JP2001174917A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an image forming device capable of always obtaining an excellent projected image on the surface of a screen or the surface of a reading element by shielding flare light generated in a rotation prism. SOLUTION: In this image forming device, the projected image 6 illuminated by an illumination means LX is projected to the surface of the screen 12 or the surface of the reading element 14 by a projection lens 8 so as to form the projected image. The device is provided with the rotation prism 9 for rotating the projected image projected to the emitting side of the projection lens and provided with a light shielding means 21 at least in the partial area of a surface where effective luminous flux contributing to projection does not pass in the rotation prism 9.

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, to projecting reduced image information such as a microfilm onto a screen or a reading element (line sensor) using a rotation prism for rotating an image. In this case, a favorable projection image is always obtained by shielding flare light, which is a harmful light beam generated in the rotation prism, by a light shielding unit, and relates to an image forming apparatus suitable for an apparatus such as a micro reader scanner. is there.

[0002]

2. Description of the Related Art A microreader scanner is an image forming apparatus capable of selecting a desired image from a projected image projected on a screen surface and digitally reading the image by a reading element (line sensor).

In this microreader scanner, when a projection image projected on a screen is tilted in the screen plane, the projection image is rotated by a rotation prism for image rotation so that digital reading can be performed in a good condition. The image tilt is being adjusted.

[0004]

In recent years, the microreader scanner has been required to be compact in its entirety in order to make it easy to handle and install. For example, the optical path of the light beam emitted from the rotation prism is appropriately bent by using a bending mirror to reduce the size of the entire apparatus.
At that time, the rotation prism is arranged near the screen surface. Therefore, in the conventional micro-reader scanner, a harmful light beam (flare light) which does not contribute to the projection in the rotation prism is directly incident on the screen surface, that is, generates a flare, and the projected image formed on the screen surface or the reading element surface is generated. There was a problem of having an adverse effect.

According to the present invention, in an image forming apparatus utilizing a rotation prism for rotating an image, light shielding means is provided in at least a part of a surface of the rotation prism through which an effective light beam contributing to projection does not pass. An object of the present invention is to provide a compact image forming apparatus that blocks flare light generated in a rotation prism and always obtains a good projection image on a screen surface or a reading element surface.

[0006]

An image forming apparatus according to a first aspect of the invention forms a projection image by projecting a projection image illuminated by illumination means onto a screen surface or a reading element surface by a projection lens. In the image forming apparatus, a rotation prism for rotating the projection image projected on the emission side of the projection lens is provided, and at least a partial area of a surface of the rotation prism through which an effective light beam contributing to projection does not pass is shielded. It is characterized in that means are provided.

According to a second aspect of the present invention, in the first aspect of the present invention, the rotation prism has an incident surface on which a light beam enters from the projection lens side, a reflecting surface for reflecting the light beam incident from the incident surface in the rotation prism, It has a facing surface facing the reflecting surface, and an emitting surface for emitting the light beam reflected by the reflecting surface, and the light shielding means is provided on the facing surface.

A third aspect of the present invention is characterized in that, in the second aspect of the present invention, the light shielding means is provided on a side of the facing surface closer to the emission surface than the incident surface.

According to a fourth aspect of the present invention, in any one of the first to third aspects of the present invention, the light blocking means removes flare light generated in the rotation prism.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects of the present invention, the light shielding means comprises a light shielding groove and / or a light shielding line.

[0011]

FIG. 1 shows an embodiment 1 in which the image forming apparatus of the present invention is applied to a micro reader scanner.
FIG.

In FIG. 1, reference numeral 1 denotes a light source means, which is, for example, a lamp with a cold mirror (halogen lamp). Reference numeral 2 denotes a heat insulating glass, which removes an infrared light component of a light beam emitted from the light source means 1 to suppress a rise in temperature on a projection image plane. Reference numeral 3 denotes a negative lens, which is configured to be insertable into and removable from the optical path. 4 is a reflection mirror,
Reference numeral 5 denotes a field lens, which is configured to be movable in the optical path.

Each element such as the light source 1, the heat insulating glass 2, the negative lens 3, the reflecting mirror 4, and the field lens 5 constitutes one element of the illumination means (illumination optical system) LX.

Reference numeral 6 denotes a transmission type projection image (image information), which is made of, for example, a microfilm. 7a,
7b is a holding plate glass, and the microfilm 6
Holding. Reference numeral 8 denotes a replaceable projection lens, which enlarges and projects the projection image 6 on a screen surface or a reading element surface.

Reference numeral 9 denotes a rotation prism for image rotation (roof type rotation prism), which is provided on the exit surface side of the projection lens 8 and which is, for example, a microfilm image (projected image) which is arranged inclined in the plane of the microfilm. Is corrected to an arbitrary angle on the screen surface or the reading element surface. In the present embodiment, a light-shielding means 21 formed of, for example, a light-shielding groove or / and a light-shielding line described later is provided in at least a part of a surface (roof surface) 9d in the rotation prism 9 through which an effective light beam contributing to projection does not pass. Thus, flare light, which is a harmful light flux generated in the rotation prism 9, is removed.

