JPH06167660A - Optical scanning device - Google Patents

Abstract

PURPOSE:To reduce the overall size of the device by arranging a reflection optical system outside an optical scanning unit and almost equalizing the optical path length from a deflection point to an image formation plane to the optical path length from the deflection point to a synchronous detecting element. CONSTITUTION:A substrate 12 is fixed to a housing wherein a reflecting mirror 16, a scanner motor 14, a right-angled prism 15 as a reflection body, and a meniscus lens 17 are assembled; and a semiconductor laser oscillator 13 is fitted on one surface side of the substrate 12 and the synchronous detecting element 19 is fitted on the other surface side. Then the optical path length from the reflection point of the right-angled prism 15, i.e., the deflection point to the synchronous detecting element 19 is nearly equalized to the optical path length from the deflection point elongated by the reflection of respective reflecting mirrors 21, 23, and 24 of the reflection optical system arranged outside the optical scanning unit to a photosensitive drum 3. Then the synchronous detecting element 19 performs synchronous detection for image formation on the photosensitive surface of the photosensitive drum 3.

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 used for laser printers, laser fax machines, digital copying machines and the like.

[0002]

2. Description of the Related Art Generally, a laser printer puts recording information on a laser beam emitted from a semiconductor laser device, deflects and scans the laser beam by an optical system, and converges the laser beam on a charged photoconductor surface which is an image forming surface. Thus, the photoconductor is exposed and the recording information is recorded on the photoconductor as an electrostatic latent image.

In such a laser printer, there is an increasing demand for miniaturization and stabilization while improving basic performance such as print quality and low noise. Further, in such a device, an optical scanning device is used to deflect and scan the laser light from the semiconductor laser device and focus it on the surface of the photoconductor, but the optical scanning device is miniaturized similarly to the demand of the entire device. The demand for stabilization is increasing and it is unitized.

Conventionally, as a unitized optical scanning device, one disclosed in Japanese Patent Laid-Open No. 1-282516 is known. As shown in FIG. 4, the polygon mirror 2, the cylindrical lens 3, the f-θ lens 4, the mirrors 5 and 6 are arranged in the unit case 1, and the substrate 7 is attached to the outside of the side wall of the unit case 1, A semiconductor laser element and a photodiode serving as a synchronous detection element are fixed to this substrate 7. Then, the laser beam from the semiconductor laser element is provided on the side wall of the case 1 through the hole 8
The polygon mirror 2 is irradiated with the light through the collimator lens 9 and the cylindrical lens 3 provided in the unit 6 to deflect and scan the deflected light, and the deflected light is reflected by the mirror 6 via the f-θ lens 4, and is reflected on the bottom of the unit case 1. The light is emitted to the outside through the slit provided. The deflected light emitted to the outside is guided to the photoconductor. Further, a part of the deflected light emitted through the f-θ lens 4 is reflected by the mirror 5 and a mirror provided near the side wall on the opposite side of the mirror 5, and then the substrate 7 is passed through a hole 10 provided in the side wall. It is designed to be guided to the photodiode attached to.

[0005]

In such an optical scanning device, a part of the deflected light to be scanned is guided to a photodiode which is a synchronous detection element, and data for performing repeated scanning and image formation on the photosensitive member. Need to be synchronized with.
Further, the beam diameter of the deflected light guided to the photodiode must be sufficiently narrowed in the vicinity of the incident light to the photodiode due to the light receiving sensitivity and detection accuracy of the element.

Therefore, it is necessary to make the optical path length from the deflection point on the polygon mirror 2 to the photodiode approximately equal to the optical path length from the deflection point to the photoconductor.

For this reason, the arrangement of the semiconductor laser element and the photodiode in the conventional optical scanning device has a problem that the unit case cannot be sufficiently miniaturized.

Therefore, the present invention is to provide an optical scanning device which can be sufficiently miniaturized.

[0009]

According to the present invention, there is provided a substrate fixed to a casing, a light emitting element which is mounted on the substrate and emits a light beam into the casing, and the light emitting device is incorporated into the casing and is incident from the light emitting device by rotation. A reflector for deflecting and scanning a light beam to be scanned, and a synchronous detection element mounted on the side of the substrate opposite to the side where the light emitting element is mounted to capture a part of the deflected light from the reflector and perform synchronous detection for image formation. And an optical scanning unit provided outside the optical scanning unit, which reflects the deflected light from the reflector and guides the deflected light to the photoconductor for image formation and a part of the deflected light to the synchronous detection element. The optical path length from the reflector to the photoconductor and the optical path length from the reflector to the synchronous detection element are substantially equal.

