Overhead projector with a copying device

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BACKGROUND OF THE INVENTION

The present invention relates to an overhead projector with a copying device, capable of monochromatic or color copying.

These days, overhead projectors are used indispensably in conferences, research study, various presentations, etc. They are useful means for visually giving precise information or data, carried by original papers, to participants or attendants, using a screen for projection. However, the conventional overhead projectors do not have a copying function.

In presentations and the like, using the overhead projectors, the contents of the original have often been expected to be distributed or handed, in the form of copies, to the individual attendants, besides being projected on the screen. Such copies would be required especially when the contents of the original should be amended or supplemented. In such a case, the copies conventionally must be made by means of a separate copying machine, thus delaying the presentations considerably.

SUMMARY OF THE INVENTION

The present invention has been developed in consideration of these circumstances, and is intended to provide an overhead projector which can produce clear copies of an original for overhead projectors, on the spot, without requiring use of a separate copying machine.

In order to achieve the above object, according to the present invention, a copying section is provided in addition to a projector section of a projector for projecting an image of an original on a screen. The copying section includes an exposure optical system, which delivers the original image, received from a projection optical system of the projector section, to a record medium, thereby exposing the medium to the image.

With use of the projector constructed in this manner, a clear image of the original can be obtained easily on the spot, without removing the original from the projector. In the case of a prior art projector, having no copying function, the original must be set in the projector again, after it is removed therefrom to be copied by means of a separate copying machine. Thus, the conventional projector requires troublesome operations, which inevitably suspend projection, thereby delaying the presentations and lowering the operating efficiency of the projector. The present invention can settle these problems.

According to a preferred arrangement of the invention, the original image is transported from the projection optical system by means of a half-mirror. Thus, the two optical systems can be connected easily with high optical accuracy.

According to another preferred arrangement, the exposure optical system includes a shutter member, which can be shifted alternatively between a shielding mode, in which the optical path of the exposure optical system is closed by the shutter member, and a copying mode in which the optical path is open. When using the projector as a regular one, the shutter member is set to the shielding mode, so that the record medium is prevented from being exposed. In starting a copying operation, the shutter member is shifted to the copying mode by turning on a manual copy switch on the projector, for example. In the copying mode, the record medium is allowed to be exposed to the original image.

According to still another preferred arrangement, the record medium used is a color light- and pressure-sensitive sheet, which is composed of a substrate, a layer of microcapsules reactive individually to radiations of different wavelengths, and a layer of developer material adapted to develop color when the microcapsules are ruptured, the two layers being put successively on the substrate.

Thus, the overhead projector according to the present invention can produce color copies of the original image, and can enjoy a compact design, as a whole, without entailing a high manufacturing cost.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of an overhead projector with a copying device according to an embodiment of the present invention;

FIG. 2 is a schematic cross-sectional view showing the construction of a color light- and pressure-sensitive sheet used in the overhead projector of FIG. 1; and

FIGS. 3, 4 and 5 are schematic views showing processes of exposure and development of the color light- and pressure-sensitive sheet of FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in FIG. 1, an overhead projector 1 has a vertical frame 2, which is composed of upper and lower portions 2a and 2b and a middle portion 2c connecting them. The middle portion 2c is fitted with a stage holder 7, which serves as support means capable of carrying thereon an original 6 for overhead projector. Under the stage holder 7, a projection/exposure lamp 8, for use as a light source, is located inside the lower portion 2b. Between the holder 7 and the lamp 8, moreover, a Fresnel lens 9, as a condenser, and a disk-shaped filter 10 are arranged also inside the lower portion 2b. The filter 10, which is rotatable around a vertial axis 3, comprises a projection filter portion or sector 10a, filter portions or sectors 10b, 10c and 10d corresponding to red, green, and blue, as basic colors, and a filter portion or sector 10e for monochromatic exposure.

A projection lens 11 and a half-mirror 12 are arranged succesiively over the stage holder 7. They are supported by a support frame 4 in front of the middle portion 2c of the frame 2, that is, on that side of portion 2c facing a screen 22.

The lens 11 and half-mirror 12, along with the Fresnel lens 9 and the filter 10, constitute a projection optical system 24. A light emitted from the light-source lamp 8 is transmitted through the filter 10 and the lens 9, along a vertical optical path P1, to be applied to the original 6, which is formed of a light-permeable sheet. Thereupon, an original image is formed, and it is transmitted through the projection lens 11 and then reflected by the overlying half-mirror 12. Thereafter, the image is delivered to the screen 22 along an optical path P2 which extends substantially at right angles to the optical path P1. Thus, the image is projected on the screen 22 with a predetermined magnification.

