JPH112772A - Laser beam scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a mechanism rich in reliability through the constitution of the scanner is simple and the number of parts is reduced by constituting a beam shaping means for shaping a laser beam generated by a laser beam generating means into luminous flux having specified shape so that it can advance and retreat. SOLUTION: This scanner is provided with an optical housing 1 whose upper surface is opened, a cover 2 covering the upper surface of the housing 1, a laser unit (laser beam generating means) 3 fixed on the side surface of the housing 1 and oscillating the laser beams, and an aperture (beam shaping means) 4. The aperture 4 is supported to move up and down with respect to the inner base of the housing 1 and the upper and the lower positions of the aperture 4 are changed, so that the aperture opening part is optionally advanced and retreated between the optical path of the laser beam and a position where it is retreated from the optical path, then it achieves a shutter function. Therefore, the special shutter mechanism need not be provided, whereby the number of parts is reduced and cost is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a laser scanning apparatus in a laser printer, a digital copying machine, a plain paper facsimile, etc. using a laser beam as an exposure means for forming an electrostatic latent image on a photosensitive member. More particularly, the present invention relates to a laser light shielding mechanism in a laser scanning device capable of preventing a laser beam from leaking outside when a cover of the apparatus is opened for maintenance or the like with a simple configuration having a small number of components.

[0002]

2. Description of the Related Art An image forming apparatus in which a laser beam scanning apparatus as an exposure apparatus and an electrophotographic image forming section are combined has been widely used as a laser printer, a digital copying machine, and a plain paper facsimile. With the spread of these devices, their prices have been reduced, the usage ratio by individuals has increased, and the maintenance and inspection work has been simplified. For this reason, since most failures can be repaired by the work of the user side, there is an increasing demand for the design of equipment that protects the human body from invisible laser light leaking to the outside during maintenance, inspection, repair, etc. by the user. That is, as is well known, the laser beam is harmful to human eyes and skin,
There is a need for safety measures to prevent the laser beam from leaking to the outside. As a safety measure for a laser beam used in a conventional image forming apparatus, it is necessary to design the apparatus so that exposure of a harmful laser beam is eliminated in all operation aspects such as maintenance, inspection, and repair by a user. For this purpose, conventionally, a design has been made in which prevention of laser exposure at an emission opening provided in a laser beam scanning device is ensured by a double safety device. Specifically, a stop switch for stopping laser oscillation, or a shutter that shields either the opening itself or the optical path to the opening to prevent emission of the laser beam, Or both were provided at the same time.

As a conventional example provided with such a shutter mechanism, for example, Japanese Patent Application Laid-Open No. Hei 5-19603 discloses a shutter which is rotatable in conjunction with a main body cover at an outlet opening of an optical box. When the is opened, the exit opening is shielded by the shutter. This device has disadvantages in that the shutter is large because the opening is relatively long, a failure that hinders rotation is likely to occur, the reliability is low, and the cost of equipment is high because large components are used. Was. Further, in a device disclosed as a conventional example in the publication, a shutter interlocked with a drum cartridge of a main body is provided in a portion where laser is emitted from a laser unit opening inside an optical box. Although this conventional example can reduce the size of the shutter member itself, as described in the above-mentioned publication, the movable mechanism is complicated and it is difficult to transmit power. In addition, in the device disclosed in Japanese Utility Model Laid-Open No. 5-79524, the opening / closing cover is operated in conjunction with the opening / closing operation of the opening / closing cover.
A light-shielding structure with a small number of components has been disclosed which shields an opening of a laser unit by elastically deforming an optical housing. In this conventional apparatus, since the optical path is opened when the cover is closed, the housing is constantly elastically deformed except during maintenance, and there is a great concern that the elastic force, such as creep fatigue, will deteriorate with time when left for a long time. Therefore, it also has the disadvantage of lacking reliability.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and has been made in consideration of the above circumstances. In an image forming apparatus using a laser scanning apparatus as an exposure optical system, when an apparatus body cover is opened for maintenance or the like. The present invention relates to a laser light shielding mechanism in a laser scanning device which realizes prevention of leakage of a laser beam to the outside with a simple configuration having a small number of components. That is, when a configuration using a shutter mechanism is adopted as a laser safety device, it is an object to provide a highly reliable mechanism with a simple configuration while reducing the number of components.

