JPH1172383A - Method and apparatus for evaluation of characteristic of light beam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a method and an apparatus in which every characteristic required from a light beam can be evaluated by a method wherein a beam light source which is used to scan a face to be scanned linearly is turned on during its scanning operation during a specific scanning time. SOLUTION: A beam light source which is used to scan a face to be measured linearly is turned on during its scanning operation during the scanning time corresponding to one dot, and a characteristic which is required from a light beam P1 is evaluated. At this time, on a face 31 to be scanned corresponding to the surface of a photoreceptor drum, area-type imaging elements 32a to 34a in CCD cameras 32 to 34 as light-beam detection means are installed at equal intervals toward the scanning finish side from the scanning start side of the light beam P1. A laser diode is controlled so as to be turned on by a one-dot turning-on control circuit 35. The one-dot turning-on control circuit 35 is provided with a clock pulse oscillator 36 which oscilates clock pulses for time clocking and with a counting circuit 37 which counts the clock pulses.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an evaluation apparatus for an image forming apparatus such as a laser printer and a copying machine, and more particularly, to a latent image carrier such as a photosensitive drum and a photosensitive belt from a writing unit of the image forming apparatus. TECHNICAL FIELD The present invention relates to a method for evaluating characteristics required for a light beam irradiated toward a light source and a light beam characteristic evaluation apparatus used for evaluating the characteristics.

[0002]

2. Description of the Related Art Conventionally, laser printers, copiers,
2. Description of the Related Art In an image forming apparatus such as a facsimile apparatus, the surface of a photosensitive drum serving as a latent image carrier provided in an image forming unit is scanned in a main scanning direction using a light beam from a writing unit and is moved in a sub-scanning direction. The electrostatic latent image is formed by scanning and writing on the surface of the photosensitive drum, and the toner image is formed by attaching toner to the surface of the photosensitive drum on which the electrostatic latent image is formed and visualizing the toner. Is formed, and the toner image is transferred and fixed on a transfer sheet to form an image on the transfer sheet.

The writing unit is provided with a scanning optical system for scanning a light beam, and the scanning of the surface of the photosensitive drum in the main scanning direction is performed by the scanning optical system. Scanning in the sub-scanning direction is performed by rotation of the photosensitive drum.

By the way, in these image forming apparatuses, when writing is performed on the surface of a photosensitive drum to be written, characteristics required for a light beam of the writing unit are evaluated.

For example, in the case of a copying machine, for example, image information of a document is sequentially read and this image information is converted into a light beam. However, the writing position of the light beam on the surface of the photosensitive drum is designed. If the reference position deviates from the expected reference position, an inconvenience occurs that an image corresponding to the image information of the document cannot be formed at the reference position. In particular, the writing unit is provided with two laser light sources for generating light beams, and simultaneously scans the surface of the photosensitive drum in the main scanning direction with the two light beams, and operates the photosensitive drum at twice the normal speed. In an image forming apparatus that performs writing on the front surface, if the writing position of one light beam and the writing position of the other light beam are shifted in the middle of the main scanning direction, an image faithful to the original image is reproduced. It is not possible to perform the evaluation of the writing position of one light beam and the evaluation of the writing position of the other light beam.

[0006] In the case of a writing unit for writing on a photosensitive drum with one light beam, a main scanning on each surface of the polygon mirror is performed by obtaining a writing position for each surface of the polygon mirror constituting the scanning optical system. The positional deviation in the direction (uniform pitch in the main scanning direction) and the positional deviation in the sub-scanning direction on each surface of the polygon mirror (non-uniform pitch in the sub-scanning direction) are also evaluated.

[0007] In the case of a writing unit for writing on a photosensitive drum with a plurality of multiplexed light beams, in addition to these evaluations, the pitch between beams is also subject to evaluation.

Further, two points on the document corresponding to the main scanning direction are extracted, and two points of the copy image on the transfer paper corresponding to the two points are extracted to determine the distance between the two points on the document and the copy. Image 2
When comparing the distance between the points, they must be the same as long as copying is performed at the same magnification, but the distance between the two points on this document and the distance between the two points on the copied image must exactly match. For example, a magnification error occurs, and an image cannot be faithfully reproduced on the transfer paper, and it is required to evaluate the magnification error. In addition, when enlarging or reducing, the ratio of the copy image formed on the transfer paper to the image on the document must be equal to the magnification to be enlarged or reduced. The image cannot be reproduced, and in this case, the evaluation of the magnification error is required.

[0009] In addition, if the left point and the right point are shifted in the sub-scanning direction, the scanning line is inclined.
This scanning line inclination is also an evaluation target.

Further, three points are extracted from the left side to the right side of the original in correspondence with the main scanning direction, and if there are two remaining points at a position equidistant from the center point, the copy on the transfer paper is performed. If the distances to the left and right points are not equal with respect to the three center points in the main scanning direction corresponding to these three points in the image, the copied image to be formed lacks the balance between the left and right, so that the center It is also required to evaluate whether the distance to the left point is equal to the distance from the middle point to the right point.

In this case, the difference between the writing position of the left point and the writing position of the middle point along the sub-scanning direction is not equal to the difference between the writing position of the right point and the writing position of the middle point. In this case, the scanning line has a bend. In this case, an image is not faithfully reproduced, and it is also required to evaluate whether or not the scanning line has a bend.

Conventionally, for example, the configuration shown in FIG. 1 is known for evaluating the characteristics of a light beam in the main scanning direction (see Japanese Patent Application Laid-Open No. 5-284293).

In FIG. 1, reference numeral 1 denotes a writing unit (optical unit). Inside the writing unit 1, a beam light source (laser light source) composed of a semiconductor laser 2, a polygon mirror (rotating polygon mirror) 3, and an fθ lens 4 are provided. The semiconductor laser 2 is modulated and driven by the optical analog modulator 5. Optical analog modulator 5
Modulates the intensity of the laser light emitted from the semiconductor laser 2 according to the original image. The laser light emitted from the semiconductor laser 2 is scanned and deflected by the rotation of the polygon mirror 3.

A pair of photoelectric conversion elements 7a and 7b are provided on the surface to be scanned 6 corresponding to the surface of the photosensitive drum provided in the image forming unit at intervals in the main scanning direction. Immediately before the photoelectric conversion elements 7a and 7b, light-shielding plates 8a and 8b having pinholes (round small holes) are provided to enhance the light receiving position accuracy (writing position accuracy). Let L be the distance between this pair of pinholes.

When the light beam P1 is scanned in the main scanning direction Q1 by rotating the polygon mirror 3 while the semiconductor laser 2 is constantly turned on during one scanning period, the photoelectric conversion element 7
After a receives the light beam P1, the photoelectric conversion element 7b receives the light beam P1.
The actual scanning speed of the light beam P1 of the writing unit 1 can be calculated and obtained. If the actually measured scanning speed of the light beam P1 is too fast or too slow with respect to the designed scanning speed designed by the design, the writing reference position is shifted.

Therefore, it is evaluated whether the actually measured scanning speed of the light beam is within the allowable error of the designed scanning speed, and when the actual scanning speed exceeds the allowable error, the scanning speed of the writing unit is adjusted to the allowable error. The rotation speed and the like of the polygon mirror 3 are adjusted so as to fall within the range.

In this conventional light beam characteristic evaluation device, the write position itself cannot be directly obtained, and if the write position is to be obtained, the output position is output from the photoelectric conversion element 7a and then the output position is output from the photoelectric conversion element 7b. The time until the signal is output is obtained, the distance L is divided by this time to obtain the actual scanning speed, and an operation for converting this scanning speed into the writing position is required. The calculation procedure becomes complicated. In addition, the evaluation characteristics of the light beam to be evaluated are limited.

Next, when the beam diameter of the light beam P1 on the surface of the photosensitive drum deviates from the design value planned in the design, the edge of the image formed on the transfer paper is blurred,
There is a disadvantage that the image quality is deteriorated due to the occurrence of scanning lines. Therefore, it is also required to evaluate the beam diameter or the beam shape of the light beam on the surface to be scanned.

Conventionally, the beam diameter of a light beam is evaluated by providing a pinhole or a slit at a position corresponding to the surface of the photosensitive drum, and providing a light-receiving element immediately after the pinhole or slit, and measuring the beam diameter of the light beam in a stationary state. A device for measuring is known. However, this conventional beam diameter measuring method cannot measure the beam diameter in the scanning state.

In order to measure the beam diameter in the scanning state, as shown in FIG. 2, a one-dimensional CCD 9 is provided on a surface 6 to be scanned corresponding to the surface of the photosensitive drum. An objective lens 10 for forming an image of the light beam P1 on a surface corresponding to the surface to be scanned is provided in the optical path of the light beam P1 traveling in the direction of the arrow, and the beam spot S of the light beam P is moved in the direction of arrow Q1 along the main scanning direction. While moving, the one-dimensional CCD 9 is driven and scanned n times in the direction of arrow Q2 to accumulate and store one scan of the light amount signal of each pixel C1 to Cn, and calculate the signal from this storage circuit. An evaluation method and a light beam diameter evaluation apparatus for calculating a light beam diameter by using the method have been proposed (see Japanese Patent Application Laid-Open No. 4-351928).

In the conventional evaluation method, when the one-dimensional CCD 9 is driven and scanned once in the direction of the arrow Q2, and then the one-dimensional CCD 9 is driven and scanned again in the direction of the arrow Q2, the one-dimensional CCD 9 is scanned for one scanning period. Since the time elapses by t1, the light beam P1 moves in the main scanning direction (the direction of the arrow Q1) during this one scanning period t1. Therefore, this evaluation method is equivalent to a configuration in which the beam spot S is stationary and n one-dimensional CCDs 9 are arranged at equal intervals as schematically shown in FIG.

In this evaluation method, as is apparent from FIG. 3, the light beam P is emitted during one scanning period t1 of the one-dimensional CCD 9.
Numeral 1 moves in the main scanning direction, and the beam spot S is taken into the one-dimensional CCD 9 in a state of being thinned out. Further, a certain pixel Ci of the one-dimensional CCD 9 is driven and scanned, the pixel information thereof is read, and then a pixel C adjacent thereto is read.
Since the light beam P1 moves in the main scanning direction (the direction of the arrow Q1) even during the driving scanning time Δt from the time of driving scanning of i + 1 to reading the pixel information, the one-dimensional CCD 9 is moved with respect to the light beam P1. This is equivalent to capturing the image of the beam spot S by driving and scanning obliquely, and an error is likely to occur when the beam diameter is quantized. The evaluation error at the time of quantization of the beam diameter increases as the scanning speed of the light beam P1 increases.

Therefore, the conventional method of evaluating the light beam characteristics (the method of evaluating the beam diameter of the light beam) still has a problem that it is difficult to improve the evaluation accuracy of the beam diameter.

As described above, the characteristics required for the light beam include a writing position characteristic on the surface of the photosensitive drum, a pitch unevenness in the main scanning direction, a pitch unevenness in the sub-scanning direction, a pitch between beams, a magnification error, and a left-right balance. There are various types such as (magnification error deviation), scanning line bending, light beam diameter, and beam shape. Conventionally, each of these beam characteristics has been performed using a dedicated evaluation device. However, there is a concern that the reliability of the evaluation is slightly unsatisfactory because the evaluation is not comprehensive and is not performed under the same conditions.

Further, with respect to the method of evaluating the beam spot diameter or the beam spot shape, there is a demand for further improving the evaluation accuracy of the beam spot diameter or the beam spot shape in the scanning state.

In addition, in order to perform these evaluations, a reference position is required.

For example, Japanese Patent Application Laid-Open No. 8-86616 discloses that a laser head that generates a cross-slit light for a three-dimensional shape measurement object can be rotated about the intersection of the cross-slit and can be translated in the vertical and horizontal directions. Laser head mount and CC for imaging the measurement target
There is disclosed a three-dimensional image measurement apparatus including a D camera, and a computer including an image processing unit that processes an image signal captured by the CCD camera and a laser head operation control unit. In the device, CC
The center of the lens of the D camera and the center of the tip of the laser head are located on the X-axis of the three-dimensional absolute coordinate system, and the imaging surface of the CCD camera is arranged to be parallel to the XY plane.

In this image measuring device, the position of the area type CCD of the CCD camera is only adjusted by adjusting the area type CCD to a specific position in accordance with the imaging position of the area type CCD. However, there is a problem in that the deviation between the reference pixel and the position of the laser beam cannot be accurately grasped.