The above described arrangement, which serves to accomplish the projecting operation, constitutes a projector section of the projector. At least those regions of the holder 7 and the support frame 4 which are intended to permit the passage of the light, are formed of light-permeable material.

A copying device 13 is located at the upper portion 2a of the overhead projector 1. The device 13 constitutes a copying section which is used to copy the original 6 placed on the stage holder 7. A color light- and pressure-sensitive sheet 14 of a positive type is used as a record medium for the copying device 13.

In copying the original image to the light- and pressure-sensitive sheet 14, the image is transferred along optical paths P3 and P4 and exposed by means of an exposure optical system 25, which will be described in detail later.

The half-mirror 12 has a function to transmit the original image from the optical path P1 to the path P3, as well as the function to reflect the image onto the screen 22.

Referring now to FIGS. 2 to 5, the structure of the color light- and pressure-sensitive sheet 14, for use as the record medium, will be described in brief.

As shown in FIG. 2, the light- and pressure-sensitive sheet 14 has a three-layer construction, including a substrate 14b, a coating layer 14a of developer material thereon, and a layer 14c of microcapsules. The microcapsule layer 14c includes microcapsules of three types, i.e., microcapsules C, M and Y which harden when exposed to ultraviolet radiations of wavelengths .lambda.C, .lambda.M and .lambda.Y of, e.g., about 340 nm, 385 nm, and 470 nm, respectively. When the light from the original image is applied to the sheet 14, as indicated by arrows in FIG. 2, the individual microcapsules C, M and Y of the microcapsule layer 14c react selectively to the light.

More specifically, an achromatic dye contained in the microcapsules C reacts to the developer layer 14a, thereby developing a color of cyan. Also,(achromatic dyes contained in the microcapsules M and Y develop colors of magenta and yellow, respectively. Thus, if the light- and pressure-sensitive sheet 14 is exposed to the radiation of the wavelength .lambda.C, only the microcapsules C harden. In a developing process, therefore, the microcapsules M and Y are ruptured, thereby developing colors of magenta and yellow, as shown in FIG. 3. As a result, a red color appears on the sheet 14.

A pair of developing rollers 19, which are used in the developing process, are located under and close to a cassette 21 in which the light- and pressure-sensitive sheets 14 are stored in layers. As the outermost sheet 14 is delivered downward from the cassette 21, after exposure, the developing rollers 19 receive the sheet 14 and apply a pressure to it. As a result, those microcapsules remaining unhardened in the microcapsule layer 14c are ruptured and react to the developer layer 14a.

After the developing process, the sheet 14 is fed further downward along a guide 26, as indicated by an arrow in FIG. 1, and is then discharged into a tray 20. The tray 20 is situated on the rear side of the middle portion 2c of the frame 2, opposite to the front side thereof facing the screen 22. Thus, the tray 20 does not interfere with the projection optical system 24 of the projector 1, and enables a user or operator, who is expected to stand behind the projector 1, to take out the copied sheet 14 smoothly.

If the light- and pressure-sensitive sheet 14 is exposed to the radiation of the wavelength .lambda.M, only the microcapsules M harden. In the developing process, therefore, the microcapsules C and Y are ruptured, thereby developing colors of cyan and yellow, as shown in FIG. 4. As a result, a green color appears on the sheet 14. Likewise, if the sheet 14 is exposed to the radiation of the wavelength .lambda.Y, only the microcapsules Y harden. In the developing process, therefore, the microcapsules C and M are ruptured, thereby developing colors of cyan and magenta, as shown in FIG. 5. As a result, a blue color appears on the sheet 14.

Since the structure of the sheet 14 itself is generally known (refer to U.S. Pat. No. 4,440,846), a further detailed description thereof is omitted herein.

Arranged over the half-mirror 12 are an exposure lens 15, a shutter member 6, a wavelength changing element 17, and a mirror 18, which constitute the exposure optical system 25. The light from the projection/exposure lamp 8 is projected onto the sheet 14 along the optical path P3, which extends vertically in line with the optical path P1, and the path P4, which extends substantially at right angles to the path P3 and is directed toward the sheet 14.

The wavelength changing element 17 serves to change red, green, and blue lights into lights of the wavelengths .lambda.C, .lambda.M and .lambda.Y, respectively. Thus, the element 17 is used to make the three basic colors, red, green, and blue, of the original image correspond to the different microcapsules C, M and Y, respectively, of the microcapsule layer 14c on the sheet 14.

