JP2001051218A - Optical write device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To preferably correct beam diameter in the main scanning direction, the beam diameter in the sub-scanning direction and pitch of the subscanning direction on a plane to be scanned. SOLUTION: This device is equipped with a light source unit 1, composed of an emission light source 1a and an optical element 1c, a first optical system 20 to introduce the light beam from the light source unit 1 to a deflector 4 by using a plurality of optical elements 2, 3, a second optical system 5 to form an image of the light beam deflected by the deflector 4 as a scanning line on the plane to be scanned, a detecting means 9 to detect the imaged state of the imaging beam on the plane to be scanned, a support and guide means (including a spindle as a guiding member, the auxiliary spindle to guide this spindle, a circular hole and a slot hole) to support the plurality of the optical elements 2, 3 of the first optical system 20 and the emission light source 1a and to guide movement of these in the optical axis direction, a plurality of driving means (including a carriage, a pulse motor, lead screw or the like), to independently drive the plurality of optical elements 3, 4 of the first optical system 20 and the emission light source 1a in the optical axis direction, and a control means 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical writing device of a writing optical system such as a digital copying machine or a printer, and more particularly to an optical writing device applicable to an image forming apparatus, a measuring instrument, an inspection apparatus, and the like. Device.

[0002]

2. Description of the Related Art Conventionally, there has been proposed an optical scanning device which adjusts a focal position of a laser beam by moving a focus lens in an optical axis direction. For example, JP-A-10-
Japanese Patent Application Laid-Open No. 20225 discloses a laser that detects a defocus amount of a beam spot on a scanned surface of a photoreceptor with a sensor, and moves a focus lens in the optical axis direction according to the defocus amount. The focus position of the beam is adjusted.

[0003]

However, in a multi-beam optical scanning device that scans a plurality of beams simultaneously, the focus position of the laser beam can be adjusted by moving the focus lens in the optical axis direction. The pitch of the beam in the sub-scanning direction on the surface to be scanned is shifted.

Further, when the optical lens is formed of resin, a change in the refractive index distribution and a change in the shape of the lens due to a rise in temperature causes a shift in the image forming position on the surface to be scanned and a change in the beam spot diameter. Conventionally, the imaging position on the surface to be scanned is corrected by moving the cylindrical lens in the optical axis direction to obtain an appropriate beam spot diameter. In this manner, the cylindrical lens is moved in the optical axis direction. If it is moved, the optical magnification in the sub-scanning direction before being deflected by the deflector changes greatly, and a good image cannot be obtained.

The present invention has been made to solve the above-mentioned problems of the prior art. In a multi-beam optical scanning device, a plurality of optical elements and light-emitting sources are independently driven by a driving means in the direction of the optical axis. And a common support and guide unit guides each unit, so that the beam diameter in the main scanning direction, the beam diameter in the sub-scanning direction, and the pitch in the sub-scanning direction on the surface to be scanned can be satisfactorily corrected. An object is to provide an optical writing device.

[0006]

According to the first aspect of the present invention,
A light source unit formed of a light emitting source and an optical element; a first optical system for guiding a light beam from the light source unit to a deflector using a plurality of optical elements; and a light scanning surface deflected by the deflector. To form a second image as a scanning line
An optical system, detecting means for detecting an image forming state of an image forming beam on a surface to be scanned, a plurality of optical elements of the first optical system and the light emitting source, and the plurality of optical elements and the light emitting source And a plurality of driving means and control means for independently driving the plurality of optical elements and the light emitting source of the first optical system in the optical axis direction. It is characterized by having.

According to a second aspect of the present invention, in the first aspect of the present invention, the light emitting source has a plurality of light emitting points.

[0008] The invention described in claim 3 is claim 1 or 2.
In the invention described in the above, the reference for setting the support guide means in a direction perpendicular to the optical axis direction is formed on the same extension surface.

The invention according to claim 4 is the invention according to claim 1 or 2.
In the invention described in the above, the guide member of the support and guide means is shared.

