and showing a part of the 1st embodiment. It is a figure for demonstrating the gain adjustment of the CCD camera in the said 1st Embodiment. It is a perspective view which expands and shows a part of said 1st Embodiment. It is a cross-sectional schematic diagram which shows the scanning optical system optical characteristic measuring apparatus and scanning optical system which are 2nd Embodiment of this invention. It is a figure which shows a structure and CCD output in case the light beam of a scanning optical system unit is a single beam in the said 2nd Embodiment. It is a figure which shows a structure and CCD output in case the light beam of a scanning optical system unit is a multi-beam in the said 2nd Embodiment. It is a wave form diagram which shows the processing waveform of the raw data from the CCD camera of the said 2nd Embodiment. It is a cross-sectional schematic diagram which shows the scanning optical system optical characteristic measuring apparatus which is 3rd Embodiment of this invention. It is a top view which shows the sensor which can detect the main scanning position of the 3rd Embodiment. It is a figure which shows the subscanning direction shift | offset | difference of the pixel of the same address in two photosensors. It is the schematic which shows 1 aspect of 4th Embodiment of this invention. It is the schematic which shows the other aspect of the said 4th Embodiment. It is a schematic diagram showing another mode of the 4th embodiment. It is the schematic which shows 5th Embodiment of this invention. It is a perspective view which shows a part which shows the same 5th Embodiment. It is the schematic which shows 6th Embodiment of this invention. It is a figure which shows the example of an optical sensor. It is the cross-sectional schematic which shows the conventional optical sensor moving type measuring machine.

Explanation of symbols

2 Semiconductor Laser 3 Collimator Lens and Cylindrical Lens 4 Polygon Mirror 5 fθ Lens 6 Scanning Optical System Unit 7, 7 (1), 7 (2), 7 (3)... 7 (7) CCD Camera 7
8, 8 (1), 8 (2), 8 (3) ... 8 (7) CCD light receiving unit 9 Switching box 10, 10 (1), 10 (2), 10 (3) ... 10 (7) Image input Board 11 Personal computer 12 (12 (1), 12 (2), 12 (3)... 12 (7)) Position adjusting means 13 ND filter 14 Beam splitting means 15 Sensor 19 Parallel light emitting means 20 Microscope 21 Support body 22 4 stations Scanning optical system for tandem 23 Scanning optical system optical characteristic measuring device 24 Fixing member 25 Optical sensor

Claims (18)