An object of the present invention is to provide a light beam characteristic evaluation apparatus capable of evaluating various characteristics required for a light beam by a single device.

[0030]

According to a first aspect of the present invention, in order to solve the above-described problems, a beam light source used for linearly scanning a surface to be scanned is scanned by a scanning method corresponding to one dot during scanning. The characteristic required for the light beam is evaluated by turning on the light for a time.

According to a second aspect of the present invention, in order to solve the above-mentioned problem, at least two light beam detecting means provided at a predetermined distance in the scanning direction of the surface to be scanned are provided, and the surface to be scanned is linearly moved. By turning on a beam light source used for scanning during a scanning time corresponding to one dot during scanning, a light beam is irradiated on a light beam detecting means on a scanning start side, and a scanning speed and a scanning speed designed in advance are designed. By turning on the beam light source again during the scanning time corresponding to the one dot after the elapse of the light-off time calculated by the predetermined distance, the light beam is irradiated on the light beam detecting means on the scanning end side, and each light beam is irradiated. The scanning characteristic required for the light beam is evaluated based on the detection result of the beam detecting means.

According to a third aspect of the present invention, in the light beam characteristic evaluation method according to the second aspect, the beam light source is a semiconductor laser, the light beam detecting means is an area type solid-state imaging device, The scanning characteristic is evaluated by calculating a deviation between a position of the beam on the imaging surface of the solid-state imaging device and a reference position designed in advance.

According to a fourth aspect of the present invention, in the light beam characteristic evaluation method according to the third aspect, the scanning time and the extinguishing time are defined based on a clock signal generated by a clock oscillator, and The light source is turned on until the number of clocks corresponding to one dot is counted, and is turned off until the number of clocks corresponding to the turn-off time is counted.

According to a fifth aspect of the present invention, there is provided a lighting control circuit capable of lighting a beam light source used for scanning a surface to be scanned during a scanning period corresponding to one dot during scanning, and Light beam detection means provided on a scanning surface and detecting a light beam emitted from the beam light source; and evaluation processing means for evaluating characteristics required for the light beam based on a detection result of the light beam detection means. It is characterized by having.

According to a sixth aspect of the present invention, in the light beam characteristic evaluation apparatus according to the fifth aspect, the beam light source is incorporated in a writing unit having a scanning optical system, and the light beam detecting means is an area type solid-state. An imaging device, wherein the evaluation processing means calculates a writing position as a characteristic required for the light beam based on a detection result of the area solid-state imaging device.

According to a seventh aspect of the present invention, in the light beam characteristic evaluation apparatus according to the sixth aspect, at least two area type solid-state image pickup devices are provided at a predetermined distance in the main scanning direction, and the design is improved. Calculating means for calculating an extinguishing time based on the scheduled scanning speed and the predetermined distance, and irradiating the light beam to the light beam detecting means on the scanning start side, and then extinguishing the beam light source during the extinguishing time. And
By turning on the beam light source again during the scanning time corresponding to the one dot after the lapse of the light-off time, the light beam is irradiated to the light beam detecting means on the scanning end side, and the detection result of each light beam detecting means is obtained. The scanning characteristic required for the light beam is evaluated based on the characteristic.

According to an eighth aspect of the present invention, a laser light source provided in a writing unit having a scanning optical system and used for scanning a surface to be scanned is turned on during a scanning period corresponding to one dot during scanning. Lighting control circuit capable of, and an area-type solid-state imaging device provided on the surface to be scanned and detecting a light beam emitted from the laser light source,
Evaluation processing means for evaluating a writing position as a characteristic required for the light beam based on a detection result of the area-type solid-state imaging device.

According to a ninth aspect of the present invention, in the light beam characteristic evaluation apparatus according to the eighth aspect, two area type solid-state imaging devices are provided at a predetermined designed distance in the main scanning direction. The laser light source is turned on and off during a scanning period corresponding to one dot toward the area-type solid-state imaging device on the scanning start side, and is turned off. The laser light source is calculated based on a designed scanning speed and the predetermined distance. Is turned on again during the scanning period corresponding to one dot after the extinction time has elapsed,
The evaluation processing means compares a distance from a writing position detected by the area-type solid-state imaging device on the scanning start side to a writing position detected by the area-type solid-state imaging device on the scanning end side with the predetermined distance to determine a magnification error. Is calculated.

According to a tenth aspect of the present invention, in the light beam characteristic evaluation device according to the eighth aspect, three area type solid-state imaging devices are provided at intervals in the main scanning direction.
One of the area solid-state imaging devices is provided at the center position, one of the remaining area solid-state imaging devices is provided at the scanning start side, and the other of the remaining area solid-state imaging devices is provided at the scanning end side. The distance between the area-type solid-state imaging device at the center position and the two-area solid-state imaging device is equal, and the laser light source is directed toward the scanning-start-side area-type solid-state imaging device during a scanning period corresponding to one dot. After the light is turned on, the light is turned off, and after the elapse of the light-off time calculated by the scanning speed and the distance that are designed in advance, the light is turned on again during the scanning period corresponding to one dot toward the remaining area-type solid-state imaging device. The evaluation processing means includes a distance from a writing position detected by the area-type solid-state imaging device on the scanning start side to a writing position detected by the central area-type solid-state imaging device; By comparing the distance from the writing position detected by the rear solid-state imaging device to the writing position detected by the area-type solid-state imaging device on the scanning end side, evaluating the left and right image balance as the scanning characteristics. It is characterized by.

According to an eleventh aspect of the present invention, in the light beam characteristic evaluation device according to the ninth or tenth aspect, a clock pulse oscillator for defining a scan time corresponding to the one dot and the extinguishing time. Wherein the laser light source is turned on until the number of clocks corresponding to one dot is counted, and is turned off until the number of clocks corresponding to the turn-off time is counted.

According to a twelfth aspect of the present invention, in the light beam characteristic evaluation apparatus according to the eleventh aspect, there is provided a calculating means for calculating the turn-off time based on the scanning speed and the distance that are designed and planned. It is characterized by being.

According to a thirteenth aspect of the present invention, in the light beam characteristic evaluation apparatus of the eleventh aspect, the writing unit is provided with a synchronization sensor for determining a writing timing on both sides in the main scanning direction, and The light source is continuously turned on until the synchronization sensor on the scanning start side is detected, and is turned off once for lighting one dot after the light beam is detected by the synchronization sensor on the scanning start side. .

According to a fourteenth aspect of the present invention, in the light beam characteristic evaluation apparatus according to the eleventh aspect, two laser light sources are provided, and writing on the surface to be scanned can be performed by two light beams. There is a feature.

According to a fifteenth aspect of the present invention, in the light beam characteristic evaluation device according to the fourteenth aspect, the evaluation processing means includes a light emitted from one of the laser light sources and received by the area type solid-state imaging device. The beam pitch is calculated based on the light receiving position of the beam and the light receiving position of the light beam emitted from the other laser light source and received by the area-type solid-state imaging device. It is characterized in that the degree of parallelism of two light beams is evaluated by opening and obtaining at least two points.

According to a sixteenth aspect of the present invention, in the light beam characteristic evaluation apparatus according to the tenth aspect, the evaluation processing means calculates a beam center in the sub-scanning direction of each of the area type solid-state imaging devices. The scanning line bending of the light beam is evaluated based on the center.

According to a seventeenth aspect of the present invention, in the light beam characteristic evaluation apparatus according to the eighth aspect, the writing unit includes a synchronous sensor for determining a writing timing on a scanning start side, and the area type solid-state imaging device. The device is movable in the main scanning direction, and the lighting control circuit is controlled to turn on the laser light source by one dot after a light-off time related to a distance from the synchronous sensor to the area type solid-state imaging device has elapsed. It is characterized by that.

According to an eighteenth aspect of the present invention, in the light beam characteristic evaluation apparatus according to the seventeenth aspect, the extinguishing time is calculated based on the distance and a theoretically planned scanning speed. .

[0048]

FIG. 4 shows a light beam light source (laser light source) to be evaluated by the light beam characteristic evaluation method of the present invention.
FIG. 2 is a perspective view showing an example of a positional relationship between a writing unit on which the image forming apparatus is mounted and a photosensitive drum as a latent image carrier on which a light beam emitted from the writing unit is written.

In FIG. 4, 11 and 12 are laser diodes (semiconductor lasers), 13 and 14 are collimating lenses, 15 is an optical member for synthesizing an optical path, 16 is a 1/4 wavelength plate, and 17 and 18 are beam shaping optical systems. It is. These optical elements 11 to 18 constitute a laser light source unit (beam light source) Sou. The laser light source section Sou
Are collimated by the collimator lenses P1 and P2, and are guided to a polygon mirror 19 which forms a part of a scanning optical system. Each of the surfaces 20a to 20f of the polygon mirror 19 In the main scanning direction Q
It is reflected and deflected to 1.

The reflected and deflected light beam is guided to reflection mirrors 21 and 22 constituting a part of the fθ optical system, and the light beam reflected and deflected by the reflection mirror 22 passes through the fθ optical system 23 and is obliquely reflected. And is guided to the surface 26 of the photosensitive drum 25 as a latent image carrier by the oblique reflection mirror 24. The surface 26 of the photosensitive drum 25 is linearly scanned by the light beam P1 in the main scanning direction Q1. This surface 26 is the surface to be scanned by the light beam P1, and writing is performed on this surface to be scanned.

The laser light source Sou, the polygon mirror 19, the reflection mirrors 21 and 22, the fθ lens 23, and the reflection mirror 24 are mounted on the writing unit 1, and the photosensitive drum 25 is mounted on the image forming unit (described later). I have.

The writing unit 1 has a reflection mirror 24
Are provided on both sides in the longitudinal direction (main scanning direction Q1 of the light beam). The synchronous sensor 27 is used to determine the write start timing, and the synchronous sensor 2
8 is used to determine the write end timing.

The characteristics of the light beam P1 emitted from the writing unit 1 are to be evaluated. In FIG. 4, the writing on the surface 26 of the photosensitive drum 25 is performed using two scanning lines. However, the principle of the evaluation of the light beam characteristics is as follows. Since there is essentially no difference from the case of the single laser diode, the characteristics evaluation items of the light beam according to the present invention will be described with reference to Table 1 while referring to Table 1 for the case of one laser diode. .

[0054]

[Table 1] As shown in Table 1, the light beam characteristic evaluation items include a: a writing position in the main scanning direction, b: a writing position in the sub-scanning direction, c: unevenness in the main scanning pitch, d: sub-scanning surface inclination, and e: main scanning. Beam diameter, f: sub-scanning beam diameter, g: magnification error,
h: scanning line inclination, i: magnification error deviation, j: scanning line bending, k: scanning time, l: depth: m: pitch between beams (in the case of a writing unit capable of simultaneously irradiating a plurality of light beams) (See USAP 96-675722): In the embodiment of the invention of this patent application, since the arrangement direction of the laser diodes 11 and 12 (also referred to as LD) is two along the sub-scanning direction, the pitch between beams is The scanning direction.).

The details of each evaluation item will be described below.

A: Evaluation of writing position in the main scanning direction The light beam emitted from the LD is reflected by the polygon mirror 19 and is irradiated on the photosensitive member through the fθ lens optical system. The position or timing in the main scanning direction at which writing is started is evaluated.

For example, as shown in FIG. 19A, assuming that a predetermined write position center (write timing) is “0” and a position written to an area type image sensor described later is zz, the write position center is 0. And writing position zz
Are shifted by Δx in the main scanning direction. This shift amount Δx is evaluated.

B: Evaluation of the writing position in the sub-scanning direction The light beam emitted from the LD is reflected by the polygon mirror 19 and is irradiated on the photosensitive member through the fθ lens optical system. The position or timing in the sub-scanning direction at which writing is started is evaluated.

For example, as shown in FIG. 19B, assuming that a predetermined write position center (write timing) is “0” and a position written to an area type image sensor described later is zz, the write position center is 0. And writing position zz
Are shifted by Δy in the sub-scanning direction. The deviation Δy is evaluated.

C: Evaluation of Main Scanning Pitch Unevenness By writing a light beam many times in the main scanning direction, a desired image is formed. , Six mirror surfaces) are formed, and since the light beam is reflected by each mirror surface to perform writing, the writing position (writing position) by the light beam may change depending on the accuracy of each mirror surface.

