JPH0753338Y2 - projector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a projector that allows a display image of an image display device such as a liquid crystal display device to be greatly enlarged for viewing.

[Conventional technology]

Recently, a liquid crystal display device such as a liquid crystal television receiver for displaying an image using a liquid crystal display panel has appeared on the market. However, with the current technology, the area of the liquid crystal display panel cannot be increased so much. The device has the problem that its display screen is small.

For this reason, conventionally, a projector has been considered in which a display image of the liquid crystal display device can be greatly enlarged and viewed.

FIG. 3 shows a conventional projector, in which 1 is a case of the projector, and a display window 2 having a transmissive screen 3 is provided on the front surface of the case 1. Reference numeral 4 denotes a transmissive liquid crystal display panel which is arranged in the case 1 so as to face the display window 2, 5 denotes a light source section for illuminating the liquid crystal display panel 4 from its rear side, and 6 denotes a display image of the liquid crystal display panel 4. Is a projection lens for enlarging and projecting on the transmissive screen 3 of the display window 2, and the projection lens 6 is configured by combining a plurality of optical lenses.

The light source unit 5 is a high-intensity light source lamp such as a halogen lamp.
5a and the illumination light from the light source lamp 5a are used for the liquid crystal display panel 4
And a reflector (a parabolic reflector having a parabolic reflection surface that reflects the light from the light source lamp 5a as parallel light) toward the light source 5b.
The illuminating light emitted from is removed from the infrared component by the infrared absorption filter 7 and enters the liquid crystal display panel 4. The liquid crystal display panel 4 is a dot matrix display panel for displaying a television image or the like, and the display image of the liquid crystal display panel 4 by the light passing through the liquid crystal display panel 4 is transmitted by the projection lens 6 to the transmissive screen of the display window 2. 3 is enlarged and projected.

In FIG. 3, the reflector 5b of the light source unit 5 is a parabolic reflector. The reflected light from the reflector is collimated by this condenser lens and is incident on the liquid crystal display panel.

In this projector, the display image of the liquid crystal display panel 4 is enlarged and projected onto a transmissive screen 3 provided in a display window 2 on the front of the case, and the image projected on the transmissive screen 3 is viewed from the front side of the screen 3. Thus, according to this projector, the display image on the small liquid crystal display panel 4 can be greatly enlarged and viewed.

[Problems to be solved by the invention]

By the way, in the above projector, the projection lens 6
The longer the optical path from the screen to the screen 3, the projection lens 6
Since the light flux passing through the screen spreads widely and reaches the screen 3, a large screen image can be projected on the screen 3 by increasing the optical path length from the projection lens 6 to the screen 3. Since the projection lens 6 is directly opposed to the projection lens 3, the projection lens 6 must be placed far away from the screen 3 in order to increase the optical path length from the projection lens 6 to the screen 3. Since the depth length of 1 is considerably large, there is a problem that the device is large compared to the size of the screen projection screen.

The present invention has been made in consideration of the above situation, and its purpose is to enlarge a display image of an image display device such as a liquid crystal display device to a transmissive screen provided in a display window on the front of the case. It is an object of the present invention to provide a projector that can be made to project, but can also reduce the depth of the case to reduce the size of the entire apparatus.

[Means for solving problems]

This invention relates to a projector in which an image display device and a projection means for projecting a display image of the image display device toward the transmissive screen are provided in a case having a display window having a transmissive screen on the front surface. The projection means includes a projection optical system that projects a display image of the image display device toward the screen from an oblique direction, and light projected by the projection optical system that is in contact with or close to an inner surface of the transmissive screen. And a light emitting surface that reflects the light in the rear surface direction of the case and transmits the incident light from the rear surface direction of the case to emit the light toward the screen side, and a light emitting surface that faces the light emitting surface from the rear surface direction of the case. A prism having a reflecting surface that reflects the reflected light toward the light emitting surface, and the projection optical system and the light emitting surface, The projection light from the projection optical system is arranged in a relationship of being reflected by the law of total reflection on the light emitting surface, and the reflecting surface is the projection reflected on the light emitting surface with respect to the light emitting surface. It is characterized in that it is arranged in such a relationship that the light is directed toward the light emitting surface and reflected at an angle of transmitting the light emitting surface.

