JPH0497235A - Liquid crystal display device for projection - Google Patents

Abstract

PURPOSE:To effectively prevent the temperature of a liquid crystal display board from rising caused by the light source of a projecting means and to obtain an enlarged projected image having high resolution by blowing air to the inside of a housing by means of an air blowing means and making it circulate inside the housing. CONSTITUTION:An interval between a liquid crystal display board 22 and an original placing stage is narrowed by making use of the liquid crystal display board 22 to which the frame 24 is attached. Then, the surface of the liquid crystal display board 22 is set to be opposed to the original placing stage of the projecting means, and an inverted image is displayed on the liquid crystal display board 22. And the air blown the inside of a main body through the air blowing means 32 is guided to the back surface and the surface of the liquid crystal display board 22 by air guiding means 34 and 36 and is made to circulate along the liquid crystal display board 22, so that the liquid crystal display board 22 is effectively cooled. Thus, the temperature rising of the liquid crystal display board 22 due to heat from the light source of the projecting means is prevented and the enlarged projected image having the high resolution can be obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a projection liquid crystal display device used in an electronic blackboard system, etc., in which liquid crystal display contents are projected onto a screen by an overhead projector (hereinafter also referred to as OHP). It is related to.

[Conventional technology]

OHPs are widely used to provide easy-to-understand explanations using charts and graphs in meetings with a large number of people. Usually, OH
P uses what is written on a transparent sheet and projects it onto a screen as a manuscript, but in addition to this, OH
2. Description of the Related Art A liquid crystal display device is known in which a liquid crystal display device is installed on a screen and the contents displayed thereon are projected onto a screen using an OHP. In other words, a transmissive liquid crystal display device is
The document is placed on a document placement stage P, and light from a light source located at the bottom of this document placement stage is passed through a liquid crystal display device.
The content displayed on the liquid crystal display device is projected onto a screen by adjusting the focus using an optical system such as a mirror.

By using the content displayed on this liquid crystal display device as an OHP document, CR of a personal computer can be improved.
The same image as the T screen can be enlarged and projected, allowing a large number of people to see it at the same time.

[Problem to be solved by the invention]

However, the liquid crystal display panel of the conventional projection liquid crystal display device has 6
Since it was limited to 40 x 400 dots or 640 x 480 dots, it is possible to connect it to a personal computer that uses a CRT or LCD screen with the same number of dots, but with a higher resolution, such as 1.
It is generally not possible to connect to a computer that supports 024 x 768 dots. Therefore, with conventional projection liquid crystal display devices, such high-resolution computer image information cannot be enlarged and projected onto a screen by OHP.

Furthermore, commercially available liquid crystal display boards with 1000 dots or more in the horizontal direction (for example, the 1024 x 768 dots mentioned above) were not originally intended to be used for projection, but were only used as components for laptop personal computers. It is offered on the market. For this reason, when such a liquid crystal display board is used in a projection liquid crystal display device in a normal display state, the frame that is attached to the laptop personal computer will cast a shadow on the screen, reducing the quality of the image. Resulting in.

Furthermore, due to problems such as the color of the liquid crystal changing due to heat from the OHP light source, it cannot be installed as is on the OHP original stage.

The present invention has been made based on the above circumstances, and provides a projection liquid crystal display device that is connected to a computer that supports a high resolution dot count and that can enlarge and project image information sent from the computer using an OHP. The purpose is to

[Means to solve the problem]

In order to achieve the above object, the present invention provides a projection liquid crystal display device that displays content to be projected on a screen by a projection means. a high-resolution liquid crystal display board having a frame attached to the inside of the housing, and an air guide means for guiding air blown by the air blowing means to the rear surface and the front surface of the liquid crystal display board, The present invention is characterized in that the front side of a liquid crystal display board is placed so as to face the original stage of the projection means, and an inverted image is displayed on the liquid crystal display board.

Further, it is desirable to provide heat ray absorbing glass on the front surface side of the liquid crystal display panel.