Therefore, the light beam is reflected by each surface of the polygon mirror 19, and the variation of the center position in the main scanning direction of the beam spot S corresponding to each surface is evaluated.

For example, if there are six mirror surfaces, each surface 20
The light beam is reflected by a to 20f and a CCD described later
Capture to camera. It is assumed that the position written in the area type imaging device of the CCD camera is as shown in FIG.

Further, with respect to the reference center position “0”, the center position of writing on each surface is kz1, kz2, kz3,
kz4, kz5, and kz6, and the shift amount in the main scanning direction is △
It is assumed that x1, Δx2, and Δx3.

In this case, when the average value Δx of the variation in the main scanning direction of each surface is obtained, Δx = (2 △ x1 + 2 △ x2 + 2 △ x3) / 6. It can be evaluated whether there is a degree of pitch unevenness.

Here, the reference center position “0” is used to evaluate this variation, but one of the center positions of each beam spot S reflected by each surface is used as a reference position to perform main scanning. The pitch unevenness may be evaluated.

For example, the center position of the beam spot S taken first may be used as a reference, or the difference between the center positions of the beam spots S may be determined, and the center position of the beam spot S with the least error may be used as the reference position. Alternatively, the beam spot S having the highest coincidence rate may be used as a reference.

D: Evaluation of sub-scanning plane tilt A desired image is formed by writing a light beam many times along the main scanning direction. , Six mirror surfaces) are formed, and since the light beam is reflected by each mirror surface to perform writing, the writing position (writing position) by the light beam may change depending on the accuracy of each mirror surface.

Therefore, the light beam is reflected on each surface of the polygon mirror 19, and the variation of the center position in the main scanning direction of the beam spot S corresponding to each surface is evaluated.

For example, if there are six mirror surfaces, each surface 20
The light beam is reflected by a to 20f and a CCD described later
Capture to camera. It is assumed that the position written in the area type image sensor of the CCD camera is as shown in FIG.

Further, with respect to the reference center position “0”, the center position of writing on each surface is kz1, kz2, kz3,
kz4, kz5, and kz6, and the shift amount in the sub-scanning direction is △
It is assumed that y1, △ y2, and △ y3.

In this case, when the average value Δy of the variation in the sub-scanning direction of each surface is obtained, Δy = (2 △ y1 + 2 △ y2 + 2 △ y3) / 6. It can be evaluated whether there is a degree of pitch unevenness.

Here, the reference center position “0” is used to evaluate this variation, but any one of the center positions of the beam spots S reflected by each surface is used as a reference position to perform sub-scanning. You may evaluate the trouble.

For example, the center position of the beam spot S taken first may be used as a reference, or the difference between the center positions of the beam spots S is obtained, and the center position of the beam spot S with the least error is used as the reference position. Alternatively, the beam spot S having the highest coincidence rate may be used as a reference.

E: Evaluation of Main Scanning Beam Diameter The beam diameter of the light beam spot S in the main scanning direction is evaluated.

F: Evaluation of sub-scanning beam diameter The beam diameter of the light beam spot S in the sub-scanning direction is evaluated.

G: Evaluation of magnification error It is evaluated whether or not the interval between the two beam spots S is a predetermined interval. That is, the magnification is evaluated depending on whether the interval is shorter or longer than a predetermined interval.

For example, as shown in FIG. 19 (e), the distance L4 between the design reference planned writing reference positions Z1 and Z2 on the transfer paper corresponding to two points on the original in the main scanning direction Q1 is actually measured. The magnification error can be evaluated by determining the ratio of the writing positions Z1 and Z1 'on the surface to be scanned obtained by the above to the distance L5.

H: Evaluation of scanning line inclination When a light beam is scanned in the main scanning direction, one scanning line is obtained. It is evaluated whether or not this scanning line is parallel to the main scanning direction.

For example, as shown in FIG. 19F, the deviation d0 in the sub-scanning direction Q3 of the writing position Z1 'obtained by the measurement on the main scanning start side and the deviation d0 in the main scanning direction are obtained by measurement. The inclination angle θ of the scanning line and the total deviation Δd are evaluated based on the difference between the deviation of the writing position Z2 ′ in the sub-scanning direction Q3 and the distance L6.

I: Evaluation of Magnification Error Deviation In item g, the magnification error was evaluated by evaluating the writing positions of the two beam spots S. However, by incorporating three or more beam spots S into the area type image sensor, Then, the magnification of each spot is compared, and the deviation of each interval is evaluated.

For example, as shown in FIG. 19 (g), the distance L from the middle writing position Zm ′ obtained by measurement to the writing position Z1 ′ on the writing start side in the main scanning direction.
7 and the distance L8 from the middle writing position Zm 'to the writing position Z2' on the writing end side in the main scanning direction, the magnification error deviation (left-right balance) can be evaluated.

J: Evaluation of scanning line bending In item h, it was evaluated whether or not the light beam was scanned in parallel in the main scanning direction based on the writing positions of the two beam spots S. Is taken into an area-type imaging device, and the inclination between the respective beam spots with respect to the main scanning direction is evaluated to evaluate the scanning line bending.

For example, as shown in FIG. 19H, the deviation d2 in the sub-scanning direction Q3 of the writing position Z1 'on the writing start side obtained by measurement and the middle writing position Zm' obtained by measurement. In the sub-scanning direction Q3
4 and the deviation d3 in the sub-scanning direction Q3 of the writing position Z2 'on the writing end side obtained by the measurement,
Evaluate scan line bending.

K: Evaluation of scanning time The scanning time of the light beam was determined by using two CCD cameras.
The scanning time can be calculated by counting the time from when the beam spot is taken into one CCD camera to when the beam spot is taken into the other CCD camera, and the distance between the two CCD cameras can be calculated. Is divided by the scanning time to determine the scanning speed.

In this case, one of the CCD cameras may be replaced by a synchronization sensor (scan start detection sensor, scan end detection sensor) provided in the writing unit 1 for synchronization detection. Details will be described later.

L: Depth evaluation A state in which the light beam is fixed in the main scanning direction by moving the CCD camera in a direction perpendicular to the main scanning direction (the same direction as the optical axis of the light beam emitted to the CCD camera). Then, the beam diameter in the moving direction of the light beam is measured, and the depth at the design position is evaluated.

For example, when the CCD camera is sequentially moved at equal intervals in the direction of travel of the light beam and stopped, and the beam diameter D of the beam spot S at each stop position is sequentially obtained.
A beam diameter curve (depth curve) Qm shown in (i) can be obtained. Bw is the beam waist.

As a result, the depth of the light beam can be evaluated.

M: Evaluation of pitch between beams The pitch between a plurality of beams irradiated simultaneously is evaluated.

For example, as shown in FIG. 19 (j), the center positions KK and KK 'of two beam spots S received by one area type image pickup device are obtained, and the interval ΔKK in the sub-scanning direction is obtained. By calculating, the pitch interval ΔKK between the two beams can be evaluated.

The light beam characteristic evaluation apparatus shown in FIG. 5 can evaluate all the evaluation items a to k and m except for the evaluation item l: depth evaluation.

[0092]

[Embodiment 1 of the evaluation apparatus] Next, an embodiment of the evaluation apparatus is shown in FIG.
This will be described with reference to FIG.

In FIG. 5, 29 is a pulse motor for driving the polygon mirror, and 30 is a drive control circuit for controlling the drive of the pulse motor. Surface 2 of photoconductor drum 25
The area-type image pickup devices (image pickup planes) 32a to 34a of the CCD cameras 32 to 34 as light beam detection means are provided on the surface 31 to be scanned corresponding to 6 from the scanning start side of the light beam P1 to the scanning end side. They are provided at equal intervals toward each other.

That is, the CCD cameras 32 to 34 are image forming apparatuses (such as copying machines) on which the writing unit is mounted.
A light beam irradiation member (latent image carrier) to which a light beam emitted from the writing unit is irradiated is provided at a light irradiation start position (light irradiation start position of a sheet maximum size), a light irradiation end position, and an intermediate position; The position to be actually used can be evaluated.

The lighting of the laser diode 11 or 12 is controlled by a one-dot lighting control circuit 35. The one-dot lighting control circuit 35 includes a clock pulse oscillator 36 that oscillates a clock pulse for clocking a time and a count circuit 37 that counts the clock pulse. The one-dot lighting control circuit 37 receives a synchronization pulse from the synchronization sensor 27.

The one-dot lighting control circuit 35 and the drive control circuit 30 are controlled by a control circuit 38 comprising a personal computer. The control circuit 38 is provided with an input board 39 for image processing. Here, the input board 39 has three input systems, for example,
An image processing board having R, G, and B input systems is used.

The area type image sensor 32a is provided at the start side in the main scanning direction, the area type image sensor 34a is provided at the end side in the main scanning direction, the area type image sensor 33a is provided at the center position in the main scanning direction, and Type image sensor 32a-34
The image output of a is taken into the control circuit 38 through the input board 39. The control circuit 38 has a calculation circuit 40 as calculation means and an evaluation processing circuit 41.

A reference pixel K as a coordinate origin of the arithmetic processing is set as shown in FIG. 6 from among the pixels of each of the area type image sensors 32a to 34a. The reference pixel K corresponds to a reference writing position designed in design. The setting of the reference pixel K will be described later. Here, it is assumed that the distance L1 from the reference pixel K to the reference pixel K is set. It is also assumed that an ideal image (beam spot S) to be drawn on the surface to be scanned is designed as shown in FIG. Symbol R1 is the beam diameter of the ideal beam spot S.

The control circuit 38 is calibrated "0" so that the reference pixel K is at the origin position. The calculation circuit 40
FIG. 8 shows the relationship between the distance L1 and the scanning speed that has been designed.
As shown in (1), the scanning time T between the area-type image sensors is calculated, and the scanning time t corresponding to one dot is calculated from the scanning time T and the diameter R1 in the scanning direction of the beam spot S designed and designed. calculate. Signals representing the scanning times T and t are input to the count circuit 37 of the one-dot lighting control circuit 35.

The scanning time T and the one-dot scanning time t are defined by the number of clock pulses output from the clock oscillator 36. The one-dot lighting control circuit 35 controls the counting circuit 37 from the time when the laser diode 11 or 12 is turned off. When the number of clocks corresponding to the scanning time T is counted, the laser diode 11 or 12 in the off state is controlled to be turned on, and the count circuit 37 determines the number of clocks corresponding to the scanning time t from the time when the laser diode 11 or 12 is turned on. After counting, the laser diode 11 or 12 is controlled to be turned off. In this sense, the scanning time T defines the turn-off time (write timing time) of the laser diode 11 or 12.

The laser diode 11 or 12 is controlled by the one-dot lighting control circuit 35 to be continuously turned on until the synchronization pulse from the synchronization sensor 27 is input, and the synchronization pulse from the synchronization sensor 27 is input. Is turned off by the one-dot lighting control circuit 35, and after the scanning time T elapses, the light is turned on by the one-dot control circuit 35 for the scanning time t corresponding to one dot, and then turned off until the scanning time T elapses again. When the scanning time T elapses, the light is turned on again for the scanning time t corresponding to one dot and then turned off. Then, the one-dot lighting control circuit 35
Is turned on again after the return time (about 2T) to the scanning start side has elapsed when the synchronization pulse of the synchronization sensor 28 is input.

In FIG. 8, black circles indicate the formation state of the beam spot S corresponding to one dot (the lighting state of the laser diode 11 or 12), and white circles indicate the non-formation state of the beam spot S corresponding to one dot. (Light-off state of the laser diode 11 or 12).

As described above, when the laser diode 11 or 12 is turned on during the scanning time corresponding to one dot by the one-dot lighting control circuit 35 during scanning, as shown in FIG. 9, each of the area type image sensors 32a to 34a A beam spot S is formed.

Using the evaluation processing circuit 41, the main scanning direction Q1
By obtaining the center positions O1, O2, and O3 of the beam spot S, the shift amount d in the main scanning direction with respect to the reference pixel K can be obtained. In FIG. 9, as an example, the reference position on the writing start side is shifted to the right by d = X1, the reference position on the writing end side is shifted to the left by d = X3, and the shift amount d = X2 = 0 at the center position. It is shown that

Also, using the evaluation processing circuit 41, the center positions O1 ', O2',
If O3 'is obtained, the sub-scanning direction Q3
Can be obtained. In FIG. 9, the shift amount d 'in the sub-scanning direction is d' = 0.