[0010] The invention according to claim 5 is the invention according to claim 1 or 2.
In the described invention, the driving point of the driving means is set near the support and guide means.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of an optical writing apparatus according to the present invention will be described with reference to the drawings. In FIG. 1, reference numeral 1 denotes a light source unit having a semiconductor laser as a light emitting source (hereinafter, referred to as an “LD unit”).
Is shown. The LD unit 1 includes an LD array 1a as a light emitting source having a plurality of light emitting points and emitting a plurality of light beams, and an aperture 1 for shaping the light beams into a predetermined shape.
b and a collimating lens 1c as an optical element for converting a light beam into parallel light.

The LD array 1a can be moved in the optical axis direction by first driving means 30, which will be described later. By moving the LD array 1a in the optical axis direction, the LD array 1a can be moved on the surface to be scanned. The scanning pitch of the light beam in the sub-scanning direction can be adjusted. A specific description of this will be described later.

A first optical system 20 composed of a plurality of optical elements for guiding the light beam emitted from the LD unit 1 to the rotary polygon mirror 4 as a deflector is arranged on the emission side of the LD unit 1. I have. The first optical system 20 includes a cylindrical lens 2 and a cylindrical lens 3. The cylindrical lens 2 has power only in the main scanning direction, while the cylindrical lens 3 has power only in the sub-scanning direction.

The cylindrical lens 2 can be moved in the direction of the optical axis by a second driving means 40 (see FIG. 2) which will be described later, and by moving the cylindrical lens 2 in the direction of the optical axis. The light beam diameter in the main scanning direction can be adjusted. Further, the cylindrical lens 3 is also provided with a third driving unit 5 described later.
By moving the cylindrical lens 3 in the optical axis direction, the optical beam diameter in the sub-scanning direction can be adjusted by moving the cylindrical lens 3 in the optical axis direction. Specific description of these will be described later.

The first driving means 30, the second driving means 40, and the third driving means 50 independently drive the LD array 1a, the cylindrical lens 2, and the cylindrical lens 3 in the optical axis direction. Is controlled by The first driving means 30, the second driving means 40,
A specific description of the third driving means 50 will be described later.

On the reflection optical path of the light beam deflected by the deflecting / reflecting surface of the rotary polygon mirror 5, a plurality of light beams deflected by the rotary polygon mirror 5 are scanned by a scanning line with respect to the surface to be scanned of the photosensitive member 8. Lens 5 as a second optical system for forming an image, and a reflection mirror 7 for reflecting a light beam transmitted through the fθ lens 5 toward a surface to be scanned of the photoconductor 8. .

Further, at a position equivalent to the surface to be scanned of the photosensitive member 8 and immediately before the start of scanning, a detecting means for detecting an image forming state of the light beam formed on the surface to be scanned is provided. A light receiving surface of a photodiode (hereinafter referred to as “PD”) 9 is arranged. A slit-shaped opening is provided on the light receiving surface of the PD 9. Therefore, the light beam transmitted through the fθ lens 5 and reflected by the reflection mirror 7 passes through the aperture and is received by the light receiving surface. PD
The light receiving signal of the light beam received by the
Input to 0.

Next, the operation of the above embodiment will be described. As shown in FIG. 1, a light beam emitted from the LD array 1a of the LD unit 1 is shaped into a fixed shape by passing through an aperture 1b, and is converted into parallel light by passing through a collimating lens 1c. , Cylindrical lens 2, cylindrical lens 3
And is condensed near the deflection reflection surface of the rotary polygon mirror 4 as a linear image long in the main scanning direction. The light beam condensed near the deflecting / reflecting surface of the rotating polygon mirror 4 is deflected and reflected by the rotation of the rotating polygon mirror 4, passes through the fθ lens 5, is reflected by the reflecting mirror 7, and is scanned by the scanning surface of the photoconductor 8. Before scanning the upper surface, the light beam passing through the aperture provided on the light receiving surface is received as a light spot by the light receiving surface of the PD 9 provided at a position equivalent to the surface to be scanned.

