JP2002277805A - Optical scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately form a shape, by which a luminous flux diameter of a light beam can be accurately regulated and which is suitable for incidence and emission, when the substrate where an aperture is formed in made thick or the light beam is inclined and made incident from a direction orthogonal to the surface of the substrate. SOLUTION: An opening 11 is formed by using a means such as etching in opening holes on silicon substrates 15c and 16 used as apertures. By performing work from the front and back surfaces of the substrate, so that front and back patterns is the same or different, the openings 11 and so on are formed in an arbitrary shape, whereby light is prevented from being eclipsed at a light passing allowable part 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical scanning device of an optical apparatus, and more particularly, to an optical scanning device of a writing optical system used for a laser printer or the like.

[0002]

2. Description of the Related Art Conventionally, a writing optical system of a laser printer obtains an angle of view (scanning angle, hereinafter referred to as a scanning angle) by scanning a light beam in a main scanning direction using a polygon mirror. Imaged above. In order to improve the image quality of the printer, it is necessary to reduce the focused spot diameter of the beam. However, the focused spot diameter is proportional to the product of the laser wavelength and the focal length. And (2) a method of shortening the focal length.

In the case of shortening the wavelength of the laser in the above (1), it is necessary to use a blue laser diode and to design an optical system such as a lens corresponding thereto. In the case of shortening the focal length in the above (2), it is necessary to bring an optical system subsequent to the deflecting unit for deflecting the light beam closer to the photosensitive member. In this case, it is difficult to achieve uniform pixels in the main scanning direction with a single deflecting unit, and it is necessary to use a plurality of modularized deflecting units arranged in the main scanning direction.
The use of one deflecting unit is referred to as a batch scanning method, whereas the division scanning method is used.

[0004] Among the above-mentioned divided scanning methods, there is a method using a micromirror in addition to using a conventional polygon mirror having a reduced diameter. The use of a polygon mirror has the advantage that it is advantageous for speeding up and miniaturization. Also, among the micromirrors, there are three types, the electromagnetic type, the piezoelectric type, and the electrostatic type, depending on the driving method. The electromagnetic force method and the piezoelectric method can easily obtain a large scanning angle, but on the other hand, use permanent magnets and piezoelectric elements, so that the number of parts is large and miniaturization is difficult. On the other hand, while the electrostatic force method can be easily miniaturized, the scanning angle and the driving voltage have a relationship such as a trade-off, and it is difficult to obtain a large scanning angle. Therefore, in the case of the electrostatic force method, an attempt has been made to provide a reflection mirror (hereinafter referred to as an opposing mirror) at a position facing the micromirror and cause multiple reflections between the micromirror and the reflection mirror to obtain a large scanning angle. is there.

The facing mirror used for the above-mentioned multiple reflection type electrostatic micromirror needs to be provided with an opening between the micromirror and the facing mirror for transmitting and receiving a light beam.
Here, for example, if the entrance aperture of the opposed mirror can be used also as an aperture for defining the light beam diameter of the light beam,
The aperture provided next to the collimating lens can be omitted, and the number of components can be reduced. Furthermore,
Since it is a module part, the effect of reducing the number of parts is great. In the case of a multiple reflection type electrostatic micromirror formed by aligning the micromirror and the opposing mirror with a high-precision alignment device, the incident aperture of the opposing mirror is also used as an aperture for defining the light beam diameter of the light beam. This also has the effect that the alignment of the light beam with the multiple reflection type electrostatic micromirror is facilitated.

[0006]

However, there are the following problems in using the entrance aperture of the opposing mirror as an aperture for defining the light beam diameter of the light beam. First, in order to use the mirror as a facing mirror, a certain thickness is required so that the mirror surface is not distorted. Therefore, when forming an opening that can be used as an aperture in a thick opposing mirror, it is necessary to accurately form the opening edge and the inner surface of the opening. When the substrate is thin, it is easy to process, and the shape of the inner surface of the opening does not affect the light beam passing through much.However, as the thickness of the substrate increases, the processing becomes more difficult, and The shape is more likely to affect the passing light beam.