In FIG. 8, the distance L1 from the area-type image sensor 32a on the main scanning start side to the area-type image sensor 33a at the center and the area-type image sensor 33a at the center from the area-type image sensor 34a on the scan end side. The description has been made assuming that the distance L1 is equal to the distance, but the present invention is not limited to this.

[0107]

Second Embodiment of Evaluation Apparatus FIG. 10 shows a second embodiment of this evaluation apparatus. In this embodiment, a single image processing board is used as an input board 39, and two writing circuits designed in design are used. This is to evaluate the deviation from the reference book position. In this evaluation device, an input board changeover switch 43 is provided, and the 1-dot lighting control circuit 35 operates so that the image is fetched from the area type imager 34a at the same time as the image is fetched from the area type imager 32a. Switch. Other configurations are the same as those of the evaluation device shown in FIG. 8, and therefore, the same reference numerals are given and the detailed description thereof will be omitted. FIG.
Numeral 1 indicates the control timing of the one-dot lighting control circuit 35, and the scanning time (light-off time) T is obtained by dividing the distance L2 by a scanning speed designed in advance.

In this light beam characteristic evaluation apparatus, since two CCD cameras are provided at an interval in the main scanning direction, evaluation items a to h and evaluation items k and m can be evaluated. Of course, if the number of CCD cameras is three as in the embodiment of the invention shown in FIG.
Evaluation of k and m is possible.

[0109]

Third Embodiment of Evaluation Apparatus FIG. 12 shows a third embodiment of this evaluation apparatus. In this embodiment, a single image processing board is used as the input board 39, and one writing standard designed in design is used. This is to evaluate the deviation from the writing position.

Here, the number of the CCD camera 43 is one, and the CCD camera 43 is mounted on a movable body 45 installed on a guide shaft 44 extending long in the main scanning direction. The movable body 45 is controlled by the control circuit 38 to reciprocate along the guide shaft 44, and the CCD camera 43 is set at a desired writing reference position.

That is, by moving the CCD camera 43 in the main scanning direction, the evaluation item a
F, k, and m can be evaluated. In addition, by setting the moving position of the CCD camera 43 to the same position as that of the evaluation device shown in FIGS. 5 and 10, the evaluation of items a to k and m can be performed in the same manner.

The distance from the synchronous sensor 27 to the set position of the CCD camera 43 is defined as L3. If the distance L3 is divided by the writing speed that is designed in advance, the reference pixel of the area image sensor 43a of the CCD camera 43 can be obtained from the synchronous sensor 27. K
The scanning time T (see FIG. 13) required until this can be obtained.

Therefore, the laser light source unit Sou is turned off during the period from the detection of the synchronization pulse by the synchronization sensor 27 to the scanning time T, and the one-dot lighting control circuit 35 switches the laser light source unit Sou off when the scanning time T elapses. If the light is turned on during the scanning time t, the laser spot S corresponding to one dot can be imaged on the area type imaging device 43a of the CCD camera 43 during the scanning as shown in FIG.

The center position of the beam spot S of each of the above evaluation devices is obtained as follows.

Each pixel of the area type image pickup device 43a is Zij
Defined by Z1j, Z2j, ..., Zij,
, ..., Znj mean pixels arranged in the main scanning direction Q1, Zi1, Zi2, ..., Zij, ..., Zim mean pixels arranged in the sub-scanning direction Q3, and reference numerals i (1 to n)
) Means the i-th counting from the left, and the code j
(An integer from 1 to m) means the j-th counting from the bottom.

Therefore, the total sum Wj (Wj = Z1j + Z2j +) of the output signals output from the pixels Z1j, Z2j,..., Zij,..., Znj arranged in the main scanning direction Q1.
.. + Zij +... + Znj) in the sub-scanning direction Q3.
= 1 to j = m, a light beam intensity distribution curve B1 in the sub-scanning direction Q3 can be obtained as shown in FIG. The total sum Wi (Wi = Zi1 + Zi2 +...) Of the output signals output from the pixels Zi1, Zi2,..., Zij,.
+ Zij +... + Zim) in the main scanning direction Q1.
When sequentially obtained from 1 to i = n, a light beam intensity distribution curve B2 in the main scanning direction Q1 can be obtained as shown in FIG.

FIG. 16 shows an example of the light beam intensity distribution curve obtained in this way, and shows a beam intensity distribution curve B2 in the main scanning direction Q1.

The evaluation processing circuit 41 sets a threshold value P1h for the beam intensity distribution curve B2, and addresses X of the pixels in the main scanning direction Q1 corresponding to the intensity crossing the threshold value P1h.
1, X2 are specified, and the address Xim of the pixel corresponding to the average value of the sum of the addresses X1 and X2 is obtained. Thus, the center position O1 of the light beam P1 in the main scanning direction Q1 is obtained. The shift amount d in the main scanning direction Q1 is obtained from the difference between the center position O1 and the reference pixel K. By performing the same processing on the beam intensity distribution curve B1, the center position O1 'in the sub-scanning direction Q3 is obtained, and the shift amount d' is also obtained from the difference between the center position O1 'and the reference pixel K.

The beam diameter D in the main scanning direction Q1 is obtained by calculating the difference D between the addresses X1 and X2, and the same processing is performed on the beam intensity distribution curve B1 to obtain the beam diameter D in the sub-scanning direction Q3. The diameter D 'is also required.

Note that the threshold value P1h is equal to the peak P
It is set at a value equal to 1 / square of e (natural logarithm) from max.

Here, the sum Wj of the output signals output from the pixels Z1j, Z2j,..., Zij,. , Zij,..., Zim, the center positions O1 and O1 ′ of the light beam P1 are determined based on the total sum Wi of the output signals.
Beam intensity distribution curves B1, B2 from several pixels near max
And the peak of the beam intensity distribution curves B1 and B2 is determined as the center of the light beam P1, and the pixel corresponding to this peak may be set as the center pixel of the light beam P1.

Since the output of each pixel is quantized, the quantized output distribution of each pixel is three-dimensionally expressed, and the pixel corresponding to the position of the center of gravity is displayed in the main scanning direction Q.
1. The center positions O1, O of the light beam P1 in the sub-scanning direction Q3.
It may be 1 '.

Even if the CCD camera 43 is arranged at a reference writing position designed (designed at the image height 0 meaning the optical axis of the fθ optical system 23), the beam diameter is slightly different from the reference writing position. If the measurement is performed at a position deviated from the position, an accurate beam shape cannot be obtained. Therefore, based on the deviation d, the scanning time T shown in FIG. It can also be turned on.

[0124]

Fourth Embodiment of Evaluation Apparatus FIG. 17 shows a fourth embodiment of this evaluation apparatus. A guide shaft 46 is provided in a depth direction (optical axis direction) Q4 orthogonal to the main scanning direction Q1. Along with the main scanning direction Q1 and reciprocally along the guide shaft 46 in the depth direction Q4. It is possible to evaluate the light beam characteristics at a desired writing reference position scheduled for the above.

In the fourth embodiment, the evaluation items a to k and m can be evaluated. In addition, since the CCD camera 43 is movable in the depth direction, the evaluation item l can be evaluated.

The means for moving the CCD camera 43 in the depth direction can also be mounted on the evaluation device shown in FIGS. 5, 10 and 12, and this moving means can be mounted on the evaluation device shown in FIGS. 5, 10 and 12. If installed in the device, the depth of the evaluation item 1 can be evaluated using the evaluation devices shown in FIGS. 5, 10, and 12.

Evaluation is made as follows for the traveling direction (depth direction) Q4 of the light beam.

That is, as shown in FIG.
The D camera 43 is attached to the movable body 45,
Is mounted on a guide shaft 44 extending in the depth direction Q4. The movable body 45 is sequentially moved at equal intervals in the depth direction Q4 of the light beam P1, and the light beam P at the movement stop position is moved.
When the beam diameter D (see FIGS. 14 and 16) of one beam spot S is sequentially obtained, a beam diameter curve (depth curve) Qm in the depth direction Q4 can be obtained as shown in FIG. 31B.

Although the beam diameter curve Qm is determined in the main scanning direction Q1 here,
A beam diameter curve may be obtained for No. 3.

The position of the beam waist Bw is evaluated from the beam diameter curve Qm, and the depth direction Q4
Is determined based on the reference writing position and the position of the beam waist Bw.

FIG. 18 is a flowchart showing an example of the control of the evaluation apparatus shown in FIG. 17, in which the control circuit 38 is first set to the initial state (S.1), and then the pulse motor 2 is set.
9 is started (S.2). Next, the control circuit 38
Outputs a signal to the one-dot lighting control circuit 35 to turn on the laser diode 11 or 12 (laser light source unit Sou) at the point in time when it is considered that the pulse motor 29 has reached the steady speed. (S.
3). On the other hand, the one-dot lighting control circuit 35 is a synchronous sensor 2
7 to detect whether or not a synchronization pulse has been input, and if no synchronization pulse is detected after a predetermined time has elapsed, an error occurrence signal is output to the control circuit 38 (S.4,
S. 5). When the error generation signal is input, the control circuit 38 sends a signal for turning off the laser diode 11 or 12 (laser light source unit Sou) to the one-dot lighting control circuit 3.
5 (S.6), and based on the error occurrence signal, the rotation of the pulse motor 29 is stopped (S.7), and it is determined whether or not the measurement is completed (S.8).

When a synchronization pulse is detected within a predetermined time, the one-dot lighting control circuit 35 turns off the laser diode 11 or 12 (laser light source unit Sou) at the same time as the detection of the synchronization pulse, and the counting circuit 37 sets the scanning time T to the scanning time T. When the number of clocks is counted, a lighting signal for turning on the laser diode 11 or 12 (laser light source unit Sou) by one dot is output (S.9). Control circuit 38
Obtains an image of the beam spot S by lighting this one dot (S.10). The evaluation processing circuit 41 performs an operation based on the image of the beam spot S actually obtained,
Each characteristic required for the light beam P1 is evaluated (S.1)
1). Then, monitor the evaluation result (not shown).
Alternatively, it is output to a recording means (not shown) (S.12).
Thereafter, the control circuit 38 controls the laser diode 11 or 1
A signal for turning off the laser light source unit (Sou) is output to the one-dot control circuit 35 and (S.
6) The driving of the pulse motor 29 is stopped. When repeating the measurement, 1 to S.N. The processing up to 12 is executed again.

The evaluation of the characteristics of the light beam is based on the light beam P1
By processing the center positions O1 and O1 ', the beam diameters D1 and D1', and the shift amounts d and d '.

By determining the ratio between the beam diameters D1 and D1 ', it is determined whether the shape of the light beam P1 is an ellipse long in the main scanning direction Q1, an ellipse close to a circle, or the sub-scanning direction Q3.
Can be evaluated as a long ellipse.

[0135]

[Specific Structure of Evaluation Devices 1-4] The following evaluation devices are currently being implemented.

The claims set forth this evaluation device as a protection range.

FIGS. 35 and 36 show how the writing unit 1 is attached to the image forming apparatus. Reference numeral 100 denotes a base of the image forming apparatus. 35, 36
The writing unit positioning member 101 is fixed as shown in FIG.

The writing unit 1 has the appearance shown in FIG. 37, and one side wall of the writing unit 1 has
Positioning projections 102 are provided, and positioning holes 103 are provided on the other side wall of the writing unit 1. The writing unit 1 has an elongated slit hole 104 extending in the main scanning direction, and a laser beam P1 is emitted from the elongated slit hole 104 'toward a photosensitive drum (not shown).

The writing unit positioning member 101 is
As shown in FIG. 36, FIG. 38, and FIG.
105. An insertion hole 106 is formed in the upright wall 104, and a positioning pin 107 is fixed to the upright wall 105. The outer wall 108 of the upright wall 105 serves as a positioning surface for positioning the writing unit 1 in the main scanning direction. Write unit positioning member 10
The leading end of 1 is a reference base attaching portion 109 as shown in FIG. This reference base mounting portion 109
Is provided with a reference base mounting pin 110.

The reference base mounting portion 110 has a structure shown in FIG.
The positioning reference base 111 shown in FIG. 0 (a) to FIG. 40 (d) is attached. This positioning reference base 11
Reference numeral 1 extends long in the main scanning direction. A positioning pin 112 and a positioning block mounting hole 113 are formed on the upper surface of the positioning reference base 111. At the lower part of the positioning reference base 111, a fitting hole 114 to be fitted to the reference base mounting pin 110 is formed.

