JPH0833582B2 - Mirror scanning optics - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a mirror scanning optical system that blocks unnecessary light in a mirror scanning optical system.

[Prior art]

An electrophotographic apparatus which is an image recording apparatus capable of shooting and recording an image on a predetermined frame of a photosensitive film such as a microfilm and projecting the recorded image on a screen or copying paper. However, the special public Sho 58
-22744, U.S. Pat.No. 4,461,566, Japanese Patent Publication No. 49-27446,
It is known by Jitsuko Sho 53-45635, etc.

When copying images to copy paper with this device,
The recorded image is transmitted by the light beam from the light source, and the transmitted light beam is diverged through the lens and guided to the mirror scanning system. In the mirror scanning system, so-called slit exposure is performed by moving a mirror and sequentially scanning from one side to the other side of the image to focus it on the peripheral surface of the exposure drum, which is a photoconductor. An exposure slit is provided immediately upstream of the exposure drum, and unnecessary light is blocked by allowing the divergent light scanned by the mirror to pass through the exposure slit.

However, leaked light may reach the exposure drum in addition to the light passing through the exposure slit, and in such a case, the copy image is significantly deteriorated.

In order to solve this, conventionally, it has been considered to provide a mask on the optical path before reaching the exposure slit. This is because two mirrors are arranged as an optical system so as to face each other in a V shape (tilt at 45 °), and the light beam emitted from the light source is reflected by the first mirror to the second mirror, and further, the second mirror. It is configured to reflect on the exposure drum with a mirror. In this case, the light beam to be scanned is once focused (on a line in the case of line scanning) at an intermediate portion between the first mirror and the second mirror. By arranging the mask in the shape of a circle, unnecessary light rays can be eliminated.

[Problems to be Solved by the Invention]

However, in the electrophotographic apparatus applied to the present invention, the optical system does not have the above-mentioned basic configuration, and therefore, there is no portion that is focused in a line during scanning. For this reason,
As described above, it is not possible to simply dispose a fixed slit mask.

In consideration of the above facts, an object of the present invention is to obtain a mirror scanning optical system capable of eliminating unnecessary light rays during scanning when performing scanning without a condensing portion in the optical system.

[Means for solving the problem]

The mirror scanning optical system according to claim (1) comprises: a moving mirror on which divergent light transmitted through an image is incident; a scanning unit for moving the moving mirror to scan from one side of the image to the other; A mirror scanning optical system comprising: a fixed mirror that reflects the reflected light from the moving mirror in a predetermined direction, the mirror scanning optical system being arranged on a light beam upstream of the moving mirror and having the same amount as the moving amount of the scanning means. It has a light-shielding mask that is moved and shields a light beam other than the initial scanning portion during the initial scanning.

Further, the mirror scanning optical system according to claim (2) includes a moving mirror on which the divergent light transmitted through the image is incident, a scanning unit for moving the moving mirror to scan from one side of the image to the other side, and a scanning unit of the scanning unit. A mirror scanning optical system comprising: a fixed mirror that reflects the reflected light from the moving mirror by movement in a predetermined direction, and a slit hole is provided in a part of the light beam on the upstream side of the moving mirror. And a light blocking mask for blocking the light to be scanned at the time of scanning 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 arranged. Moving means for moving the mask.

[Action]

In the invention described in claim (1), since the light shielding mask disposed on the upstream side of the moving mirror can shield the light beam other than the initial scanning line portion at the start of scanning, it is possible to reduce the leakage light. . Further, the light-shielding mask is moved together with the moving mirror as the scanning progresses, so that the light flux to be scanned is not blocked.

In the invention according to claim (2), the light-shielding mask is moved according to the movement of the moving mirror for scanning, and the light-shielding mask is diverged at the scanning width of the moving mirror and the position where the light-shielding mask is arranged. Since it is moved according to the ratio of the divergence width of the light, it is possible to absorb the shift of the slit hole due to the difference between the scanning width and the diffusion width. As a result, the slit hole can be made to correspond to the light beam to be constantly scanned, and the light unnecessary 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 device 10 is
The recording / projecting unit 12, the scanning unit 14, and the copying unit 16 are provided, and a document placing table 18 is arranged at the top. The document table 18 includes a transparent glass plate 20 on which a document is placed, and a pressing plate 22 which is closed so as to press the document against the glass plate 20. The pressing plate 22 is rotatable around one side thereof, and is opened when the document is taken out.