Further, when a light beam is incident at an angle from a direction perpendicular to the substrate surface, the light beam diameter defined by the aperture is defined by the overlapping portion of the opening edge on the front and back of the substrate. There is a problem that the luminous flux cannot be defined with high accuracy because the positional deviation of the edge (in the case of double-sided processing) and the variation of the substrate thickness affect the luminous flux diameter.

According to the present invention, when a substrate on which an aperture is formed is made thicker, or when a light beam is incident obliquely from a direction perpendicular to the substrate surface, the light beam diameter of the light beam can be defined with high accuracy. An object is to form a shape suitable for emission with high precision.

[0009]

SUMMARY OF THE INVENTION The present invention provides a light source having a light source, a movable mirror for scanning a light beam from the light source, and a substrate having an aperture defining at least one side of the light beam diameter. It relates to a scanning device. In the present invention, a single crystal silicon substrate having a crystal plane orientation of [100] is used, and the inner surface of the opening in the thickness direction of the substrate is the same as or less than the surface connecting the opening edges on the front and back of the substrate. Or
The light beam is defined by one of the opening edges of the front and back surfaces of the substrate.

[0010] With the above-described configuration, the inner surface in the thickness direction of the opening of the opening that defines at least one side of the light beam diameter is equal to or larger than the surface connecting the opening edges of the front and back surfaces of the substrate. Because of the concave shape, the cross-sectional shape of the aperture does not affect the light beam diameter. Also, when the light beam passes through the aperture, it does not hit the inner surface of the aperture, or even if it hits, the reflected beam does not proceed in the direction of travel of the light beam, so it does not have a significant effect The diameter of the light beam after passing through the aperture can be defined with high accuracy, and the influence of the reflected beam can be suppressed. Furthermore, since a single crystal silicon substrate having a crystal plane orientation of [100] is used as the substrate material, the inner surface of the hole corresponding to the shape of the opening edge is formed along the crystal plane by anisotropic etching using an alkaline aqueous solution. It is formed with high accuracy, and it is possible to achieve effects such as remarkable improvement of the accuracy of the aperture and the accuracy of the light beam diameter associated therewith.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a production flow when an opening which can be the aperture is formed by anisotropic etching using a silicon substrate. Here, the silicon substrate 12 uses a plane orientation [110] substrate. First, FIG.
As shown in FIG. 1A, an SiN film 13 is formed on both sides of a silicon substrate 12 by an LPCVD method, and an opening pattern 14 is formed as shown in FIG. Form. Thereafter, the anisotropic etching is performed with an alkaline aqueous solution such as a KOH aqueous solution having a concentration of 25 wt% and a temperature of 80 ° C., so that the [111] plane perpendicular to the substrate surface has an extremely low etching rate. In FIG. 12, a vertical opening 11 is formed as shown in FIG. Finally, SiN
By removing the film 13 by wet etching,
A substrate member 10 as shown in FIG. 1D is completed. Here, when a silicon substrate having a plane orientation of [110] is used, since the [111] plane forms 54.7 ° with the substrate surface, an opening forming 54.7 ° with the substrate surface is formed.

Next, FIG. 2 shows a production flow when an opening pattern 14 is formed on the front and back surfaces of a [100] silicon substrate 12a using a silicon substrate 12a and anisotropic etching is performed from both surfaces. In the example shown in FIG. 2, a SiN film 13 is formed on both sides of a silicon substrate 12 by LPCVD as shown in FIG. 2A by the same method as the example shown in FIG. And dry etching of SiN to form an opening pattern 1 as shown in FIGS.
4, 14a are formed. Then, after forming up to FIG. 2C, for example, KOH having a concentration of 25 Wt% and a temperature of 80 ° is used.
Anisotropically etch from both sides with aqueous solution. As the etching proceeds, it forms 54.7 ° with the substrate surface [11].
1] A hole is formed along the plane, and penetrates at the center of the substrate as shown in FIG. Then, since the [110] plane having a high etching rate and perpendicular to the substrate surface is exposed, the etching starts to start inside the substrate as shown in FIG. Then, as shown in FIG. 2 (f), the [111] plane forming 125.3 ° with the substrate surface reappears, so that the etching stops spontaneously. Hereinafter, FIG.
Through the same steps as described above, the substrate member 10a as shown in FIG. 2A is completed. By using this method, a shape in which the inner side surface in the thickness direction of the substrate is depressed from the surface connecting the opening edges of the front and back surfaces of the substrate can be obtained.