Based on the light receiving signal from the PD 9, the control unit 10 determines the scanning pitch of the light beam on the surface to be scanned in the sub-scanning direction, the light beam diameter in the main scanning direction, and the light beam diameter in the sub-scanning direction. Each data value is calculated, and each data value is compared with a normal value recorded in advance. Then, in order to set each of the data values to a normal value, the first driving means 30, the second driving means 40,
By controlling the driving means 50, the LD array 1a, the cylindrical lens 2, and the cylindrical lens 3 are moved in the optical axis direction.

It should be noted that not all of the LD array 1a, the cylindrical lens 2, and the cylindrical lens 3 are moved in the optical axis direction, but only those having data values different from normal values. For example, the data values of the light beam diameter in the main scanning direction and the light beam diameter in the sub-scanning direction match the normal values, and only the data value of the scanning pitch of the light beam in the sub-scanning direction on the surface to be scanned is normal. If it is different from the value, only the first driving unit 30 is controlled, and the LD array 1a is moved in the optical axis direction by driving the first driving unit 30.

Next, the first driving means 30, the second driving means 40, and the third driving means 50, which are characteristic parts of the present invention, will be described. As described above, the first driving unit 30 moves the LD array 1a in the optical axis direction, the second driving unit 40 moves the cylindrical lens 2 in the optical axis direction, and the third driving unit 40 moves the LD array 1a in the optical axis direction. The driving means 50 moves the cylindrical lens 3 in the optical axis direction. FIG.
3 shows an exploded perspective view of the first driving means 30, the second driving means 40, and the third driving means 50, and FIG. 3 shows an assembled perspective view.

The first driving means 30 includes the carriage 1
h, a pulse motor 1i, a lead screw 1q, and the like. Hereinafter, a specific description will be given. As shown in FIGS. 2 and 3, the LD array 1a is fitted into the center hole of the base 1e, and is also pressed by the base 1e by the leaf spring 1f and inserted into the hole of the leaf spring 1f. 1g is fixed to the base 1e by being screwed into the base 1e. The collimator lens 1c is fitted into the center hole of the holder 11 and is fixed to the holder 11 by a set screw 1m inserted into a hole formed in the holder 11 in the radial direction. A hole 1p penetrated in the optical axis direction is formed in the carriage 1h. A base 1e is attached to one surface of the carriage 1h in which the hole 1p is formed (the surface on the near side in FIG. 2) so that the LD array 1a faces the hole 1p. Also, from the other side of the carriage 1h in which the hole 1p is formed, the hole 1p is formed.
The holder 11 is screwed into p, and the LD array 1a faces the collimating lens 1c.

Around the hole 1p of the carriage 1h,
A round hole 1n and a long hole 1o extending in the optical axis direction are formed. The round hole 1n and the long hole 1o constitute a part of the support and guide means, and are machined so as to be highly parallel to each other. As shown in FIG. 3, a shaft 11 as a guide member of the support and guide means extending in the optical axis direction is fitted in the round hole 1n in a highly accurate state with almost no gap. The carriage 1h is guided to move in the optical axis direction with the axis 11 as a reference. On the other hand, a shaft 12 extending in the optical axis direction, which constitutes a part of the support and guide means, is inserted into the elongated hole 1o so as to be in sliding contact with a part of the inner peripheral surface of the elongated hole 1o. This axis 1
Reference numeral 2 denotes an auxiliary member provided to guide the carriage 1h on the shaft 11 in the optical axis direction with high accuracy.

A screw 1k is provided on the upper surface of the carriage 1h.
This fixes the resin spring 1j. Resin spring 1j
A screw groove (not shown) is formed on the lower surface of the lead screw, and this screw groove is screwed with a lead screw 1q fixed to a housing in which the optical writing device is installed. A pulse motor 1i is attached to one end of the lead screw 1q. The rotation of the pulse motor 1i causes the rotation of the lead screw 1q, and the carriage 1h is moved in the optical axis direction by the lead of the lead screw 1q via the resin spring 1j. Moved to The rotational drive of the pulse motor 1i is controlled by the control unit 10.