[Action]

In the projector of the present invention, the light projected from the oblique direction toward the transmissive screen by the projection optical system for projecting the display image of the image display device is totally transmitted by the light emitting surface which is in contact with or close to the inner surface of the screen. According to the law of reflection, the light is once reflected in the rear surface direction of the case, and then is reflected toward the light emission surface by the reflection surface facing the light emission surface from the rear surface direction of the case. Then, the light reflected by the reflecting surface toward the light emitting surface passes through the light emitting surface and enters the transmissive screen.

That is, this invention is such that the projection light from the projection optical system is made to come and go between the light emitting surface and the reflecting surface in a zigzag manner, and then is made incident on the screen,
By doing so, the optical path length from the projection optical system to the screen can be increased, and a large-screen image can be projected on the screen.

Moreover, in this invention, the light emitting surface is arranged in contact with or close to the inner surface of the screen, and the reflecting surface is opposed to the light emitting surface from the rear side of the case, so that the space inside the screen is rearward. Since the projection light is moved back and forth in a zigzag pattern, the tilt angle of the reflection surface (the screen that is necessary to reflect the projection light reflected by the light emission surface in contact with or close to the inner surface of the screen toward this light emission surface (screen The angle with respect to the surface and the light exit surface) may be small.

If the angle of inclination of the reflecting surface is small, the extending length of the reflecting surface that extends obliquely toward the rear surface of the case is also small. Therefore, the depth length of the case can be reduced, and the entire apparatus can be downsized.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. The projector of this embodiment is used as a liquid crystal television receiver.

In the figure, 11 is the case of the projector. The case 11 has a vertically long rectangular thin box shape, and a large screen (for example, a 14-inch screen) display window 12 provided with a transmissive screen 13 is provided in a substantially upper half area of the front surface of the case 11. .

Reference numeral 14 denotes a prism provided in the case 11. The prism 14 is provided laterally with its light incident surface 14a facing downward and its light emitting surface 14b facing the display window 12. The prism 14 has such a size that the area of its light emitting surface 14b is larger than that of the display window 12, and its length (horizontal dimension) is set to be slightly larger than the width of the display window 12, and the width ( The height of the light emitting surface 14b) is set to be sufficiently larger than the vertical width of the display window 12. Then, the prism 14 is arranged such that the upper edge of the light emitting surface 14b thereof is slightly above the upper edge of the display window 12, and the light emitting surface 14b is on the inner surface of the transmissive screen 13 provided in the display window 12. It is fixed in the case 11 in a state of being in contact with or close to (contact surface in FIG. 1). The rear surface of the prism 14, that is, the reflecting surface 14c facing the light emitting surface 14b.
A reflective film 15 such as an aluminum vapor deposition film is provided on the entire surface of the light emitting surface 14b below the display window 12.

On the other hand, in the lower part of the case 11, a transmissive dot matrix liquid crystal display panel 16 for displaying a television screen image,
A light source section for illuminating the liquid crystal display panel 16 from the back side thereof.
17 and a projection lens 17 for enlarging and projecting the display image of the liquid crystal display panel 16 on the transmissive screen 13 of the display window 12.

The light source unit 17 is a high-intensity light source lamp 17a such as a halogen lamp.
And a parabolic reflector 17b having a parabolic reflection surface that reflects the light from the light source lamp 17a as parallel light.
The light source section 17 is provided laterally on one side of the lower end of the case 11 so as to horizontally project light toward the other side surface of the case 11. In addition, 19a, 19b
Is an infrared absorption film and an infrared reflection filter arranged in front of the light source unit 17.

Reference numeral 20 denotes an illumination light reflecting mirror arranged in the center of the lower end of the case 11. The illumination light reflection mirror 20 is provided so as to be inclined obliquely so that the illumination light a from the light source unit 17 is reflected obliquely upward toward the front side of the case, and the transmissive liquid crystal display panel 16 is The center thereof is aligned with the optical axis of the illumination light a reflected by the illumination light reflection mirror 20, and is arranged obliquely above the illumination light reflection mirror 20. The liquid crystal display panel 16 has a display screen size of about 2 inches.

Above the liquid crystal display panel 16, a circular Fresnel lens 21 for condensing the light passing through the liquid crystal display panel 16 on the projection lens 18 is provided in parallel with the liquid crystal display panel 16.

Reference numeral 22 denotes an image reflection mirror located on the front side of the case 11 above the Fresnel lens 21 and obliquely opposed to the Fresnel lens 21, and 23 denotes the image reflection mirror on the back side of the case 11. 22 is a projection mirror positioned diagonally above 22.The projection mirror 23 has an upper edge close to the rear edge of the light incident surface 14a of the prism 14 and has an angle of 45 ° with respect to the light incident surface 14a. The image reflection mirror 22 is provided in parallel with the projection mirror 23.