The image recorded on the original is reduced by the optical system 23 and reaches the process head 24. The head portion 24A of the process head 24 is loaded with the cassette 26 from the cassette loading portion 25, and corresponds to a film (both not shown) wound on a pair of reels in the cassette 26. In the head portion 24A, the image is exposed, developed, fixed, and dried according to the movement of one reel of the film to the other reel, and the image is recorded on the film.

The image recorded on the film can be enlarged and projected on the screen 28. That is, the light source 30 and the mirror 32 are arranged on the left side of the film in FIG. 1 (B),
The light emitted from the light source 30 is applied to the image on the film through the mirror 32, and the transmitted image is guided to the screen 28 by using a part of the optical system 23.

Further, the image recorded on the film can be copied. That is, the mirror 34 is arranged on the optical axis from the projection image from the film to the screen 28. The mirror 34 is rotatable about the upper end of FIG. 1 (B) as a rotation axis, and at the time of projection on the screen 28, it is driven by a driving means (not shown) to drive the mirror. It is held in a horizontal position as indicated by the imaginary line. On the other hand, at the time of copying, the mirror 34 is rotated clockwise around the upper end portion thereof as shown in FIG. 1 (B) and tilted at about 45 ° as shown by the solid line. As a result, the light rays from the process head 24 are transmitted to the electrophotographic device.
It will be guided to the scanning unit 14 below 10.

As shown in FIGS. 3 and 5, the scanning unit 14 is composed of first and second mirrors 36 and 38 as moving mirrors and a third mirror 40 as a fixed mirror. First
The second mirrors 36 and 38 are attached to the moving base 100, respectively. The moving base 100 is pivotally supported by the guide shaft 104 via a bearing (not shown). The moving base 100 is locked to a part of a belt 110 wound between a drive pulley 106 and a turn pulley 108 shown in FIG. 5, and the drive pulley 106 is rotated by the driving force of a driving means (not shown). As a result, the moving base 100 can be moved along the guide shaft 104 in the direction of arrow J in FIG. In this case, since the first and second mirrors 36 and 38 are fixed at predetermined positions of the moving base 100, the relative positions of the first and second mirrors 36 and 38 are not changed. The first mirror
The reflecting surface of 36 is tilted toward the upper rear of the electrophotographic apparatus 10, and the second mirror 38 is tilted toward the upper front of the electrophotographic apparatus 10.

Here, by moving the first and second mirrors 36 and 38 from the left side to the right side in FIG. 3, the light beam from the mirror 34 is line-scanned and sequentially guided to the third mirror 40. It is like this. The third mirror 40 is a recording projection unit.
It is fixed to a partition plate 112 that partitions 12 and the scanning unit 14.
The third mirror 40 has a role of guiding the incident light from the second mirror 38 to an entrance 42 of the copying section 16 which will be described later, and the light beam entering the entrance 42 is a photosensitive drum. The light is focused at the position of arrow B in FIG. 2 on the circumferential surface of 44.

A light shielding mask 114 is attached to the upper end of the moving base 100. The light-shielding mask 114 is formed of a thin flat plate and has a substantially U-shaped planar shape (see FIG. 3). The leg portions 116 forming the U-shape of the light shielding mask 114 are attached along the side plates 122A and 122B of the moving base 100, respectively, and the openings between the leg portions 116 correspond to the first mirror 36. Here, as shown in FIG. 4 (A), the moving base 100
Is in the scanning start position, a ridgeline 118 connecting the bases of the legs 116 intersects within the divergent light from the mirror 34. As a result, the light indicated by the arrows K, L, and M in FIG. 4A can be blocked, and only the initial scanning line portion of the divergent light from the mirror 34 is guided to the first mirror 36. The light-shielding mask 114 is moved by the same amount as the movable base 100 moves during scanning, and does not block the light flux of divergent light at the end of scanning as shown in FIG.
Is moved, the scanned light beam is reflected by the second mirror 38 and the third mirror 40 and is guided to the copying unit 16. The light-shielding mask 114 is designed to enter between the third mirror 38 and the partition plate 112 as it moves during scanning.