[0013] By configuring as described above,
The inner surface of the aperture defining at least one side of the light beam luminous flux diameter in the thickness direction of the substrate has the same shape as the surface connecting the opening edges of the front and back surfaces of the substrate or is depressed therefrom, so the cross-sectional shape of the aperture Does not affect the beam diameter of the light beam. Also, when the light beam passes through the aperture, it does not hit the inner surface of the aperture, or even if it hits, the reflected beam does not proceed in the direction of travel of the light beam, so it does not have a significant effect The diameter of the light beam after passing through the aperture can be defined with high accuracy, and the influence of the reflected beam can be suppressed. Furthermore, since a single crystal silicon substrate having a crystal plane orientation of [100] is used as the substrate material, the inner surface of the hole corresponding to the shape of the opening edge is formed along the crystal plane by anisotropic etching using an alkaline aqueous solution. It is formed with high precision, and there is an effect that the precision of the aperture and the precision of the beam diameter associated therewith are significantly improved.

FIG. 3 shows four types of substrates having holes formed by anisotropic etching using a silicon substrate. FIG.
(A) uses a [100] plane orientation substrate, etches from the upper surface of the silicon substrate 15, and opens the openings 11 and 11a, and (b) uses a [100] plane orientation substrate. Etching was performed from the lower surface of the substrate, and the shape provided with each opening was used.
(D) shows a shape in which an opening is provided by etching from the upper surface of the substrate (the same applies to the lower surface), and (d) shows a shape in which an opening is provided by etching from both surfaces of the substrate using a [100] substrate. ing. Each of the silicon substrates 15, 1
In the example of 5a..., The number of apertures provided in the silicon substrate is two each, and a light beam R1 having an incident angle b is incident from one side (left side in the figure) and is shown in the figure. It shows the optical path of the light beam R that is reflected by the micromirror, reflected once between two opposing apertures, reflected again by the micromirror, and finally emitted from the other aperture.

Assuming that the aperture on the entrance side is an aperture, the diameter of the light beam 17 in the traveling direction of the incident beam is the lower aperture edge in FIG. 3 (a) and the upper aperture edge in FIG. 3 (b). 3
In (c) and (d), when the lower opening diameter is a and the substrate thickness is T, it is defined by (a−T × tan (b)). In order to define the light beam diameter with high accuracy, it is preferable that the light beam diameter is not affected by the thickness (T ± ΔT) of the substrate. However, FIG.
Regarding (b), the luminous flux is defined at the opening edge opposite to the opening pattern formed at the time of etching, so that the light flux varies by 2 × (2 × ΔT) tan (54.7).

Referring to FIGS. 3C and 3D, there is an effect of variations in the substrate thickness as expressed by the above equations. Further, referring to FIG. 3B, there is almost no distance between the openings facing the micromirrors, and there is actually no multiple reflection. FIG.
As for (a), there is no problem with multiple reflection, but since there is almost no distance between the openings on the upper surface, the structure has no margin for use as an aperture.
However, in the structure of FIG. 3D, all of the above-mentioned problems can be solved by shifting the aperture patterns on the front and back according to the inclination direction of the incident beam.

Therefore, when the opening pattern on the front and back of the silicon substrate 15c is shifted by the method shown in FIG. 3D, the pattern is divided into three types depending on the difference in the amount of the shift. To (c). Looking at the shape of FIG. 4 and the optical path of the incident beam, for example, in the case of FIG. 4A, the same one as the example of FIG. 3D is illustrated, but in the silicon substrate 15c, The case where the incident angle can be formed at 54.7 ° is shown. Further, in the example of the silicon substrates 16 and 16a shown in FIGS. 4B and 4C, by displacing the opening patterns on the front and back of the silicon substrate, the incident beam R1 and the incident beam R1 are independent of the variation in the substrate thickness. The reflected beam R can be defined as a highly accurate light beam 17. Further, by setting the aperture pattern diameter to be different for each of the front and back sides, the aperture edge for defining the light flux can be set in a state where it is shifted upward or downward.

