JP2008037047A - Light beam displacement calculation method, light scanning device, and image formation apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize constant scanning intervals even when the environment is varied and good image formation without uneven pitches. <P>SOLUTION: A light scanning device is composed of a rotary polygonal mirror which simultaneously subjects light beams from a combination light source to deflection scanning by the same reflecting surface and an image formation lens which forms an image on an image supporter by the light beams undergone deflection scanning by the rotary polygonal mirror. The light scanning device has a combined light source having a plurality of light source units composed of a light source, a light source holder which holds the light source, an optical system lens installed in a lens tube which causes the light beams from the light source to be parallel light beams, and a lens holder which fixes the lens tube. The combined light source solves the problems by setting the plurality of light source units so that the displacement direction caused by a change of environmental conditions of the light beams from the plural light source units become the same. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a light beam displacement calculation method, an optical scanning device, and an image forming apparatus, and more particularly, a light beam displacement calculation method for acquiring a light beam displacement due to environmental fluctuations with high accuracy and realizing good image formation without pitch unevenness. The present invention relates to an optical scanning device and an image forming apparatus.

  Conventionally, in a light source unit, an optical scanning device, and an image forming apparatus using the same, a technique related to a method for fixing a light source or a collimator lens in a light source unit in order to suppress changes in environmental conditions such as temperature and humidity. It is disclosed (for example, see Patent Documents 1 to 3).

  In the technique disclosed in Patent Document 1, a lens barrel is fixed to a base using laser welding means in order to suppress fluctuations in an optical element such as a collimator lens. In Patent Document 1, the welding position is a plane including the principal point of the optical element orthogonal to the optical axis, and a plurality of welding points are better.

  The technique disclosed in Patent Document 2 presses an intermediate fixing member between a cylindrical holder and a lens barrel of a collimator lens in order to suppress fluctuations of an optical element such as a collimator lens, In the case of three positions, one is on the scanning direction line including the optical axis, and the other two positions are symmetrical with respect to the scanning direction line including the optical axis. It is said. In this method, stress is generated but the center point of the optical element is not changed.

Further, the technique disclosed in Patent Document 3 is fixed using a V-shaped groove having a predetermined angle in order to suppress fluctuations in an optical element such as a collimator lens. Patent Document 3 also shows an example of a synthetic light source.
JP 2001-111155 A Japanese Patent Laid-Open No. 9-193451 JP 2004-170771 A

  By the way, in the technique shown in Patent Document 1 described above, the spot diameter increases due to the deviation of the image formation position on the photoconductor, so that the image formation position and the irradiation position on the photoconductor are made constant. In order to form an accurate electrostatic latent image, the lens barrel of the collimator lens is fixed to the base by laser welding as the means.

  However, even if it is fixed to the base by welding, the degree of contact with the collimator lens, distortion caused by welding, etc. are not constant, and there are variations in assembly and differences in individual parts. It is difficult to make the displacement of the collimator lens perpendicular to the optical axis zero.

  In the technique disclosed in Patent Document 2, since the spot diameter increases due to the deviation of the imaging position on the photosensitive member, the imaging position on the photosensitive member and the irradiation position on the photosensitive member are correctly set. In order to obtain a good color image, an optical component is put in a lens barrel as means for providing intermediate fixing members at two or three locations.

  However, even if an intermediate fixing member is provided, the degree of contact with the collimator lens, distortion, and the like are not constant, and there are variations in assembling and differences in individual parts. It is difficult to make the displacement of the collimator lens in the direction perpendicular to the optical axis due to changes in temperature or the like zero.

  Furthermore, the technique disclosed in Patent Document 3 aims to stably maintain the positional relationship between the light source and the collimator lens even when environmental conditions such as temperature and humidity fluctuate. An optical element such as a lens is fixed using a V-shaped groove having a predetermined angle. The basis of this method is that the collimator lens is likely to rotate α when the angle of the V-shaped groove is narrow, and β rotation is likely to occur when the angle of the V-shaped groove is wide. It is. However, even if the angle of the V-shaped groove is a predetermined value, the contact state and distortion of the collimator lens and the V-shaped groove are not always constant. Since there is a difference for each component, it is difficult to make the displacement in the direction perpendicular to the optical axis of the collimator lens particularly due to a change in environmental temperature or the like zero.

  Patent Document 3 shows an example of a synthetic light source, but does not describe a means for reducing the relative displacement of a spot on the photosensitive member accompanying an environmental change. Therefore, when the light source unit is a single unit, the scanning interval does not change even if the absolute position of the spot on the photosensitive member varies slightly in the direction perpendicular to the optical axis, and therefore printing defects such as uneven pitch are rarely caused. However, in the case of a combined light source that combines a plurality of light sources, if the position of the spot on the photoconductor is relatively slightly shifted, the scanning interval on the photoconductor becomes non-uniform, resulting in uneven pitch called banding in printing. Occurs.

  Further, one of the causes of the relative positional deviation of the spot on the photoconductor is a change in the spot position on the photoconductor of light obtained from the light source unit. The light source unit slightly expands and contracts due to a change in the environmental temperature or the like, and the portion holding the collimator lens slightly changes. The direction of change varies depending on the light source unit, and it is unknown which direction it changes. Note that this fluctuation is very small. For example, in a conventional method in which a spot change at the time of environmental change is simply measured with a TV camera or the like, it is accompanied by fluctuations in the environmental temperature of the parts holding the light source unit and the parts holding the measuring machine. Since the change and the change of the light source unit alone overlap, it is impossible to accurately acquire the deviation of the light beam caused by the light source unit alone. For this reason, in the case of a combined light source that combines a plurality of light source units, conventionally, the light source units have been assembled without considering the direction of variation due to environmental temperature changes.