Further, the projection lens 18 is configured by combining a plurality of optical lenses. The projection lens 18 is arranged between the image reflection mirror 22 and the projection mirror 23. The image reflection mirror 22, the projection lens 18 and the projection mirror 23 cause the display image of the liquid crystal display panel 16 to be transmitted through a transmission screen.
A projection optical system for projecting obliquely toward 13 is configured.

Explaining the display operation of this projector, the illumination light a from the light source unit 17 has its infrared component removed by the infrared absorption filter 19a and the infrared reflection filter 19b, and then is reflected upward by the illumination light reflection mirror 20 to be transmitted. The liquid crystal display panel 16 is illuminated from the back side.

When the light that has passed through the liquid crystal display panel 16 is called image light, the image light is condensed by the Fresnel lens 21 on the projection lens 18 via the image reflection mirror 22. That is,
The image reflection mirror 22 reflects the image light that has passed through the Fresnel lens 21 toward the projection lens 18, and the image light that has passed through the Fresnel lens 21 is reflected by the image reflection mirror 22 and is reflected by the projection lens 18. It enters and is enlarged by this projection lens 18.

The projection mirror 23 reflects the image light passing through the projection lens 18 toward the light incident surface 14a of the prism 14,
The image light that has passed through the projection lens 18 is reflected by the projection mirror 23 and enters the light incident surface 14a of the prism 14 from a substantially vertical direction.

The image light that has entered the prism 14 from its light incident surface 14a strikes the light exit surface 14b of the prism 14 from an oblique direction, as shown by the broken line in FIG. After being reflected toward 14c, this reflective surface 1
4c is reflected again toward the light emitting surface 14b, and this light emitting surface 1
The light is emitted from 4b and enlarged and projected on the transmissive screen 13 of the display window 12.

That is, in this projector, the area of the light emitting surface 14b is equal to or larger than the area of the display window 12 on the front surface of the case.
The light exit surface 14b is provided in contact with or close to the inner surface of the transmissive screen 13 provided in the display window 12, and the light passing through the liquid crystal display panel 16 and the projection lens 18 is provided in the prism 14 as the light. By making the light incident from the incident surface 14a, this light is refracted in the prism 14 and its light emitting surface 14
The image is projected from b to the screen 13.

In this way, the light projected by the projection lens 18 toward the transmissive screen 13 is, as shown in FIG.
The prism 13 travels in a zigzag manner between the light emitting surface 14b and the reflecting surface 14c and then passes through the light emitting surface 14b to pass through the screen 13
Incident on.

Therefore, according to this projector, the projection light emitted from the projection optical system (the light reflected by the projection mirror 23) is displayed on the screen.
Since the optical path length up to 13 can be earned, the linear distance from the projection optical system to the screen 13 can be shortened accordingly.

Moreover, in the above projector, the light emitting surface 14b of the prism 14 is brought into contact with or close to the inner surface of the screen, and the reflecting surface 14c of the prism 14 is opposed to the light emitting surface 14b from the case rear surface direction, thereby 13
Since the projection light is zigzag back and forth within the space behind, it is necessary to reflect the projection light reflected by the light exit surface 14b in contact with or close to the inner surface of the screen toward this light exit surface 14b. Tilt angle of reflecting surface 14c (Screen 1
The angles with respect to the three surfaces and the light emitting surface 14b) may be small.

If the inclination angle of the reflection surface 14c is small, the extension length of the reflection surface 14c that extends obliquely toward the rear surface of the case is also small, so that the depth length of the case 11 can be reduced.

Therefore, according to this projector, as compared with the conventional projector in which the projection lens is directly opposed to the screen, the depth length of the case 11 can be made much smaller, and the entire apparatus can be downsized. Since the projection light from the optical system is zigzag back and forth in the space behind the screen 13 to gain the optical path length, the optical path length from the projection lens 18 of the projection optical system to the screen 13 is made large enough to make a large screen. Image can be projected on the screen.

Moreover, in the above-described embodiment, the light source unit 17 is provided laterally so that the illumination light a from the light source unit 17 is incident on the liquid crystal display panel 16 via the illumination light reflection mirror 20.
The light passing through the liquid crystal display panel 16 is reflected by the illumination light reflection mirror 20 toward the projection lens 18, and the projection lens 18
Since the light passing therethrough is reflected toward the prism 14 by the illumination light reflection mirror 20, the light path from the light source section 17 to the prism 14 is a zigzag light path, so the light source section 17 and the liquid crystal display panel 16 and The projection lens 18 can be housed in the space below the prism 14.