[0005]

As described above, the invention of claim 1 comprises a laser beam generating means, a beam shaping means for shaping a laser beam generated by the laser beam generating means into a light beam having a predetermined shape, A first condensing unit that condenses the light beam shaped into a predetermined shape by the beam shaping unit in the sub-scanning direction, and deflects and scans the laser beam condensed in the sub-scanning direction by the first condensing unit. A laser beam scanning device, comprising: a deflection scanning means for performing scanning; and an imaging means for forming a laser beam to be deflected and scanned on a predetermined image plane with a predetermined spot diameter and scanning at substantially constant speed. Are configured to be able to advance and retreat, so that the laser beam can be shielded. Claim 2
In the invention, the beam shaping means is configured to be movable so that an opening thereof moves forward and backward between an initial position through which the laser beam passes and a shielding position through which the laser beam does not pass. The above-mentioned reciprocating operation is realized by cooperation of an actuating means for reciprocating the means and the elastic member. According to the third aspect of the present invention, the operating means is provided on the side of the image forming apparatus main body containing the laser beam scanning device, and the operating means opens and closes a cover for opening and closing a part of the image forming apparatus main body. By operating in conjunction with the operation, the forward and backward operation of the beam shaping means is realized. In the invention of claim 4, the operating means is provided on the image forming apparatus main body side containing the laser beam scanning device, and the operating means mounts the cartridge including the laser beam scanning device on the image forming apparatus main body. It is characterized in that it operates in conjunction with the operation of attaching and detaching the beam shaping means to realize the forward and backward operation of the beam shaping means.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments shown in the drawings. FIG. 1 is a developed perspective view showing the overall configuration of a laser beam scanning device to which the present invention is applied.
This laser beam scanning device includes an optical housing 1 having an open upper surface, and a cover 2 for closing the upper surface of the optical housing.
And a laser unit (laser beam generating means) fixed to the side surface of the optical housing 1 and oscillating a laser beam
3, an aperture (beam shaping unit) 4, a cylindrical lens (first focusing unit) 5, a polygon scanner (deflection scanning unit) 6, an fθ lens (imaging unit) 7,
Opening 8 as an emission port formed in optical housing 1
Consisting of The laser unit 3 is an example of a laser beam generating means, and includes a laser diode 3a to be described later, a base 3b supporting the laser diode 3a, and a collimating lens which is adhered and fixed to the base 3b so as to make the beam substantially parallel. 3c, a laser driving board (not shown) for supplying a current for driving the laser diode 3b, and the like. The beam converted into a parallel beam by the laser unit 3 is rectangular, elliptical,
After beam shaping by aperture 4 such as ellipse,
The light enters the cylindrical lens 5 as the first light condensing means, and is narrowed in the sub-scanning direction. A polygon scanner 4 as a deflection scanning means is located at the position of the image forming point of this beam.
The scanning beam reflected by each mirror passes through the fθ lens 7. The fθ lens 7 is designed to have fθ characteristics as main scanning characteristics, and is designed to have surface tilt correction characteristics in the sub-scanning direction so that an image point and an image plane formed by the first light condensing unit have a conjugate relationship. Generally, it is used as a plurality of lens groups. Each of these components is housed in the optical housing 1 with a predetermined accuracy. As means for fixing each component, pressing by a leaf spring, bonding, snap-fit stop, and the like are known, and any fixing method may be used. The laser opening 8 may be open,
In many cases, the entire opening is closed with dust-proof glass for dust protection. Cleaning of the dust-proof glass is one of the necessary operations in maintenance of the equipment, but according to the structure of the present invention as described later, cleaning is easy.