  As described above, conventionally, when the environment changes, there is a difference for each part in the variation direction and the amount of the spot on the photosensitive member in the vertical direction of the optical axis. Was a problem.

  The present invention has been made in view of the above-described problems. It obtains a high-precision light beam displacement due to environmental fluctuations, makes a scanning interval constant even when there are environmental fluctuations, and realizes good image formation without pitch unevenness. An object of the present invention is to provide a light beam displacement calculation method, an optical scanning device, and an image forming apparatus.

  In order to solve the above problems, the present invention employs means for solving the problems having the following characteristics.

  The invention described in claim 1 is the light beam displacement calculation method for calculating the light beam displacement due to the change in the environmental condition of the light source unit, wherein the position in the optical axis vertical plane of the light beam from the light source unit in the first environmental condition is A first measuring step that is measured by an imaging means installed on an extension of the light source unit and a lens system provided at a predetermined distance from the light source unit, and a light source in a second environmental condition different from the first environmental condition A first measurement step of measuring a position in a plane perpendicular to the optical axis of the light beam from the unit by the imaging means, a first displacement of the light beam position obtained by the first measurement step and the second measurement step; Obtaining the first environmental condition and the second environmental condition after rotating the light source unit by a predetermined angle about the optical axis, and rotating the light source unit by a predetermined angle. The optical axis vertical plane position of the light beam from the light source unit is measured by the imaging means, and the second displacement is obtained, and the light beam displacement is calculated based on the difference between the first displacement and the second displacement. And a calculating step.

  According to the first aspect of the present invention, the deviation (displacement) of the light beam caused by the light source unit alone can be accurately calculated. Further, using the calculated light beam displacement, for example, in an optical scanning device, the scanning interval can be made constant even if there is an environmental variation, and in the image forming device, there is a good pitch unevenness even if there is an environmental variation. Image formation can be realized.

  The invention described in claim 2 has a step of determining a direction of displacement due to a change in environmental conditions based on the light beam displacement obtained by the calculating step.

  According to the second aspect of the present invention, it is possible to know the direction of displacement of the light source unit, which slightly varies with changes in environmental conditions. By using this direction of displacement, for example, in an optical scanning device, the scanning interval can be made constant even when there is environmental variation, and in an image forming device, good image formation without pitch unevenness can be achieved even if there is environmental variation. Can be realized.

  According to a third aspect of the present invention, there is provided a rotary polygon mirror that simultaneously deflects and scans light beams from a combined light source using the same reflecting surface, and an image that forms an image of the light beams deflected and scanned by the rotary polygon mirror on an image carrier. In an optical scanning device including a lens, a light source, a light source holder that holds the light source, an optical system lens that is provided in a lens barrel that converts light from the light source into parallel rays, and a lens that fixes the lens barrel A combined light source including a plurality of light source units each including a holder, wherein the combined light source includes the plurality of light source units arranged to have the same displacement direction due to changes in environmental conditions of light rays from the plurality of light source units; It is characterized by that.

  According to the third aspect of the present invention, the plurality of light source units used as the combined light source are installed with the same displacement direction, so that the scanning interval can be made constant even when there is an environmental change. Further, by providing this optical scanning device in an image forming apparatus or the like, it is possible to realize good image formation without pitch unevenness.

  The invention described in claim 4 is characterized in that the combined light source uses light source units having substantially the same amount of displacement due to changes in environmental conditions of light rays from the plurality of light source units.

  According to the fourth aspect of the invention, by making the displacement amounts of the plurality of light source units used as the combined light source the same, the scanning interval can be made constant even when there is an environmental change.

  The invention described in claim 5 is characterized in that the combined light source is installed in such a manner that the direction of displacement of light from the plurality of light source units corresponds to the scanning direction.

  According to the fifth aspect of the present invention, the displacement in the sub-scanning direction due to environmental changes or the like can be minimized by installing the displacement direction of the light beam corresponding to the scanning direction.

  According to a sixth aspect of the present invention, there is provided a rotary polygon mirror that simultaneously deflects and scans light beams from a combined light source by the same reflecting surface, and an image that forms an image of the light beams deflected and scanned by the rotary polygon mirror on an image carrier. In an optical scanning device including a lens, a light source, a light source holder that holds the light source, an optical system lens that is provided in a lens barrel that converts light from the light source into parallel rays, and a lens that fixes the lens barrel A combined light source including a plurality of light source units each including a holder is used, and light source units having substantially the same amount of displacement due to changes in environmental conditions of light rays from the plurality of light source units are selectively used.

  According to the sixth aspect of the present invention, the error can be minimized by using the light source unit having a small difference in displacement amount among the plurality of light source units used as the combined light source.

  According to a seventh aspect of the present invention, the displacement direction or the displacement amount is a displacement caused by a change in an environmental condition of a light beam from the light source unit obtained by using the light beam displacement amount calculation method according to the first or second aspect. It is a direction or an amount of displacement.

  According to the seventh aspect of the present invention, it is possible to accurately calculate the deviation of the light beam caused by the light source unit alone using the light beam displacement amount calculation method according to the first or second aspect. Further, the calculated light beam displacement can make the scanning interval constant even when there is an environmental change.

