JPH09222576A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve detective precision in an optical system for detecting a horizontal synchronizing signal by miniaturizing the system and improving attaching positional precision of components. SOLUTION: In an optical path of a laser beam L in a laser beam scan system 11, a reflection means 57 receiving a part (signal detecting laser beam) Lp of the scanning liaser beam L and deflecting it in the direction of a light receiving element 56 is fixed to the position being one side part of a frame body 55 holding a lens 46 being an optical part placing to downmost-stream based on a polygon mirror 42 and answering to out of a main scan area of a photosensitive body drum surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus applied to a printer, a facsimile machine, a copying machine and the like and applied to an image forming section using a laser beam scanning system.

[0002]

2. Description of the Related Art Conventionally, various types of laser beam scanning systems have been proposed and provided.
The scanning optical device shown in Japanese Patent No. 13 can be exemplified. FIG. 4 is a perspective view for explaining the configuration of a conventional laser beam scanning system. 101 is a photosensitive drum which is an image carrier, 102 is a laser light source, 103 is a polygon mirror which is an optical deflector, and 104 is fθ. A lens, 105 is a lens for focusing the laser beam L on the surface of the photoconductor drum 101, and 106 is a light receiving element including a lens for receiving a part L _P of the laser beam L for obtaining the timing (horizontal synchronization signal) of optical writing. , 1
Reference numeral 07 is a reflection mirror for deflecting a part of the laser beam L _P toward the light receiving element 106, and reference numeral 108 is a housing for holding the various optical members. Since the scanning with the laser beam L in the laser beam scanning system having the above-mentioned configuration is known, its description is omitted.

In FIG. 4, a laser beam L emitted from a laser light source 102 whose emission is controlled based on a video signal.
In the known manner, the main scanning area H on the surface of the photosensitive drum 101 is subjected to photosensitive scanning in a known manner through the polygon mirror 103, the fθ lens 104, and the lens 105 to form an electrostatic latent image. The electrostatic latent image is visualized, and an image is formed on the recording paper. Further, in the scanning, a horizontal synchronizing signal is detected by a photodiode (not shown) or the like by receiving optical information from the light receiving element 106 which receives a part L _P of the laser beam L.

[0004]

In the laser beam scanning system shown in FIG. 4, the light receiving element 106 and the reflecting mirror 107 which form the optical system for detecting the horizontal synchronizing signal are formed in the main scanning area of the photosensitive drum 101. It is installed at both ends of H so as to face each other. Therefore, the light receiving element 106
The reflection mirror 107 and the reflection mirror 107 need to be installed at a position that does not interfere with the laser beam L incident on the main scanning region H of the photosensitive drum 101.

Therefore, the height of the housing 108 is designed to be increased so that the interference does not occur in the vertical direction in the housing 108 for holding the optical member, and a part of the laser beam L L _P Optical path in
This has been dealt with by setting (distance between the light receiving element 106 and the reflection mirror 107) S sufficiently longer than the main scanning area H of the photosensitive drum 101.

However, any of the above measures inevitably leads to an increase in size of the apparatus, and in order to maintain the predetermined optical characteristics as the optical path length is increased,
High accuracy is required for mounting the optical member in the optical path. Therefore, as in the latter case, lengthening the optical path S of the part L _P of the laser beam L requires high precision in their attachment in order to maintain good optical characteristics, and high precision of the holding member and the like. Needs to be converted.

However, if a high accuracy of parts cannot be ensured, the optical parts and the mounting members are adjusted so that the angle or distance is adjusted within a predetermined reference range. However, this adjustment work requires precision and a skilled technique, and it takes a lot of time and cost.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned conventional problems, downsize an optical system for detecting a horizontal synchronizing signal, improve the mounting position accuracy of components, and detect the same. An object is to provide an image forming apparatus capable of improving accuracy.