Next, the second driving means 40 will be described. The second driving means 40 mainly includes a carriage 2h, a pulse motor 2i, a lead screw 2q, and the like. Hereinafter, a specific description will be given. As shown in FIGS. 2 and 3, the carriage 2h has a square hole 2 penetrated in the optical axis direction.
p is formed. The cylinder lens 2 is fitted into the square hole 2p, the cylinder lens 2 is pressed by the carriage 2h by the leaf spring 2r, and the screw 2s inserted into the hole of the leaf spring 2r is screwed into the carriage 2h. Is fixed to the carriage 2h.

Around the square hole 2p of the carriage 2h, a round hole 2n and a long hole 2o extending in the optical axis direction are formed. The round hole 2n and the long hole 2o constitute a part of the support and guide means, and are machined so as to be highly parallel to each other. As shown in FIG. 3, a shaft 11 as a guide member of a support guide extending in the optical axis direction is fitted in the round hole 2n in a highly accurate state with almost no gap. The carriage 2h is guided to move in the optical axis direction based on the shaft 11. On the other hand, a shaft 12 extending in the optical axis direction, which constitutes a part of the support and guide means, is inserted into the elongated hole 2o so as to be in sliding contact with a part of the inner peripheral surface of the elongated hole 2o. The shaft 12 is provided to assist the guide of the carriage 2h in the optical axis direction on the shaft 11 with high accuracy.

A screw 2k is provided on the upper surface of the carriage 2h.
This fixes the resin spring 2j. Resin spring 2j
A screw groove (not shown) is formed on the lower surface of the lead screw, and the screw groove is screwed with a lead screw 2q fixed to a housing in which the optical writing device is installed. A pulse motor 2i is attached to one end of the lead screw 2q. The rotation of the pulse motor 2i causes the lead screw 2q to rotate, and the carriage 2h is moved in the optical axis direction by the lead of the lead screw 2q via the resin spring 2j. Moved to The rotational drive of the pulse motor 2i is controlled by the control unit 10.

Next, the third driving means 50 will be described. The third driving means 50 mainly includes a carriage 3h, a pulse motor 3i, a lead screw 3q, and the like. Hereinafter, a specific description will be given. As shown in FIGS. 2 and 3, the carriage 3h has a square hole 3 penetrated in the optical axis direction.
p is formed. The cylindrical lens 3 is fitted into the square hole 3p, and the cylindrical lens 3 is pressed against the carriage 3h by a leaf spring 3r.
The screw 3s inserted into the hole of the leaf spring 3r is the carriage 3h.
Is fixed to the carriage 3h.

Around the square hole 3p of the carriage 3h, a round hole 3n and a long hole 3o extending in the optical axis direction are formed. The round hole 3n and the long hole 3o constitute a part of the supporting and guiding means, and are machined so as to be highly parallel to each other. As shown in FIG. 3, a shaft 11 as a guide member of the support and guide means extending in the optical axis direction is fitted in the round hole 3n in a highly accurate state with almost no gap. The carriage 3h is guided to move in the optical axis direction with the axis 11 as a reference. On the other hand, the shaft 12 extending in the optical axis direction, which constitutes a part of the support and guide means, is inserted into the elongated hole 3o so as to be in sliding contact with a part of the inner peripheral surface of the elongated hole 3o. The shaft 12 is provided to assist the guide of the carriage 3h in the optical axis direction on the shaft 11 with high accuracy.

A screw 3k is provided on the upper surface of the carriage 3h.
This fixes the resin spring 3j. Resin spring 3j
A screw groove (not shown) is formed on the lower surface of the lead screw, and this screw groove is screwed with a lead screw 3q fixed to a housing in which the optical writing device is installed. A pulse motor 3i is attached to one end of the lead screw 3q. The rotation of the pulse motor 3i causes the lead screw 3q to rotate, and the carriage 3h is moved in the optical axis direction by the lead of the lead screw 3q via the resin spring 3j. Moved to The rotational drive of the pulse motor 3i is controlled by the control unit 10.