[Effect]

Since the present invention utilizes a liquid crystal display board to which a frame is attached with the above-described configuration, the surface of the liquid crystal display board is The scanner is placed opposite the original document stage, and the inverted image is displayed on the liquid crystal display. In addition, since the air blown into the main body by the blowing means can be guided to the back and front surfaces of the liquid crystal display board by the air guiding means and circulated along the liquid crystal display board, the liquid crystal display board can be effectively cooled. can. As a result, it is possible to prevent the temperature of the liquid crystal display board from rising due to the heat emitted by the light source of the projection means, so that the display can be displayed on a high-resolution liquid crystal display board without deterioration of characteristics such as discoloration of the liquid crystal display board due to temperature rise. The high-quality image can be clearly projected onto the screen by the projection means.

By providing heat-absorbing glass on the surface side of the liquid crystal display board, it is possible to more reliably prevent the temperature rise of the liquid crystal display board, thereby preventing deterioration of characteristics such as discoloration of the liquid crystal display board and displaying the liquid crystal display. High-quality images displayed on the board can be projected onto a screen.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 is a schematic longitudinal sectional view of an OHP liquid crystal display device according to an embodiment of the present invention, and FIG. 2 is an overall configuration diagram of an electronic whiteboard system constructed using this OHP liquid crystal display device.

The electronic whiteboard system shown in FIG. It is equipped with an OHP 8 for projecting the displayed image, a printer 10 for printing the image displayed on the liquid crystal display device 6, and a pen with a built-in magnetic material (not shown) that is a means for inputting image information. The liquid crystal display device 6 is installed at a predetermined position on the original stage of the OHP 8 so that the liquid crystal display surface faces the original stage. Although this OHP 8 is of a type in which a light source is located below the document placement stage, it may also be of a type in which the light source is located above the document placement stage. An electronic blackboard 4 is installed in front of the 0HP8. The position of the electronic whiteboard 4 is determined relative to the OHP 8 so that the projected image from the OHP 8 is reflected at a predetermined position on the electronic whiteboard 4.

A magnetic detection device is provided inside the writing surface of the electronic blackboard 4. This device consists of a large number of amorphous alloys arranged in the X direction and the The magnetic permeability of the alloy changes. By sensing this change with a coordinate decoder, the coordinates of the pen on the writing surface of the electronic blackboard are recognized.

The coordinate information obtained by the coordinate decoder is sent to the computer 2 shown in FIG. 2, processed for image display, and supplied to the liquid crystal display device 6. The computer 2 inverts this image information and displays it on the liquid crystal display device 6. This inverted image appears normal when the liquid crystal display device 6 is viewed from above, since the display surface of the liquid crystal display device 6 is installed so as to face the document mounting stage of 0HP8. This image is projected onto the electronic blackboard 4 by the OHP 8.

In addition to the magnetic material, the pen contains a microswitch and an LC resonant circuit. The microswitch is turned on by bringing the pen into contact with the writing surface of the electronic blackboard 4.
The LC resonant circuit starts oscillating. This resonant frequency is set to a different value depending on the color you want to display, and this frequency is sensed by a coil embedded inside the electronic blackboard. Since information on the color to be displayed is set in advance in the computer based on this resonance frequency, text can be displayed in color by using a color liquid crystal display device, and the color display image can be displayed using an over rad projector. By doing this, it is possible to project the image onto the electronic blackboard. still,
Naturally, if a monochrome liquid crystal display device is used, the projection will be monochrome. Further, such a device is also provided in an eraser for erasing a projected image, and it is possible to recognize that the eraser is an eraser by identifying a predetermined resonance frequency. When it is recognized that the frequency is the eraser frequency, the content displayed on the writing surface in the area through which the eraser passes is erased in real time.

In this way, on the writing surface of the electronic blackboard 4, an image is projected in real time by the liquid crystal display device 6 in accordance with the locus of movement of the pen having a magnetic substance as described above. Therefore, it appears as if the image is being drawn directly on the writing surface with a pen.

Next, this liquid crystal display device 6 will be explained.

FIG. 1 is a schematic longitudinal sectional view taken along arrow C of the liquid crystal display device shown in FIG. The liquid crystal display device 6 includes the liquid crystal display board 2
2, a housing 26, a support 28 for fixing the liquid crystal display board 22 to the housing 26, a heat ray absorbing glass 30, a blower 32 that is an air blower, and a flow divider plate 34 and a guide 36 that are air guide devices. It is. The liquid crystal display board 22 is 102
It is possible to display at a resolution of 4 x 768 dots, and the widely used 640 x 400 dots or 640 x 4
A higher resolution can be obtained than that of about 80 dots.