[0009]

In order to achieve the above object, the present invention provides an optical writing means for exposing the surface of an image carrier by an optical system including at least a laser light source and an optical deflector, and the timing of the optical writing. In order to obtain the above, in the image forming apparatus having the light receiving means for receiving a part of the laser beam reflected by the optical deflector, the optical writing means is constituted by the reflecting means for guiding the laser beam to the light receiving means. Of the optical components, the optical deflector is set as a reference so as to receive the laser beam after passing through the optical component located on the most downstream side of the optical path, and at least one of the light receiving means or the reflecting means is located on the most downstream side. It is characterized in that it is provided in an optical component, and with this configuration, at least one of the light receiving means and the reflecting means interferes with the optical path of the laser beam. Attached accurately to have a position,
Since the laser beam for detecting the horizontal synchronizing signal is accurately guided to the light receiving element, the detection of the horizontal synchronizing signal by the light receiving means is favorably performed.

Further, the optical path between the light receiving element and the light detecting element for receiving the information from the light receiving element and detecting the timing of optical writing is constituted by an optical fiber, and a holding means for holding the optical fiber is provided. By providing the optical fiber at the most downstream position, the optical fiber is held by the holding means without vibrating or loosening, so that the optical fiber can be securely fixed at a position where it does not block the laser beam.

Further, in the optical writing means, the optical path from the optical deflector to the exposure of the surface of the image carrier is formed in a substantially U shape in side view, which is necessary for forming the optical path in the apparatus. The horizontal projection area can be reduced.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram of a laser printer for explaining one embodiment of the present invention, in which 1 is a main body 2.
And a printer body 5 composed of an opening / closing body 4 which is openably and closably supported around a shaft 3 provided on the right side of the main body 2.
The photoconductor unit 11, which is a recording unit including the photoconductor drum 6, the cleaning unit 7, the charging unit 8, the toner accommodating unit 9, the developing roller 10, and the like, emits a laser beam L as described later, and based on the image data. Laser beam scanning system for exposing the photosensitive drum 6 by the laser beam L, 12 is a controller unit, 13 is a cooling fan, 14 is a registration roller, and 15 is a paper feed cassette detachably provided under the print main body 1. , 16 are paper feed rollers provided above the paper feed cassette 15, and 17 is in contact with a part of the paper feed roller 16 to feed the recording papers P stored in the paper feed cassette 15 one by one. A separation pad 18 for that purpose is a registration sensor provided in the recording paper conveyance path between the registration roller 14 and the paper feed roller 16.

On the opening / closing body 4, a transfer roller 20 for transferring the toner image on the surface of the photosensitive drum 6 to the recording paper P conveyed by the registration roller 14 at a timing.
And a fixing device for fixing the toner image on the recording paper P after transfer
21, a paper ejection roller 22, and a paper ejection sensor 23 provided in a recording paper conveyance path between the fixing device 21 and the paper ejection roller 22 are internally provided. An operation panel 24 for displaying these is provided.

At the lower right portion of the opening / closing body 4 of the printer body 1, a small-sized paper feeding cassette 25 is detachably provided, and the recording paper P stored in the paper feeding cassette 25 is A sheet feed roller 26 and a separation pad 27 provided on the shaft 3 are provided to feed the sheets one by one toward the registration roller 13.

The upper side of the main body 2 of the printer body 1 constitutes a paper discharge tray 28 for receiving the recording paper P discharged from the paper discharge roller 22 with the recording surface facing downward, and a part of the tray is rotated by a shaft 29. A cover body 30 is supported as much as possible, and further, on the upper left part of the main body 2, a discharge receiving stopper 31 is provided so that the discharged recording paper P can be received in accordance with its size. Is provided so as to be movable diagonally laterally and detachably.

Since the paper feeding, conveying, or image forming operation of the recording paper P in the printer having the above-mentioned structure is known, its detailed description will be omitted.

FIG. 2 is an exploded perspective view of the laser beam scanning system. Reference numeral 40 is a frame formed of glass fiber reinforced plastic whose main component is polycarbonate or the like, and the laser beam scanning system which is an optical writing means.
It has a space to store 11 components.