The photosensitive drum 44 of the copying unit 16 is rotated in the clockwise direction (arrow H direction) in FIG. 2 in synchronization with the line scanning of the light rays. A charging corona charger 46 is arranged upstream of the light collected at the position of the arrow B, corresponding to the position of the arrow A in FIG. The charging function of the charging corona charger 46 charges the entire surface of the photosensitive member.

The bottom of the entrance 42 is formed in a slit shape, and forms an exposure slit 48. As a result, the extra rays are blocked, and the light is focused on the photoconductor 50 covered by the photoconductive drum 44 at a constant width.

A light source 66 is associated with a position of an arrow C in FIG. 2 on the downstream side of the light collecting position (position B in FIG. 2) via a charge elimination slit 64 to form a charge eliminating unit 68. The light beam emitted from the light source 66 passes through the static elimination slit 64 and is applied to the photoconductor 50. This light ray has a role of removing the charge of the excess charge of the photoconductor 50, and mainly removes the charge corresponding to the front and rear ends of the recording paper 70 described later.

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

A transfer corona charger 78 is disposed on the downstream side of the developing section 74 (position indicated by an arrow E in FIG. 2), and the recording paper 70 is sandwiched between the transfer corona charger 78 and the photosensitive drum 44. It is designed to be conveyed in the I direction.
Due to the action of the transfer corona charger 78, the photoconductor 50
The developer attached to 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, but only the uppermost recording paper 70 is rotated by the rotation of the half-moon-shaped paper feed roller 82. It is taken out, guided by the conveyance roller 84, and conveyed between the photosensitive drum 44 and the transfer corona charger 78. The conveying speed is synchronized with the rotation speed of the photosensitive drum 44.

A cleaning unit 86 and an entire surface charge erasing unit 88 are respectively arranged at the positions of the arrow F and the arrow G of the photosensitive drum 44 in FIG. 2, and the surface of the photoconductor 50 that has been copied onto the recording paper 70 is cleaned and left. It is designed to eliminate all the electric charges that are being applied.

As described above, in the copying unit 16, by rotating the photosensitive drum 44, the processes of charging, exposure, edge charge removal, development, transfer, cleaning, and full charge removal are performed at the positions indicated by arrows A to G in FIG. The side that is recorded on the film is the recording paper 70
It is a structure to be copied to. The copied recording paper 70 is taken out to the take-out tray 94 via the conveyance belt 90 and the fixing heat roller 92.

 The operation of the first embodiment will be described below.

When an image is recorded on the film, the document on which the recording image is recorded is placed on the mounting table 18 and the pressing plate 22 is closed.
The image recorded on the original is reflected by the light beam from the light source, reduced through the optical system 23, and processed by the process head 24.
Leading to. The head portion 24A of the process head 24 is loaded with a cassette 26, and the film surfaces correspond to each other, so that the film is exposed, and then the take-up reel of the cassette 26 is rotated so that one reel is rotated to the other reel. By moving the film to the reel, development, fixing, and drying processes are sequentially performed to record an image.

Next, when projecting the image recorded on the film onto the screen 28, the light beam from the light source 30 is applied to the mirror 32 arranged on the surface opposite to the surface corresponding to the head portion 24A of the film, The image reflected on the mirror 32 and recorded on the film is transmitted. The transmitted light beam passes through the optical system 23.
A part of the image is recorded in the opposite direction to the recording on the film, enlarged, and projected on the screen 28. Document holder
The switching of the guide to the 18 and the screen 28 is performed by the optical system 23
This can be easily performed by rotating the one and changing the reflection direction.

On the other hand, when copying the image recorded on the film,
The mirror 34 is tilted as shown by the broken line in FIG. As a result, the moving base 100 is moved so that one end of the divergent light from the mirror 34 is incident on the first mirror 36. At the beginning of this scanning, the ridgeline 118 of the light-shielding mask 114 crosses the divergent light, so that it is possible to shield the portion other than the scanning initial line portion. Therefore, at the start of scanning, unnecessary light does not reach the first mirror 36 direction, and there is no inconvenience such as overexposure due to leaked light.

