JPH0254240A - Mirror scanning optical system - Google Patents

Abstract

PURPOSE:To eliminate unnecessary rays of light at scanning time by moving a light interrupting mask by the same quantity as that of a scanning means so that luminous fluxes to sections other than an initial scanning section can be shielded at the initial scanning time. CONSTITUTION:A light interrupting mask 114 is fitted to a moving base 100 so that the mask 114 can be moved together with the base 100. Therefore, unnecessary luminous fluxes of the rays of light diverged by a mirror 34 can be interrupted on the upstream side of the 1st mirror 36 at, at least, the initial stage of scanning and overexposure, etc., due to leaking rays of light can be prevented. Moreover, since the light interrupting mask 114 moves together with the moving base 100 at the time of scanning, the mask 114 does not interfere with line scanning rays of light and line scanning can be performed appropriately. Thus unnecessary rays of light can be eliminated at the scanning time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a mirror scanning optical system that blocks unnecessary light in the mirror scanning optical system.

[Prior art]

An electrophotographic device that is an image recording device that can capture and record images on predetermined frames of photosensitive film such as microfilm, and project the recorded images onto a screen or copy them onto copy paper. However, the special public
-22744, U.S. Patent No. 4461566, Special Publication No. 4
It is known from No. 9-27446, Utility Model Publication No. 53-45635, etc.

When an image is copied onto copy paper using this apparatus, the recorded image is transmitted by a light beam from a light source, and the transmitted light beam is diverged through a lens and guided to a mirror scanning system. In a mirror scanning system, a mirror is moved to sequentially scan an image from one side to the other, and the light is focused on the circumferential surface of an exposure drum, which is a photoreceptor, to perform so-called slit a light. An exposure slit is provided immediately before the upstream side of the exposure drum, and unnecessary light is blocked by passing the mirror-scanned divergent light through the exposure slit.

However, in addition to the light that passes through the exposure slit, leaked light may reach the exposure drum, and in such a case, the copy image will be significantly deteriorated.

In order to solve this problem, conventionally it has been considered to provide a mask on the optical path before reaching the exposure slit. This is an optical system in which two mirrors are arranged facing each other in a V-shape (
(each tilted at 45°), the light beam emitted from the light source is reflected by the first mirror to the second mirror, and further reflected to the exposure drum by the second mirror. In this case, the scanned light beam is once condensed (condensed on a line in the case of line scanning) at an intermediate part between the first mirror and the second mirror, so a fixed slit is placed in this condensing part. By arranging a mask like this, unnecessary light rays can be excluded.

[Problem to be solved by the invention]

However, in the electrophotographic apparatus applied to the present invention, the optical system does not have the above basic configuration, and therefore,
There is no part where the light is focused in a single line during scanning. For this reason, it is not possible to simply arrange a fixed slit-shaped mask as described above.

The present invention has been made in consideration of the above-mentioned facts, and an object of the present invention is to obtain a mirror scanning optical system that can eliminate unnecessary light rays during scanning when the optical system performs scanning without a condensing portion.

[Means to solve the problem]

The mirror scanning optical system according to claim (1) includes a movable mirror into which the diverging light transmitted through the image is incident, a scanning means for moving the movable mirror to scan from one side of the image to the other, and a scanning means for scanning the image from one side to the other. A mirror scanning optical system comprising: a fixed mirror that reflects reflected light from a moving mirror in a predetermined direction; It has a light-shielding mask that is moved by a certain amount and blocks light beams other than the initial scanning portion during initial scanning.

Further, the mirror scanning optical system according to claim (2) includes a movable mirror into which the diverging light transmitted through the image is incident, a scanning means for moving the movable mirror to scan from one side of the image to the other, and a scanning means for moving the movable mirror to scan from one side of the image to the other. A mirror scanning optical system comprising a fixed mirror that reflects reflected light from a movable mirror in a predetermined direction due to movement, the mirror scanning optical system being disposed on a light beam upstream of the movable mirror and having a slit hole in a part thereof. a light-blocking mask,
A moving means for moving the light-shielding mask so that the light beam to be scanned during scanning matches the slit hole according to the ratio of the scanning width of the movable mirror and the divergence width of the diverging light at the position where the light-shielding mask is placed. It has .

[Effect]

In the invention described in claim (1), the light-shielding mask placed upstream of the movable mirror can block light beams other than the initial scanning line portion at the start of scanning, so that light leakage can be reduced. . Further, as the scanning progresses, the light blocking mask is moved together with the moving mirror, so it does not block the scanned light beam.