Next, FIGS. 2A and 2B are diagrams showing typical examples of the structure of a conventional aperture (beam shaping means) 4, respectively. The aperture 4a shown in FIG. This is an example in which an opening 4a 'of a plate bent into a mold is fixed to the bottom surface of the housing 1 so as to be located on the optical path of the beam. The aperture 4b shown in FIG. This is an example in which the opening 4b 'is integrally fixed to the laser unit 3 so as to be located on the optical path. In each of these examples, the position of the aperture of the aperture is fixed, and in order to provide a mechanism for shielding the laser beam, it is necessary to arrange a special shielding means in another portion on the optical path. On the other hand, in the embodiment of the present invention shown in FIGS. 3 and 4, the aperture (beam shaping means) 4 is supported so as to be vertically movable with respect to the inner bottom surface of the housing 1, and the vertical position of the aperture is changed. By doing so, the aperture opening can be arbitrarily moved between the position on the optical path of the laser beam (initial position) and the position retracted from the optical path (shielding position), thereby realizing emission and shielding of the laser beam by the aperture. I have to. In other words, by including the shutter mechanism in the beam shaping means, an increase in the number of components and an increase in size are prevented.

FIG. 3 is an exploded perspective view (explanatory view of a main part of FIG. 1) showing an attachment structure of an aperture constituting a laser light shielding mechanism (shutter) of the present invention, and FIGS. 4 (a) and 4 (b) show the aperture. It is a longitudinal section showing an example of composition of an operation mechanism. The aperture (beam shaping means) 4 is provided with a sheet metal member having elasticity such as stainless steel or a copper alloy for spring provided with an aperture opening 4B so as to perform a normal aperture function. It is formed into an L-shape by applying a surface treatment, and the bottom piece 4C is fixed to a screw hole 1A on the optical housing 1 with a screw 11. In order to obtain desired optical characteristics, the aperture 4 needs to be strictly positioned and arranged with high precision like lenses. However, the aperture 4 has a notch-shaped detent 4D and a positioning projection 1B provided on the housing side. The position regulation, the contact between the aperture positioning section 4E and the optical housing 1, and the position regulation by maintaining the contact by its own elastic force are established. Aperture positioning unit 4E
Is a substantially V-shaped (including U-shaped) projection extending from the bottom edge of the main body 4A of the aperture 4. A step 4E 'having a flat lower surface is formed at the base of the positioning portion 4E. Bottom piece 4
C into the screw hole 1A on the bottom of the housing 1.
By screwing the screw 11 in a state where the aperture 4 is aligned, when the aperture 4 is positioned on the inner bottom surface of the housing,
The positioning portion 4E is fitted into a housing hole 1C formed in the bottom surface of the housing for fitting the positioning portion 4E. In addition, the positioning part 4E can maintain the state fitted in the housing hole 1C by the elasticity of the entire L-shaped aperture. As shown in FIG. 4 (a), when the positioning portion 4E is fitted into the housing hole 1C,
By contacting the flat lower surface of the step 4E ′ on the inner bottom surface of the housing 1, the aperture is stably supported on the inner bottom surface of the housing. In the state shown in FIG. 4A, the aperture opening 4B is in a positional relationship with the laser beam L.

Reference numeral 15 in FIG. 4 denotes an aperture operating mechanism. The aperture operating mechanism 15 is supported at a position directly below (or in an empty space) the inner bottom surface of the optical housing 1 so as to be able to advance and retreat in the direction of the arrow. Actuator 16,
An elastic member 17 is disposed at one axial end of the actuator 16 and applies a force for urging the actuator 16 rightward in the drawing to move to the retracted position shown in FIG. 4B. And an operating means 18 capable of moving forward and backward in the direction of arrow A. The actuating means 18 may be a means for moving the part 18a back and forth in the direction of arrow a by a solenoid or other driving means, or a member which moves back and forth in the same direction in conjunction with opening and closing operations of a cover and a door (not shown) of the apparatus main body. It may be. Further, the actuating means 18 is connected as shown in FIG.
A cartridge (unit) type laser beam scanning device (or a cartridge including an image forming unit including a photosensitive drum, or a cartridge including the image forming unit and a scanning device) ) May be configured to operate the actuator 16 by attaching one end of the actuator 16 to the fixing projection of the operating means 18 when the device 16 is mounted on the apparatus main body.

