JPH08190076A - Image forming device - Google Patents

Abstract

(57) [Summary] [Object] In an image forming apparatus using a rotation prism for rotating an image, by removing ghost light generated in the rotation prism, good projection is achieved on a screen surface or a recording medium surface. To obtain an image forming apparatus capable of obtaining an image. A projection image 6 illuminated by an illumination means LX is projected onto a screen 14 surface or a recording medium 17 by a projection lens 7.
Rotation prism 8 for rotating the projection image on the exit side of the projection lens when projecting on a projection surface such as a plane
And a light blocking member is provided in a position where the effective area of the light beam emitted from the rotation prism changes in association with the rotation of the rotation prism, at a position where the effective area is not shielded.

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, and more particularly, when it is used to magnify and project reduced image information such as microfilm on a screen surface by using a rotation prism for image rotation, or When a projection image is copied by projecting image information on a photosensitive drum which is a photoreceptor, a good projection image can always be obtained by blocking the ghost light generated in the rotation prism with a light blocking member. The present invention relates to an image forming apparatus suitable for a device such as a film reader or a micro film reader printer.

[0002]

2. Description of the Related Art An image forming apparatus such as a general microfilm reader printer is provided with a reader unit as an observation system for enlarging and projecting a projection image (image information) of a microfilm, which is reduced and recorded, onto a screen surface by a projection lens. And a printer unit as a recording system for projecting and recording the projected image on a photoconductor by a projection lens and outputting it as a copy.

In this type of image forming apparatus, the in-plane angle adjustment of the projected image on the screen surface or the photosensitive drum surface is generally performed using a film carrier. However, in many recent image forming apparatuses such as microfilm reader printers, a rotation prism having a trapezoidal cross-section is provided on the exit side of the projection lens so that the image can be easily rotated. By rotating, the in-plane angle adjustment of the projected image on the screen surface or the photosensitive drum surface is performed.

[0004]

In recent years, there has been a demand for downsizing of this type of image forming apparatus, and it is not easy to handle the above-described rotation prism in the apparatus body, which increases the size of the apparatus as a whole. , There was a problem. Therefore, the compactness of the device had to be secured to some extent.

Therefore, in the conventional image forming apparatus such as a micro film reader printer, the optical path of the optical system is appropriately bent by using, for example, an optical path bending mirror (reflection mirror), so that the entire apparatus can be made compact. There is.

Therefore, in this type of image forming apparatus, there is no margin (degree of freedom) in bending the optical path as compared with an image forming apparatus that does not use a rotation prism, and the ghost light generated in the rotation prism is projected into the projection optical system. However, there is a problem that ghost light is projected on the screen surface as a result.

According to the present invention, in an image forming apparatus using a rotation prism for rotating a projected image, a light blocking member is provided in an area where the effective area of a light beam emitted from the rotation prism changes in association with the rotation of the rotation prism. An object of the present invention is to provide an image forming apparatus in which only the ghost light generated in the rotation prism is shielded by providing the effective area at a position where it is not shielded, and a good projection image is always obtained on the screen surface or the photosensitive drum surface. And

[0008]

The image forming apparatus of the present invention is such that, when a projection image illuminated by an illumination means is projected by a projection lens onto a projection surface such as a screen surface or a recording medium surface, the exit side of the projection lens. A rotation prism for rotating the projected image, and a light blocking member provided in a position where the effective area of the light beam emitted from the rotation prism changes in conjunction with the rotation of the rotation prism, at a position not blocking the effective area It is characterized by that.

In particular, the light-shielding member is disposed integrally with the rotation prism and rotates in conjunction with the rotation of the rotation prism, or moves up and down in the optical axis direction in association with the rotation of the rotation prism. When ghost light is generated in the rotation prism, the effective area of the light beam emitted from the rotation prism is located in a changing area, and the ghost light generated in the rotation prism is removed. It has a feature.

[0010]

Embodiment 1 FIG. 1 is a schematic view of the essential portions of Embodiment 1 of the present invention.