As described above, the support and guide means is constituted by the shaft 11 as a guide member, the shaft 12 for assisting the guide of the shaft 11, the round holes 1n, 2n, 3n, and the elongated holes 1o, 2o, 3o. , The LD array 1a, the cylindrical lens 2 and the cylindrical lens 3, and guides the movement in the optical axis direction. That is, the LD array 1a
Is supported by the shaft 11 fitted into the round hole 1n of the carriage 1h and the shaft 12 inserted into the elongated hole 1o. Move to is guided. The rotation of the pulse motor 1i causes the lead screw 1q to rotate, whereby the carriage 1 is moved via the resin spring 1j.
h moves in the optical axis direction, so that the LD array 1a
Can be moved in the optical axis direction while being guided by the shaft 11, and the scanning pitch of the light beam in the sub-scanning direction on the surface to be scanned can be adjusted.

The cylindrical lens 2 is supported by the shaft 11 fitted in the round hole 2n of the carriage 2h and the shaft 12 inserted in the elongated hole 2o, and the carriage 2h is guided by the shaft 11. This guides the movement in the optical axis direction. In addition, the pulse motor 2i
The lead screw 2q is rotated by this rotation, whereby the carriage 2h moves in the optical axis direction via the resin spring 2j, so that the cylindrical lens 2 can move in the optical axis direction while being guided by the shaft 11. ,
The light beam diameter in the main scanning direction can be adjusted.

The cylindrical lens 3 is supported by the shaft 11 fitted in the round hole 3n of the carriage 3h and the shaft 12 inserted in the elongated hole 3o, and the carriage 3h is guided by the shaft 11. This guides the movement in the optical axis direction. Also, the pulse motor 3i
The lead screw 3q is rotated by this rotation, whereby the carriage 3h moves in the optical axis direction via the resin spring 3j, whereby the cylindrical lens 3 can move in the optical axis direction while being guided by the shaft 11. ,
The light beam diameter in the sub-scanning direction can be adjusted.

As described above, the LD array 1a, the cylindrical lens 2, and the cylindrical lens 3
It is guided by a book shaft 11. In other words, axis 1
1 is shared by the LD array 1a, the cylindrical lens 2, and the cylindrical lens 3. Therefore,
The relative positional accuracy of the LD array 1a, the cylindrical lens 2, and the cylindrical lens 3 can be kept high.

The LD array 1a, the cylindrical lens 2, and the cylindrical lens 3 are configured such that the shafts 11 and 12 have the mounting portions 20a, 20b, 20c, 20d, 21
By being attached to the optical writing devices a, 21b, 21c, and 21d, the optical writing device is provided so as to be movable in the optical axis direction. As shown in FIGS. 3 and 4, mounting portions 20a and 20
b, 20c, 20d, 21a, 21b, 21c, 21d
Is provided. More specifically, the mounting portion 20
a, 20b, 20c, and 20d are provided in this order at appropriate intervals in the optical axis direction and in the light beam emission direction. In addition, the mounting portions 21a, 21b, 21c, 21d also
In this order, they are provided at appropriate intervals in the optical axis direction and the light beam emission direction. In addition, the mounting portion 20a and the mounting portion 21a, the mounting portion 20b and the mounting portion 21b,
c and the mounting portion 21c, and the mounting portion 20d and the mounting portion 21d are arranged to face each other.

The mounting portions 20a, 20b, 20c, 20
Each of d, 21a, 21b, 21c, and 21d is formed in a stepped shape having an L-shaped cross section, and has a surface B parallel to the optical axis direction and a surface A perpendicular to the surface B. . The surface A of the mounting portions 20a, 20b, 20c, 20d is a reference for installation in a direction perpendicular to the optical axis direction of the shaft 11 of the supporting and guiding means, and is provided on the same extension surface with high precision. . Also, the mounting portions 21a, 21b, 21c, 21
The surface B of d serves as an installation reference in a direction perpendicular to the optical axis direction of the shaft 12 of the support and guide means, and is provided on the same extension surface with high precision. The surface A and the surface B can be formed into a high-precision processing surface using, for example, machining. In the case of molding such as injection molding or die-casting, a high-precision identical die is used. A surface can be formed.