In the invention according to claim (2), the light-shielding mask is moved in accordance with the movement of the movable mirror for scanning, and
This light-shielding mask is moved according to the ratio of the scanning width of the movable mirror to the divergence width of the diverging light at the position where the light-shielding mask is placed, so the shift of the slit hole due to the difference between this scanning width and the diffusion width is absorbed. can do. Thereby, the slit hole can always be made to correspond to the light beam to be scanned, and unnecessary light for scanning can be blocked.

[First Embodiment] FIGS. 1A and 1B show an electrophotographic apparatus 10 to which the present invention is applied. This electrophotographic apparatus 10 is composed of a recording projection section 12, a scanning section 14, and a copying section 16, and a document mounting table 18 is disposed at the top. The original table 18 includes a transparent glass plate 20 on which the original is placed, and a pressing plate 22 that is closed so as to press the original against the glass plate 20. The pressing plate 22 is rotatable around one side, and is opened when the original is taken out.

The image recorded on the document is reduced in size by an optical system 23 and then delivered to a process head 24 . A cassette 26 is loaded into the head section 24A of the process head 24 from the cassette loading section 25, and a film (both not shown) that is wound around a pair of reels in the cassette 26 is accommodated therein.

In the head section 24A, the image is exposed, developed, fixed, and dried as the film moves from one IJ reel to the other reel, and the image is recorded on the film.

The image recorded on the film can be enlarged and projected onto the screen 28. That is, Figure 1 of the film (B
) A light source 30 and a mirror 32 are arranged on the left side of the
The light beam emitted from the light source 30 is emitted onto the image on the film via the mirror 32, and the transmitted image is transmitted to the optical system 2.
3 to be guided to the screen 28.

Images recorded on film can also be copied. That is, a mirror 34 is disposed on the optical axis extending from the projected image from the film to the screen 28. This mirror 34 is movable around its upper end in FIG. 1(B) as a rotation axis, and the screen 28
When projecting to the first image, the driving force of a driving means (not shown)
As shown by the imaginary line in Figure (B), it is held in a horizontal state. On the other hand, during copying, the mirror 34 is rotated clockwise in FIG. 1(B) about the upper end and is tilted at approximately 45 degrees as shown by the solid line.

Thereby, the light beam reaching from the process head 24 is guided to the scanning section 14 below the electrophotographic apparatus 10.

As shown in FIGS. 3 and 5, the scanning section 14 is composed of first and second mirrors 36, 38 as movable mirrors, and a third mirror 40 as a fixed mirror. The first and second mirrors 36,38 are each mounted on the moving base 100. This moving base 10
0 is a guide shaft 104 via a bearing (not shown).
It is pivoted on. A part of a belt 110, which is wound between a drive pulley 106 and a turn pulley 108 shown in FIG. By this, the movable base 100 is connected to the guide shaft 104.
It can be moved in the direction of arrow J in FIG. 3 along the arrow J in FIG.

In this case, since the first and second mirrors 36.38 are fixed at predetermined positions on the movable base 100, the relative positions of the first and second mirrors 36.38 are not changed. Note that the first mirror 36 has a reflective surface tilted toward the upper rear of the electrophotographic apparatus 10, and the second mirror 38 has a reflective surface tilted toward the upper front of the electrophotographic apparatus 10.

Here, by moving the first and second mirrors 36, 38 from the left side to the right side in FIG.
The light beams from the mirrors are line-scanned and guided to the third mirror 40 in sequence. The third mirror 40 is fixed to a partition plate 112 that partitions the recording projection section 12 and the scanning section 14.

This third mirror 40 has the role of guiding the incident light from the second mirror 38 to an entrance port 42 of the copying section 16, which will be described later. The light is focused at the position indicated by arrow B in FIG. 2 on the circumferential surface of 44.

The movable base 100 has a light shielding mask 114 at its upper end.
is installed. The light-shielding mask 114 is formed of a thin flat plate, and has a substantially U-shaped planar shape (third
(see figure). Legs 1 forming a U-shape of the light-shielding mask 114
16 are side plates 122A and 12 of the movable base 100, respectively.
2B, and the opening between the legs 116 corresponds to the first mirror 36. Here, Fig. 4 (A
), when the movable base 100 is at the scanning start position, the ridge line 118 connecting the bases of the legs 116 is the mirror 34.
The light emitted from the rays crosses within.