In the figure, reference numeral 1 denotes a light source means, which is composed of, for example, a halogen lamp or a fluorescent lamp. Reference numeral 2 denotes a condenser lens which collects the light flux from the light source means 1.
Reference numeral 3 is a heat insulating glass, and 4 is a cold mirror. The optical members 3 and 4 remove the infrared light component from the light flux emitted from the light source means 1 to suppress the temperature rise on the projected image 6 surface. There is. 5 is a field lens. Incidentally, in this embodiment, the illumination means (illumination optical system) LX is constituted by the elements denoted by reference numerals 1, 2, 3, 4, and 5.

Reference numeral 6 denotes a transmission type projection image (image information), which is made of, for example, a microfilm. Reference numeral 7 denotes a projection lens, which magnifies and projects the projection image 6 onto the screen 14 surface or the photosensitive drum (recording medium) 17 surface.

The movement of the projection lens 7 is controlled by the drive means 20 based on the signal obtained by the focus detection means (not shown) as shown by the arrow B on the optical axis, whereby the focus of the projection image on the screen 14 is adjusted. ing.

A rotation prism 8 for image rotation is provided on the exit surface side of the projection lens 7, and, for example, a microfilm image (projection image) tilted in the film plane is projected on the screen 14 surface. Alternatively, it has a function of correcting an arbitrary angle on the surface of the photosensitive drum 17. In this embodiment, the incident point 8a1 and the exit point 8d1 of the light beam are displaced from each other on the exit surface side of the projection lens 7, that is, the optical axis S1 on the incident side and the optical axis S2 on the exit side are displaced from each other. The rotation prism 8 is downsized.

Reference numeral 9 denotes a light-shielding member, which is provided integrally with the lens barrel 18 of the rotation prism 8, and the effective area of the light beam emitted from the rotation prism 8 changes in association with the rotation of the rotation prism 8. It is provided at a position where the effective luminous flux that contributes to the projection is not blocked.
As a result, in the present embodiment, as will be described later, only the ghost light generated in the rotation prism 8 is removed so that the ghost light is not projected on the screen 14 surface (the photosensitive drum 17 surface).

Reference numerals 10 and 11 denote optical path bending mirrors (reflection mirrors), which prevent an increase in size of the apparatus main body caused by disposing the rotation prism 8 by appropriately bending the optical path of the light beam emitted from the rotation prism 8. are doing.

Reference numeral 100 denotes a movable printing scanning unit, which has a scanning mirror 15 and a reflection mirror 16, and is moved as shown by an arrow A in the figure so as to be positioned in the optical path during printing, and the reader is moved. Sometimes shelters out of the optical path. 19
Is a slit for printing, which limits the amount of light exposed on the surface of the photosensitive drum 17. Reference numeral 17 is a photosensitive drum as a recording medium.

Reference numeral 12 is a reflection mirror for the reader, and 13 is a rotatable rotation mirror for the reader, which is rotated to a position 13a at the time of the reader as indicated by an arrow C and at a position 13 at the time of printing.
It is turning to b.

In this embodiment, the luminous flux emitted from the light source means 1 is condensed by the condenser lens 2, passes through the heat insulating glass 3 and is reflected by the cold mirror 4, and then the projected image 6 of the projected image 6 is passed through the field lens 5. Illuminates the effective illumination area. Then, the light flux based on the projection image 6 that has passed through the projection lens 7 passes through the rotation prism 8 and then enters the optical path bending mirror 10. At this time, in the present embodiment, the light blocking member 9 is provided at a position where the effective light beam E is not blocked in a region where the effective region of the light beam emitted from the rotation prism 8 changes in association with the rotation of the rotation prism 8. The ghost light G generated in 8 is shielded.

In this embodiment, each element is set so that the light beam from the light source means 1 is focused (imaged) in the vicinity of the entrance pupil position of the projection lens 7, that is, Koehler illumination is performed.

At the time of a reader observing the projected image 6 on the screen 14 surface, the effective luminous flux E that has passed through the optical path bending mirrors 10 and 11 is passed through the reflection mirror 12 for the reader and the rotary mirror 13 and then onto the screen 14 surface. The light is guided to, and an enlarged projection image is formed on the surface.

Further, when the printer forms a projected image on the surface of the photosensitive drum 17, the scanning unit 10 for the printer is used.
Move as shown by arrow A in the figure so that 0 is located in the optical path,
The effective light beam E that has passed through the optical path bending mirrors 10 and 11 is reflected by the scanning mirror 15 and the reflection mirror 16 and is incident on the surface of the photosensitive drum 17. Then, an enlarged projection image is formed on the surface of the photosensitive drum 17.