The shaft 11 has mounting portions 20a, 20b, 2
0c and 20d are in contact with both surface A and surface B,
The leaf spring 60 presses against the surfaces A and B,
The mounting portion 2 is formed by screws 61 inserted into holes formed in the mounting portion 2.
0a, 20b, 20c, and 20d. The shaft 12 is in contact with both the surface A and the surface B of the mounting portions 21a, 21b, 21c, and 21d, and is pressed by the surface A and the surface B by the plate spring 60 to form the plate spring 60. With the screws 61 inserted into the holes, the mounting portions 21a, 21b,
It is fixed to 21c, 21d. As described above, since the surface A and the surface B of each mounting portion are formed and provided with high precision, the movement of the carriages 1h, 2h, 3h can be improved with high accuracy, and the LD array 1a, The cylindrical lens 2 and the cylindrical lens 3 can be moved in the optical axis direction with high accuracy.

The pulse motors 1i, 2i, 3i
Between the carriage 1h, 2
This is an important factor for improving the stability of the movement of h and 3h. FIG. 5 shows the relationship between the pulse motor 2i and the shaft 11. As shown in FIG.
The distance between the center axis of i, that is, the center axis of the lead screw 2q and the center of the shaft 11 is d, and the carriage 2h
When the contact points between the shaft 11 and the shaft 11 are P and Q, the driving force F of the pulse motor 2i generates reaction forces R at the contact points P and Q in directions perpendicular to the shaft 11 and opposite to each other. A friction force μR (μ = friction coefficient) in the same direction is generated. The contact point between the extension line of the resultant force of the reaction force R and the frictional force μR at the contact point P and the extension line of the resultant force of the reaction force R and the frictional force μR at the contact point Q is defined as O. When the vertical distance is x, according to the principle of the narrow guide,
If the distance d <x, the carriage 2h can move in the optical axis direction, but if d> x, the carriage 2h
Cannot move in the optical axis direction. This is because an eccentric load is generated due to the positional relationship between the pulse motor 2i and the shaft 11, and the carriage 2h is twisted and meshes with the shaft 11.

Therefore, the pulse motors 1i, 2i, 3i and the shaft 11 must be arranged so as to satisfy the distance d <x.
With the arrangement of i, 2i, 3i and the shaft 11, the carriages 1h, 2h, 3h can be moved in the optical axis direction, but the carriages 1h, 2h, 3h can be moved with high precision and stability. Can not. Therefore, the pulse motor 1 is set so that the vertical distance x is sufficiently larger than the distance d.
i, 2i, 3i and the shaft 11 must be arranged.
Therefore, in the above embodiment, the distance d is made as small as possible to reduce the distance between the pulse motors 1i, 2i, 3i and the shaft 11. That is, the pulse motors 1i, 2i,
The driving point 3i is located near the shaft 11. As a result, the generation of an extra moment due to the eccentric load generated on the shaft 11 of the carriage can be prevented, the power consumption of the pulse motor can be reduced, and the life of the shaft 11 can be extended. Further, the LD array 1a, the cylindrical lens 2, and the cylindrical lens 3 can be moved in the optical axis direction with high precision and smoothness. Also, axis 1
Assuming that the diameter of the shaft 1 is b and the distance between the contact point P and the contact point Q in the optical axis direction is 1, the diameter b of the shaft 11 is made as large as possible and the value of b / l is made small.
h, 2h and 3h can be moved more accurately and stably.

As described above, the carriages 1h, 2h
When the shafts h and 3h move in the direction of the optical axis, frictional force is generated at the contact portions between the shaft 11 and the carriages 1h, 2h and 3h. Therefore, a sintered metal bearing or a ball bearing is used for the contact portions. Thus, the frictional force can be reduced. However, when a sintered metal bearing, a ball bearing, or the like is used, the number of parts increases and the cost increases accordingly. Further, since a sintered metal bearing or a ball bearing is used, the positional accuracy between the shaft 11 and the carriage may be deteriorated. Therefore, a sintered metal bearing or a ball bearing may be used in consideration of the load on the carriage, the moving speed of the carriage, and the like.