Reference numerals 10 and 11 denote optical path bending mirrors, respectively, which appropriately bend the optical path of the light beam emitted from the rotation prism 9 to prevent the apparatus main body from being enlarged due to the arrangement of the rotation prism 9. . In this embodiment, as described above, the optical path bending mirrors 10 and 11 are used to reduce the size of the apparatus main body, so that the height difference between the rotation prism 9 and the screen 12 is small. Reference numeral 12 denotes an observation screen. SU is a sensor unit having a reflection mirror 13 for reading and a reading element (line sensor) 14 having a plurality of pixels in a direction perpendicular to the paper surface. The reading element 14 reads the projection image 6. At the time of reading (at the time of reading), the image information of the projection image 6 is read by scanning the area immediately before the surface of the screen 12 along the direction of arrow C in FIG. When observing the projection image 6 (at the time of observation), it is retracted to the position 17b outside the optical path.

In the present embodiment, the light beam emitted from the light source means 1 passes through the heat insulating glass 2 and the negative lens 3 and is reflected by the reflection mirror 4, and then the effective illumination area of the projection image 6 via the field lens 5. Lighting. The light flux based on the projection image 6 that has passed through the projection lens 8 passes through the rotation prism 9 and then is turned on the optical path bending mirror 1.
It is incident on 0,11. In this embodiment, each element is set so that the light beam from the light source 1 converges (images) near the entrance pupil position of the projection lens 8, that is, Koehler illumination is performed.

When observing the projected image 6 on the screen 12, the effective light flux passing through the optical path bending mirrors 10 and 11 is guided onto the screen 12 to form an enlarged projected image on the surface. I have. Also, the sensor unit SU
When reading an image projected on the screen 12 with the sensor unit SU, the sensor unit SU is moved so as to be located in the optical path, and a desired image is selected from the projected images projected on the screen 12 An enlarged projected image is formed on the surface of the reading element 14.

Here, means for removing flare light generated in the rotation prism 9 will be described. FIG.
FIG. 2 is an enlarged explanatory view showing the inside of the rotation prism 9 shown in FIG. 1 in an enlarged manner.

In FIG. 2, a rotation prism 9 has an incident surface 9a on which a light beam enters from a projection lens (not shown) 8 side, a reflecting surface 9b for reflecting the light beam incident from the incident surface 9a in the rotation prism 9, and the reflection surface. Surface 9b
Surface (roof surface) 9d and the reflection surface 9b
In this embodiment, a light-shielding groove or a light-shielding line as light-shielding means 21 is provided in a part of the opposing surface 9d in the present embodiment.

In the direction of the rotation prism 9 shown in FIG. 1, the optical path of the projected image 6 projected on the lower end of the screen 12 is substantially as shown by N. In the optical path N, the number of reflections of the light beam in the rotation prism 9 is one. The light flux from the microfilm position further outside than the microfilm position conjugate to the lower end of the screen 12 is usually shielded somewhere and the screen 12
Although the light does not reach the surface, when a certain angle of view is reached, a part of the light flux is reflected four times in the order of the surfaces 9b, 9d, 9c and 9b in the rotation prism 9 as shown in the optical path F of FIG. Then, the light is emitted from the emission surface 9c of the rotation prism. This light beam is reflected by optical path bending mirrors 10 and 11.
The light is directly incident on the screen 12 without passing through. This light beam F becomes a flare. This is because the difference in height of the rotation prism 9 with respect to the screen 12 is reduced in order to reduce the size of the entire apparatus as described above.
This flare is incident on the surface of the screen 12 and may affect the projected image 6 on the surface of the screen 12. In addition, the flare may affect the projected image 6 read by the sensor unit SU that scans the vicinity of the screen 12. Can also have an effect.

Here, an optical path through which the flare light F passes through the rotation prism 9 will be described with reference to FIG.
The flare light F enters from the incident surface 9a as shown in the figure, and is reflected four times in the order of the reflecting surface 9b, the facing surface 9d, the emitting surface 9c, and again the reflecting surface 9b, and the optical path emitted from the emitting surface 9c. Follow The hatched area A in the figure is an area through which an effective light beam contributing to projection does not pass.

Therefore, in this embodiment, in order to remove flare light, as shown in FIGS. 3A and 3B, a light-shielding groove as light-shielding means is formed in a part of the opposing surface 9d which does not affect the effective light flux. By providing the light shielding lines 15 or 16, flare light generated in the rotation prism 9 is removed.

That is, FIG. 3A shows an example in which a light shielding groove 15 is provided in a part of the opposing surface 9d, and flare light is blocked by the light shielding groove 15. FIG. 3B shows the facing surface 9d.
In this example, the direction in which flare light is reflected by the opposing surface 9d is largely changed by the light-shielding line 16 so that flare light does not reach the screen 12 surface. Thus, in the present embodiment, flare light is prevented from being incident on the screen 12 or the reading element 14 so that a good projection image 6 is always obtained on the screen 12 or the reading element 14.