  According to an eighth aspect of the present invention, the light source unit has at least one hole on an end surface of the lens holder, and the light source holder is rotatably fixed using the hole and the attachment member. Features.

  According to the eighth aspect of the invention, the light source holder can be fixed with a simple configuration.

  The invention described in claim 9 has at least one elongated hole in the end face of the light source holder, inserts a mounting member into the elongated hole, and can rotate the light source holder using the hole and the mounting member. It is characterized by being fixed to.

  According to the ninth aspect of the present invention, the light source holder can be rotated within a predetermined range with respect to the optical axis while the attachment member is inserted into the elongated hole. Moreover, since it is a long hole shape, a highly accurate angle setting can be performed.

  According to a tenth aspect of the present invention, the combined light source includes a base member having a plurality of unit fixing openings for fixing the light source unit, and the plurality of light source units are respectively provided in the plurality of unit fixing openings. It is characterized by being fixed by insertion.

  According to the tenth aspect of the invention, it is possible to improve the stability and adjust the scanning direction, the sub-scanning direction, and the optical axis rotation direction with respect to the optical axis.

  The invention described in claim 11 is characterized in that the base member presses and fixes the plurality of light source units inserted into the unit fixing openings against the base member by a support member.

  According to the eleventh aspect of the invention, it is possible to improve the stability and adjust the scanning direction, the sub-scanning direction, and the optical axis rotation direction with respect to the optical axis.

  According to a twelfth aspect of the present invention, the base member is provided with a plurality of holes for attaching the light source unit to the outer periphery of the unit fixing opening, and a plurality of holes are provided at end portions of the plurality of light source units. An opening is provided, an attachment member is inserted into the opening of the light source unit inserted into the unit fixing opening, and the light source unit is fixed to the base member using the hole and the attachment member. Features.

  According to the twelfth aspect of the present invention, the stability can be improved and the scanning direction, the sub-scanning direction, and the optical axis rotation direction can be adjusted with respect to the optical axis.

  The invention described in claim 13 is characterized in that the opening has an elongated hole shape corresponding to the rotation direction of the light source unit.

  According to the thirteenth aspect of the present invention, the light source unit can be rotated within a predetermined range with respect to the optical axis while the attachment member is inserted into the elongated hole. Moreover, since it is a long hole shape, a highly accurate angle setting can be performed.

  A fourteenth aspect of the present invention is an image forming apparatus including the optical scanning device according to any one of the third to thirteenth aspects.

  According to the fourteenth aspect of the present invention, it is possible to realize good image formation without pitch unevenness even if there is an environmental change.

  According to the present invention, it is possible to acquire a light beam displacement due to environmental fluctuations with high accuracy, to make the scanning interval constant even when there are environmental fluctuations, and to realize good image formation without pitch unevenness.

  Hereinafter, embodiments in which a method for calculating a light beam displacement from a light source unit, an optical scanning device, and an image forming apparatus according to the present invention are suitably implemented will be described with reference to the drawings. In the following embodiment, an optical scanning device and an image forming apparatus using the optical scanning device will be described as an example of a device configuration using the method for calculating the light displacement from the light source unit. The apparatus configuration using the is not limited to this.

<Image forming apparatus>
FIG. 1 is a diagram illustrating a configuration example of an image forming apparatus to which the present invention is applied. An image forming apparatus 10 shown in FIG. 1 includes a photoreceptor 11, a charging device 12, an optical scanning device 13, a developing device 14, a conveying device 15, a transfer device 16, a cleaning device 17, and a fixing device 18. It is comprised so that it may have. Further, the image forming apparatus 10 shown in FIG. 1 forms a predetermined image on a printing paper 19 as a recording medium.

  An image forming apparatus 10 shown in FIG. 1 rotates a drum-shaped photoreceptor 11 that is an image carrier for forming a toner image in a predetermined direction. The photoconductor 11 is uniformly charged to a specific polarity by the charging device 12 and then exposed to light from an optical scanning device 13 to be described later to form an electrostatic latent image.

  Further, a developing device 14 is disposed on the downstream side of the photosensitive member 11 with respect to the optical scanning device 13. The developing device 14 develops a predetermined toner image on the photoconductor 11. Here, the printing paper 19 is transported by the transport device 15. The transfer device 16 charges the back surface of the printing paper 19 with a polarity opposite to that of the toner, and transfers the toner image on the photoconductor 11 onto the printing paper 19. After the transfer, the toner that has not been transferred is removed by the cleaning device 17.

  The printing paper 19 having the toner image transferred from the photoconductor 11 is conveyed to the fixing device 18. The fixing device 18 includes a heat roller 18-1 that is controlled to be heated to a constant temperature and a pressure roller 18-2 that is in pressure contact with the heat roller 18-1. When passing through this, the toner image held on the printing paper 19 is pressurized and melted and fixed on the printing paper 19. After this fixing process, the printing paper 19 is discharged to the outside of the image forming apparatus 10 and printing is completed.

<Optical scanning device 13>
Next, the optical scanning device 13 described above will be specifically described. FIG. 2 is a diagram illustrating a configuration example of an optical scanning device provided in the image forming apparatus. The optical scanning device 13 shown in FIG. 2 is configured to include a synthetic light source 21, a cylindrical lens 22, a rotary polygon mirror 23, an Fθ lens 24, a folding mirror 25, a mirror 26, and a sensor 27. . In addition, although the synthetic | combination light source 21 demonstrates as what has two light source units as an example, in this invention, it is not limited to two, What is necessary is just two or more.