The laser beam scanning system 11 includes a laser beam L
A laser oscillator 41 which is a light source for generating a laser beam, a polygon mirror 42 for deflecting the laser beam L, an fθ lens 43,
A pair of upper and lower reflection mirrors 44 and 45 installed in the deflection direction of the laser beam L of the polygon mirror 42, and an upper reflection mirror.
A lens 46 which is provided in the deflection direction of the laser beam L of 45 and focuses the laser beam L on the surface of the photosensitive drum 6.
And a horizontal synchronizing signal detecting means, which will be described later, provided for detecting a horizontal synchronizing signal which is a signal for timing of writing with the laser beam L.

The upper opening of the frame 40 is covered with a pair of left and right upper cover bodies 50 and 51 to prevent dust.
On the upper cover 51 of the photoconductor unit 5 side (right side in the figure),
A light transmission window 53 covered with glass 52 is formed so as not to obstruct the optical path of the laser beam L. Further, recesses 54a are formed in the wall portions 54 provided upright on both sides of the frame 40, and the recesses 54a project on both sides of the photoconductor unit 5 disposed above the right upper cover body 51. Support shaft 5 installed
I am supposed to receive a.

As shown in FIGS. 1 and 2, the laser beam L
, The polygon mirror 42 to the pair of reflection mirrors 44,
The optical path through 45 to the photoconductor drum 6 is substantially U-shaped when viewed from the side, and the horizontal projection area required to form the optical path in the frame 40 is reduced.

FIG. 3 is a perspective view showing the configuration of the horizontal synchronizing signal detecting means portion. In the optical path of the laser beam L of the laser beam scanning system 11, the optical component located at the most downstream side with respect to the polygon mirror 42. A part of the laser beam L (laser beam for signal detection) at a position corresponding to the outside of the main scanning region H on the surface of the photosensitive drum 6 on one side of the frame 55 holding the lens 46. ) Fixing the fixed frame 58 provided with the reflection means 57 for receiving L _P and deflecting it toward the light receiving element 56. A reflection mirror is used as the reflection means 57, and the fixed frame 58 is fixed to the frame body 55 by screws, adhesion, or a known snap-fit mechanism.
Fixed to Of course, the reflection mirror may be directly fixed to the frame body 55. A condensing lens is used as the light receiving element 56, and the condensing lens is held by a fixed arm body 59, and the fixed arm body 59 is screwed or bonded in the same manner as described above, or the frame is formed by a known snap fit mechanism. It is fixed to the lower side of the body 55.

Laser beam L received by the light receiving element 56
_P is transmitted by an optical fiber 60 to a photodiode 62 as a light detecting means provided on a driver board 61 in the controller unit 12, a detection signal is detected, and writing control is performed based on this signal. Be seen. The optical fiber 60 is arranged along the lower side of the frame body 55 of the lens 46, and the frame body is similar to the light receiving element 56.
It is fixed to 55 via a support member 63. By fixing the optical fiber 60 in this way, it is possible to prevent an external force from vibrating and causing the connecting portion to loosen.

As described above, since the reflecting means 57 and the light receiving means 56 are accurately attached to the lens 46, which is the optical component located on the most downstream side of the optical path of the laser beam L, the light receiving means 56 is connected to the lens 46. The beam incidence is stable, and the horizontal sync signal is detected well. If at least one of the reflecting means 57 and the light receiving means 56 is fixed to the lens 46, the light receiving means 56
It is possible to further stabilize the beam incidence on the beam.

The fixed frame 58, the fixed arm 59, and the support member 63 may be fixed to the frame body 55 via a member separate from the frame body 55, and may be formed by resin molding. Body 55
You may make it perform via the member provided integrally with.

By the way, in the laser beam scanning system 11 capable of forming a large-sized image, the main scanning area H (see FIG. 3) on the surface of the photosensitive drum 6 is enlarged and the polygon mirror 42 is used to move the photosensitive drum 6 to the surface. It is necessary to increase the optical path length of the laser beam L to the surface (see FIGS. 1 and 2),
This has been a cause of increasing the size of the entire apparatus. The reason for increasing the optical path length of the laser beam L is that if only the main scanning region H is lengthened, the scanning angle of the laser beam L increases,
This is because it becomes a so-called wide-angle optical system, which causes a technical problem for ensuring the accuracy of the components forming the optical system or a problem such as an increase in cost.