In the silicon substrate, the luminous flux is defined by one of the opening edges of the front and back of the substrate.
When the luminous flux is defined by the overlapping portion of the front and back opening edges of the substrate, the positional deviation of the front and back opening edges varies,
Since there is no problem that the variation in the thickness of the substrate affects the beam diameter, the beam can be defined with high accuracy. In addition, since the light beam is defined by the opening edge on the side where the light beam is incident, there is no reflected beam hitting the inner surface of the opening, and the emitted beam is only the beam with the defined light beam. The reliability is improved without affecting the above optical system. Furthermore, when the light beam is incident from a direction perpendicular to the substrate surface, the position of the opening edge between the front and back of the substrate is shifted according to the inclination direction of the light beam, so that either one of the front and back surfaces of the substrate can be used. The luminous flux can be defined by the opening edge of.

Next, the configuration of an optical scanning device in which the substrate member formed by the above-described method is incorporated as a counter mirror or another substrate, the configuration of a laser printer, and the operation of light reflection in the optical scanning device will be described. . In FIG.
1 shows a configuration of a mirror unit 1 provided in an optical scanning device, and a mirror substrate is formed by joining two Si substrates. The movable mirror 3 and the torsion bar 3a supporting the same are etched by etching the first substrate 2.
It is formed integrally with the central part of the substrate 2. A mirror surface is formed in the center of the movable mirror 3 by depositing a metal film or the like, and both ends of the movable mirror 3 are formed into a comb-shaped uneven surface with the torsion bars 3a, 3a therebetween. The electrode 4 is formed. In addition, by making the movable electrode 4 in a comb shape, the area of the facing electrode can be enlarged, and the driving voltage can be reduced.

A second substrate 5 is combined with the lower surface of the first substrate 2, and a space is formed in the center of the second substrate 5 to allow the movable mirror 3 to swing. Have been. Further, a spacer 6 is disposed between the first mirror and the opposing mirror substrate 7 disposed on the first substrate, and both sides of the spacer 6 are matched with the comb shape of the movable mirror 3. The movable mirror 3 is formed as a comb-shaped space that allows the movable mirror 3 to swing. Electrode substrates 8 and 8a are provided on the first substrate 2 corresponding to the movable electrodes 4 provided on the movable mirror 3, and fixed electrodes 9 and 9a are formed on the lower surface of the opposing mirror substrate 7, respectively. ing. A movable electrode 4 provided on the movable mirror 3
Then, by applying a predetermined voltage to the fixed electrodes 8 and 9 at the timing described below, the movable mirror 3 is swung about the torsion bar.

The counter mirror substrate 7 has a light-permitting portion formed thereon as disclosed in the silicon substrate forming method, and is provided on the lower surface of the substrate between the two light-permitting portions. Is provided with a facing mirror 7a having a mirror surface formed by evaporating a metal film or the like. In the mirror unit 1 shown in FIG. 5, the incident light beam R1 is obliquely incident from one of the openings provided in the scanning direction, and is between the movable mirror 3 and the reflection surface of the counter mirror 7a. Move in the sub-scanning direction while repeating reflection a plurality of times, and are emitted as scanning light R from the other opening.
According to the configuration described above, in the optical scanning device, by providing the second aperture through which the light beam reflected by the movable mirror passes, when the light beam passes through the first aperture, the reflection generated on the inner side surface is generated. Even if the beam is reflected by the movable mirror, a component returning in the traveling direction of the light beam can be blocked. In addition, the optical scanning device can scan by reflecting the light beam to the movable mirror twice or more, so that a larger scanning angle can be obtained by a simple change of the deflection unit.

In the example of the mirror unit 1 shown in FIG. 5, the movable mirror 3 is supported by a torsion bar 3a.
As a result, an electrostatic attraction is generated between the movable electrode 4 and the corresponding fixed electrode 8, the torsion bar is twisted, and the movable mirror 3 starts to tilt from a horizontal state. Furthermore, the torsion bar can be inclined to an angle balanced with the restoring force of the torsion bar to be returned to the horizontal state by being attracted by the electrostatic attraction generated between the second fixed electrode 9 and the second fixed electrode 9 formed on the opposed mirror substrate 7. . In this state, the application to the fixed electrodes 8 and 9 is released, and the fixed electrodes 8a and symmetrically formed with the torsion bar interposed therebetween.
If the electrostatic attraction is generated alternately between the movable mirror 9a and the movable mirror 9a, the movable mirror can reciprocate.