The upper surface of the positioning reference base 111 is inclined. The upper surface of the positioning reference base 111 is
3a are formed at intervals in the longitudinal direction. A positioning block member 115 as an angle positioning determining member shown in FIG. 41 is attached to this upper surface. Here, as shown in FIGS. 42 (a) to 42 (d), the positioning block members 115 are
7. It has a flat plate portion 118. An LD holder plate 119 as a cylindrical holding member is attached to the upright plate portion 116. A circular fitting hole 120 is formed in the upright plate portion 116, and an engaging pin 121 is fixed thereto. An upright portion 117 of the CCD camera is formed on the upright plate portion 117. The contact portion 121 has a through hole 122 formed therein. The circular fitting hole 120 is precisely finished in a perfect circular shape.

A cylindrical boss 123 is formed on the LD holder plate 119 as shown in FIG. The outer shape of the cylindrical boss 123 is also precisely finished. The cylindrical boss 123 is fitted in the circular fitting hole 120.
FIG. 43 shows the disk portion 119a of the LD holder plate 119.
As shown in (b), laser diode positioning hole 1
24, a screw hole 125 for mounting a laser diode, and an engagement hole 126 for determining an angular position. Here, the engagement hole 126 for determining the angular position is formed by the cylindrical boss portion 123.
Are provided every 90 degrees.

As shown in FIG. 41, a reference laser diode (semiconductor laser) 127 as a reference position determining reference laser light source is mounted on the LD holder plate 119. A mounting base 128 is fixed to the base 100, a support base 129 is fixed to the mounting base 128, and a slide base 131 is slidably provided on the support base 129.
This slide base 131 has a CCD camera unit 1
30 are provided. The CCD camera unit 130 includes a mounting base 131 ′ and a CCD camera 132. An attaching plate 131'a is formed upright on the mounting base 131 '. Slide base 13
A micrometer 133 is attached to 1. The micrometer 133 is an imaging surface 130 of the area type imaging device.
It functions as adjusting means for adjusting so that a is positioned on the surface to be scanned corresponding to the surface to be scanned. The tip of the CCD camera unit 130 is applied to the application unit 121.

As shown in FIG. 35, a bent plate portion 134 is formed on the slide base 131, and an elongated hole 135 extending in the sliding direction is formed in the bent plate portion 134. The CCD camera unit 130 has an area type image pickup device 130a. Is adjusted in the sliding direction by the micrometer 133 so that the image pickup surface of the photosensitive drum is located on the surface to be scanned 31 corresponding to the surface of the photosensitive drum (surface to be scanned), and the bent plate portion 134 is tightened by the fixing screw 136. It is fixed to the support base 129.

Here, three CCD camera units 130 are provided at equal intervals in the longitudinal direction of the positioning reference base 111, and the interval is L10 as shown in FIG.
In FIG. 44, the left CCD camera unit 13
0 is provided at the write start position, the middle CCD camera unit 130 is provided at the write center position, and the right CCD camera unit 130 is provided at the write end position.

As described in the first embodiment of the present invention, the laser light source section Sou is provided inside the writing unit 1 and the scanning optical system is provided. The scanning surface of the photosensitive drum is linearly moved by the laser light source. Scanning and writing are performed.

The center of the circular fitting hole 120 coincides with the emission trajectory (emission light beam) Qn in the main scanning direction and the sub-scanning direction of the laser beam P1 designed in design as shown in FIG. The reference laser light emitted from the reference laser diode 127 is not always emitted along the emission trajectory Qn, and simply emitting the reference laser light simply causes the area type imaging existing on the extension of the emission trajectory Qn. Reference pixel K as reference position of element 130a
Cannot be specified using a reference laser beam.

Therefore, first, the reference laser diode 127 is made to face the CCD camera unit 130 on the writing start side. As shown in FIG. 45 (a), the LD holder plate 119 is fitted into the circular fitting hole 120, and the engaging pin 121 is fitted into one of the angular position determining engaging holes 126 of the LD holder plate 119. By rotating the LD holder plate 119 about the center of the circular fitting hole 120 as the center of rotation,
21 is an engagement hole 1 for determining an angular position of the LD holder plate 119.
The reference laser diode 127 is angularly positioned by bringing the peripheral wall 126a of the 26 into contact with the rotating direction.

Then, the reference laser diode 127 is turned on using a lighting control circuit not shown (the lighting control circuit of the writing unit 1 may be used). The emission direction of the laser beam at this time is Qm as shown in FIG.
Assume that it was a direction. It is also assumed that the coordinates of the light receiving pixel G of the area type image sensor 130a that has received the laser beam in the emission direction Qm are G (x1, y1). Next, as shown in FIG. 45 (b), the engagement between the engagement pin 121 and the engagement hole 126 for determining the angular position is released, and the LD holder plate 119 is rotated by 180 degrees so that the engagement pin 121 and the angular position are determined. The engaging pin 126 is fitted with the engaging hole 126 ′ for determination.
The engagement hole 12 for determining the angular position of the LD holder plate 119
The reference laser diode 127 is angularly positioned by bringing the peripheral wall 126'a of the 6 'into contact with the rotating direction.

Then, the reference laser diode 127 is turned on using a lighting control circuit not shown (the lighting control circuit of the writing unit 1 may be used). The emission direction of the laser beam at this time is Q as shown in FIG.
Assume that it was in the m 'direction. In addition, the injection direction Q
It is assumed that the coordinates of the light receiving pixel G of the area type imaging device 130a that has received the light beam of m 'are G (x2, y2).

Then, the coordinates K (X10, Y1) of the reference pixel K existing on the extension of the emission trajectory Qn on the writing start side are obtained.
0) is obtained by X10 = {(x1-x2) / 2} + x2 Y10 = {(y1-y2) / 2} + y2

Therefore, the position of the reference pixel K can be obtained with high accuracy without using a laser whose emission optical axis is strictly adjusted as the reference laser diode 127.

Next, the positioning block member 115 is positioned so as to face the CCD camera unit 130 at the writing center position, and the position of the reference pixel K existing on the extension of the emission trajectory Qn 'at the writing center position designed in advance is determined. Coordinate K
The case where (X12, Y12) is obtained will be described.

First, the CCD camera unit 1 at the center position
The reference laser diode 127 is turned on with the reference laser diode 127 facing 30.

The emission direction of the laser beam at this time is Q
Assume that m ''. In addition, the emission direction Qm ′
It is assumed that the coordinates of the light receiving pixel G of the image sensor 130a that has received the light beam are G (x3, y3).

The coordinates K (X12, Y12) of the reference pixel K existing on the extension of the emission trajectory Qn 'at the writing center position and the coordinates K (X10, X10, Y10) of the reference pixel K existing on the extension of the reference pixel on the writing start side. Y10) is different from the ejection direction Q
The coordinates G (x3, x3) of the light receiving pixel G that has received the light beam of m ′
y3) is equal to the difference between the coordinates G (x2, y2) of the light receiving pixel G of the image sensor 130a that has received the light beam in the emission direction Qm '.

Therefore, X12-X10 = x3-x2 Y12-Y10 = y3-y2 Therefore, X12 = X10 + x3-x2 = {(x1-x2) / 2}
+ X3 Y12 = Y10 + y3-y2 = {(y1-y2) / 2}
+ Y3 CCD camera 132 provided at the write end side position
The coordinates K (X14, Y) of the reference pixel K of the image sensor 130a
14) Similarly, the coordinates of the light receiving pixel G are represented by G (x5, y5).
Then, X14 = {(x1-x2) / 2} + x5 Y14 = {(y1-y2) / 2} + y5

Therefore, once the CCD camera 132
After specifying the coordinates of the reference pixel K for the CCD camera 132 by rotating the LD holder plate 119, the reference pixel K for the remaining CCD camera 132 can be specified without rotating the LD holder plate 119.

FIG. 39 shows a state in which a positioning block 115 as an angular position determining member is provided at the center position.

The beam diameter in the depth direction can be measured by moving the slide base 131 in the longitudinal direction by the micrometer 133.

In this specific structure, one positioning block 115 can be rearranged to obtain the reference pixel K at each position. However, one positioning block 115 is provided on the positioning reference base 111 so as to be slidable. Alternatively, the positioning block 115 may be provided at each of the write start side position, the center position, and the write end side position.

[0162]

Modifications FIGS. 46 to 51 are views showing modifications of the above specific structure. FIGS. 46 to 48 show the mounting state of the writing unit 1 to the image forming apparatus. The writing unit positioning member 101 is fixed to an upper end of the support 140. Here, the writing unit positioning member 101 is a flat plate.

The writing unit positioning member 101 has an opening 141 formed at the center thereof. The writing unit positioning member 101 has three clamping devices 14.
2 is provided, and 143 is a clamp lever. The writing unit 1 is fixed to the writing unit positioning member 101 by the clamp device 142. Base 100
The mounting base 128 is fixed to the mounting base 128, and the supporting base 129 is fixed to the mounting base 128.
A slide base 131 is slidably provided on 29.

The slide base 131 is provided with a CCD camera unit 130. The CCD camera unit 130 includes the CCD camera 132 and the mounting base 13.
1 '. The attached base 131 'has an upright 131'a applied thereto. A micrometer 133 is attached to the slide base 131, and the micrometer 133 plays a role of adjusting the imaging surface 130a of the area-type imaging device so that the imaging surface 130a is located on the surface to be scanned.

The holding frame 144 is provided on the support base 129 as shown in FIG.
Reference numeral 145 denotes a guide hole. The guide hole 145 extends in the sliding direction of the slide base 131. The slide base 131 is fixed to the support base 129 by tightening a fixing screw 136.

A positioning reference base 111 is attached to the writing unit positioning member 101 as shown in FIG. The positioning reference base 111 is held by the clamp device 142 by the writing unit positioning member 10.
Fixed to 1. A contact portion 147 is formed below the positioning reference base 111. A positioning block member 115 shown in FIG. 51 is attached to the upper portion of the positioning reference base 111.

The angle positioning block member 115 has a circular fitting hole 120 and an engaging pin 121. The LD holder plate 119 is attached to the angle positioning member 115. This LD holder plate 1
A reference laser diode 127 is attached to 19. The center of the circular fitting hole 120 is oriented in the same direction as the designed injection trajectory Qn.

In this modification, when specifying the reference pixel K using the reference laser diode 127, the writing unit 1 is removed from the writing unit positioning member 101, and the reference laser diode 127 is set on the writing unit positioning member 101. When the evaluation of the laser light source of the writing unit 1 is performed, the reference laser diode 127 and the positioning reference base 111 are removed, and the writing unit 1 is set on the writing unit positioning member 101.

[0169]

[Adjustment Device Based on Evaluation Results] An adjustment device based on the evaluation results of these evaluation devices 1 to 4 will be described below.

FIG. 20 relates to an adjusting device based on the evaluation of the evaluation item a.

[0171]

[Structure for adjusting write position in main scanning direction by moving synchronous sensor] As shown in FIG.
This relates to the configuration of the writing start position adjusting means when the beam center O1 of the beam spot S is shifted from the (reference writing position Z1) by ΔX in the main scanning direction.

With respect to the reference position Z1 on the writing start side,
When the beam center O1 is shifted by ΔX in the main scanning direction Q1, the synchronization sensor 27 is adjusted by moving the synchronization sensor 27 in the main scanning direction Q1 orthogonal to the beam traveling direction.

The synchronous sensor 27 is attached to a movable body 47 as shown in FIG.
A guide shaft 48 extending to 1 is movably provided.
The guide shaft 48 is hung over constituent walls 49 and 49 ′ constituting a part of the writing unit 1, and an adjusting screw 50 is provided on the constituent wall 49, and the adjusting screw 50 is a screw portion formed on the constituent wall 49. 51 is screwed.

A tension spring 52 as a biasing means is stretched between the movable body 47 and the constituent wall 49, and the movable body 47 is urged toward the constituent wall 49. The tip 50a of the adjusting screw 50 is in contact with the wall of the movable body 47.

By rotating the adjusting screw 50 forward and backward, the movable body 47 is finely moved in the main scanning direction Q1, and as shown in FIG.
The distance L6 to the (reference position Z1) is adjusted, whereby the beam center O1 can be made to coincide with the designed writing reference position Z1 in the main scanning direction, and the writing timing of the writing start position can be corrected. Become.