  In the optical scanning device 13 shown in FIG. 2, two light beams 28 emitted from a synthetic light source 21 described later pass through a cylindrical lens 22 having a predetermined curvature only in the sub-scanning direction, and intersect at the position of the rotary polygon mirror 23. Are simultaneously deflected and scanned on the same reflecting surface. Further, the light beam 28 deflected and scanned by the rotary polygon mirror 23 passes through the Fθ lens 24, is folded back in the direction of the photoconductor 11 by the folding mirror 25, and scans in the direction of the arrow 29 on the photoconductor 11 shown in FIG. To form an electrostatic latent image.

  A part (dotted line shown in FIG. 2) of the deflected and scanned light beam 28 is guided from the combined light source 21 by the output signal obtained from the light received by the sensor 27 and guided to the sensor 27 by the mirror 26. The modulation for exposing (writing) the photosensitive member 11 to the light beam 28 is started.

<Synthetic light source 21>
Next, the internal configuration of the above-described combined light source 21 will be described with reference to the drawings. FIG. 3 is a diagram showing a configuration example of the synthetic light source in the present invention. The synthetic light source 21 shown in FIG. 3 includes a light source unit 31, a mark 32, a screw member 33 as an attachment member, a support member 34 made of sheet metal or the like, and a base member 35.

  In the present embodiment, the light source units 31-1 and 31-2 are arranged in parallel and each generate a predetermined light beam. In addition, the mark 32 can be placed on the light source units 31-1 and 31-2 so that the direction of the light beam displacement due to changes in environmental conditions such as temperature and humidity can be matched when the light source unit 31 is installed on the base member 35. It is a mark written in each light fluctuation direction. In addition, even if the mark 32 is not described, it is only necessary to be able to recognize the displacement direction of the light beam in the light source unit 31 by another method such as a cut or a groove.

  In the example of FIG. 3, the base member 35 has an opening for fitting the light source units 31-1 and 31-2. The base member 35 is fixed by the screw member 33 by pressing the light source units 31-1 and 31-2 fitted in the openings by the support member 34.

  In FIG. 3, since the outer shape of the light source units 31-1 and 31-2 is circular, the light source units 31-1 and 31-2 can be rotated with respect to the base member. Therefore, the scanning direction, sub-scanning direction, and optical axis rotation direction can be adjusted with respect to the optical axis.

  Here, the light source units 31-1 and 31-2 used in the present embodiment describe the displacement direction of each light beam and the displacement amount of the light beam according to, for example, changes in environmental conditions such as temperature and humidity (environmental variation) in advance. It may be measured by a measurement method (light displacement calculation method).

  As shown in FIG. 3, when the light source units 31-1 and 31-2 are arranged in parallel, the light beams 28 emitted from the respective units intersect at the position of the rotary polygon mirror 23 as shown in FIG. However, it is arranged so as to be a combined light source.

<Installation Example of Synthetic Light Source: First Installation Example>
Here, the 1st installation example of the synthetic | combination light source 21 which consists of the light source units 31-1 and 31-2 mentioned above is demonstrated. In the first installation example, the direction of the mark 32 of the light source units 31-1 and 31-2 (the displacement direction of the light beam from the light source unit 31 due to environmental fluctuation) is installed as the same direction. Thereby, since the displacement of the light from the plurality of light source units in the environment change is in the same direction, the amount of relative displacement of the light from the combined light source 21 can be further reduced even if there is an environmental change. Therefore, it is possible to realize a combined light source in which the relative displacement of light rays from a plurality of light sources is small.

<Installation example of synthetic light source: second installation example>
Next, a second installation example of the synthetic light source 21 will be described. In the second installation example, the direction of the mark 32 (the direction of displacement of the light beam from the light source unit 31 due to environmental changes) is set to the same direction, and the same amount of displacement is used. As a result, the direction of change from the plurality of light source units and the amount thereof when the environment changes are the same. Therefore, the amount of relative displacement of the light beam from the installed combined light source 21 can be zero even if there is an environmental change or the like. By using the second installation example described above, it is possible to realize a combined light source in which there is no relative displacement of light rays from a plurality of light sources.

<Installation example of synthetic light source: Third installation example>
Next, a third installation example of the synthetic light source 21 will be described. In the third installation example, the marks 32 are arranged in correspondence with each other so that the direction of the mark 32 (the direction of displacement of the light beam from the light source unit 31 due to environmental change) is the scanning direction. As a result, the fluctuation direction of the light beams from the plurality of light source units when the environment changes can be set as the scanning direction, and the shift in the sub-scanning direction due to the environmental change or the like can be minimized.

  Here, for example, when the light source units 31-1 and 31-2 have different positional deviation directions, the width of the light beam 28 to the rotary polygon mirror 23 shown in FIG. However, by applying the third installation example, the problem can be solved.

<Installation Example of Synthetic Light Source: Fourth Installation Example>
Next, a fourth installation example of the synthetic light source 21 will be described. In the fourth installation example, a light source unit having a small light beam displacement direction due to environmental fluctuation is selectively used from among a plurality of light source units. Thereby, the fluctuation | variation from the several light source unit at the time of environmental changes can be made small, and the relative displacement and absolute displacement of the light ray from the synthetic | combination light source 21 in which the light source unit was installed can be made small, even if there are environmental fluctuations. Therefore, according to the fourth installation example, it is possible to realize a combined light source in which there is no relative displacement of light beams from a plurality of light sources.