When the timing at which the electrostatic attractive force is generated approaches the natural frequency of the movable mirror, a resonance state is established, and a large deflection angle can be obtained with a low applied voltage.
In the embodiment, the natural frequency of the movable mirror is set to match the recording speed, that is, the thickness and length of the torsion bar are determined. As the recording speed increases, the rigidity of the torsion bar increases and the deflection angle is suppressed. Therefore, by providing the opposing mirror, the light beam is deflected a plurality of times by the movable mirror, and the scanning angle is enlarged. The light beam R1 is incident from above, and once reflected by the movable mirror 3, the scanning angle becomes twice as large as the deflection angle. Corner 2
Double is added. As described above, the scanning angle can be increased according to the number of times of reflection by the movable mirror.

FIG. 7 is a block diagram of a control device for driving the movable mirror 3, and FIG. 8 is a timing chart of voltage application to each electrode for driving the movable mirror. 5 and 6
In order to drive the movable mirror 3, a control device 70 as shown in FIG. In the control device 70, a calculation unit 71 for inputting detection signals of the synchronization detection sensor 58 and the termination detection sensor 59, a writing control unit 73, and the semiconductor laser 7 for writing an image.
8 is provided with an LD conversion section 72 for controlling a write signal. Further, a frequency setting unit 74 for controlling the vibration of the movable mirror 3 based on a signal from the writing control unit 73 is provided.
Are connected to each other to apply a voltage to each of the fixed electrodes provided on each substrate.

The fixed electrodes are first fixed electrodes 8 and 8a symmetrically opposed to the end face of the movable mirror 3 with the axis (torsion bar 3a) of the movable mirror 3 interposed therebetween.
Are provided. Electrode modulators 75 and 76 for one side of the movable mirror 3 and electrode modulators 75a and 76a for the other electrode are arranged between the electrodes and the frequency setting unit 74, respectively. The control device 70 controls the application of voltage to each component, controls the writing operation by the semiconductor laser, and controls the driving of the movable mirror, as shown in the timing chart of FIG.

In the example shown in FIGS.
Is in a horizontal state (θ = 0) in a steady state. First, a voltage is applied to the first fixed electrode 8, and after a predetermined time has passed, a voltage is applied to the second fixed electrode 9, to reach the angle (−θ). Rotate. When the voltage is released at this time, the movable mirror is inverted by the restoring force, and when the movable mirror has passed the horizontal position, the first mirror on the opposite side has been moved.
By applying a voltage to the second electrode 9a and subsequently applying a voltage to the second electrode 9a, the electrode 8a rotates to the angle (+ θ). By repeating this operation, the mirror reciprocates. On the other hand, the semiconductor laser 78 has + θ starting from the angle −θ.
Is reached, the forward scanning is performed, and from the angle + θ as the starting point, the backward scanning is performed until the angle reaches -θ, and image recording is performed in a reciprocating manner. The semiconductor laser 78 is turned on when the applied voltage is released, and the synchronization detection sensor 58 detects a light beam to generate a synchronization signal. Based on this signal, the timing of recording start in either forward scanning or backward scanning I am taking it.

The frequency is set and a voltage is applied to each fixed electrode so that the movable mirror is in a resonance state. However, the scanning speed fluctuates because the resonance frequency is shifted due to a change in environmental temperature or the like. Therefore, the end detection sensor 59 detects the light beam at the end of scanning, measures the time between the end detection signal and the synchronization detection signal from the synchronization detection sensor, and sets the semiconductor laser so that the recording width of the image becomes constant. Is variable. As described above, the image writing in the printer or the like is performed by controlling the operation of oscillating the movable mirror 3 and the operation of reflecting the scanning light.