[0176]

[Write Position Adjustment Structure 1 in the Main Scanning Direction by Moving Writing Unit or Imaging Unit] In the above example, the synchronous sensor 27 is moved in the main scanning direction to correct the write timing at the write start position. In the first modification, the writing timing is adjusted by relatively moving the writing unit 1 and the image forming unit 53 in the main scanning direction Q1.

FIG. 23 shows the positional relationship between the writing unit 1 and the image forming unit 53. In this case, at least the image forming unit 53 has a developing roller unit 54, a transfer unit 55, a charging unit 55 in the rotation range of the photosensitive drum 25. Unit 5
6 are provided. Note that the transfer unit 55 and the charging unit 56 may be integrated. Further, a cleaning unit for the latent image carrier and a charge removing unit (not shown) may be provided integrally with the image forming unit 53. The sub-scanning direction Q3 is orthogonal to the optical axis of the light beam applied to the photosensitive drum 25.

The main body constituting wall 57 of the image forming apparatus is
As shown in FIG. 4, a guide hole 58 extending in the main scanning direction Q1 is formed, and a support pin 53b and a boss 53c protrude from an image forming unit constituting wall 53a constituting the image forming unit 53. Have been. A screw portion 53d is formed in the boss portion 53c, and the support pin 53b is
Is fitted.

An adjusting screw 59 is provided on the main body constituting wall 57, and the adjusting screw 59 is screwed to a screw portion 53d of the boss 53c. When the adjustment screw 59 is adjusted, the image forming unit 53 is moved in the main scanning direction Q1 relative to the writing unit 1, whereby the light beam P1 is moved in the main scanning direction with respect to the image forming unit (photosensitive drum 25) 53. The position adjustment of Q1 is performed, whereby the write timing of the write start position designed in the main scanning direction is corrected.

[0180]

[Structure 2 for Adjusting Writing Position in Main Scanning Direction by Moving Writing Unit or Image Forming Unit] In the adjusting structure 1, the image forming unit 53 is moved in the main scanning direction Q1 by screwing the adjusting screw 59 and the screw portion 53d of the boss 53c. To move the light beam P1 in the main scanning direction Q1 with respect to the image forming unit 53.
In the second modification, as shown in FIG. 25, the image forming unit 53 is moved in the main scanning direction Q1.
And is movable on a guide rail 60 extending to the right. The image forming unit 53 is pulled toward the main body constituting wall 57 by a spring 61 as an elastic member. A screw portion 62 is formed on the main body constituting wall 57, and the adjusting screw 59 is screwed to the screw portion 62, and a tip 59 a of the adjusting screw 59 is in contact with the image forming unit constituting wall 53 a.

When the adjusting screw 59 is rotated in a direction in which the tip 59a of the adjusting screw 59 is weakly pressed against the image forming unit forming wall 53a, the image forming unit 53
1 is moved in the direction of arrow a1 by the urging force of
When the adjusting screw 59 is rotated in a direction in which the front end portion 59a of the No. 9 is more strongly pressed against the image forming unit constituting wall 53a, the image forming unit 53 is pressed against the adjusting screw 59 so as to resist the urging force of the spring 61. The light beam P1 is moved in the direction a2, thereby adjusting the position of the light beam P1 in the main scanning direction Q1 with respect to the image forming unit 53.

[0182]

[Write Position Adjustment Structure 3 in the Main Scanning Direction by Movement of Writing Unit or Image Forming Unit] In this adjustment structure 3, as shown in FIG. 26, the image forming unit 53 is moved by being placed on a guide rail 60 extending in the main scanning direction Q1. A rack 63 is formed on the image forming unit 53, and an adjusting shaft 64 with an operation knob is provided on the main body constituting wall 57, and the rack 63 is attached to the shaft of the adjusting shaft 64. A meshing pinion 65 is provided, and the image forming unit 53 can be moved in the main scanning direction Q1 by meshing the pinion 65 and the rack 63.

[0183]

[Write Position Adjusting Structure 4 in the Main Scanning Direction by Moving Writing Unit or Image Forming Unit] In the adjusting structures 1 to 3, the image forming unit 53 is moved in the main scanning direction Q1, and the image forming unit 53 for the light beam P1 is moved. In the fourth modification, FIG. 27 is used.
As shown in the figure, the writing unit 1 is moved in the main scanning direction Q1 to adjust the position of the light beam P1 in the main scanning direction Q1, while the image forming unit 53 is kept fixed. The main scanning direction Q
1, a guide hole 66 extending long is formed at a position corresponding to the writing unit 1, and a support pin 67 and a boss 68 are projected from the writing unit constituting wall 1b. A screw portion 69 is formed in the boss portion 68, and the support pin 67 is fitted in the guide hole 66.

An adjusting screw 70 is provided on the main body constituting wall 57, and the adjusting screw 70 is provided on the writing unit constituting wall 1 b, and the adjusting screw 70 is screwed to a screw portion 69 of the boss 68. When the adjusting screw 70 is adjusted, the writing unit 1 is moved relatively in the main scanning direction Q1 with respect to the image forming unit 53, whereby the position of the light beam P1 in the main scanning direction Q1 with respect to the image forming unit 53 is adjusted. Will be

[0185]

[Write Position Adjusting Structure 5 in the Main Scanning Direction by Movement of Writing Unit or Image Forming Unit] In the adjusting structures 1 to 4, the image forming unit 53 is provided below, the writing unit 1 is provided above, and the light beam P1 is adjusted. Imaging unit 53
Is adjusted in the main scanning direction Q1 of the light beam P1 with respect to.
Is provided below, and the image forming unit 53 is provided above, so that the position adjustment of the light beam P1 with respect to the image forming unit 53 in the main scanning direction Q1 is performed.

In the fifth modification, as shown in FIG.
The image forming unit 53 is fixed, and the writing unit 1 is movable on a guide rail 71 extending in the main scanning direction Q1. The writing unit 1 is pulled by a spring 72 toward the main body constituting wall 57. A screw hole 73 is formed in the main body constituting wall 57, the adjusting screw 74 is screwed into the screw hole 73, and a tip 74 a of the adjusting screw 74 is in contact with the writing unit constituting wall 1 b.

When the adjusting screw 74 is rotated in such a direction that the pressing of the tip end portion 74a of the adjusting screw 74 against the writing unit forming wall 1b is weakened, the writing unit 1 is moved in the direction of arrow a3 by the urging force of the spring 72. When the adjusting screw 74 is rotated in a direction in which the tip 74a of the screw 74 is more strongly pressed against the writing unit constituting wall 1b, the writing unit 1 is pressed in the direction of the arrow against the urging force of the spring 72 by pressing the adjusting screw 74. a4, whereby the image forming unit 5 for the light beam P1 is moved.
3 is adjusted in the main scanning direction Q1.

[0188]

[Structure for adjusting writing position in main scanning direction by moving sheet stacking position] FIG. 52 shows a structure for adjusting the writing position by shifting the sheet stacking position in the main scanning direction Q1.

In this embodiment, as shown in FIG. 52 (a), LEDs 1 to LEDn for side races are provided facing the surface 26 of the photosensitive drum 25. This L
ED1 to LEDn are arranged in a direction corresponding to the main scanning direction Q1 as shown in FIG.

The lighting of these LEDs 1 to LEDn is controlled in accordance with the sheet size. The LEDs 1 to LEDn are used to prevent the developing toner from adhering to the side race (conveying direction (sub-scanning direction Q3)) of the photosensitive drum 25 according to the sheet size. That is, LED1
The LEDn is used for exposing both ends of the photosensitive drum 25.

In the image forming unit 53, the sheet stacking tray 1
00 and 101 are provided. Here, a side guide fixing plate mounting portion 102 is provided on the sheet stacking tray 100. This side guide fixing plate mounting part 1
02 is provided with a side guide fixing plate 103, and a side guide 104 is slidably attached to the side guide fixing plate 103 in accordance with the sheet size.
The sliding direction of the side guide 104 is the main scanning direction Q.
1 (direction orthogonal to the sheet conveying direction).

The side guide fixing plate 103 can be slidably adjusted in the same direction as the side guide 104 with respect to the side guide fixing plate mounting portion 102, and is based on the writing position correction amount based on the evaluation results of the evaluation devices 1 to 4. In order to adjust the writing position in the main scanning direction Q1, a slot 105 is provided, and a memory corresponding to the writing position correction amount is provided in the slot 105. After this adjustment, the side guide fixing plate 103 is fixed to the side guide fixing plate mounting portion 102 with fixing screws or the like.

For example, when the side race of A3 landscape is performed, the CPU controls the LED1, LED2 and LEDn-
1. LEDn is turned on. If it is necessary to correct the writing position by one LED in the main scanning direction Q1 (when the writing position is shifted upward in FIG. 52B), the size of each size is reduced. The LED lighting control is shifted by that amount, and in the case of the A3 landscape sheet, LED1, LEDn-2, LEDn-1, LEDn
Is controlled to be turned on.

The point is that if the writing position is shifted and adjusted in the main scanning direction Q1, the sheet conveyance position may be shifted. Furthermore,
While the sheet is being conveyed to the photosensitive drum 25, the sheet may be slid in the main scanning direction Q1 while being conveyed.

[0195]

[Structure for adjusting writing position in sub-scanning direction by moving writing unit or image forming unit] This adjusting structure is based on the result of evaluation (evaluation item b) of the writing position in the sub-scanning direction shown in FIG. Based on this, adjustment is made along the traveling direction of the light beam emitted from the writing unit 1 and irradiated on the photosensitive drum and along the sub-scanning direction Q3 orthogonal to the main scanning direction Q1.

That is, in this position adjusting structure, the writing timing is adjusted by relatively moving the writing unit 1 and the image forming unit 53 in the sub-scanning direction Q3, as shown in FIG. like,
The beam center O1 'of the beam spot S is in the sub-scanning direction Q3.
And a means for adjusting the writing start position when it is shifted by ΔY.

As shown in FIG. 30, the main body constituting wall 57 is provided with an adjusting screw 75 constituting a part of the moving means and a guide hole 76 extending in the sub-scanning direction Q3. The writing unit 1 has a support pin 77 and a boss 78. A screw 79 is formed on the boss 78, and the adjusting screw 75 is screwed into the screw 79 of the boss 78. When the adjustment screw 75 is adjusted, the writing unit 1 is moved relatively in the sub-scanning direction Q3 with respect to the image forming unit 53.
Sub-scanning direction Q of light beam P1 with respect to image forming unit 53
Position adjustment 3 is performed.

In this adjusting structure, the writing unit 1 is moved in the sub-scanning direction Q3 to adjust the position of the light beam P1 in the sub-scanning direction Q3 with respect to the image forming unit 53. A support pin 76 and a boss 78 that form a part of the unit are formed, and the image forming unit 53 is moved in the sub-scanning direction Q3 to adjust the position of the light beam P1 with respect to the image forming unit 53. You can also.

Further, the moving means may be constituted by a pinion which is rotated by an adjustment shaft having an operation knob, and a rack which meshes with the pinion.

[0200]

[Depth Adjustment Structure by Laser Diode (LD) Unit] Here, the collimating lenses 13 and 14 are moved along the optical path of the light beam P1 based on the beam waist correction appropriate amount △ W obtained by the depth evaluation. The optical path length is to be adjusted, and the optical path length adjusting means will be described below with reference to FIG.

The mounting base 81 of the laser diode 11 (12) is provided with a screw 8 on the writing unit configuration wall 1b.
The mounting base 81 is provided with a mounting hole 83 for the laser diode 11 (12) and a mounting hole 84 for the collimating lens 13 (14). The laser diode 11 is provided in the mounting hole 83.
(12) is fitted and fixed. The collimating lens 13 (14) is held by a lens barrel 85, and a male screw part 86 is formed on the outer peripheral part of the lens barrel 85. Mounting hole 84
Is formed with a female screw portion 87, and the lens barrel 85 is provided with a male screw portion 86.
Is screwed into the female screw portion 97 and is held by the mounting base 81 so as to be movable in the axial direction.

The position of the beam waist Bw is adjusted by adjusting the lens barrel 8
By rotating 5, the laser diode 11,
12 is performed by moving the collimating lens 13 (14) in the optical axis direction Q5 of the collimating lens 13 (14). After the adjustment of the beam waist Bw, the lens barrel 85 is fixed to the mounting base 81 by, for example, an adhesive.