At this time, the scanning mirror 15 and the reflection mirror 1
6 is moved integrally to scan the surface of the photosensitive drum 17 in the sub-scanning direction, whereby the image information of the entire projected image 6 is projected and recorded on the surface of the photosensitive drum 17.

In the present embodiment, the rotation prism 8 is arranged in the apparatus as described above, and the optical path is appropriately bent by the optical path bending mirrors 10 and 11 so that the apparatus as a whole does not become large. As a result, the light beam G outside the screen shown in FIG.
The light flux G emitted from the rotation prism 8 does not reflect on the optical path bending mirror 10 disposed in the regular optical path, but directly enters the optical path bending mirror 11 (light blocking in this embodiment). When the member 9 is not provided),
For example, at the time of the reader, it is projected as ghost light on the surface of the screen 14 via the reflection mirror 12 and the rotating mirror 13 as shown by the dashed line in the figure, and adversely affects the projected image. FIG. 3 is an explanatory view showing how the ghost image 14G generated on the surface of the screen 14 at this time looks.

Therefore, in the present embodiment, as shown in FIG. 1, the light blocking member 9 does not block the effective light beam E in the region where the effective region of the light beam emitted from the rotation prism 8 changes in association with the rotation of the rotation prism 8. By providing it at the position, only the ghost light G generated in the rotation prism 8 is blocked, and a good projection image can be obtained on the screen 14 surface (or the photosensitive drum 17 surface).

Next, the cause of the generation of ghost light in the rotation prism 8 and the method of shielding the ghost light will be described with reference to FIGS. 2 (A), (B), (C) and (D). 2 (A), (B), (C), and (D) are explanatory views showing light rays when passing through the rotation prism and passing through the optical path bending mirror. In the figure, the same elements as those shown in FIG. 1 are designated by the same reference numerals.

In the present embodiment, the rotation prism 8 is constructed by shifting the incident point and the exit point of the projection optical axis with respect to the prism 8 in order to suppress the size of the prism itself, that is, both optical axes. It is configured by shifting.

Therefore, when the rotation prism 8 is rotated with the optical axis of the projection lens 7 as the rotation axis, the light beam emitted from the rotation prism 8 is rotated by a certain amount with respect to the original projection optical axis. As a result, the positions of the light fluxes that strike the optical path bending mirrors 10 and 11 also fluctuate, and of course the reflection mirror 12 and the rotating mirror 13 (or the scanning mirror 1
5 and the position of the luminous flux which hits the reflection mirror 16) also fluctuate.

Further, since the prism angle on the exit side of the rotation prism 8 is set to be slightly deviated from 45 ° for performance reasons, on the screen 14 surface, the original projection is performed regardless of the rotation of the rotation prism 8. The center of the projected image comes on the extension line of the optical axis.

Therefore, the deflection of the light beam striking the optical path bending mirrors 10 and 11 located near the exit surface of the rotation prism 8 is the largest, and the shape of the optical path folding mirrors 10 and 11 is covered so as to cover the deflection ( (Size) has been decided.

As shown in FIG. 2A, the ghost light in the rotation prism 8 which is a problem here is that the light beam G outside the screen refracted by the incident surface 8a of the prism 8 reaches the reflection surface 8c on the bottom surface. Instead, the light directly goes to the exit surface 8d, is totally reflected by the exit surface 8d, is then reflected by the bottom reflecting surface 8c, and exits from the exit surface 8d. The emission direction of the ghost light G at this time is substantially orthogonal to the emission direction of the effective light beam E.

When the ghost light G is generated, as shown in FIG. 2A, the bottom surface (reflection surface) 8c of the rotation prism 8 faces the screen 14 side. At the rotational position, the ghost light G incident on the optical path bending mirror 11 is outside the effective luminous flux.

Therefore, in this embodiment, as shown in FIG. 2B, the ghost light G generated in the rotation prism 8 is effectively shielded by the light shielding member 9 provided near the rotation prism 8.

However, as described above, the effective light beam sways due to the rotation of the rotation prism 8.
As shown in (C), when the bottom surface (reflection surface) 8c of the rotation prism 8 rotates in the direction opposite to the screen 14 side, fixing the light blocking member 9 results in blocking the effective light beam E. .