FIGS. 6 and 9 show examples in which the mirror unit 1 is incorporated to constitute an optical scanning module. The example shown in FIG. 6 will be further described.
The support substrate 30 disposed at the lower part of the base plate 0 is formed of a sintered metal or the like, and the lead terminals 43 are inserted through an insulating material.
The support substrate 30 has a bonding surface 31 for bonding the mirror substrate 5, a V-groove (tilted support surface) 32 for positioning and bonding the coupling lens 38, and a mounting portion for an LD chip 36 formed perpendicular to the bonding surface 31. Is provided. Also, LD
The mounting surface 33 of the monitor PD chip 37 for receiving the back light of 36 and the support portion 34 of the prism mirror 41 for turning the light beam output from the LD chip back to the movable mirror 3 are formed. Further, a stepped portion 35 for locking and holding the lower end of the cover 40 is provided around the support substrate 30.
Is formed.

The coupling lens 38 disposed between the mirror unit 1 and the LD chip 36 is formed in a shape in which the upper and lower portions of a cylinder are cut, and the first surface is an axisymmetric aspherical surface, and the second surface is a sub surface. The cylinder surface has a curvature in the scanning direction. When the cylindrical outer peripheral surface of the coupling lens 38 comes into contact with the V groove 32 provided in the support substrate 30, the width and angle are set so that the optical axis matches the light emitting point of the LD chip 36. By adjusting in the axial direction, the divergent light beam is adhered and fixed so as to become a substantially parallel light beam in the main scanning direction and a focused light beam converged on the movable mirror surface in the sub-scanning direction.
The cut surface of the lens 38 is formed parallel to the generatrix of the cylinder surface so that positioning around the optical axis is performed.

The inner cover 44 disposed so as to cover the mirror unit 1 is provided with an aperture 46 for shaping the light beam from the coupling lens 38 into a predetermined diameter. A spring part 45 for positioning the part is formed. The light beam as the scanning light deflected by the movable mirror 3 of the mirror unit 1 passes through an aperture 47 (shown in FIG. 5) provided on the upper surface and is emitted upward. The cover member 40 provided so as to cover the optical scanning module 20 is formed into a cap shape by sheet metal, and a glass plate 48 is joined to an emission opening of the light beam from the inside. 30
Is fitted into a step 35 provided on the outer periphery of the module to constitute a module. LD chip 36, monitor PD chip 3
7. Each of the above-mentioned fixed electrodes is connected by wire bonding to an end protruding above the lead terminal 43.

FIG. 9 is a sectional view of an optical scanning device provided with an optical scanning module.
In the example shown in FIG.
The reference numeral 0 denotes a plurality of (three in this embodiment) arrayed in the main scanning direction on a printed circuit board 50 on which electronic components constituting an LD driving circuit and a movable mirror driving circuit are mounted.
When the optical scanning module 20 is mounted, the bottom surface of the support substrate 30 is brought into contact with the printed circuit board through the lead terminal 43 projecting downward through the through hole, and the light on the substrate is set within the clearance of the through hole. The scanning modules are aligned and temporarily fixed, soldered together with other electronic components, and fixed collectively.

In the example shown in FIGS. 10 and 11, the optical scanning device 21 has three optical scanning modules 20 arranged in parallel so as to irradiate the surface of the photosensitive drum with image light. . In the optical scanning device 21, the scanning lines 18,...
As shown in FIG. 1, the scanning is performed in a state where the scanning range of each optical scanning module 20 is defined, and writing is performed by adjusting so that a scan image by the adjacent optical scanning module 20 does not shift. I do. In the optical scanning device 21 in which the plurality of optical scanning modules 20 are arranged in combination, each optical scanning module 20 is positioned on the printed circuit board 50, and a housing 51 incorporating a lens or the like is mounted. And the optical scanning device 2
It is integrated as 1.

The printed circuit board 50 supporting the plurality of optical scanning modules is abutted so as to close the lower opening of the housing 51, and is held and held between a pair of snap claws 52 provided integrally with the housing 51. The printed board is provided with a notch 56 that engages with the width of the snap claw, and is positioned in the main scanning direction, and at the same time, the locking portion 55 is engaged with the board edge to fix the sub scanning direction. .
The locking portion 55 is bent in the direction of the arrow to
Pushes down on the upper end of the substrate and can be easily removed.
Inside the housing 51, a positioning surface for arranging and joining first scanning lenses 60 constituting an imaging unit in the main scanning direction, and a positioning unit 5 for holding a second scanning lens 61
3, and a holding portion for the synchronous mirror 57 are formed.