[0203]

[Depth Adjustment Structure 1 by Writing Unit or Imaging Unit] In the above example, the beam waist is adjusted by moving the collimating lenses 13 and 14 in the optical axis direction. 33, a guide hole 88a extending in the height direction in the main body constituting wall 57.
And a screw mounting portion 88b, and a guide pin 8 fitted in the guide hole 58 is formed in the writing unit configuration wall 1b.
9, the writing unit 1 is urged upward by the urging force of the tension spring 90, and a screw portion 92 for screwing with the adjustment screw 91 is provided on the screw attachment portion 88 b, and the tip end 91 a of the adjustment screw 91 is connected to a guide pin. 89, and by rotating the adjusting screw 91, the distance between the writing unit 1 and the image forming unit 53 is adjusted, whereby the optical path length is changed and the surface 26 of the photosensitive drum 25 is changed.
In this case, the position of the beam waist is adjusted.

[0204]

[Depth Adjusting Structure 2 by Writing Unit or Image Forming Unit] In the adjusting structure 1, the interval between the writing unit 1 and the image forming unit 53 is determined by providing an adjusting screw 91. As shown in FIG. 7, an adjusting knob 94 is provided on the main body constituting wall 57, an eccentric cam 96 is provided on a shaft portion 95 of the adjusting knob, and a contact portion 97 is provided on the writing unit 1 to abut on a cam surface 96a of the eccentric cam 96. The contact portion 97 is formed on the cam surface 9 by a tension spring 90 bridged between the locking pin 93 and the guide pin 89.
6a, the adjustment knob 94 is rotated to change the optical path length between the writing unit 1 and the image forming unit 53, and the surface 26 of the photosensitive drum 25 is changed.
In this case, the position of the beam waist is adjusted.

The optical path length adjusting means may be constituted by a pinion that is rotated by an adjusting screw and a rack that meshes with the pinion.

Here, the writing unit 1 is moved in the sub-scanning direction, but the image forming unit 53 may be moved.

[0207]

[Adjustment based on evaluation results for other evaluation items]

(A) When the evaluation based on the evaluation items c and d is out of the allowable range, it is considered that the polygon mirror 19 is defective.
It is desirable to replace 9.

(B) When the evaluation using the evaluation items e and f is out of the allowable range, the aperture diameter of the aperture member (not shown) provided in the optical path between the laser diode LD and the polygon mirror 19 is adjusted. I do. The aperture member is usually disposed immediately after the collimator lens in the light traveling direction. The aperture diameter of the aperture member may be adjusted by mechanically adjusting the aperture diameter of the aperture member, or by removing the aperture member that is currently disposed in the optical path from the optical path, and by opening an aperture having a different aperture diameter. It may be performed by replacing the member.

(C) The adjustment based on the evaluation of the magnification error and the magnification error deviation of the evaluation items g and i is desirably performed by exchanging the fθ lens and exchanging the reflection mirror.

This is due to the optical defect of the optical elements such as the fθ lens 23 and the reflection mirror 24 constituting the optical system for guiding the light beam reflected from the polygon mirror 19 to the photosensitive drum 25, with respect to the optical axis O10. This is because the possibility of occurrence is high as a result of affecting the optical path length in the left-right direction.

When only the magnification error of the evaluation item g is present, as shown in FIG.
The θ lens 23 can be adjusted at a predetermined angle around the optical axis O10.

(D) The adjustment based on the evaluation of the scanning line inclination and the scanning line bending of the evaluation items h and j is also performed by the fθ lens 2.
It is desirable that the replacement be performed by replacing the third mirror and the reflecting mirror 24.

This is caused by optical defects in the optical elements such as the fθ lens 23 and the reflection mirror 24 which constitute the optical system for guiding the light beam reflected from the polygon mirror 19 to the photosensitive drum 25, so that the right and left with respect to the optical axis. This is because there is a high possibility that this occurs as a result of affecting the optical path length in the direction.

When only the scanning line inclination of the evaluation item h is used, as shown in FIG. 53 (b), the fθ lens 23 is adjusted by a predetermined angle around its optical axis O10, and the inclination of the reflection mirror 24 is adjusted. This can be done by adjusting the corner in the direction of arrow O11.

(E) The adjustment based on the evaluation of the pitch interval of the evaluation item m is performed by adjusting a unit to which a plurality of LDs are attached by a predetermined angle around the optical axis.

(F) The adjustment based on the evaluation of the scanning time of the evaluation item k is performed by adjusting the rotation speed of the polygon mirror 19. As shown in FIG. 53 (a), the scanning time can be adjusted by adjusting the reflection mirror 24 or the fθ lens 23 by a predetermined angle around the optical axis O10.

(G) The adjustment of the evaluation item 1 based on the depth evaluation is as described with reference to FIGS.

[0218]

According to the present invention, it is possible to evaluate each characteristic required for a light beam by one device.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a conventional example of a light beam scanning characteristic evaluation device.

FIG. 2 is a diagram showing a conventional example of a light beam scanning characteristic evaluation device, and is an explanatory diagram showing a state where beam diameter measurement during scanning of a light beam is measured using a one-dimensional line CCD.

3 is an explanatory diagram when it is considered that the light beam during scanning shown in FIG. 2 is stationary and the beam diameter of the light beam during scanning is measured using the one-dimensional line CCD shown in FIG. 2; .

FIG. 4 is a perspective view schematically showing an internal configuration of a writing unit according to the present invention.

FIG. 5 is a view for explaining the principle of the first embodiment of the light beam characteristic evaluation apparatus according to the present invention, in which three CCDs are used.
FIG. 3 is a diagram illustrating a case where cameras are provided at intervals in a main scanning direction.

6 is a diagram conceptually showing an area type imaging device of the CCD camera shown in FIG.

FIG. 7 is a diagram for explaining an ideal image (beam spot) designed and designed to be drawn on the surface to be scanned by the writing unit shown in FIG. 4;

FIG. 8 is an explanatory diagram for explaining the timing of one dot control of the light beam shown in FIG. 5;

9 is a diagram showing a beam spot formed on an area type imaging device of each CCD camera shown in FIG.

FIG. 10 is a diagram for explaining a second embodiment of the evaluation device, showing a case where two CCD cameras are provided at an interval in the main scanning direction.

FIG. 11 is an explanatory diagram for explaining the timing of one dot control of the light beam shown in FIG. 10;

FIG. 12 is a diagram for explaining a third embodiment of the evaluation device, showing a case where one CCD camera is provided at the center in the main scanning direction.

13 is an explanatory diagram for explaining the timing of one dot control of the light beam shown in FIG.

FIG. 14 is an explanatory diagram of a beam spot (laser spot) formed on the area type imaging device shown in FIG.

FIG. 15 is an explanatory diagram used for explanation for obtaining a light beam intensity distribution curve based on the beam spot shown in FIG. 14;

16 is a light beam intensity distribution curve diagram used for explanation for obtaining a center position of a light beam by an evaluation processing circuit based on the light beam intensity distribution curve shown in FIG.

FIG. 17 is a diagram for explaining Embodiment 4 of the evaluation device, and is an explanatory diagram showing a configuration in which one CCD camera is movable in the main scanning direction and the depth direction.

18 is a flowchart illustrating an example of processing of the light beam characteristic evaluation device illustrated in FIG.

FIG. 19 is an explanatory diagram for explaining an example of an evaluation characteristic by the light beam characteristic evaluation device according to the present invention;
(A) is a diagram showing a shift of a writing position in the main scanning direction,
(B) is a diagram showing a shift in a writing position in the sub-scanning direction;
(C) is an explanatory diagram of pitch unevenness in the main scanning direction for each surface of the polygon mirror, (d) is an explanatory diagram of pitch unevenness in the sub-scanning direction for each surface of the polygon mirror, and (e) is an explanatory diagram of magnification error. , (F) is an explanatory view of the inclination of the scanning line, (g)
7A is an explanatory diagram of a magnification error deviation, FIG. 7H is an explanatory diagram of a scan line curve, FIG. 7I is an explanatory diagram of a depth curve, and FIG.

FIG. 20 is a diagram used for describing the writing position adjustment structure in the main scanning direction, and is an explanatory diagram showing a state in which the beam center is shifted in the main scanning direction with respect to a reference position on the writing start side.

21 is a diagram showing an example of a writing position adjusting unit for adjusting the deviation of the beam center from the reference position on the writing start side shown in FIG. 20 in the main scanning direction, and conceptually shows a position adjustment structure of the synchronous sensor. FIG.

FIG. 22 is a diagram for explaining write adjustment timing by a synchronous sensor.

FIG. 23 is an explanatory diagram of the writing position adjustment structure 1 in the main scanning direction by moving the writing unit or the image forming unit, and is a diagram illustrating a relative positional relationship between the writing unit and the image forming unit.

24 is a partial cross-sectional view conceptually showing an adjustment structure for adjusting a writing start timing by moving an image forming unit relatively in the main scanning direction with respect to the writing unit shown in FIG.

25 is an explanatory diagram of a writing position adjusting structure 2 in the main scanning direction by moving a writing unit or an image forming unit, and moves the image forming unit in the main scanning direction relatively to the writing unit shown in FIG. 23; FIG. 11 is a partial cross-sectional view conceptually showing an adjustment structure for adjusting a write start timing by using the adjustment structure.

26 is an explanatory view of a writing position adjusting structure 3 in the main scanning direction by moving a writing unit or an image forming unit, and moves the image forming unit in the main scanning direction relatively to the writing unit shown in FIG. 23; FIG. 11 is a partial cross-sectional view conceptually showing an adjustment structure for adjusting a write start timing by using the adjustment structure.

27 is an explanatory diagram of a writing position adjusting structure 4 in the main scanning direction by moving a writing unit or an image forming unit, and writes by moving the writing unit shown in FIG. 23 in the main scanning direction with respect to the image forming unit. It is a fragmentary sectional view showing notionally the adjustment structure which adjusts start timing.

28 is an explanatory view of a writing position adjusting structure 5 in the main scanning direction by moving a writing unit or an image forming unit. FIG. 28 illustrates writing by moving the writing unit shown in FIG. 23 in the main scanning direction with respect to the image forming unit. It is a fragmentary sectional view showing notionally the adjustment structure which adjusts start timing.

FIG. 29 is a diagram used for a writing position adjustment structure in the sub-scanning direction by moving a writing unit or an image forming unit, showing a state in which the beam center is shifted in the sub-scanning direction with respect to a reference position on the writing start side. FIG.

30 is an explanatory diagram of a writing position adjustment structure in the sub-scanning direction by moving the writing unit or the image forming unit, and moving the image forming unit in the sub-scanning direction relatively to the writing unit shown in FIG. 23; FIG. 4 is a partial cross-sectional view conceptually showing an adjustment structure for adjusting a write start timing by using FIG.

FIG. 31 is an explanatory view used in Embodiment 4 of the light beam characteristic evaluation apparatus, in which (a) is a light beam for evaluating a depth curve of a light beam by moving a CCD camera in a main scanning direction and a sub-scanning direction. It is explanatory drawing of a characteristic evaluation apparatus, (b) is a figure which shows an example of the depth curve obtained by the light beam characteristic evaluation apparatus shown to (a).

FIG. 32 is an explanatory diagram of a depth adjustment structure using a laser diode unit. The position of a collimator lens is adjusted in the optical axis direction based on a depth curve obtained by a light beam characteristic evaluation device according to a fourth embodiment, and the optical path length is adjusted. FIG. 6 is a partial cross-sectional view showing an optical path length adjusting structure for adjusting the distance.

FIG. 33 is an explanatory diagram of a depth adjustment structure 1 using a writing unit or an image forming unit. FIG. 33 illustrates the distance between the writing unit and the image forming unit based on a depth curve obtained by the light beam characteristic evaluation device according to the fourth embodiment. FIG. 4 is a partial cross-sectional view illustrating an optical path length adjustment structure that adjusts an optical path length.

FIG. 34 is an explanatory diagram of a depth adjustment structure 2 using a writing unit or an image forming unit. FIG. 34 is a diagram illustrating the distance between the writing unit and the image forming unit based on a depth curve obtained by the light beam characteristic evaluation apparatus according to the fourth embodiment. FIG. 4 is a partial cross-sectional view illustrating an optical path length adjustment structure that adjusts an optical path length.

FIG. 35 is a side view showing a specific structure of the evaluation devices 1 to 4 and showing a state where the writing unit is attached to the image forming apparatus.

FIG. 36 is a plan view illustrating a state where the writing unit is attached to the image forming apparatus.

