JPS63124021A - Image projecting device - Google Patents

Abstract

PURPOSE:To prevent the generation of unevenness of the light quantity by diffusing a luminous flux by a diffusion plate and radiating it to a film, and allowing a diffused light to be made incident on a Fresnel lens, in a device for projecting an image of the film and reading a projected image. CONSTITUTION:A luminous flux emitted from a lamp 4 is condensed by a condensing lens 5, diffused in all directions by a transmission and diffusion plate 15, and illuminates the surface of a film 6. Subsequently, an image of its film 6 is enlarged, reflected by a turning-back mirror 8 through a projection lens 7, and projected to a Fresnel lens 10. By its Fresnel lens 10, an image is formed on an original placing table glass 9, and its image is read by a CCD solid-state image pickup element 14 through a read lens 13. At that time, the light beam is diffused by the transmission and diffusion plate 15 and projected extending over plural projecting parts of the Fresnel lens 10, and an influence by a reflection and a diffusion by the projecting part is reduced. Accordingly, unevenness of the light quantity caused by a pitch of the Fresnel lens can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an image projection device, and particularly to an image projection device used for projecting an image on a film or the like and reading the projected image.

(Prior Art) Conventionally, there are the following devices as this type of device. That is, the image on the film is illuminated by a light source through a condensing lens, and the image on the film is projected by a projection lens onto a document table glass of a reading device through a folding mirror. that time.

Since the image on the film is projected in an enlarged manner, the image projected onto the platen glass has light directivity at different angles at the center and at the periphery. Therefore, a Fresnel lens is provided on the document table glass to correct this and make all the light beams perpendicularly incident on the document table glass. The image projected onto the document table glass is read by a solid-state imaging device such as a COD. By the way, the condensing lens is set to form an image of the filament of the condensing lens on the pupil of the projection lens so as to efficiently illuminate the film.

(Problems to be Solved by the Invention) However, this prior art has the following problems. That is, since the image 20 of the filament of the light source is set to be projected onto the projection lens @21 as shown in FIG. 3, the image projected from one point on the film is the pupil of the projection lens. 21, it has a certain area, so the image from one point on the film is refracted by the projection lens 21, and passes over the Fresnel lens 22 with a small area, as shown for example by the light beam R. , and is imaged by the Fresnel lens 22 onto a point P on the document table glass 23.

By the way, the Fresnel lens 22 has a saw-shaped convex portion 2.
2a continuously, the light beam projected across the two convex portions 22a of the Fresnel lens 22, like the light beam S, is reflected and scattered by the side surfaces 22a of the convex portions 22a, so that the light is weakened. . On the other hand, like the luminous flux R, one convex portion 2
The light beam projected onto the platen 2a is directly imaged on the document glass 23 without being weakened by light scattering or the like, so the image projected onto the document glass 23 is reflected by the Fresnel lens 2
There was a problem in that periodic light intensity unevenness occurred corresponding to the pitch of the second convex portion 22a.

Therefore, in order to solve the above-mentioned problems, the Fresnel lens 22 is placed well above the document platen glass 23 to blur the unevenness of the light amount, and the signal output from the solid-state image sensor is subjected to electrical shading processing. It is also possible to prevent unevenness in the amount of light from occurring.

In addition, the size of the filament image of the light source projected onto the pupil 21 of the projection lens is increased, and the amount of light reaching the surface of the Fresnel lens 22 is increased, so that even if there is reflection or scattering, it will not affect the overall amount of light. It is also possible to reduce the number of

However, in the former case, if the Fresnel lens 22 is placed far above the document table glass 23, image aberrations due to the Fresnel lens 22 will occur and the image will become blurred, or even if electrical sharding processing is performed. , there was a problem that the sharpness of the image was lost.

In the latter case, the filament image of the light source is usually a coiled line image, so the area cannot be increased, and even if the filament image is enlarged by moving the condensing lens closer to the light source, There was a problem in that there were limitations in the design of the optical system.

Therefore, the present invention has been made to solve the above-mentioned problems of the prior art, and its purpose is to provide a device for projecting an image using a Fresnel lens. It is an object of the present invention to provide an image projection device that can prevent uneven light amount from occurring and also allows easy design of an illumination optical system.

(Means for Solving the Problems) In order to achieve the above object, the present invention illuminates an image recording medium with a light source, and projects an image of the image recording medium through a Fresnel lens onto a projected member. The image projection device for projecting upward is provided with a diffusion means for diffusing the light beam from the light source and irradiating the image recording medium, and is configured so that the diffused light is incident on the Fresnel lens.

(Function) In the present invention, the light flux from the light source is diffused by the diffusion means, and this diffused light enters the Fresnel lens and illuminates the image recording medium, so that the image recording medium itself emits light. Similarly, the image on the image recording medium is projected by the entire projection lens. Therefore, the image projected onto the surface of the Fresnel lens has an area larger than the pitch thereof, and unevenness in light amount corresponding to the pitch of the Fresnel lens is prevented from occurring.

(Example) The present invention will be explained below based on illustrated embodiments.