In this embodiment, the second scanning lens of each optical scanning module is integrally formed of resin, and the synchronizing mirror 57 is formed by connecting a high-luminance aluminum plate to emit a light beam. It is inserted and attached to the opening from the outside.
Synchronous detection sensors 58 (PIN photodiodes) are arranged at intermediate positions and both end positions shared by the adjacent optical scanning modules, and the printed circuit board 50 is arranged so that a beam can be detected at the scanning start side and the scanning end side of each optical scanning module. Implemented above. The synchronizing mirror 57 is shaped like a square so that the reflection surfaces of the adjacent optical scanning module scanning start side and the scanning end side face each other, reflects each light beam, and guides the light beam to a common synchronization detection sensor 58. Have to be able to. In the figure, a connector 62 projecting below the printed circuit board 50 supplies power to all optical scanning modules provided in the optical scanning device and exchanges data signals and the like collectively.

Spacers 63 are disposed on both side surfaces of the housing 51, and light is applied to a cartridge holding a photosensitive drum, which will be described later, according to the cylindrical surface of a cartridge frame provided concentrically with the photosensitive drum. Scanning device 2
1 is positioned. The spacer 6
Reference numeral 3 denotes a part in which the projections 66 and 66a of the housing 51 are locked to the main body as an upright member, and attached to both ends of the housing 51 by, for example, attaching screws. An arcuate surface 64 formed at the upper end of the spacer 63 is provided as a surface that abuts against the cartridge frame, and is configured to be urged by a spring 68 via the base 64. Studs 67 are provided on the frame of the apparatus main body corresponding to the spacers 63, and the studs 67 are inserted into holes of the lower flange 65 of the spacer 63, and are supported in a state of being urged upward by a spring 68. Then, by adjusting the mounting state of the optical scanning device 21 using the positioning means of the housing,
The positioning of the plurality of optical scanning modules with respect to the surface to be scanned can be collectively and reliably performed.

FIG. 12 shows an example of an image forming apparatus in which the optical scanning device is applied to a laser printer. In the image forming apparatus 80, the photosensitive drum 81 and the components for image formation are configured as one unit, and each of these components is integrally configured as a replaceable cartridge. That is, the photosensitive drum 8
1, a charging roller 8 for charging the photosensitive member to a high pressure
2. A developing roller 83 for adhering toner to the electrostatic latent image recorded by the optical scanning device 21 for visualization, a toner hopper 84 for storing toner, and a blade for scraping residual toner after being transferred to paper. Cleaning case 85 that accumulates
Is deployed. In the image forming apparatus 80, the optical scanning device 21 for writing an image on the photosensitive drum 81 is disposed in a state of being positioned with respect to the frame 92 of the cartridge, and determines the length of the scanning optical path. It is adjusted by the member (spacer) 63.

The paper is supplied from a paper feed tray 86 by a paper feed roller 87, is conveyed along a paper conveyance path 93, and is sent by a registration roller pair 88 to the image transfer section at the timing of printing. Then, the image is transferred by the photosensitive drum 81 rotating in the sheet transport direction, is fixed by the fixing roller 89, and is discharged toward the discharge tray 90.
The apparatus cover 91 is rotatably supported so as to be able to clean the second scanning lens in addition to exchanging the cartridge or removing a sheet having a paper jam.

In the embodiment, the method of driving the movable mirror by generating an electrostatic attraction is shown. However, a coil is formed on the movable mirror, and the movable mirror is arranged so that the magnetic force lines pass in a direction intersecting with the torsion bar. Even a method of driving by applying a voltage to generate an electromagnetic force, a method of coupling a piezoelectric element to a torsion bar, applying a voltage to the piezoelectric element to directly generate a displacement on a movable mirror, and the like. Can be implemented with a similar configuration. Although the optical scanning device is constituted by three optical scanning modules, the number may be any number, and the number may be increased or decreased according to the recording width of the image forming apparatus.