<Configuration example of light source unit 31>
Next, a specific configuration example of the light source unit 31 described above will be described. FIG. 4 is a perspective view illustrating a configuration example of the light source unit. FIG. 5 is a cross-sectional view of the light source unit shown in FIG. 4 in the optical axis direction.

  As shown in FIGS. 4 and 5, the light source unit 31 shown in this embodiment includes a light source 41, a light source holder 42, a screw member 43 as a mounting member for the light source 41, a collimator lens holder 44, and a collimator lens 45. And a screw member 46 as an attachment member for the collimator lens 45, a screw member 47 as an attachment member for the light source holder 42, and a support member 48 made of sheet metal or the like.

  In the light source unit 31, the light source 41 is screwed by a hole provided in the light source holder 42 and a screw member 43 to fix the light source 41. The collimator lens 45 is an optical system lens provided in a lens barrel for making the light beam from the light source 41 into a parallel beam. The collimator lens holder 44 is a lens tube containing the collimator lens 45 from the outside of the holder. Is collided with a screw member 46 to fix the collimator lens 45 at a predetermined position.

  The light source holder 42 is fixed using a plurality of the screw members 47 and the support members 48 described above so that the light source holder 42 can be fixed at any position in the plane perpendicular to the optical axis of the collimator lens holder 44 by rotating it to a predetermined position. Yes. In the example shown in FIG. 4, the number of fixing points is four, but the present invention is not limited to this.

  4 and 5, the light source holder 42 has the scanning direction with respect to the optical axis of the collimator lens 45 and the sub-axis regardless of the position of the collimator lens holder 44 fixed to the base member 35. The scanning direction and the optical axis rotation direction can be adjusted and fixed. Therefore, the light source holder can be fixed with a simple configuration.

<Another configuration example of the light source unit 31>
Next, another configuration example of the light source unit 31 will be described with reference to the drawings. FIG. 6 is a perspective view showing another configuration example of the light source unit. In the example shown in FIG. 6, the light source holder 42 is provided with one or a plurality of long holes 49 (for example, four places in FIG. 6). The long holes 49 have circular openings in the long holes 49 so that the optical axis holder 42 can be rotated by a predetermined angle in the rotation direction of the optical axis in a state where the optical axis holder 42 is lightly screwed by a screw member 50 as an attachment member. It is formed into a shape.

  In other words, the optical axis holder 42 can be rotated to a predetermined position while the screw member 50 is inserted into the opening, and the optical axis holder 42 is moved by the screw head by tightening the screw member 50 at an appropriate position. Can be fixed.

  Therefore, the light source holder 42 can be rotated with respect to the optical axis 41 within a predetermined range while the screw member 50 is inserted into the elongated hole. In addition, since the opening has an elongated hole shape, it is possible to perform highly accurate angle setting.

  In this case, by setting the number of holes for screwing with the screw member 50 provided on the collimator lens holder 44 side to be larger than the number of the long holes 49, the light source holder 42 can be formed at an arbitrary angle with respect to the center of the optical axis. The position in the scanning direction and the sub-scanning direction can be adjusted and fixed at a predetermined position.

<Fixing method of the light source unit 31>
Next, the fixing method to the base member 35 in the light source unit 31 mentioned above is demonstrated concretely. FIG. 7 is a diagram illustrating an example of the base member in the present embodiment. FIG. 8 is a diagram illustrating an example of the screw fixing opening of the light source unit.

  In the present embodiment, the light source unit 31 is configured so that it can be attached to the base member 35 regardless of the displacement direction of the light beam from the light source unit 31 alone due to environmental changes. In order to fix the light source unit 31 to the base member 35, the base member 35 fixes at least one hole 51 screwed with the screw member 33 and the light source unit 31 and allows the light source from the light source unit 31 to pass through. And an opening 52 for fixing the unit. The example of the fixing method of the light source unit 31 is shown below.

<Example of fixing light source unit 31: first fixing example>
The first fixing example of the light source unit 31 is a method of fixing the light source unit 31 by fitting the collimator lens holder 44 shown in FIG. In this case, the shapes of the unit fixing openings 52 and the collimator lens holder 44 are set so that they can be further fixed to the extent that they are rubbed. By inserting in this way, the light source unit 31 can be easily fixed. As a result, the installation position can be adjusted and fixed regardless of the direction of displacement of the light beam from the light source unit 31 alone due to environmental fluctuations.

<Example of fixing light source unit 31: second example of fixing>
Next, a second fixing example of the light source unit 31 will be described. In the second fixing example, in the example of FIG. 7A, the support member 34 is screwed by the hole 51, and the light source unit 31 is pressed and fixed to the base member 35 by the support member 34. Note that the stability of the light source unit 31 can be improved by increasing the number of support members 34. The light source unit 31 is inserted into the opening 52 of the base member 35 and has a shape that can rotate around the optical axis of the light source unit 31. As a result, the installation position can be adjusted and fixed regardless of the direction of displacement of the light beam from the light source unit 31 alone due to environmental fluctuations.

<Example of fixing light source unit 31: Third example of fixing>
Next, a third fixing example of the light source unit 31 will be described. In the third fixed example, as shown in FIG. 8A, a plurality of openings 53 are provided at the end of the light source unit 31. 7B, the screw member 33 is inserted into a predetermined opening 53 provided at the end of the light source unit 31, and the light source unit 31 is screwed into the hole 51 of the base member 35. be able to. Therefore, the installation position can be adjusted and fixed regardless of the direction of displacement of the light beam from the light source unit 31 alone due to environmental fluctuations.