At the same time when the mirror 34 is tilted, the drive means is driven and the drive pulley 106 starts rotating. This allows
The moving base 100 is moved, and the divergent light is sequentially incident on the first mirror 36 from the one end, and is reflected toward the third mirror 40 via the second mirror 38. The light beam reflected by the third mirror 40 reaches the entrance 42 of the copying section 16, passes through the exposure slit 48, and is focused on the photoconductor 50 of the photoconductive drum 44. Since the light blocking mask 114 is moved together with the moving base 100, it does not block the divergent light line-scanned during scanning.

The entire surface of the photoconductor 50 is charged at the position indicated by the arrow A in FIG. 2, and only the portion exposed to light at the position indicated by the arrow B in FIG. 2 is discharged. The photosensitive drum is rotated in the clockwise direction, the end portion thereof is discharged at the position of arrow C in FIG. 2, and the phenomenon processing is performed at the position of arrow D in FIG. In this developing process, the developer in the developing tank 76 is guided to the photoconductor by the developing roller 72, and adheres to the photoconductor in a portion having a different sign of charge.

At the position indicated by the arrow E in FIG. 2, the adhered developer is transferred to the recording paper 70 by the transfer corona charger 78 to make a copy. The copied recording paper 70 is guided by the conveyance belt 90, fixed by the heat roller 92, and taken out from the ejection tray 94.
It can be taken up and a duplicate image can be obtained.

As described above, in the first embodiment, since the light shielding mask 114 is attached to the moving base 100 and moved together with the moving base 100, the unnecessary light flux of the divergent light from the mirror 34 is generated at least at the beginning of scanning. It is possible to block light on the upstream side of the mirror 36 and prevent overexposure due to leaked light. When scanning, the moving base 100
Since it moves together with the scanning line light, the line scanning can be appropriately performed without interfering with the scanning line light.

[Second Embodiment] A second embodiment of the present invention will be described below. Book second
In the embodiment, the recording projection unit 12 and the copying unit 16 are the same as those in the first embodiment, so the description of the configuration will be omitted and the scanning unit 14, which is a feature of the second embodiment, will also be described. The same parts as those in the first embodiment are designated by the same reference numerals, and the description of the configuration will be omitted.

As shown in FIGS. 6 and 7, the guide shaft 10
A rack gear 120 is formed at 4. The rack gear 120 is in mesh with a gear 126 that constitutes a part of a moving unit that is axially supported by a side plate 122A of the moving base 100 via a shaft 124, and is rotated according to the movement of the moving base 100. ing. A take-up reel 128 is stretched between the side plates 122A and 122B of the moving base 100, and a gear 130, which is a moving means together with the gear 126, is provided at a portion protruding from the side plate 122A.
Are fixed coaxially. This gear 130 is the gear 126
Meshes with the moving base 10 during scanning.
The take-up reel 128 is rotated counterclockwise in FIG. 6 according to the movement of 0. The take-up reel 128 has a slit-shaped notch (not shown) at an intermediate portion in the longitudinal direction thereof.
Is formed, and one end of the mask screen 132 is locked. The middle portion of the mask screen 132 is wound in layers on the take-up reel 128, and the other end portion is the moving base 100.
Is extended toward the third mirror 40 along the upper end of the. The other extended end is engaged with a hook 136 formed on the moving 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, and the tensioned state is always maintained.