[0039]

According to the structure described above, the inner surface of the aperture defining at least one side of the light beam luminous flux diameter in the thickness direction of the substrate is the same as or similar to the surface connecting the aperture edges of the front and back surfaces of the substrate. Since it has a more concave shape, the cross-sectional shape of the aperture does not affect the light beam diameter. Also,
When the light beam passes through the aperture, it does not hit the inner surface of the aperture, or even if it does, the reflected beam does not travel in the direction of travel of the light beam, so it does not have a significant effect. The light beam diameter after passing through the hole can be defined with high accuracy, and the influence of the reflected beam can be suppressed. Furthermore, since a single crystal silicon substrate having a crystal plane orientation of [100] is used as the substrate material, the inner surface of the hole corresponding to the shape of the opening edge is formed along the crystal plane by anisotropic etching using an alkaline aqueous solution. It is formed with high accuracy, and it is possible to achieve effects such as remarkable improvement of the accuracy of the aperture and the accuracy of the light beam diameter associated therewith.

[Brief description of the drawings]

FIGS. 1A to 1D are explanatory views showing a process of forming an opening in a substrate in order.

2 (a) to 2 (c) are explanatory views showing steps of forming an opening by a method different from that of FIG. 1 in order.

FIGS. 3 (a) to 3 (d) are illustrations of a state of an optical path depending on an opening shape of a substrate.

4A to 4C are explanatory diagrams of another example different from FIG.

FIG. 5 is a sectional view showing a configuration of a mirror unit.

FIG. 6 is an exploded perspective view of the optical scanning module.

FIG. 7 is an explanatory diagram illustrating a configuration of a control device.

FIG. 8 is a timing chart of control by the control device.

FIG. 9 is a sectional view of the optical scanning module.

FIG. 10 is a perspective view of an optical scanning device.

FIG. 11 is an explanatory diagram showing an internal configuration of the optical scanning device.

FIG. 12 is an explanatory diagram of an image forming apparatus using an optical scanning device.

[Explanation of symbols]

 Reference Signs List 1 mirror unit 2 first substrate 3 movable mirror 4 mirror electrode 7 opposed mirror substrate 7a opposed mirror 8.9 fixed electrode 10.12 silicon substrate 11 opening, 13 SiN film 15 silicon substrate 20 optical scanning module 21 optical scanning device 30 support Substrate 36 LD chip 37 PD chip 38 Coupling lens 40 Cover 41 Prism mirror 44 Inner cover 48 Glass plate 50 Printed circuit board 51 Housing 57 Synchronous mirror 58 Synchronous detection sensor 60 First scanning lens 61 Second scanning lens 63 Spacer 70 Control Apparatus 71 Operation section 72 LD modulation section 73 Write control section 75/76 Electrode modulation section 80 Image forming apparatus 81 Photoconductor drum 92 Cartridge frame

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 2C362 AA26 AA40 2H045 AB16 AB73 DA02 5C051 AA02 CA07 DA03 DB02 DB22 DB24 DB30 DC04 DC07 5C072 AA03 BA04 DA02 DA04 DA18 DA21 HA02 HA06 HA14 HB10 WA05 XA05

Claims (7)

[Claims] 1. An optical scanning device comprising: a light emitting source; a movable mirror that scans a light beam from the light emitting source; and a substrate provided with an opening that defines at least one side of the light beam diameter. An optical scanning device characterized in that the inner side surface of the substrate in the thickness direction of the substrate is the same as the surface connecting the opening edges of the front and back surfaces of the substrate or is depressed. 2. The optical scanning device according to claim 1, wherein the substrate is a single crystal silicon substrate having a crystal plane orientation of [100]. 3. The optical scanning device according to claim 1, wherein the light beam is defined by one of the opening edges of the front and back surfaces of the substrate. 4. The optical scanning device according to claim 3, wherein a light beam is defined by an opening edge on a side where the light beam is incident. 5. The method according to claim 1, wherein the light beam is incident at an angle from a direction perpendicular to the substrate surface, and the positions of the opening edges of the front and back surfaces of the substrate are shifted according to the inclination direction of the light beam. The optical scanning device according to claim 1. 6. The substrate is provided with a first opening through which a light beam incident on a movable mirror passes and a second opening through which a light beam reflected by the movable mirror passes. The optical scanning device according to claim 5, wherein: 7. A reflecting means defined by an edge of a first opening and a second opening facing a movable mirror, wherein a light beam incident on the movable mirror by the reflecting means is provided on the substrate. 7. The optical scanning device according to claim 6, wherein scanning is performed at least once after reflection.