<Example of Fixing Light Source Unit 31: Fourth Fixing Example>
Next, a fourth fixing example of the light source unit 31 will be described. In the fourth fixing example, as shown in FIG. 8B, the light source unit 31 has a plurality of long holes 54 (for example, four places in FIG. 8B). That is, the opening 53 in the above-described third fixing example is formed in a long hole shape corresponding to the rotation direction of the light source unit 31.

  Accordingly, as shown in FIG. 7C, the screw member 33 is inserted into the long hole 54 provided at the end of the light source unit 31, and the light source unit 31 is screwed by the hole 51 of the base member 35. Can do.

  The elongated hole 54 is formed in a circular shape so that it can be rotated by a predetermined angle in the direction of rotation of the optical axis while being lightly screwed by the screw member 33. That is, the light source unit 31 can be fixed by the screw head by inserting the screw member 33 into the elongated hole and fastening the light source unit 31 at a predetermined position. Therefore, the installation position can be adjusted and fixed regardless of the direction of displacement of the light beam from the light source unit 31 alone due to environmental fluctuations.

<Synthesis Example of Synthetic Light Source 21>
Next, a synthesis example of the synthetic light source 21 will be described. In addition to the case where a plurality of light source units are arranged in parallel as shown in FIG. 3 and the like described above, the synthesis light source 21 can be synthesized without using a prism or the like, for example. Here, FIG. 9 is a figure which shows the 2nd example of the synthetic | combination light source in this invention.

  As shown in FIG. 9, the combined light source 21 a uses the prism 61 to combine one by transmitting one of the light beams from the light source unit 31 and reflecting the other. In this case, the composite light source 21a is assembled so that the mark 32 of the light source unit 31 is in the same direction in the scanning direction and in each light source unit.

  In the example of FIG. 9, since the optical axes from the two light source units 31 can be matched in the combined light source, the deviation of each light beam from the optical axis is smaller than the configuration of FIG. Therefore, it is preferable.

  FIG. 10 is a diagram showing a third example of the combined light source in the present invention. As shown in FIG. 10, the combined light source 21 b combines by transmitting one of the light beams from the light source unit 31 and reflecting the other twice using the prism 62 with a reflecting surface. In this case, the combined light source 21b is assembled so that the mark 32 of the light source unit 31 is in the same direction in the scanning direction and in each light source unit. Accordingly, since the optical axes from the two light source units can be made coincident with each other, it is preferable from the configuration of FIG. 3 in terms of optical characteristics, and even if the reflecting surface-equipped prism 62 fluctuates, the angle of the light beam on the reflecting side changes accordingly. Therefore, there is an effect that relative displacement hardly occurs.

  In the present embodiment, the number of the light source units 31 of the above-described combined light source has been described as two. However, the present invention is not limited to this, and may be three or more. Furthermore, although the example shown in FIGS. 9 and 10 shows an example in which the light source of five elements (arrows in FIGS. 9 and 10) is used as the light source, the present invention is not limited to the number of light source elements.

<Measurement system of the displacement direction of the light beam>
Next, the measurement system for measuring the displacement direction of the light beam from the light source unit 31 alone when the environment changes in the present invention will be described. FIG. 11 is a diagram illustrating a schematic configuration example of a measurement system of the light source unit.

  In FIG. 11, a light beam emitted from the light source 71 is converted into a parallel light beam 73 through a collimator lens 72 having a focal length f1. Whether or not the light beam is a parallel light beam can be confirmed using, for example, a collimation checker or the like, and its means can be obtained by, for example, moving the collimator lens in the optical axis direction.

  Thereafter, the parallel light beam 73 passes through a convex lens 74 having a focal length f2 as an optical system, and is imaged on an imaging means 75 such as a television camera. The video obtained by the imaging means 75 is projected by display means such as a monitor, and the coordinates of the spot in the vertical plane of the optical axis are obtained based on the projected video. In this example, the number of lenses 74 is one, but the same is true for a plurality of lenses.

  Next, the measurement procedure in the displacement direction of the single light source unit when the environment changes in the measurement system described above will be described using a flowchart. FIG. 12 is a flowchart illustrating an example of a procedure for measuring the displacement direction of the light beam from the light source unit when the environment changes. In the following measurement procedure, temperature is described as an example of the environmental condition to be changed. However, the present invention is not limited to this, and humidity and other conditions may be changed.

  First, under the first environmental temperature condition (for example, 20 ° C.), the light beam 73 from the light source unit 31 passes through the convex lens 74 and reaches the imaging means 75. At this time, the position (X1, Y1) in the optical axis vertical plane is measured by the imaging means 75 such as a television camera (S01). Here, FIG. 13 is a diagram for explaining the step of S01. In FIG. 13, an arrow 81 is shown to clarify the orientation of the measured light source unit 31. That is, in S01, after the light source unit is positioned in a certain predetermined direction, the position in the optical axis vertical plane (X1) of the spot 83 displayed on the monitor 82 when the light beam 73 from the light source unit 31 reaches the imaging means 75. , Y1). In FIG. 13, as an example, the position (X1, Y1) of the spot 83 on the monitor 82 is (−1 μm, −1 μm).