[0010]

In the present invention having such a structure, the substrate is fixed to the housing in which the reflector for deflecting and scanning the light beam is incorporated.
A light emitting element that emits a light beam is attached to the substrate, and a synchronization detection element for performing synchronization detection is attached to the side of the substrate opposite to the side where the light emission element is attached to form an optical scanning unit. By providing a reflection optical system that externally guides the deflected light from the reflector to the photoconductor for image formation and guides a part of the deflected light to the synchronous detection element, the deflected light from the reflector can be transmitted to the outside. After the light is reflected by the reflection optical system, a part of it returns and enters the synchronous detection element provided in the optical scanning unit, so the optical path length from the reflector to the photoconductor and the synchronous detection element from the reflector. Even if the optical path lengths are set to be substantially equal, it is possible to reduce the size of the entire device.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, 1 is an optical scanning unit, 2 is an exterior of the optical scanning unit 1, a reflection optical system for reflecting the scanning deflected light from the optical scanning unit 1, and 3 is the reflection optical system 2. Is a photosensitive drum that forms an electrostatic latent image by being exposed to the scanning deflected light from. Reference numeral 4 denotes a main body frame which fixes the optical scanning unit 1, the reflection optical system 2 and the like.

In the optical scanning unit 1, as shown in FIG. 2, a substrate 12 is fixed to the front part of a housing 11, and the substrate 11 is fixed.
In addition, the semiconductor laser oscillator 13 which is a light emitting element with the light emitting port facing the inside of the housing so as to emit the light beam into the housing.
Is installed.

In the housing 11, a scanner motor 14,
The rotary shaft 14b of the rotor 14a of the scanner motor 14
A right-angle prism 15 as a reflector fixed above, a light beam from the semiconductor laser oscillator 13 is reflected, and two 45 ° reflecting surfaces of the right-angle prism 15 are provided with a rotating shaft 14b.
A case 18 in which a meniscus lens 17 having a curvature radius of an exit surface smaller than that of the entrance surface and a reflection mirror 16 which is made to enter in parallel to is incident and which is convex toward the imaging surface side is disposed.

In the scanner motor 14, a magnet 14c is integrally attached to a rotor 14a. The rotating shaft 1
4b is rotatably attached to a stator member 14d via a ball bearing 14e. The stator member 14
fix the circuit board 14g to the d via the spacer 14f,
A coil 14h is attached to the back surface side of the portion of the circuit board 14g facing the magnet 14c.

On the side of the substrate 12 opposite to the side where the semiconductor laser oscillator 13 is attached, a sync detecting element 19 for picking up a part of the deflected light and performing sync detection for image formation is attached.

In the optical scanning unit 1, the laser light emitted from the semiconductor laser oscillator 13 is reflected by the reflection mirror 16 and then reflected by the scanner motor 1.
The light is incident on the reflecting surface of the rectangular prism 15 which is rotationally driven by 4 and is converted into deflected light which is deflected and scanned in a plane direction perpendicular to the rotation axis 14b of the scanner motor 14. That is, the reflecting surface of the rectangular prism 15 serves as a deflection point. Then, the scanning deflected light from the reflecting surface of the rectangular prism 15 is emitted through the meniscus lens 17 to the reflective optical system 2 arranged outside.

As shown in FIG. 3, the reflection optical system 2 includes a first large reflection mirror 21 which first reflects the deflected light emitted to the outside through the meniscus lens 17, and the first large reflection mirror 21.
The second large reflection mirror 22 for reflecting the reflected light from the large reflection mirror 21 and irradiating it to the photosensitive drum 3 and the first large reflection mirror 21 are arranged in the vicinity of one end of the first large reflection mirror 21. The first small reflection mirror 23 that reflects a part of the reflected light from the first reflection mirror 21 and the other end of the first large reflection mirror 21 are arranged in the vicinity of the first small reflection mirror 23 to reflect the reflected light from the first small reflection mirror 23. It is composed of a second small reflection mirror 24, and the reflected light from the second small reflection mirror 24 is reflected by the first large reflection mirror 21 and then made incident on the synchronization detection element 19. .