As a result, the light indicated by the arrows L and M in FIG. 4(A) can be blocked, and only the initial scanning line portion of the diverging light from the mirror 34 is guided to the first mirror 36. Note that the light-shielding mask 114 is moved by the same amount as the moving base 100 moves during scanning, and the 45th! At the end of scanning as shown in J(B), the beam of divergent light is not interrupted, and the scanned light beam is reflected by the second mirror 38 and the third mirror 40 by the movement of the moving base 100.
The user is guided to the copying section 16. Note that the light-shielding mask 114 moves between the third mirror 38 and the partition plate 11 as it moves during scanning.
It is designed to fit between the two.

The photosensitive drum 44 of the copying section 16 is rotated clockwise (in the direction of arrow H) in FIG. 2 in synchronization with the line scanning of the light beam. A corona charger 46 is disposed upstream from where the light is focused at the position of the arrow B, corresponding to the position of the arrow A in FIG. The entire surface of the photoreceptor is charged by the charging action of the charging corona charger 46.

The bottom of the entrance port 42 is formed into a slit shape, forming an exposure slit 48 . As a result, the photosensitive drum 44 is coated with the photosensitive drum 44 at intervals of a certain width by blocking excess light rays.
The light will be focused on 0.

Arrow C in Figure 2 on the downstream side of the light condensing position (arrow B position in Figure 2)
At the position, a light source 66 is disposed correspondingly through the static eliminating slit 64, and serves as a static eliminating section 68.

The light rays emitted from this light source 66 pass through the static elimination slit 64.
The light passes through and is irradiated onto the photoreceptor 50. This light beam has the role of removing excess charge from the photoreceptor 50, and mainly removes the charge corresponding to the front and rear ends of the recording paper 70, which will be described later.

As shown in FIG. 1, a developing roller 72 is in contact with the photoreceptor 50 downstream of the static eliminating section 68 (see the arrowed position in FIG. 2). The developing roller 72 constitutes a part of the developing section 74 and guides the developer (toner particles) in the developing tank 76 to the photoreceptor 50. As a result, the electrostatic latent image formed on the photoreceptor 50 is visualized.

A transfer corona charger 78 is arranged downstream of the developing section 74 (arrow E position in FIG. 2), and the recording paper 70 is placed between the transfer corona charger 78 and the photosensitive drum 44.
is held in place and conveyed in the direction indicated by the arrow (■) in Fig. 2. Due to the action of the transfer corona charger 780, the developer attached to the photoreceptor 50 is transferred to the recording paper 70.

The recording paper 70 is stacked in layers on a paper feed tray 80 disposed below the photosensitive drum 44, and the uppermost layer of the recording paper 70 is rotated by a half-moon-shaped paper feed roller 82.
The photosensitive drum 44 is guided by a conveying roller 84 and conveyed between the photosensitive drum 44 and the transfer corona charger 78, and the conveying speed is synchronized with the rotational speed of the photosensitive drum 440. There is.

Further, a cleaning section 86 and a full-surface charge eliminating section 88 are respectively disposed at the arrow F position and the arrow G position in FIG. It is designed to remove all charges that are present.

As described above, in the copying section 16, by rotating the photosensitive drum 44, the steps of charging, exposure, edge static elimination, development, transfer, cleaning, and entire surface static elimination are performed at the positions indicated by arrows A to G in FIG. The configuration is such that an image recorded on a film is copied onto a recording paper 70. The copied recording paper 70 is taken out to a takeout tray 94 via a conveyor belt 90 and a fixing heat roller 92.

The operation of the first embodiment will be explained below.

When recording an image on film, the document on which the recorded image has been recorded is placed on the mounting table 18, and the press plate 22 is closed. The image recorded on the document is reflected by the light beam from the light source, is reduced through the optical system 23, and reaches the process head 24. Head section 24A of process head 24
The cassette 26 is loaded with corresponding film surfaces so that the film is exposed, and the cassette 260 take-up reel is rotated to move the film from one reel to the other. Developing, fixing, and drying processes are sequentially performed to record an image.

Next, when projecting the image recorded on the film onto the screen 28, a light beam from the light source 30 is irradiated onto a mirror 32 disposed on the surface opposite to the surface corresponding to the head portion 24A of the film. The image reflected by the mirror 32 and recorded on the film is transmitted. The transmitted light beam travels in a direction opposite to that recorded on the film by a part of the optical system 23, is enlarged, and is projected onto the screen 28.

The guidance to the original table 18 and the screen 28 can be easily switched by rotating one of the optical systems 23 and changing the direction of reflection.