First, an example in which the operating means 18 is a movable member which operates in conjunction with a driving force from a driving means (not shown) or an opening / closing operation of a cover or the like to advance or retreat a part 18a thereof will be described as an example. I do. When a portion 18a of the operating means 18 projects to the left in the drawing as shown in FIG. 4A, the actuator 16 is held at the initial position shown in FIG. Thus, when the actuator 16 retreats to the right, the force of the elastic member 17 is released to retreat the actuator 16 to the right as shown in FIG. Actuator 1
A concave portion 16a for receiving the positioning portion 4E protruding from the housing hole 1C is formed on the upper surface of 6.

Therefore, in the state shown in FIG. 4A in which the operating means 18 operates to affect the actuator 16, the recess 16a of the actuator is opposed to the urging force of the elastic member 17.
Is located directly below the housing hole 1C, the lower surface of the step 4E 'of the positioning portion 4E is fixed on the inner bottom surface of the housing, and the aperture opening 4B is positioned on the optical path of the laser beam L. On the other hand, when the operating means 18 is not operated as in (b), the actuator retreats from the position immediately below the housing hole 1C by the force of the elastic member 18, so that the positioning portion 4E is The actuator 16 rides at the place 16a and is pushed up by the upper surface (non-recess) of the actuator. At this time, the aperture 4B of the aperture is retracted from the laser beam optical path.
For this reason, the user and the maintenance man can be protected from damage by the laser. When the actuator 16 returns to the state shown in FIG. 4A by closing the cover of the apparatus main body (not shown) or mounting the laser beam scanning apparatus on the main body of the apparatus, the positioning section 4E is formed by the elasticity of the aperture itself. Enters the recess that has returned just below the housing hole 1C. For this reason, the aperture opening 4B returns to the laser beam optical path.

Contrary to the above, when the elastic member 17 is free, the recess 16a causes the housing hole 1
C while being held immediately below C.
When the actuator 8 presses the actuator 16 against the elastic member, the recess 16a may be retracted from immediately below the housing hole. When the non-recess of the actuator 16 is located immediately below the housing hole 1C, the aperture 4 is pushed up by the non-recess,
While the opening 4B is positioned on the laser beam optical path, while the actuator 16 is moved by the cooperation of the operating means 18 and the elastic member 17, the recess 16a comes to a position immediately below the housing hole 1C. When the bottom of the actuator is lowered into the recess, the opening may be retracted from the laser beam optical path and shielded. Further, by configuring the aperture to advance and retreat in a horizontal direction (including an obliquely upward direction) by a mechanism (not shown), the aperture opening may be configured to advance and retreat in the horizontal direction to pass and block the laser beam. .

As described above, in the present invention, the aperture 4 is moved up and down (or moved in the horizontal direction) by the operation of the actuator 16 to move the aperture opening 4B to a position outside the range of the laser beam. Therefore, in this shielded state, the laser beam is not emitted after the aperture 4. To return the aperture opening 4B to the range of the laser beam, the operating means 18 is operated in the reverse direction, so that the aperture 4 returns to the initial position. In the above embodiment, the actuating means 18 is configured to operate the actuator by moving forward / backward by the opening / closing operation of the cover or the driving force from the driving means. It is also possible to adopt a configuration in which the actuator abuts on the operating means 18 in conjunction with the operation of attaching and detaching the cartridge type laser beam scanning device to and from the apparatus main body, so that the actuator can be moved forward and backward. In this case, the configuration of the actuator, the configuration of the operating means, and the like in the above embodiment can be used as they are. The difference is that the operating means 18 is immovable, and the actuator incorporated in the operating device is operated when the scanning device is attached or detached. In each of the above embodiments, the actuator 16
The elastic member (coil spring) 17 is merely an example, and therefore, any technique that can achieve the same operation as these members can be used, and its material and shape may be any. When the entire surface of the laser opening 8 shown in FIG. 1 is closed with dustproof glass, it is necessary to clean the dustproof glass for maintenance of the device. According to the present invention, the opening 8 has a shutter mechanism. Since it is not provided,
Cleaning the glass is very easy.