If the overhead projector, constructed in this manner, is utilized as a regular prjector, the projection filter portion 10a, among other filter portions of the filter 10, is used to transmit visible radiations only. The filter 10 is rotated around the axis 3 so that the filter portion 10a is situated in the optical path P1. In this state, the light from the projection/exposure lamp 8 is transmitted through the original 6 on the stage holder 7 and the projection lens 11, and is then reflected by the half-mirror 12 to be projected on the screen 22.

During the aforesaid regular use of the projector, the shutter member 16 of the exposure optical system 25 is in a shielding mode, so that the light- and pressure-sensitive sheet 14 cannot be exposed. Namely, in the shielding mode, the shutter member 16 is situated in such a position that it closes the optical paths P3 and P4 of the optical system 25.

In starting to copy the contents of the original 6, a copy switch 23, for use as a manual switch member, mounted on the middle portion 2c of the frame 2 for the ease of external operation, must only be turned on, with the original 6 kept on the holder 7. Thereupon, the shutter member 16 is switched to a copying mode in which the optical paths P3 and P4 are open. In this state, the original image is allowed to be transmitted through the half-mirror 12 and the exposure optical system 25, to the light- and pressure-sensitive sheet 14.

According to this embodiment, the copying device can perform color copying. In this case, if the copy switch 23 is turned on, the color light- and pressure-sensitive sheet 14 is exposed three times for the microcapsules of yellow, magenta, and cyan, as the filter portions 10b, 10c 10d of the filter 10 are shifted successively. When the filter portion 10b is first opposed to the projection/exposure lamp 8, a red light, transmitted through the filter portion 10b, passes through red-image regions of the original 6. Then, after passing through the projection lens 11, half-mirror 12, exposure lens 15, and shutter member 16, the light reaches the wavelength changing element 17. Thereupon, the red light is changed into a light having thewwavelength .lambda.C, and is projected onto the sheet 14. As a result, the microcapsules C are hardened.

Likewise, the filter portions 10c and 10d of the filter 10 are opposed in succession to the projection/exposure lamp 8, so that the microcapsules M and Y on the color light- and pressure-sensitive sheet 14 are hardened successively in accordance with the image on the original 6. After the three cycles of exposure end, the sheet 14 is developed by means of the developing rollers 19, and then discharged into the tray 20. In this manner, a color copy of the original 6 can be obtained with ease. Thus, the projector of the present invention can be used not only for projection on the screen 22, but also for quick distribution of copies, for example, to attendants of presentations using the projector, at any time. Thus, the effects of the presentations can be improved.

The operation of the shutter member 16 is associated with the rotation of the filter 10 so that the member 16 is shifted instantaneously from the copying mode to the shielding mode before the shift of the rotating filter 10 is finished, and that the member 16 is shifted automatically to the copying mode on completion of the shift of the filter 10. Accordingly, the lamp 8 need not be turned off with every rotation of the filter 10 for shifting.

Although an illustrative embodiment has been described herein in connection with the case of color copying, the present invention may also be applied to monochromatic copying. In this case, monochromatic light- and pressure-sensitive sheets are used which are less expensive than the color copying sheets. Each monochromatic sheet is exposed through the filter portion 10e for monochromatic exposure, by turning on and off the shutter 16 once. Thereafter, the sheet is developed by means of the developing rollers 19, and then discharged into the tray 20, just as in the case of the color copying.

In the embodiment described above, the color light- and pressure-sensitive sheet 14 is used with the copying device. Alternatively, however, xerography or other copying methods may be utilized. With use of the color copying sheet 14, however, the copying device can be simplified in construction, and can therefore be made more compact and low-priced.

In the above embodiment, moreover, the light source used is designed to emit ultraviolet radiations. Alternatively, however, visible radiations may be used so that a photosensitive paper sheet, for use as the record medium, is exposed to them.

According to the above embodiment, furthermore, the color light- and pressure-sensitive sheet, as the record medium, has a self-developing structure, as disclosed in U.S. Pat. No. 4,440,846. Alternatively, a copying pad of the so-called transfer type may be used, which is composed of a sheet coated with developer material and a sheet bearing a layer of microcapsules thereon, as stated in U.S. Pat. No. 4,399,209, for example. In this copying pad, color is transferred from the microcapsule-covered sheet to the developercoated sheet.

Although a wavelength changing element is used in the foregoing embodiment, some record media may be used without requiring such an element.

Thus, the present invention is not limited to the embodiment described above, and various changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the invention.

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