A rectangular slit 1 in the middle of the mask screen 132.
38 are provided. This slit 138 is a moving base 1
At the scanning start position of 00, it is located at the left end of FIG. 6 of the luminous flux of the divergent light from the mirror 34, and a light beam having a width corresponding to one line scan at the beginning of scanning is passed in the direction of the first mirror 36. It is designed to block other unnecessary light beams. Moving base
When the movement of 100 is started, the mask screen 132 also moves integrally in the same direction, but the first mirror 36
The scanning width dimension W _{SCAN according} to the above is different from the diffusion width W _MASK of the diffused light at the position where the slit 138 of the mask screen 132 is arranged, and the moving base 100 and the slit 138 of the mask screen 132 are moved by the same amount. Then, the portion of the light beam which is line-scanned and the portion of the light beam which is passed by the slit 138 are gradually displaced. Therefore, in the second embodiment, the mask screen 132 is gradually wound by driving the gears 126 and 130 as the moving base 100 moves. The gear ratio of the gears 126 and 130 is set such that this winding amount is an amount obtained by subtracting the diffusion width of the diffused light at the position where the slit 138 is arranged from the scanning width dimension by the first mirror 36. As a result, the luminous flux passing through the slit 138 and the luminous flux to be line-scanned are always matched.

 The operation of the second embodiment will be described below.

Mirror to copy the image recorded on the film
When 34 is tilted, the diffused light reflected by this mirror 34 reaches the mask screen 132. On the mask screen 132, only the light flux corresponding to the slit 138 (the left end in FIG. 6 of the image) can be passed and the other light flux can be blocked.

The light flux passing through the slit 138 reaches the first mirror 36, is reflected by the second mirror 38 and then the third mirror 40, is guided to the entrance 42 of the copying section 16, and the photoconductor 50 is exposed. .

At the same time, the movement of the movement base 100 is started, and line scanning is sequentially performed. Here, in accordance with the movement of the moving base 100, the gear 126 meshed with the rack gear 120.
The rotation is transmitted to the gear 130, the take-up reel 128 fixed to the gear 130 is rotated, and the mask screen 132 is gradually taken up according to the movement of the moving base 100. 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. The line scanning can be performed without leaking unnecessary light.

As described above, in the second embodiment, even in the case of an optical system having a special path in which the light beam from the mirror 34 is not condensed, the fixed slit as described in the section of the prior art is passed. Similarly, since the unnecessary light flux can be shielded, the exposure accuracy is improved and the image quality of the copied image such as overexposure is not deteriorated. Also, the mask screen 13
The winding amount of 2 depends on the movement of the moving base 100 and the gears 126 and 130.
Since the structure is used, the structure is simple and the slit 13
8 movements can be controlled.

〔The invention's effect〕

As described above, the mirror scanning optical system according to the present invention is
When performing scanning without a condensing portion in the optical system, it has an excellent effect that unnecessary light rays can be eliminated during scanning.

[Brief description of drawings]

FIG. 1A 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 periphery, FIG. 3 is an exploded perspective view of the scanning portion, and FIG. 4 (A). And (B) is the first
Explanatory drawing which shows the movement state of the movement base which concerns on an Example, 5th
FIG. 7 is a side view of the scanning unit according to the first embodiment, FIG. 6 is a side view of the scanning unit according to the second embodiment, and FIG. 7 is VII-VII of FIG.
It is a line sectional view. 10 ... Electrophotographic device, 14 ... Scanning part, 100 ... Moving base, 106 ... Driving pulley, 114 ... Shading mask, 120 ...
Rack gear, 126, 130 ... Gears, 132 ... Mask screen, 138 ... Slit.

Claims (2)

[Claims] 1. A moving mirror on which divergent light transmitted through an image is incident, scanning means for moving the moving mirror to scan from one side of the image to the other side, and reflected light from the moving mirror due to movement of the scanning means in a predetermined direction. And a fixed mirror for reflecting the light to a mirror scanning optical system, the mirror scanning optical system being disposed on a light beam upstream of the moving mirror and being moved by the same amount as the moving amount of the scanning means. Mirror scanning optical system having a light-shielding mask that shields light beams other than the above. 2. A moving mirror on which divergent light transmitted through an image is incident, a scanning means for moving the moving mirror to scan from one side to the other side of the image, and reflected light from the moving mirror due to movement of the scanning means in a predetermined direction. A fixed mirror for reflecting light to a mirror scanning optical system, which is provided on a light beam upstream of the moving mirror and has a slit hole in a part thereof, and a scanning in the moving mirror. And a moving means for moving the light-shielding mask so that the light beam to be scanned and the slit hole are made to coincide with each other according to the ratio of the width and the divergence width of the diverging light at the position where the light-shielding mask is arranged. Scanning optics.