On the other hand, when copying an image recorded on a film, the mirror 34 is tilted as shown by the broken line in FIG. As a result, the movable base 100 is moved and one end of the diverging light from the mirror 34 is incident on the first mirror 36. At the beginning of this scan, the ridge line 118 of the light-shielding mask 114 crosses the diverging light, thereby making it possible to shield light from areas other than the initial scanning line portion. Therefore, at the start of scanning, unnecessary light does not reach the direction of the first mirror 36, and problems such as overexposure due to leakage light do not occur.

Further, at the same time as the mirror 34 is tilted, the driving means is driven, and the driving pulley 106 starts rotating. As a result, the movable base 100 is moved, and the diverging light is sequentially incident on the first mirror 36 from the one end, and is incident on the second mirror 38.
The light is reflected toward the third mirror 40 through the mirror. The light beam reflected by the third mirror 40 is transmitted to the entrance 42 of the copying section 16.
, passes through the exposure slit 48, and is exposed to the photosensitive drum 4.
The light is focused on the photoreceptor 50 of No. 4. Note that the light shielding mask 114
is moved together with the movable base 100, so it does not block the divergent light that is line-scanned during scanning.

The entire surface of the photoreceptor 50 is charged at the position of the arrow A in FIG. 2, and only the portion exposed to light at the position of the arrow B in FIG. 2 is neutralized. The photosensitive drum is rotated clockwise, the end of the photosensitive drum is neutralized at the position indicated by arrow C in FIG. 2, and development processing is performed at the position indicated by arrow C in FIG. In this development process, the developer in the developing tank 76 is guided by the developing roller 72 to the photoreceptor, and the developer adheres to the photoreceptor at portions having different electric charges.

At the position of arrow E in FIG. 2, the attached developer is transferred to the recording paper 70 by the transfer corona charger 78 and a copy is made. The copied recording paper 70 is transferred to the conveyor belt 9
0, is fixed by the heat roller 92, and taken out onto the takeout tray 94, so that a copy image can be obtained.

In this way, in the first embodiment, the light-shielding mask 114 is attached to the movable base 100 and is moved together with the movable base 100. Therefore, at least at the initial stage of scanning, unnecessary light beams of the divergent light from the mirror 34 are removed from the mirror 36
It is possible to block light on the upstream side of the light, and overexposure due to leakage light can be prevented. Further, during scanning, since it moves together with the movable base 100, there is no interference with the scanning line light, and line scanning can be performed appropriately.

[Second example] A second embodiment of the present invention will be described below.

In the second embodiment, the recording projection section 12 and the copying section 16
Since it is the same as that of the first embodiment, a description of its configuration will be omitted, and the same reference numerals will be used for the same parts of the scanning section 14, which is a feature of the second embodiment, as those of the first embodiment. The explanation of its configuration will be omitted.

As shown in FIGS. 6 and 7, the guide shaft 10
4, a rack gear 120 is formed. This rack gear 120 meshes with a gear 126 that constitutes a part of a moving means that is pivotally supported on the side plate 122A of the moving base 100 via a shaft 124, and rotates in accordance with the movement of the moving base 100. ing. mobile base 100
A take-up reel 128 is hung between the side plates 122A and 122B, and a gear 130, which serves as a moving means together with the gear 126, is fixed coaxially to a portion protruding from the side plate 122A. This gear 130 meshes with the gear 126, which allows the moving base 100 to move during scanning.
According to the movement of the winding wheel 128, the winding wheel 128 is rotated counterclockwise in FIG. The take-up reel 128 includes
A slit-shaped notch (not shown) is formed in the middle portion in the longitudinal direction, and one end of the mask screen 132 is locked therein. The middle part of the mask screen 132 is wound up in a layer on the take-up reel 128, and the other end part extends toward the third mirror 40 along the upper end of the movable base 100.

The other extended end is locked to a hook portion 136 formed on the movable base 100 via a tension coil spring 134. As a result, the biasing force of the tension coil spring 134 acts on the mask screen 132, so that the mask screen 132 is always maintained in a tensioned state.