Therefore, in this embodiment, as described above, a light blocking member is integrally provided on the lens barrel 18 of the rotation prism 8.
FIG. 2 (D) with the rotation of the rotation prism 8.
When the effective luminous flux E reaches the lower side of the optical path bending mirror 11 as shown in FIG. 3, the light shielding member 9 is rotated so as to be located outside the optical path. As a result, the light blocking member 9 is positioned in the optical path only when the ghost light G exists, and only the ghost light G is blocked so that the effective light flux E is not affected.

As described above, in this embodiment, as described above, the light blocking member 9 does not block the effective light beam E in the region where the effective region of the light beam emitted from the rotation prism 8 changes in association with the rotation of the rotation prism 8. By arranging it on the screen, only the ghost light generated in the rotation prism 8 is shielded, and a good projection image is obtained on the screen 14 surface or the photosensitive drum 19 surface.

FIG. 4 is a perspective view of a main part around a rotation prism according to a second embodiment of the present invention. In the figure, the same elements as those shown in FIG. 1 are designated by the same reference numerals.

In the figure, reference numeral 43 is a rotary ring, which is provided with a cam 44. Reference numeral 41 denotes a fixing member that fixes the light blocking member 49 against the rotation of the rotation prism 8.

In this embodiment, when the rotating ring 43 is rotated, the rotation prism 8 rotates, and at the same time as the rotation, the light shielding member 49 corresponding to the cam 44 follows the elongated hole 42 of the fixing member 41 in the direction of arrow A (light). Up and down in the axial direction). Thereby, the ghost light is blocked by the light blocking member 49 only when the ghost light is generated from the rotation prism 8.

As described above, in this embodiment, the light shielding member 4 is interlocked with the rotation of the rotation prism 8 as described above.
By moving 9 up and down along the optical axis direction, it is possible to effectively shield only the ghost light without blocking the effective luminous flux, and as a result, similar to the first embodiment, on the screen surface or the photosensitive drum. A good projection image is obtained on the surface.

[0041]

As described above, according to the present invention, by providing the light blocking member at a position where the effective light beam is not blocked in the region where the effective region of the light beam emitted from the rotation prism changes in association with the rotation of the rotation prism. Thus, it is possible to achieve an image forming apparatus that can shield only ghost light generated in the rotation prism and always obtain a good projection image on the screen surface or the photosensitive drum surface.

[Brief description of drawings]

FIG. 1 is a schematic view of a main part of a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a cause of ghost light in a rotation prism and a method of blocking the ghost light.

FIG. 3 is an explanatory diagram showing how a ghost image generated on a screen surface looks.

FIG. 4 is a perspective view of a main part around a rotation prism according to a second embodiment of the present invention.

[Explanation of symbols]

 LX Illumination means 1 Light source means 2 Condenser lens 3 Insulating glass 4 Cold mirror 5 Field lens 6 Projection image 7 Projection lens 8 Rotation prism 9,49 Light shielding member 10,11 Optical path bending mirror 12 Reflection mirror 13 Rotating mirror 14 Screen 15 Scanning Mirror 16 Reflecting mirror 17 Recording medium (photosensitive drum) 18 Lens barrel 19 Slit 20 Driving means 100 Scanning section 41 Fixing member 42 Long hole 43 Rotating ring 44 Cam

Claims (5)

[Claims] 1. A rotation prism for rotating the projection image on the exit side of the projection lens when the projection image illuminated by the illuminating means is projected onto the projection surface such as a screen surface or a recording medium surface by the projection lens. An image forming apparatus comprising: a light blocking member provided at a position where the effective area of a light beam emitted from the rotation prism changes in association with the rotation of the rotation prism. 2. The image forming apparatus according to claim 1, wherein the light blocking member is disposed integrally with the rotation prism and rotates in association with rotation of the rotation prism. 3. The image forming apparatus according to claim 1, wherein the light blocking member moves up and down in the optical axis direction in association with the rotation of the rotation prism. 4. The image forming apparatus according to claim 1, wherein when the ghost light is generated in the rotation prism, the light blocking member is located in a region where an effective region of a light beam emitted from the rotation prism changes. . 5. The image forming apparatus according to claim 1, wherein the light blocking member removes ghost light generated in the rotation prism.