[0014]

As described above, according to the present invention, in an image forming apparatus using a laser scanning apparatus as an exposure optical system, when a cover of the apparatus main body is opened for maintenance or the like, a laser beam leaks to the outside. The prevention can be realized by a simple configuration with a small number of parts. Also, when a configuration using a shutter mechanism is adopted as the laser safety device,
With a simple configuration, it is possible to provide a highly reliable mechanism while reducing the number of parts. As described above, according to the first aspect of the present invention, while the beam shaping means necessary for the optical function is always properly positioned at the initial position for beam shaping, it is necessary for maintenance of the image forming apparatus. When the cover is opened, the beam shaping means itself moves forward and backward, thereby retreating the opening from the optical path range of the laser beam, thereby exhibiting a shutter function. Therefore, it is not necessary to provide a special shutter mechanism, and it is possible to reduce the number of parts and cost. According to the invention of claim 2, together with the effect of the device of claim 1, the deformation of the beam shaping means is performed only during the time of beam shading during maintenance, and even if the deformation is repeated, the beam is elastically restored to its original shape. In addition, light shielding with little deterioration over time can be realized. According to the third and fourth aspects of the present invention, the aperture operating mechanism is applied to an image forming apparatus, and the operating mechanism is operated in conjunction with opening / closing of a cover of the apparatus main body or attaching / detaching operation of a cartridge including a scanning device. As a result, a safe image forming apparatus can be configured.

[Brief description of the drawings]

FIG. 1 is a developed perspective view showing the entire configuration of an example of a laser beam scanning device to which the present invention is applied.

FIGS. 2 (a) and 2 (b) are diagrams each showing a typical configuration example of a conventional aperture (beam shaping means).

FIG. 3 is a perspective view showing a configuration of a main part of one embodiment of the present invention.

FIGS. 4A and 4B are longitudinal sectional views showing a configuration of an example of an aperture operating mechanism.

[Explanation of symbols]

1 optical housing, 2 cover, 3 laser unit (laser beam generating means), 3a laser diode,
3b base, 3b, base, 3c collimating lens, 4 aperture (beam shaping means), 4a aperture, 4a 'opening 4a', 4b aperture 4b,
4b 'opening, 4A body 4B aperture opening, 4C bottom piece, 4D detent, 4E aperture positioning section, 5 cylindrical lens (first condensing means), 6 polygon scanner (deflection scanning means), 7f
θ lens (imaging means), 8 aperture, 15 aperture operation mechanism, 16 actuator, 16a recess, 17
Elastic member, 18 actuation means,

Claims (4)

[Claims] 1. A laser beam generating means, a beam shaping means for shaping a laser beam generated by the laser beam generating means into a light beam having a predetermined shape, and a light beam shaped into a predetermined shape by the beam shaping means. First condensing means for condensing in the scanning direction, deflecting scanning means for deflecting and scanning the laser beam condensed in the sub-scanning direction by the first condensing means, and An imaging unit that forms an image at a predetermined spot diameter on the image plane and scans at substantially constant speed, and in a laser beam scanning device,
A laser beam scanning device capable of blocking a laser beam. 2. The beam shaping means, wherein the opening is
It is configured to be movable so as to advance and retreat between an initial position for passing the laser beam and a shielding position for not passing the laser beam. 2. The laser beam scanning device according to claim 1, wherein the laser beam scanning device realizes a forward / backward operation. 3. The image forming apparatus according to claim 1, wherein the operating unit is provided on an image forming apparatus main body including the laser beam scanning apparatus.
3. The laser beam according to claim 2, wherein the actuating means operates in conjunction with an opening and closing operation of a cover for opening and closing a part of the image forming apparatus main body, thereby realizing the forward and backward operation of the beam shaping means. Scanning device. 4. The operating means is provided on an image forming apparatus main body side containing the laser beam scanning device,
3. The apparatus according to claim 2, wherein the actuating means operates in conjunction with an operation of attaching and detaching a cartridge including the laser beam scanning device to and from the image forming apparatus main body, thereby realizing an advancing / retreating operation of the beam shaping means. The laser beam scanning device according to claim 1.