A rectangular slit 138 is provided in the middle of the mask screen 132. At the scanning start position of the movable base 100, this slit 138 is located at the left end in FIG. The light is allowed to pass in the direction of the mirror 36, and other unnecessary light beams are blocked. When the movement of the moving base 100 is started, the mask screen 132 will also move integrally in the same direction, but the scanning width dimension W by the first mirror 36. □ and
The width of the diffused light at the position where the slit 138 of the mask screen 132 is arranged is different from the diffusion width W jl A S K of the moving base 100 and the mask screen 132 .
If the slit 138 is moved by the same amount, the portion of the light beam that performs line scanning and the portion of the light beam that is passed through the slit 138 will gradually shift. For this reason, this second book
In the embodiment, as the moving base 100 moves, the gear 1
26 and 130, the mask screen 132 is gradually wound up. The gear ratio of the gears 126 and 130 is set so that the winding amount is the amount obtained by subtracting the diffusion width of the diffused light at the position where the slit 138 is placed from the scanning width dimension by the first mirror 36. As a result, the light flux passing through the slit 138 and the light flux to be line-scanned are always matched.

The operation of the second embodiment will be explained below.

Mirror 3 is used to copy the image recorded on the film.
4 is tilted, the diffused light reflected by this mirror 34 reaches the mask screen 132. The mask screen 132 allows only the light beam corresponding to the slit 138 (the left end of the image in FIG. 6) to pass through, and blocks the other light beams.

The light flux that has passed through the slit 138 reaches the first mirror 36, is reflected by the second mirror 38, then the third mirror 40, is guided to the entrance 42 of the copying section 160, and is guided to the photoreceptor 5.
0 is exposed.

At the same time, movement of the moving base 100 is started, and line scanning is performed sequentially. Here, this moving base 100
According to the movement of the movable base 100, the gear 126 meshing with the rack gear 120 is rotated, and this rotation is transmitted to the gear 130, and the winding wheel 128 fixed to the gear 130 is rotated. , the mask screen 132 is gradually rolled up. As a result, the difference between the divergence width dimension of the divergent light at the position where the mask screen 132 is arranged and the scanning width by the first mirror 36 can be absorbed, and only the light flux that should always be line-scanned can be made to correspond to the slit 138. , line scanning can be performed without leaking unnecessary light.

In this way, in the second embodiment, even in the case of an optical system in which the light beam from the mirror 34 does not have a condensing part and has a special path, it is possible to pass the light beam from the mirror 34 through a fixed slit as shown in the section of the prior art. Similarly, since unnecessary light beams can be blocked, exposure accuracy is improved and the image quality of the copied image is not impaired due to overexposure. In addition, mask screen 13
The winding amount of 2 is determined by the gear 12 according to the movement of the movable base 100.
6.130 or the like, the structure is simple and the movement of the slit 138 can be controlled with high accuracy.

〔Effect of the invention〕

As explained above, the mirror scanning optical system according to the present invention has an excellent effect in that unnecessary light rays can be eliminated during scanning when the optical system performs scanning without a condensing part.

[Brief explanation of the drawing]

FIG. 1 (A> is a perspective view of an electrophotographic apparatus according to this embodiment,
FIG. 1(B) is a side sectional view of the electrophotographic apparatus according to this embodiment, FIG. 2 is an enlarged view showing the exposure drum and its surroundings, and FIG.
The figure is an exploded perspective view of the scanning section, FIGS. 4A and 4B are explanatory diagrams showing the moving state of the moving base according to the first embodiment, and FIG. 5 is a side view of the scanning section according to the first embodiment. Figure 6 is the second
A side view of the scanning unit according to the embodiment, FIG. 7 is the same as ■-■ in FIG.
FIG. 10... Electrophotographic device, 14... Scanning unit, 100... Moving base, 106... Drive pulley, 114... Light shielding mask, 120/126. 132・ 138・ ・Rack gear, 30...Gear, ・Mask screen, ・Slit.

Claims (2)

[Claims] (1) A movable mirror into which the diverging light that has passed through the image is incident, a scanning means that moves the movable mirror to scan from one side of the image to the other, and reflects the reflected light from the movable mirror in a predetermined direction due to the movement of the scanning means. a fixed mirror disposed on the light beam upstream of the movable mirror and moved by an amount equal to the amount of movement of the scanning means to scan a portion other than the initial scanning portion during initial scanning. A mirror scanning optical system that has a light shielding mask that blocks light beams. (2) A movable mirror into which the diverging light that has passed through the image is incident, a scanning means that moves the movable mirror to scan from one side of the image to the other, and reflects the reflected light from the movable mirror in a predetermined direction due to the movement of the scanning means. A mirror scanning optical system comprising: a fixed mirror, which is disposed on the light beam upstream of the movable mirror, and has a slit hole in a part thereof; and a scanning width of the movable mirror. a moving means for moving the light-shielding mask so that the light beam to be scanned during scanning matches the slit hole according to the ratio of the divergence width of the diverging light at the position where the light-shielding mask is arranged; system.