  Next, the optical axis vertical position (X2, Y2) of the spot of the light beam from the light source unit under the second environmental temperature condition (for example, the temperature is 30 ° C.) different from the first environmental temperature is imaged. Measurement is performed by means 75 (S02). Here, FIG. 14 is a diagram showing the state of the spots displayed on the monitor in step S02. In FIG. 14, since the environmental conditions are different, the positions of the spots 84 on the monitor 82 shown in FIGS. 13 and 14 are different. In FIG. 14, as an example, the position (X2, Y2) of the spot 83 displayed on the monitor 82 in step S02 is (+1 μm, +1 μm).

  Next, a displacement A (Xa, Ya) (= (X2-X1, Y2-Y1)) of the light beam position is obtained from (X1, Y1) and (X2, Y2) (S03). As a result of calculation using the example described above, (Xa, Ya) = (+ 2 μm, +2 μm).

  Next, the light source unit 31 is rotated by a predetermined angle about the optical axis. In this embodiment, it is fixed by half rotation (180 °) (S04). FIG. 15 is a diagram illustrating a state of the light source unit in step S04. FIG. 15 shows that the arrow 81 of the light source unit 31 is half-rotated from the state of FIG. 13 about the optical axis.

  Next, in the half-rotated state, the same measurement as S01 and S02 is performed to obtain the displacement B (Xb, Yb) (S05). Also, assume that the result obtained in step S05 is (Xb, Yb) = (− 2 μm, +2 μm).

  Thereafter, the difference between the displacement A and the displacement B is halved to calculate a light beam displacement C (Xc, Yc) (= ((Xb−Xa) / 2, (Yb−Ya) / 2) (S06). For example, (Xc, Yc) = (− 2 μm, 0 μm) is calculated using the above numerical example, and this value is the direction of displacement due to environmental fluctuation of the light source unit 31 alone, and the calculation result. The direction of displacement due to environmental fluctuations is determined based on (S07).

  Therefore, in the case of the calculation in the above example, the displacement of 20 ° C. with respect to 30 ° C. is (−2 μm, 0 μm). As described above, in the present embodiment, attention can be paid to the fact that the displacement caused by the disturbance at the time of measurement occurs in the same manner twice, and the difference can be canceled out. Thereby, the deviation (displacement) of the light beam caused by the light source unit alone can be accurately calculated.

  Here, FIG. 16 is a diagram showing a state in which marks are marked in the displacement direction of the light source unit. As a result of the above-described calculation, the displacement direction of the obtained light source unit 31 alone is (−2 μm, 0 μm). Therefore, the light source unit 31 can be marked with a mark 32 in the X-axis direction. Further, since the displacement amount can be grasped from the above-described calculation result, the displacement amount may be described, for example, in a part of the periphery of the mask 32, such as -2 μm.

<Example of installation of light source unit 31 and synthetic light source 21>
Next, an installation example of the light source unit 31 and the synthetic light source 21 will be described. As described above, the light source unit 31 is marked with the mark 32 in the direction of light beam displacement due to environmental fluctuations. Since this displacement direction is the scanning direction when mounted on the synthetic light source 21, the light source holder is also adjusted in advance so that the mark direction is also in the horizontal direction.

  For example, when a plurality of light sources arranged in a row are scanned obliquely, it is preferable that the light source arrangement direction and the mark direction of the light source unit be substantially matched. Thereafter, when assembling the composite light source, the alignment angle of the light sources may be adjusted by rotating the entire light source unit. Thereby, the scanning direction of the light source and the sub-scanning direction position do not change. When the light source alignment direction and the light source unit mark direction are not substantially aligned, after adjusting the light source unit mark in the scanning direction, adjust the light source alignment angle between the light source holder and the collimator lens holder. It is necessary to do in. For this reason, the scanning direction and sub-scanning direction positions of the light source and the collimator lens are also changed at the same time.

  As described above, according to the present invention, it is possible to acquire the light beam displacement due to the environmental variation with high accuracy, to make the scanning interval constant even when there is an environmental variation, and to realize good image formation without pitch unevenness.

  Specifically, the light beam displacement calculation method according to the present invention can accurately determine the displacement direction of the light beam from the light source unit when the environment changes, and the direction of the environmental fluctuation of the combined light source composed of a plurality of light source units can be accurately determined. Can be obtained.

  Therefore, when assembling a composite light source composed of a plurality of light source units, it is possible to make the fluctuation directions in the plane perpendicular to the optical axis when the environment of the light beam from the light source units changes the same. Therefore, the relative displacement amount can be reduced. In addition, the relative displacement can be eliminated by making the displacement direction and the displacement amount the same, and the relative displacement and the absolute displacement can be reduced by selectively using the one having a smaller displacement amount.

  Also, by using this combined light source, a highly accurate optical scanning device and image forming apparatus can be provided. The present invention can be applied to all image forming apparatuses such as digital copying machines and laser printers.

  Although the preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the specific embodiment, and various modifications, within the scope of the gist of the present invention described in the claims, It can be changed.