[0041]

According to the first aspect of the present invention, a light source unit formed of a light emitting source and an optical element, and a first optical system for guiding a light beam from the light source unit to a deflector using a plurality of optical elements. A second optical system that forms an image of the light beam deflected by the deflector on the surface to be scanned as a scanning line, a detection unit that detects an imaging state of the image beam on the surface to be scanned, Support and guide means for supporting the plurality of optical elements of the first optical system and the light emitting source, and for guiding the movement of the plurality of optical elements and the light emitting source in the optical axis direction;
Since a plurality of optical elements of the first optical system and a plurality of driving means and a control means for independently driving the light emitting source in the optical axis direction are provided, the plurality of optical elements and the light emitting source are respectively driven by the driving means. By independently driving in the optical axis direction and guiding each part by common support and guide means,
The beam diameter in the main scanning direction, the beam diameter in the sub-scanning direction, and the pitch in the sub-scanning direction on the surface to be scanned can be independently and satisfactorily corrected.

According to the second aspect of the present invention, in the first aspect of the present invention, the light emitting source has a plurality of light emitting points. The light emitting sources are independently driven in the optical axis direction by driving means, and the respective parts are guided by a common supporting and guiding means, so that the beam diameter in the main scanning direction, the beam diameter in the sub-scanning direction, and on the surface to be scanned. The pitch in the sub-scanning direction can be independently and satisfactorily corrected.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the reference for setting the support and guide means in a direction perpendicular to the optical axis direction is formed on the same extension surface. Therefore, the light emitting source and the plurality of optical elements can be moved in the optical axis direction with high accuracy.

According to the fourth aspect of the present invention, in the first or second aspect of the present invention, since the guide member of the supporting and guiding means is shared, the positional accuracy of the light emitting source and the plurality of optical elements are mutually determined. Can be kept high.

According to the fifth aspect of the present invention, in the first or second aspect of the present invention, since the driving point of the driving means is set near the supporting and guiding means, the driving point is generated with respect to the supporting and guiding means of the driving means. The generation of an extra moment due to the eccentric load can be prevented, the power consumption of the driving means can be reduced, and the life of the guide member can be extended. Further, the light emitting source and the plurality of optical elements can be moved in the optical axis direction with high precision and smoothness.

[Brief description of the drawings]

FIG. 1 is an optical layout diagram showing an embodiment of an optical writing device according to the present invention.

FIG. 2 is an exploded perspective view showing a first driving unit, a second driving unit, and a third driving unit applicable to the embodiment.

FIG. 3 is an assembled perspective view showing the first driving means, the second driving means, and the third driving means.

FIG. 4 is another assembly perspective view showing the first driving means, the second driving means, and the third driving means.

FIG. 5 is a plan view showing a positional relationship between the first driving unit, the second driving unit, and the third driving unit and a supporting and guiding unit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Light source unit 1a LD array 1h, 2h, 3h Carriage 1i, 2i, 3i Pulse motor 1q, 2q, 3q Lead screw 1n, 2n, 3n Round hole 1o, 2o, 3o Long hole 2 Cylindrical lens 3 Cylindrical lens 9 Photodiode 10 Control unit 11 axis 12 axis 20 First optical system 20a, 20b, 20c, 20d, 21a, 21b, 2
1c, 21d Mounting part 30 First driving means 40 Second driving means 50 Third driving means

Claims (5)

[Claims] A light source unit formed of a light emitting source and an optical element; a first optical system for guiding a light beam from the light source unit to a deflector using a plurality of optical elements; and light deflected by the deflector. A second optical system that forms an image of the beam as a scanning line on the surface to be scanned, a detecting unit that detects an imaging state of the image forming beam on the surface to be scanned, and a plurality of optical elements of the first optical system. A support and guide means for supporting the light emitting source and guiding movement of the plurality of optical elements and the light emitting source in the optical axis direction; and independent of the plurality of optical elements of the first optical system and the light emitting source. An optical writing device further comprising a plurality of driving means and control means for driving in the optical axis direction. 2. The optical writing device according to claim 1, wherein said light emitting source has a plurality of light emitting points. 3. The optical writing device according to claim 1, wherein the reference for setting the support guide means in a direction perpendicular to the optical axis direction is formed on the same extension surface. 4. The optical writing device according to claim 1, wherein a guide member of said support guide means is shared. 5. An optical writing apparatus according to claim 1, wherein a driving point of said driving means is provided near said supporting and guiding means.