In this embodiment, as can be understood from FIG. 2, the reflection range of the flare light F on the facing surface 9d is closer to the emission surface 9c. Therefore, in the present embodiment, FIGS.
As shown in (1), the light-shielding groove 15 or the light-shielding line 16 is provided on the side closer to the emission surface 9c than the incident surface 9a. The light shielding means 21 may be configured by combining the light shielding groove 15 and the light shielding line 16.

In this embodiment, the projection lens 8 is replaceable as described above, and if necessary, the projection magnification can be continuously changed from about 7 times to about 50 times.
Therefore, when the magnification changes, when the projection lens 8 is a zoom lens, the pupil position slightly moves. Therefore, in the present embodiment, the position of the field lens 5 in the optical path is moved corresponding to the pupil movement. For example, in FIG.
When it is located on the lower side, the field lens 5 is configured to move from the position 5a to the position 5b in accordance with the movement of the pupil. In this embodiment, the field lens 5 is used.
Is made of a Fresnel lens in order to make it thinner and lighter.

In this embodiment, for example, when the F value of the projection lens 8 is made substantially constant so that the brightness becomes substantially constant on the screen 12 on the observation side, the F value of the projection lens 8 on the microfilm side becomes low. The non-reflection part 1a which becomes larger on the magnification side and is located
, The central portion of the screen 12 becomes dark.
Therefore, in the present embodiment, the negative lens 3 is disposed slightly away from the lamp 1 with a cold mirror, thereby eliminating the influence of the non-reflective portion 1a of the lamp 1 with a cold mirror. When the projection lens 8 has a high magnification, the negative lens 3
The negative lens 3 is retracted to a position 3b outside the optical path because the light flux is excessively spread on the pupil plane and a light amount loss occurs.

As described above, in the present embodiment, as described above, the light shielding means 21 is provided in at least a part of the opposing surface (roof surface) 9d through which the effective light flux contributing to the projection does not pass in the rotation prism 9. The flare light generated in the rotation prism 9 can be shielded, so that a good projection image 6 can always be obtained on the screen 12 or the reading element 14.

In this embodiment, the light-shielding groove or the light-shielding line is used as the light-shielding means. However, the present invention is not limited to this, and any means capable of removing flare light may be used.

In this embodiment, a case where the present invention is applied to a micro-reader scanner has been described. However, the present invention is not limited to this, and can be applied to an image forming apparatus such as a micro-film reader or a micro-film reader printer.

[0031]

According to the present invention, in an image forming apparatus using a rotation prism for rotating an image as described above, at least a part of a surface of the rotation prism through which an effective light beam contributing to projection does not pass is shielded. By providing means, it is possible to shield flare light generated in the rotation prism, thereby achieving an image forming apparatus capable of always obtaining a good projection image on a screen surface or a reading element surface. Can be.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a main part of an optical system according to a first embodiment of the present invention.

FIG. 2 is an enlarged explanatory view of the rotation prism shown in FIG. 1;

FIG. 3 is an explanatory diagram showing a light shielding unit according to the first embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light source means (lamp with mirror) 2 Insulated glass 3 Negative lens 4 Reflection mirror 5 Field lens 6 Projection image (microfilm) 7a, 7b Pressing plate glass 8 Projection lens 9 Rotation prism 10, 11 Optical path bending mirror 12 Screen 13 Reflection mirror 14 Reading element (line sensor) 15 Light shielding groove 16 Light shielding line 21 Light shielding means LX Illumination means SU Sensor unit

Claims (5)

[Claims] 1. An image forming apparatus for projecting a projection image illuminated by illumination means onto a screen surface or a reading element surface by a projection lens to form the projection image, wherein the projection image is projected onto an emission side of the projection lens. An image forming apparatus, comprising: a rotation prism for rotating a projected image; and a light blocking unit provided in at least a part of a surface of the rotation prism through which an effective light beam contributing to projection does not pass. 2. The rotation prism has an incident surface on which a light beam is incident from the projection lens side, a reflection surface for reflecting the light beam incident from the incident surface in the rotation prism, an opposing surface facing the reflection surface, and The image forming apparatus according to claim 1, further comprising an emission surface that emits the light beam reflected by the reflection surface, wherein the light blocking unit is provided on the facing surface. 3. The image forming apparatus according to claim 2, wherein the light shielding unit is provided on a side of the facing surface closer to the emission surface than the incident surface. 4. The image forming apparatus according to claim 1, wherein the light shielding unit removes flare light generated in the rotation prism. 5. The light shielding means according to claim 1, wherein the light shielding means comprises a light shielding groove and / or a light shielding line.
An image forming apparatus according to any one of the preceding claims.