However, in the laser beam scanning system 11, the optical path of the laser beam L from the polygon mirror 42 through the pair of reflection mirrors 44 and 45 to the photosensitive drum 6 is formed into a substantially U shape in a side view, and the frame is formed. Since the horizontal projection area required to form the optical path at 40 is made small, it is possible to make the installation space more compact than the maximum image formation size.

Further, in the laser beam scanning system (see FIG. 2) in which the optical path has a substantially U-shape when viewed from the side, even if the light receiving element 56 in the horizontal synchronizing signal detecting means is fixed to the frame 40, the fixed position is secured. Although difficult to do, in the present laser beam scanning system 11, since the light receiving element 56 is attached to the optical component such as the lens 46, the design of the attachment position and the like is facilitated and the attachment configuration is also simplified.

[0029]

As described above, according to the image forming apparatus of the present invention, at least one of the light receiving means and the reflecting means forming the horizontal synchronizing signal detecting means is accurately positioned so as not to interfere with the optical path of the laser beam. Since the laser beam is attached and the laser beam for detecting the horizontal synchronizing signal is accurately guided to the light receiving element, excellent detection of the horizontal synchronizing signal is realized by this light receiving means.

Further, the optical fiber forming the optical path between the light receiving element and the light detecting element for receiving the information from the light receiving element and detecting the timing of optical writing can be securely held, so that the optical fiber can be held. Can be securely held at a position where the laser beam is not blocked without vibration or loosening.

Further, by constructing the optical path of the laser beam from the optical deflector to the exposure of the surface of the image carrier in a substantially U-shape in a side view, the horizontal projection area required for forming the optical path in the apparatus can be obtained. Can be made smaller.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram in a laser printer for explaining a first embodiment of the present invention.

FIG. 2 is an exploded perspective view of the laser beam scanning system of FIG.

FIG. 3 is a perspective view showing a configuration of a horizontal synchronizing signal detecting means portion of FIG.

FIG. 4 is a perspective view for explaining the configuration of a conventional laser beam scanning system.

[Explanation of symbols]

1 ... Printer main body, 5 ... Photoconductor unit, 6 ... Photoconductor drum, 11 ... Laser beam scanning system, 40 ... Frame, 41 ... Laser oscillator, 42 ... Polygon mirror, 43 ...
fθ lens, 44, 45 ... Reflective mirror, 46 ... Lens,
55 ... Frame body, 56 ... Light receiving element, 57 ... Reflecting means, 58 ... Fixed frame, 59 ... Fixed arm body, 60 ... Optical fiber, 62 ... Photodiode, 63 ... Support member.

Claims (3)

[Claims] 1. An optical writing means for exposing the surface of an image carrier by an optical system including at least a laser light source and an optical deflector, and a laser beam reflected by the optical deflector for timing optical writing. In the image forming apparatus provided with the light receiving means for receiving a part of the light receiving means, the reflecting means for guiding the laser beam to the light receiving means is the maximum optical path in the optical parts constituting the optical writing means with reference to the optical deflector. An image forming apparatus, which is installed so as to receive a laser beam that has passed through an optical component located downstream, and at least one of the light receiving means and the reflecting means is provided in the optical component located most downstream. 2. An optical path is formed by an optical fiber between the light receiving element and a light detecting element which receives information from the light receiving element and detects the timing of optical writing, and holding means for holding the optical fiber. The image forming apparatus according to claim 1, wherein the image forming apparatus is provided on an optical component located on the most downstream side. 3. The optical writing means according to claim 1 or 2, wherein an optical path from the optical deflector to the exposure of the surface of the image carrier is formed in a substantially U-shape in a side view. Image forming apparatus.