In addition, since a liquid crystal display panel with 1000 dots or more in the horizontal direction is commercially available only as a component for a lamp-top personal computer, a frame 2 is placed around it for mounting on a lamp-top personal computer.
4 is attached. Therefore, the liquid crystal display panel 22 is manufactured with the intention of being viewed from the direction of arrow A.

In a normal OHP, a document drawn on a transparent sheet or the like is placed on a document placement stage, that is, the Fresnel lens 18 in FIG. 1, so that the front side of the document is visible when viewed from the direction of arrow B. Therefore, originally, it is necessary to arrange the liquid crystal display board 22 on the top side and the frame body 24 on the bottom side, that is, the liquid crystal display board and the frame body 24 shown in FIG. 1 are upside down. There is. However, when arranged in this way, the height h of the frame body 24 including the liquid crystal display board 22 is about 4 Qmm, so the distance between the Fresnel lens 18 and the liquid crystal display board 22 is too large, and the Fresnel lens 18 is It becomes difficult to focus. Furthermore, since the shadow of the frame 24 will appear around the image projected on the electronic whiteboard 4, it will be very difficult to see.

For this reason, the liquid crystal display panel 2 with a frame 24 attached to its periphery is
2 is used, in order to narrow the distance between the liquid crystal display plate 22 and the Fresnel lens 18 and to prevent the shadow of the frame 24 from appearing on the image, the liquid crystal display plate is arranged as shown in FIG. It is necessary to arrange the front side of 22 to face the Fresnel lens 18, and to display the screen inverted.

At this time, if you look from the direction of arrow B, the screen will be normal.
An image is projected onto the electronic whiteboard 4 in a normal state by the OHP 8. This image can be easily reversed and displayed using a connected computer. The pillars 28 are for fixing the liquid crystal display panel 22 arranged in this way to the housing 26.

The power consumption of a commonly used OHP light source is, for example, 60
This is approximately 0 watts, which is much higher than the backlight of a laptop personal computer.Therefore, when the liquid crystal display board 22 is brought close to the Fresnel lens 18, the temperature of the liquid crystal display board rises due to the heat from the light source. In general, liquid crystals are weak against heat and tend to deteriorate in characteristics such as discoloration when the temperature rises.In addition, mounted parts such as X-Y drivers and lead wire bonding parts mounted inside the frame 24 of the liquid crystal display board 22 are Because peeling is likely to occur due to thermal strain,
Measures are required. To this end, first, a heat ray absorbing glass 30 is provided directly below the liquid crystal display panel 22 to block infrared components from the light source as much as possible.

In order to further increase the cooling effect, cooling air is supplied to the housing 26.
Several blowers 32 for blowing air into the interior are installed over the entire side surface of the rear housing 26. An air filter 32a is provided on the outside of the blower 32 to prevent dust and the like from flowing into the blower 32.

The air blown into the housing 26 by the blower 32 is
The flow is divided into two flow paths labeled ■■ by the flow divider plate 34. The air divided into (2) is further divided into a flow path (2) which passes through a sulin l-362 provided at the upper part of the air guide 36, and a flow path (2) which passes between the air guide 36 and the frame 24. The air in the flow path (2) flows along the top glass 38 that prevents the inflow of debris. In addition, the air in the flow path ■ flows along the back side of the liquid crystal display board 22 and takes away heat from the liquid crystal display board 22.
These ■■ airs cause mutual turbulence, further increasing the cooling effect. The air that has reached the right end joins together again at the upper part of the right frame 24, crosses the frame 24, and flows out through the slit 40 provided on the side surface of the housing 26 or the slit 42 provided on the bottom surface.

On the other hand, the air diverted to the flow path (2) passes through the suction 28a provided on the pillar 28, flows between the front side of the liquid crystal display panel 22 and the heat ray absorbing glass 30, absorbs the heat generated here, and flows to the right side. . And the slit 28 provided in the right column 28
It flows out through the slits 40 and 42 through b. The air flowing out from the slit 42 also flows between the bottom of the housing 26 and the Fresnel lens 18, increasing the cooling effect.