1 is a diagram illustrating a configuration example of an image forming apparatus to which the present invention is applied. 1 is a diagram illustrating a configuration example of an optical scanning device provided in an image forming apparatus. It is a figure which shows the example of 1 structure of the synthetic | combination light source in this invention. It is a perspective view which shows one structural example of a light source unit. It is sectional drawing of the optical axis direction of the light source unit shown in FIG. It is a perspective view which shows the other structural example of a light source unit. It is a figure which shows an example of the base member in this embodiment. It is a figure which shows an example of the opening part for screw fixation of a light source unit. It is a figure which shows the 2nd example of the synthetic | combination light source in this invention. It is a figure which shows the other example of the synthetic | combination light source in this invention. It is a figure which shows the schematic structural example of the measurement system of a light source unit. It is a flowchart which shows an example of the measurement procedure of the displacement direction of the light ray from the light source unit at the time of environmental change. It is a figure for demonstrating the step of S01. It is a figure which shows the mode of the spot displayed on a monitor by the step of S02. It is a figure which shows the mode of the light source unit in the step of S04. It is a figure which shows a mode that the mark was written in the displacement direction of the light source unit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 11 Photoconductor 12 Charging device 13 Optical scanning device 14 Developing device 15 Conveying device 16 Transfer device 17 Cleaning device 18 Fixing device 19 Printing paper 21 Synthetic light source 22 Cylindrical lens 23 Rotating polygon mirror 24 Fθ lens 25 Folding mirror 26 Mirror 27 Sensor 28 Light beam 29 Arrow 31 Light source unit 32 Mark 33, 43, 46, 47, 50 Screw member 34, 48 Support member 35 Base member 41, 71 Light source 42 Light source holder 44 Collimator lens holder 45, 72 Collimator lens 49, 54 Long Hole 51 Hole 52, 53 Opening 61 Prism 62 Reflecting surface prism 73 Parallel ray 74 Convex lens 75 Imaging means 81 Arrow 82 Monitor 83 Spot

Claims (14)

In the light displacement calculation method for calculating the light displacement due to the change in the environmental conditions of the light source unit,
The position in the optical axis vertical plane of the light beam from the light source unit in the first environmental condition is measured by an imaging unit installed on an extension of the light source unit and a lens system provided at a predetermined distance from the light source unit. A first measurement step;
A second measurement step of measuring, by the imaging means, the position in the optical axis vertical plane of the light beam from the light source unit in a second environmental condition different from the first environmental condition;
Obtaining a first displacement of a light beam position obtained by the first measurement step and the second measurement step;
Rotating the light source unit by a predetermined angle around the optical axis;
After rotating by a predetermined angle, measuring the position in the optical axis vertical plane of the light beam from the light source unit in the first environmental condition and the second environmental condition by the imaging means, and obtaining a second displacement;
And a calculation step of calculating a light beam displacement based on a difference between the first displacement and the second displacement.   The light displacement calculation method according to claim 1, further comprising a step of determining a displacement direction due to a change in environmental conditions based on the light beam displacement obtained in the calculation step. In an optical scanning device comprising a rotating polygon mirror that simultaneously deflects and scans light beams from a combined light source by the same reflecting surface, and an imaging lens that forms an image on the image carrier with the light beams deflected and scanned by the rotating polygon mirror,
A plurality of light source units each including a light source, a light source holder that holds the light source, an optical lens provided in a lens barrel that converts light rays from the light source into parallel rays, and a lens holder that fixes the lens barrel. A combined light source,
The optical scanning device according to claim 1, wherein the combined light source is provided with the plurality of light source units so that the direction of displacement caused by changes in environmental conditions of light beams from the plurality of light source units is the same. The synthetic light source is
4. The optical scanning device according to claim 3, wherein light source units having substantially the same amount of displacement due to changes in environmental conditions of light rays from the plurality of light source units are used. The synthetic light source is
5. The optical scanning device according to claim 3, wherein a displacement direction of light beams from the plurality of light source units is set in correspondence with a scanning direction. In an optical scanning device comprising a rotating polygon mirror that simultaneously deflects and scans light beams from a combined light source by the same reflecting surface, and an imaging lens that forms an image on the image carrier with the light beams deflected and scanned by the rotating polygon mirror,
A plurality of light source units each including a light source, a light source holder that holds the light source, an optical lens provided in a lens barrel that converts light rays from the light source into parallel rays, and a lens holder that fixes the lens barrel. A combined light source,
An optical scanning device characterized by selectively using light source units having substantially the same amount of displacement due to changes in environmental conditions of light rays from a plurality of light source units. The displacement direction or the displacement amount is:
The displacement direction or the displacement amount according to a change in the environmental condition of the light beam from the light source unit obtained by using the light beam displacement amount calculation method according to claim 1 or 2. 2. An optical scanning device according to item 1. The light source unit is
Having at least one hole in the end face of the lens holder;
8. The optical scanning device according to claim 3, wherein the light source holder is rotatably fixed using the hole and the attachment member. 9. Having at least one slot in the end face of the light source holder;
9. The optical scanning device according to claim 8, wherein an attachment member is inserted into the elongated hole, and the light source holder is rotatably fixed using the hole portion and the attachment member. The synthetic light source is
Providing a base member having a plurality of unit fixing openings for fixing the light source unit;
8. The optical scanning device according to claim 3, wherein the plurality of light source units are fixed by being inserted into the plurality of unit fixing openings, respectively. 9. The base member is
The optical scanning device according to claim 10, wherein the plurality of light source units inserted into the unit fixing opening are fixed to the base member by being pressed by a support member. The base member is
While providing a plurality of holes for attaching the light source unit to the outer periphery of the unit fixing opening, providing a plurality of openings at the ends of the plurality of light source units,
The mounting member is inserted into the opening of the light source unit inserted into the unit fixing opening, and the light source unit is fixed to the base member using the hole and the mounting member. The optical scanning device according to 10. The opening is
The optical scanning device according to claim 12, wherein the optical scanning device has an elongated hole shape corresponding to a rotation direction of the light source unit.   An image forming apparatus comprising the optical scanning device according to claim 3.

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