  A scanning optical system that scans the image surface with a light beam and performs at least one of writing and reading, and the positions of scanning lines where the light beam scans the image surface in the main scanning direction are arranged in the sub-scanning direction. In a scanning optical system optical characteristic measurement apparatus that measures with an optical sensor having a plurality of light receiving elements or an optical sensor capable of detecting the position of the scanning line, the optical sensor is at least in the image height direction according to the image plane. An optical characteristic measuring apparatus for scanning optical system, wherein three or more fixed optical sensors are arranged, and the optical sensor measures the sub-scanning position of the light beam on the image plane at a plurality of positions.   2. The scanning optical system optical characteristic measuring apparatus according to claim 1, further comprising an adjusting unit for adjusting the position in the image plane direction for each of the optical sensors.   2. The scanning optical system optical characteristic measuring apparatus according to claim 1, further comprising an adjusting means for adjusting a gain of sensitivity for each of the optical sensors.   2. The scanning optical system optical characteristic measuring apparatus according to claim 1, further comprising mounting means for mounting an ND filter having a different transmittance for each of the optical sensors.   2. The scanning optical system optical characteristic measurement device according to claim 1, wherein all the optical sensors are connected to a single data input processing device via an optical sensor switching means, so that measured values of the optical sensors are sequentially obtained. A scanning optical system optical characteristic measuring device characterized by being incorporated.   2. The scanning optical system optical characteristic measurement apparatus according to claim 1, wherein all the optical sensors are individually connected to separate data input processing devices, thereby simultaneously acquiring the measurement values of all the optical sensors. A scanning optical system optical characteristic measuring device.   2. The scanning optical system optical characteristic measurement apparatus according to claim 1, wherein when the scanning optical system scans a plurality of light beams simultaneously, an algorithm for recognizing each of the light beams separately is used. A scanning optical system optical characteristic measuring apparatus for measuring the scanning position.   8. The scanning optical system optical characteristic measuring apparatus according to claim 7, wherein a differential value of the raw data of the optical sensor is calculated, and each light beam is separated and recognized from the plurality of light beams based on the result. Scanning optical system optical characteristic measuring device.   2. The scanning optical system optical characteristic measuring apparatus according to claim 1, further comprising beam splitting means for separating the light beam in a plurality of scanning directions, and the light beam separated by the beam splitting means detects a main scanning position of a scanning line. A scanning optical system optical characteristic measuring apparatus for simultaneously measuring a sub-scanning position and a main scanning position of a scanning line by scanning a possible sensor.   A scanning optical system optical property measuring device calibration method for calibrating the scanning optical system optical property measuring device according to claim 1, wherein a plurality of light receiving elements constituting each of the photosensors are sub-scanned at the same address. The relative positional relationship of each direction is measured to obtain a sub-scanning direction relative positional relationship correction value of each of the optical sensors, the optical beam sub-scanning position measurement result is corrected by this correction value, and the absolute position of the light beam sub-scanning position is corrected. A method of calibrating a scanning optical system optical characteristic measuring device, characterized in that:   11. The scanning optical system optical property measuring apparatus calibration method according to claim 10, wherein the measurement of the relative positional relationship between the optical sensors in the sub-scanning direction is performed using all of the reference parallel light emitted from the parallel light emitting means. Measure the sub-scanning position of the reference parallel light by performing parallel movement or parallel rotation with respect to the scanning optical system optical property measuring device provided with the optical sensor, and correct the relative positional relationship of the optical sensors in the sub-scanning direction. A method for calibrating a scanning optical system optical characteristic measuring device, characterized by calculating a value.   11. The scanning optical system optical characteristic measuring device calibration method according to claim 10, wherein the measurement of the relative positional relationship between the optical sensors in the sub-scanning direction is performed with respect to the reference parallel light emitted from the fixed parallel light emitting means. A scanning optical system that calculates a relative positional relationship correction value in the sub-scanning direction of each optical sensor by moving in parallel the scanning optical system optical characteristic measuring device in which all the optical sensors are installed. Optical characteristic measuring device calibration method.   11. The scanning optical system optical property measuring apparatus calibration method according to claim 10, wherein the relative positional relationship between the optical sensors in the sub-scanning direction is measured by measuring the optical properties of the scanning optical system in which all the sensors are installed in a microscope. The position of the light receiving element of the actual optical sensor is measured by performing parallel movement or parallel rotation with respect to the apparatus, and the relative positional relationship correction value of each optical sensor is calculated. Scanning optical system optical property measuring device calibration method.   11. The scanning optical system optical property measuring apparatus calibration method according to claim 10, wherein the measurement of the relative positional relationship between the optical sensors in the sub-scanning direction is performed by installing all the optical sensors with respect to a fixed microscope. By translating the scanning optical system optical characteristic measuring device, the actual position of the light receiving element of the photosensor is measured, and the sub-scanning direction relative positional relationship correction value of each photosensor is calculated. Scanning optical system optical property measuring device calibration method.   2. The scanning optical system optical characteristic measuring apparatus according to claim 1, wherein the support on which the photosensor is mounted has an integral unit structure integrated with the photosensor, and all the photosensors can be removed integrally. Scanning optical system optical property measuring device. 16. A scanning optical system optical characteristic measuring apparatus according to claim 15, wherein the support on which the optical sensor is mounted is made of a material having a thermal expansion coefficient of 5 × 10 ⁻⁶ / ° C. or less. .   17. A scanning optical system comprising means capable of being mounted in a measurable state with respect to the scanning optical system optical property measuring apparatus according to claim 1. 18. An image carrier, a scanning optical system according to claim 17, a developing device for developing an electrostatic latent image written on the image carrier, and a transfer device for transferring a developed image on the image carrier to a transfer sheet. And an image forming apparatus comprising: a fixing device that fixes the transferred image transferred onto the transfer paper.

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