By effectively distributing the air flowed into the housing by the blower in this way, it is possible to effectively prevent the temperature of the liquid crystal display panel from rising, thereby preventing the negative thermal effects of the liquid crystal display device from appearing on the projection screen. Therefore, high-quality, clear images can be projected onto the screen without compromising the performance of the high-resolution LCD panel used.

In this example, a commercially available high-resolution liquid crystal display panel is used without any special processing, so production costs can be kept low and liquid crystal display devices can be provided to the market at low prices. can.

In general, a liquid crystal display panel for a laptop type personal computer has higher light transmittance when light passes from the front side to the back side than when light passes from the back side to the front side. This is because the brightness of the puncture light provided on the back side of the liquid crystal display panel of the laptop personal computer is low, so the purpose is to improve visibility by improving light transmission as much as possible. However, when strong OHP illumination is used as in this embodiment, there is no practical problem even if the light is passed from the front side to the back side of the liquid crystal display panel.

Further, in the above-mentioned embodiment, a case was explained in which a heat ray absorbing glass was provided in order to enhance the cooling effect, but it may be omitted if the light source generates little heat.

Incidentally, in the present embodiment described above, the image displayed on the liquid crystal display panel is displayed in an inverted manner. This is because the OHP is intended to be used in a normal manner in which the OHP is projected in front of the screen (the writing surface of the child blackboard). In this case, since the OHP is located on the side of the audience seats, it may be difficult for those who are behind the OHP to see the projected image because the IP gets in the way.

Therefore, the projection liquid crystal display device of this embodiment is provided with an image reversal switching device that can reverse or restore the image display, so that images can be projected not only from the front of the screen but also from the rear. You can do it like this.

When projecting from behind a screen, for example, use frosted glass instead of a regular screen, and
To display a normal screen instead of an inverted screen on a liquid crystal display device. OHP by projecting from behind the screen
A normal projected image can be obtained without any interference.

According to this embodiment, an inexpensive display device can be constructed by providing frosted glass on a part of a partition wall in a product exhibition hall, for example, and projecting from the rear.

〔Effect of the invention〕

As explained above, according to the present invention, by blowing air into the interior of the casing by the blowing means and distributing this air inside the casing, it is possible to effectively suppress the temperature rise of the liquid crystal display board caused by the light source of the projection means. Therefore, by using a commercially available high-resolution liquid crystal display board with a frame attached, it is possible to connect it to a computer that supports a high-resolution dot count, thereby obtaining a high-resolution enlarged projected image. A projection liquid crystal display device can be provided.

[Brief explanation of drawings]

FIG. 1 is a schematic vertical sectional view of an OHP liquid crystal display device according to an embodiment of the present invention, and FIG. 2 is an overall configuration diagram of an electronic blackboard system constructed using this OHP liquid crystal display device. 2... Computer, 4... Electronic blackboard, 6... Liquid crystal display device, 8... Overhead projector, 10... Printer, 18... Fresnel lens, 22... Liquid crystal display board, 24 ... Frame body, 26 ... Housing, 28 ... Support column, 30 ... Heat ray absorption glass, 32 ... Blower, 32a
...Air filter, 34...Broadcast plate, 36...Air guide, 38...Top glass, 28a, 28
b, 36a, 36b, 40. 42 ・-
·slit. Applicant Nippon Steel Information and Communication Systems Co., Ltd. Applicant Techno Plane Co., Ltd. Agent Patent Attorney Han 1) Masao

Claims (2)

[Claims] (1) In a projection liquid crystal display device that displays content to be projected on a screen by a projection means, a blowing means is provided on a side surface of a housing and blows outside air into the housing, and a blowing means is installed inside the housing. a high-resolution liquid crystal display board having a frame body formed of a high resolution, and an air guide means for guiding air blown by the air blowing means to the back surface and the front surface of the liquid crystal display board, the front side of the liquid crystal display board being directed to the projection means. 1. A projection liquid crystal display device, wherein the projection liquid crystal display device is installed to face a document placing stage of the invention, and displays an inverted image on the liquid crystal display board. (2) The projection liquid crystal display device according to claim 1, wherein a heat ray absorbing glass is provided on the front side of the liquid crystal display plate.