FIG. 2 shows an embodiment of an image reading device to which the image projection device according to the present invention is applied. This image reading device
consists of a reading section 2 that reads images of ordinary originals, and a projection section 3 consisting of an image projection device that projects images on an image recording medium such as film. It is mounted on the reading section 2 only when reading. In the projection section 3, reference numeral 4 denotes an illumination lamp as a light source, which illuminates a film 6 through a condenser lens 5, and converts the image on the film 6 by a projection lens 7 through a mirror 8 as a member to be projected. The image is projected onto the document table glass 9. This manuscript table glass 9
Above, since the light beam projected onto the original platen glass 9 has different angles between the central part near the optical axis of the projection optical system and the periphery, all the light beams are projected onto the original platen glass 9. A Fresnel lens 10 having continuous saw-shaped convex portions 10a is disposed so as to be vertically incident onto the document table glass 9.

Further, the reading section 2 is provided with a reading lens 13 having a pupil 13a for reading an image projected onto the document platen glass 9, and a solid-state image sensor 14 such as a CCD. The image on the film 6 is read.

In this embodiment, in addition to the above configuration, a transmission/diffusion means is provided which transmits and diffuses the light beam from the light source and irradiates the film. That is, between the film 6 and the condensing lens 5 and in the vicinity of the film 6, the surface of a transparent plate made of glass, plastic, etc. is formed by sandblasting or the like into a matte finish as a transmission/diffusion means to diffuse light. A transmission diffusion plate 15 is provided, and the light beam emitted from the illumination lamp 4 is condensed by the condenser lens 5, then transmitted and diffused by the diffusion plate 15, and is irradiated onto the film 6.

In the above configuration, the image reading device to which the image projection device according to the present embodiment is applied projects the image on the film in the following manner. That is, as shown in FIG. 1, the light beam emitted from the illumination lamp 4 is condensed by a condenser lens 5, and then diffused by a diffuser plate 15 and spread in all directions, illuminating the image on the film 6. . Therefore, the images on the film 6 are spread out and pass through the pupils 7a of the projection lens 7 at the same time. The light that has passed through the pupil 7a of the projection lens 7 passes through the reflection mirror 8 and passes through the Fresnel lens 10.
is projected onto the reading section 2 by the Fresnel lens 10.
The image is formed at point B on the document table glass 9. The image formed on the document table glass 9 is directed toward the reading lens 13 of the reading section 2.

In this way, the film 6 is illuminated by the light beam diffused by the transmission diffuser plate 15, so that the image on the film 6 itself is equivalent to emitting light. Therefore, as shown in FIG. 1, the image on the film 6 is projected over a large area by the entire binding lens 7 onto a region A extending over the plurality of convex portions 10a on the Fresnel lens 10. Therefore, a part of the image at one point on the film 6 is reflected by the convex portion 1 of the Fresnel lens 10.
Even if the light is reflected or scattered by the side surface 10b of 0a, the effect on the total luminous flux is small even if the light quantity changes, so there is almost no unevenness in the light quantity on the document table glass 9. In addition, the diffusion plate 15 is provided. As a result, the coherence of the light beam from the illumination lamp 4 can be reduced, and in this respect, unevenness in the amount of light in the projected image can also be prevented. Furthermore, since it is only necessary to provide a transmission diffusion plate, the design of the optical system can be easily performed.

In the above embodiment, a case has been described in which the present invention is applied to a device that reads an image by focusing an image projected on a document table glass onto a solid-state image sensor fixed by a reading lens, but the present invention is not limited to this. Instead, a solid-state image sensor may be movably disposed close to the lower surface of the document table glass, and the image may be read by scanning the solid-state image sensor.

It goes without saying that the present invention can also be applied to the case where an image projected onto a platen glass is exposed onto a photosensitive drum to copy an image on a film. In these cases, the projected image may be formed on a solid-state image sensor or the like via a short focus imaging lens.

Further, in the above embodiment, a case was explained in which a diffusion plate was arranged between the condenser lens and the film as a transmission diffusion means, but the surface of the condenser lens was made into a satin-like shape without providing a separate member as a transmission diffusion means. Furthermore, the diffusion means is not limited to the above-mentioned transmission and diffusion means, and may be diffused by using a mirror surface as a rough surface, but it is preferable that the transmission and diffusion means described above be provided. If so, the diffusion state will be good because the light beam will be diffused while it passes through.

(Effects of the Invention) The present invention has the above-described configuration and operation, and is capable of preventing unevenness in light amount due to the pitch of the Fresnel lens even in a device that projects an image using a Fresnel lens. In addition, it is also possible to easily design the light source of the illumination system.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the operation of an embodiment of an image projecting device according to the present invention, FIG. 2 is a configuration diagram showing an image reading device to which the present invention is applied, and FIG. 3 is a diagram showing a conventional image projecting device. It is an explanatory diagram. Explanation of symbols 4...Illumination lamp 5...Condensing lens 6...
・Film 7...Projection lens 9...Original table glass 10...Fresnel lens 15...Transmission diffuser plate 2nd

Claims (1)

[Claims] In an image projection device that illuminates an image recording medium with a light source and projects an image of the image recording medium onto a projection target member using a projection lens via a Fresnel lens, the light beam from the light source is diffused and irradiated onto the image recording medium. An image projection apparatus characterized in that the image projection apparatus is provided with a diffusing means, and the diffused light is incident on the Fresnel lens.