In the above embodiment, the prism 14 has its light emitting surface.
The area of 14a is larger than that of the display window 12, but depending on the shape of the prism 14, its light emitting surface 14b is used.
The area may be the same as the area of the display window 12, or the prism 14 may be provided in a vertically oriented state with its light emitting surface 14b oriented in the horizontal direction, and the projection lens 18 and the liquid crystal display panel 16 may be provided on the side thereof.
May be arranged.

Further, in the above embodiment, the projection lens 18 is opposed to the prism 14 via the projection mirror 23.
18 may be directly opposed to the prism 14, and the light source unit 17 and the liquid crystal display panel 16 may be directly opposed to the liquid crystal display panel 16 and the projection lens 18 without a mirror. Further, the light source unit 17, the liquid crystal display panel 16 and the projection lens 18 may be arranged side by side in a straight line. Even in this case, since the projection lens 18 can be arranged close to the screen 13, the depth length of the case 11 can be increased. The size is considerably smaller than that of a conventional projector.

It is needless to say that the present invention can be widely applied to not only the liquid crystal devision receiver of the above embodiment but also various types of projectors.

[Effect of device]

The projector according to the present invention includes a light emitting surface that is in contact with or close to the inner surface of the screen and a reflecting surface that faces the light emitting surface from the rear surface of the case, and projects the light projected by the projection optical system toward the transmissive screen. Since the light beam is made to come and go in a zigzag state between them and then is made incident on the screen, it is possible to obtain an optical path length from the projection optical system to the screen and project a large-screen image on the screen.

Moreover, in this invention, the light emitting surface is arranged in contact with or close to the inner surface of the screen, and the reflecting surface is opposed to the light emitting surface from the rear side of the case, so that the space inside the screen is rearward. Since the projection light is moved back and forth in a zigzag pattern, the tilt angle of the reflection surface (the screen that is necessary to reflect the projection light reflected by the light emission surface in contact with or close to the inner surface of the screen toward this light emission surface (screen Angle with respect to the surface and the light emitting surface) may be small.If the inclination angle of the reflecting surface is small, the projecting length of the reflecting surface projecting obliquely toward the rear surface of the case also becomes small. Thus, the entire device can be downsized.

[Brief description of drawings]

1 and 2 are a vertical sectional side view and a partially cutaway front view of a projector showing an embodiment of the present invention. Third
FIG. 1 is a side view showing the principle configuration of a conventional projector. 11 ... Case, 12 ... Display window, 13 ... Transmissive screen, 14 ... Prism, 14a ... Light incident surface, 14b ... Light exit surface, 14c ... Reflective surface, 15 ... Reflective film, 16 …… Liquid crystal display panel, 17 …… Light source, 18 …… Projection lens, 20 …… Illumination light reflection mirror, 21 …… Fresnel lens, 22 …… Image reflection mirror, 23 …… Projection mirror.

Continuation of the front page (72) Osamu Umeda Osamu Umeda 2-229 Sakuragaoka, Higashiyamato-shi, Tokyo Casio Computer Co., Ltd. Tokyo office (56) Reference JP-A-60-137183 (JP, A)

Claims (1)

[Scope of utility model registration request] 1. A projector provided with an image display device and a projection means for projecting a display image of the image display device toward the transmissive screen in a case having a display window provided with a transmissive screen on the front surface. In the above, the projection means includes a projection optical system for projecting a display image of the image display device toward the screen from an oblique direction, and a light projected by the projection optical system in contact with or close to the inner surface of the transmissive screen. And a light emitting surface that reflects the light in the rear surface direction of the case and transmits the incident light from the rear surface direction of the case to emit the light toward the screen side, and a light emitting surface that faces the light emitting surface from the rear surface direction of the case. A prism having a reflecting surface that reflects the reflected light toward the light emitting surface, and the projection optical system and the light emitting surface are the projection optical system and the projection optical system. The projection light from the shadow optical system is arranged in a relationship of being reflected by the law of total reflection on the light emission surface, and the reflection surface is the projection light reflected on the light emission surface with respect to the light emission surface. Is arranged so as to be reflected toward the light emitting surface at an angle of transmitting the light emitting surface.