FIG. 37 is a diagram showing an external shape of the writing unit shown in FIGS. 35 and 36.

FIG. 38 is a front view illustrating a state where the writing unit is attached to the image forming apparatus.

FIG. 39 is a partially enlarged plan view showing an arrangement relationship between a positioning reference base attached to a reference base attachment section and a CCD camera.

40 is an explanatory diagram of the positioning reference base shown in FIG. 39, where (a) is a plan view and (b) is a view of (a) taken along arrow c1.
FIG. 3C is a view as viewed from a direction c2, and FIG. 3D is a view as viewed from a direction c3 as viewed b.

FIG. 41 is a partially enlarged side view showing an arrangement relationship between a positioning reference base attached to a reference base attachment portion and a CCD camera.

FIGS. 42 and 43 are explanatory views of the positioning block member shown in FIGS. 39 and 41, where (a) is a plan view and (b) is (a).
Is a view as viewed from the direction of arrow c4, and FIG.
FIG. 3D is a view as viewed from the direction, and FIG. 4D is a view as viewed from the direction of arrow c6 in FIG.

43 is an explanatory view of the LD holder plate shown in FIG. 41, (a) is a side view, and (b) is a view of (a) viewed from the direction of arrow c7.

FIG. 44: Area-type CCD using a reference laser light source
FIG. 9 is a diagram for describing the specification of a reference pixel.

FIG. 45 is a partially enlarged view of the LD holder plate and the positioning block member.
FIG. 7B is a diagram illustrating a state before rotation by 0 degrees, and FIG. 7B is a diagram illustrating a state after rotation of the LD holder plate by 180 degrees.

FIG. 46 is a plan view illustrating a state where the writing unit is attached to the image forming apparatus.

FIG. 47 is a side view showing a state where the writing unit is attached to the image forming apparatus, and shows a state before the writing unit is clamped.

FIG. 48 is a front view showing a state where the writing unit is attached, and shows a state before the writing unit is clamped.

FIG. 49 is a plan view showing a positional relationship between a CCD camera unit attached to the support base shown in FIG. 47 and a reference laser diode.

FIG. 50 is a plan view showing a positioning reference base and a positioning block attached to the writing unit.

FIG. 51 is an enlarged side view of the positioning block shown in FIG. 49.

52A and 52B are explanatory diagrams of a writing position adjustment structure in the main scanning direction by moving a sheet stacking position, where FIG. 52A is a schematic diagram of the internal structure of an image forming unit, and FIG. 52B is an LED shown in FIG. (C) shows a side guide attached to the sheet stacking tray.

53A and 53B show an example of adjustment in the case of a magnification error and a scan line inclination failure, in which FIG. 53A shows an example of adjustment based on evaluation of a magnification error, and FIG. 53B shows an example of adjustment based on evaluation of scan line inclination.

[Explanation of symbols]

 11, 12 laser diode (beam light source) P1 light beam

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] August 20, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0077

[Correction method] Change

[Correction contents]

For example, as shown in FIG. 19 (e), the distance L4 between the design reference planned writing reference positions Z1 and Z2 on the transfer paper corresponding to two points on the original in the main scanning direction Q1 is actually measured. Position on the scanned surface obtained by
The magnification error can be evaluated by determining the ratio of Z1 ′ and Z2 ′ to the distance L5.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0150

[Correction method] Change

[Correction contents]

Then, the reference laser diode 127 is turned on using a lighting control circuit not shown (the lighting control circuit of the writing unit 1 may be used). The emission direction of the laser beam at this time is Q ′ as shown in FIG.
Assume that it was in the m direction. In addition, the injection direction Q'm
It is assumed that the coordinates of the light-receiving pixel G of the area-type image sensor 130a that has received the light beam are G (x2, y2).

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0153

[Correction method] Change

[Correction contents]

Next, the positioning block member 115 is positioned so as to face the CCD camera unit 130 at the writing center position, and the reference pixel K existing on the extension of the emission trajectory Q'n at the writing center position designed in advance. Coordinates K
The case where (X12, Y12) is obtained will be described.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name]

[Correction method] Change

[Correction contents]

At this time, the emission direction of the laser beam is
Assume that Q ″ m . In addition, the emission direction Q ′
m of the image sensor 130a that has received the light beam m
Is G (x3, y3).

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0156

[Correction method] Change

[Correction contents]

The coordinates K (X12, Y12) of the reference pixel K existing on the extension of the emission locus Q'n at the writing center position and the coordinates K (X10) of the reference pixel K existing on the extension of the reference pixel on the writing start side. , Y10) is different from the emission direction Q ′.
The coordinates G (x3, y) of the light receiving pixel G that has received the light beam of m
3) and the imaging device 1 that has received the light beam in the emission direction Q'm
It is equal to the difference from the coordinates G (x2, y2) of the light receiving pixel G of 30a.

[Procedure amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0168

[Correction method] Change

[Correction contents]

In this modification, when specifying the reference pixel K using the reference laser diode 127, the writing unit 1 is removed from the writing unit positioning member 101, and the reference laser diode 127 and the positioning
The reference base 111 to the writing unit positioning member 1
When the evaluation is performed on the laser light source of the writing unit 1, the reference laser diode 127 and the positioning reference base 111 are removed, and the writing unit 1 is set on the writing unit positioning member 101.

Claims (18)

[Claims] A characteristic required for a light beam is evaluated by turning on a beam light source used for linearly scanning a surface to be scanned during a scanning time corresponding to one dot during scanning. Light beam characteristics evaluation method. 2. The apparatus according to claim 1, further comprising at least two light beam detecting means provided at a predetermined distance from each other in the scanning direction of the surface to be scanned. By turning on the light during the scanning time corresponding to the dot, irradiate the light beam to the light beam detecting means on the scanning start side, and after the extinction time calculated by the scanning speed and the predetermined distance that are designed in advance, elapses By turning on the beam light source again during the scanning time corresponding to the one dot, the light beam is irradiated on the light beam detecting means on the scanning end side, and the light beam is requested for the light beam based on the detection result of each light beam detecting means. A light beam characteristic evaluation method comprising evaluating a scanning characteristic. 3. The light beam characteristic evaluation method according to claim 2, wherein said beam light source is a semiconductor laser, said light beam detecting means is an area type solid-state image pickup device, and said light beam detection means is a solid-state image pickup device. The scanning characteristic is evaluated by calculating a deviation from a position on the imaging surface and a reference position designed in advance. 4. The light beam characteristic evaluation method according to claim 3, wherein the scanning time and the light-off time are defined based on a clock signal generated by a clock oscillator.
The beam light source is turned on until the number of clocks corresponding to one dot is counted, and is turned off until the number of clocks corresponding to the turn-off time is counted. 5. A lighting control circuit capable of lighting a beam light source used for scanning a surface to be scanned during a scanning period corresponding to one dot during scanning; and a lighting control circuit provided on the surface to be scanned. Light beam characteristic evaluation comprising: light beam detection means for detecting a light beam emitted from a beam light source; and evaluation processing means for evaluating characteristics required for the light beam based on a detection result of the light beam detection means. apparatus. 6. A light beam characteristic evaluation apparatus according to claim 5, wherein said beam light source is incorporated in a writing unit having a scanning optical system, and said light beam detection means is an area type solid-state imaging device. The processing means calculates a writing position as a characteristic required for the light beam based on a detection result of the area type solid-state imaging device. 7. The light beam characteristic evaluation device according to claim 6, wherein at least two area-type solid-state imaging devices are provided at a predetermined distance in the main scanning direction, and the scanning speed and the scanning speed are designed. Calculation means for calculating a light-off time based on the predetermined distance is provided, and after irradiating the light beam to the light beam detection means on the scanning start side, the light source is turned off for the light-off time, and the light-off time elapses. After that, the beam light source is turned on again for the scanning time corresponding to the one dot, thereby irradiating the light beam to the light beam detecting means on the scanning end side, and forming the light beam based on the detection result of each light beam detecting means. It is characterized by evaluating required scanning characteristics. 8. A lighting control circuit provided in a writing unit having a scanning optical system and capable of lighting a laser light source used for scanning a surface to be scanned during a scanning period corresponding to one dot during scanning. An area solid-state imaging device provided on the surface to be scanned and detecting a light beam emitted from the laser light source; and a characteristic required for the light beam based on a detection result of the area solid-state imaging device. A light beam characteristic evaluation device comprising: an evaluation processing unit that evaluates a writing position of the light beam. 9. The light beam characteristic evaluation apparatus according to claim 8, wherein two area type solid-state imaging devices are provided at a predetermined distance designed in the main scanning direction at a predetermined distance. After the light is turned on during the scanning period corresponding to one dot toward the area-type solid-state imaging device on the scanning start side and then turned off, and after the light-off time calculated by the scanning speed designed in advance and the predetermined distance elapses, The evaluation processing means is turned on again during the scanning period corresponding to one dot, and the evaluation processing means operates from the writing position detected by the area-type solid-state imaging device on the scanning start side to the writing position detected by the area-type solid-state imaging device on the scanning end side. A magnification error is calculated by comparing a distance with the predetermined distance. 10. The light beam characteristic evaluation device according to claim 8, wherein three area solid-state imaging devices are provided at intervals in the main scanning direction, and one of the three area solid-state imaging devices is One of the remaining area-type solid-state imaging devices is provided on the scanning start side, and the other of the remaining area-type solid-state imaging devices is provided on the scanning end side. The distance to the area-type solid-state imaging device is set to be equal, and the laser light source is turned on during a scanning period corresponding to one dot toward the scanning-start-side area-type solid-state imaging device, and then turned off, and is designed by design. After the extinction time calculated by the scanning speed and the distance has elapsed, one more time is directed toward the remaining area-type solid-state imaging device.
The evaluation processing unit is turned on during a scanning period corresponding to a dot, and the evaluation processing unit performs a distance from a writing position detected by the area-type solid-state imaging device on the scanning start side to a writing position detected by the central area-type solid-state imaging device; By comparing the writing position detected by the area-type solid-state imaging device with the distance from the writing position detected by the area-type solid-state imaging device on the scanning end side, the left-right image balance as the scanning characteristic is evaluated. It is characterized by the following. 11. A light beam characteristic evaluation apparatus according to claim 9, further comprising a clock pulse oscillator for defining a scanning time corresponding to said one dot and said light-off time, wherein said laser light source is It is characterized in that it is turned on until the number of clocks corresponding to one dot is counted, and is turned off until the number of clocks corresponding to the turn-off time is counted. 12. The light beam characteristic evaluation apparatus according to claim 11, further comprising a calculation means for calculating the light-off time based on a scanning speed and the distance that are designed in advance. 13. A light beam characteristic evaluation apparatus according to claim 11, wherein said writing unit is provided with a synchronization sensor for determining a writing timing on both sides in the main scanning direction, and said laser light source is synchronized with a scanning start side. The light is continuously turned on until the sensor is detected, and after the light beam is detected by the synchronous sensor on the scanning start side, the light is once turned off to light one dot. 14. An apparatus for evaluating light beam characteristics according to claim 11, wherein two laser light sources are provided, and writing to said surface to be scanned can be performed by two light beams. 15. The light beam characteristic evaluation device according to claim 14, wherein said evaluation processing means is configured to detect a light receiving position of a light beam emitted from one of the laser light sources and received by the area type solid-state imaging device, and the other of the light receiving positions. The inter-beam pitch is calculated based on the light receiving position of the light beam emitted from the laser light source and received by the area-type solid-state imaging device, and the inter-beam pitch is spaced at least two points in the main scanning direction. It is characterized in that the degree of parallelism between two light beams is evaluated by calculating at a location. 16. The light beam characteristic evaluation apparatus according to claim 10, wherein said evaluation processing means calculates a beam center of each of said area type solid-state imaging devices in a sub-scanning direction, and calculates the light beam based on each beam center. It is characterized in that scanning line bending is evaluated. 17. The light beam characteristic evaluation device according to claim 8, wherein the writing unit includes a synchronization sensor for determining a writing timing on a scanning start side, and the area type solid-state imaging device moves in a main scanning direction. It is possible,
The lighting control circuit is controlled to turn on the laser light source by one dot after a lapse of a light-off time related to a distance from the synchronous sensor to the area type solid-state imaging device. 18. The light beam characteristic evaluation device according to claim 17, wherein said extinguishing time is calculated based on said distance and a theoretically planned scanning speed.