In the embodiment having such a structure, the laser light from the semiconductor laser oscillator 13 is reflected by the reflecting mirror 16 to change the optical path at a right angle, and the right angle is arranged on the rotary shaft 14b of the scanner motor 14. It enters the reflecting surface of the prism 15. Since the rectangular prism 15 is rotated by the scanner motor 14, deflected light for deflective scanning is emitted from the reflecting surface of the rectangular prism 15 to a plane perpendicular to the rotation axis of the scanner motor 14, and the deflected light is emitted from the meniscus lens 17. The light is emitted to the outside of the optical scanning unit 1 via.

The deflected light emitted to the outside of the optical scanning unit 1 is first reflected by the first large reflection mirror 21 and then reflected by the second large reflection mirror 22 and condensed on the photosensitive surface of the photosensitive drum 3. . In this way, an electrostatic latent image is formed on the photosensitive surface exposed by the deflected light scanning the photosensitive surface of the photosensitive drum 3.

The deflected light reflected by one end of the first large reflection mirror 21 in the process of repeating the scanning of the deflected light is reflected by the first small reflection mirror 23 and then by the second small reflection mirror 24. Further, the light is reflected by the first large reflection mirror 21 and enters the synchronization detection element 19.

In this way, the synchronization detection element 19 performs synchronization detection for forming an image on the photosensitive surface of the photosensitive drum 3.

The substrate 12 is fixed to the housing 11 in which the reflection mirror 16, the scanner motor 14, the right-angle prism 15 as a reflector, and the meniscus lens 17 are assembled in this way, and the semiconductor laser oscillator 13 is provided on one side of the substrate 12. And the sync detection element 19 is attached to the other surface side, and each reflection of the reflection optical system 2 in which the optical path length from the reflection point of the rectangular prism 15, that is, the deflection point to the sync detection element 19 is arranged outside the optical scanning unit 1. Since the optical path length from the deflection point to the photosensitive drum 3 is made substantially equal to the optical path length from the reflection of the mirrors 21, 23, 24, the optical scanning unit 1 can be sufficiently miniaturized, This makes it possible to sufficiently miniaturize the entire device. In addition, in the above-mentioned embodiment, the one using the rectangular prism as the reflector is described, but the present invention is not limited to this. Or may be obtained by using instead, for example, it isosceles reflecting prism or deflecting mirror and the like.

[0024]

As described above, according to the present invention, the substrate is fixed to the housing in which the reflector for deflecting and scanning the incident light beam by rotation is incorporated, and the light emitting element is attached to the substrate and the light emitting element is attached. An optical scanning unit is formed by mounting a synchronous detection element for performing synchronous detection for image formation on the side opposite to the mounting side, and a reflection optical system is arranged outside the optical scanning unit to form an image from a deflection point. Since the optical path length to the surface and the optical path length from the deflection point to the synchronization detecting element are made substantially the same, the size of the entire apparatus can be sufficiently reduced.

[Brief description of drawings]

FIG. 1 is a plan view of an essential part showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a configuration of an optical scanning unit in the embodiment.

FIG. 3 is a perspective view showing an optical path in the example.

FIG. 4 is a perspective view showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Optical scanning unit 2 ... Reflective optical system 3 ... Photosensitive drum 11 ... Housing 12 ... Substrate 13 ... Semiconductor laser oscillator 13 15 ... Right-angle prism 19 ... Synchronous detection element

Claims (1)

[Claims] 1. A substrate fixed to a housing, a light emitting element which is attached to the substrate and emits a light beam into the housing, and a light beam which is incorporated into the housing and is rotated to deflect the light beam incident from the light emitting element. A reflector to be scanned and a synchronization detection element attached to the side of the substrate opposite to the side where the light emitting element is attached, and a part of the deflected light from the reflector is taken in to perform synchronization detection for image formation are provided. And an optical scanning unit provided outside the optical scanning unit, which reflects the deflected light from the reflector and guides it to the photoconductor for image formation, and guides part of the deflected light to the synchronous detection element. And an optical path length from the reflector to the photoconductor and an optical path length from the reflector to the synchronization detection element are substantially equal to each other.