JP2683465B2 - Projection display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type display device for projecting an image of a liquid crystal panel or the like on a screen.

In recent years, projection type display devices have been equipped with liquid crystal panels.
A thin film transistor (TFT) having no crosstalk and high contrast is provided in each pixel. Since this thin film transistor malfunctions when exposed to light, it is necessary to prevent the malfunction of the thin film transistor due to the reflected light on the surface of the polarizing plate.

[0003]

2. Description of the Related Art FIG. 5 is a conceptual diagram of a conventional projection type display device. FIG. 5 (A) shows an overall view.
(B) is a structural diagram of a liquid crystal panel.

In FIG. 5A, a projection type display device 50 is provided.
Is the P-wave (or S-wave) emitted from the light source 51 in which the lamp 51b is arranged in the reflector 51a by the polarizing plate 52a.
Waves) are separated. The polarization state of this light is displayed on the liquid crystal panel 53.
The light is transmitted or blocked by the next polarizing plate 52b. Then, the polarizing plate 52b is formed by the projection lens 54.
The above image is projected on the screen 55 or the like.

Here, the liquid crystal panel 53 uses a thin film transistor, and one pixel is shown in FIG. 5 (B). That is, the transistor substrate 58 in which the pixel electrode 57 in the thin film transistor 56 is formed, and the counter electrode 5
The liquid crystal layer 61 is interposed between the liquid crystal substrate 60 and the liquid crystal substrate 60 on which 9 is formed.

By the way, the thin film transistor 56 may not operate when irradiated with light. Therefore, as shown in FIG. 6, a light-shielding film 62 made of metal or the like is provided on the side of the liquid crystal substrate 60 on which light enters to shield the thin film transistor 56 from light.

The thin film transistor 56 is sensitive to temperature and does not operate at high temperatures.
An air layer is interposed between the polarizing plate 52a on the light source 51 side and the liquid crystal panel 53 to prevent the temperature from rising by absorbing one of the S wave and the P wave as in (B).

However, from the light source 51, the liquid crystal panel 53
And several hundreds of thousand lux of light is irradiated to the liquid crystal in the reflection as shown in FIG. 6, slightly polarizer 5 2 b from the light transmitted through the liquid crystal panel 53 is a difference in refractive index (approximately 10%) Panel 5
Returning to 3, the thin film transistor 56 may malfunction.

Therefore, FIG. 7 shows a diagram for explaining a liquid crystal panel in which a countermeasure against reflected light is taken. FIG. 7 (A)
Is the one in which the polarizing plate 52b on the projection lens side is attached to the liquid crystal panel 53 to prevent reflected light. In FIG. 7B, a light shielding film 63 is formed between the transistor substrate 58 and the thin film transistor 56 of the liquid crystal panel 53 to shield the reflected light from the polarizing plate 52b. In addition, FIG.
An antireflection film 64 is formed on the polarizing plate 52b on the projection lens side to prevent reflection.

[0010]

However, in the case of FIG. 7A, since light is absorbed and heat is generated in the polarizing plate 52b, the surface of the polarizing plate 52b is protected by a fan or the like in order to prevent the heat generation. There is a problem that it needs to be cooled and the cost becomes high.

Further, in the case of FIG. 7B, there is a problem that the number of manufacturing steps of the transistor substrate 58 for forming the light shielding film 63 is increased, the yield is reduced, and the cost is increased.

Further, in the case of FIG. 7C, there is a problem that the present antireflection film 54, which takes the formation cost into consideration, allows a few% of reflection, so that the effect is small.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a projection type display device which is low in cost and prevents malfunction of a thin film transistor due to reflected light.

[0014]

The above-mentioned problems are solved by transmitting the liquid crystal display unit in a pixel unit by a liquid crystal display unit which is disposed between the first and second polarizing units and has a predetermined portion on the side of the first polarizing unit shielded from light. In a projection display device in which an image of which interruption is controlled is projected by a projection means, the liquid crystal display section is a thin film transistor.
Has a data, with assumed to absorb unwanted polarization the second polarizing means of said projecting means side, inclined at a predetermined angle to irradiate the reflected light from the polarizing means of said second to said liquid crystal display outsiders It is solved by providing it.

[0015]

As described above, the second polarizing means on the side of the projection means is provided tilted at a predetermined angle. That is, the light from the first polarization means is prevented from adversely affecting, for example, the switching element by blocking light applied to a predetermined portion of the liquid crystal display unit,
The reflected light from the second polarization means is reflected to the outside of the liquid crystal display portion due to the inclination, and the adverse effect due to the reflected light from the projection means side is prevented.

Therefore, it becomes possible to prevent the malfunction of the thin film transistor due to the reflected light from the second polarizing means on the projection means side of the liquid crystal display section using the thin film transistor.

[0017]

FIG. 1 shows a configuration diagram of a first embodiment of the present invention.

In the projection type display device shown in FIG. 1, light emitted from a light source 1 in which a lamp 1b is arranged in a reflector 1a is separated into P waves or S waves by a first polarizing plate 2 which is a polarizing means. Then, only the P wave or the S wave enters the liquid crystal panel 3 which is the liquid crystal display unit.

The liquid crystal panel 3 in FIG. 1 shows only one pixel, and a predetermined number of these are arranged side by side.
(See FIG. 2). That is, the liquid crystal panel 3 is such that the liquid crystal layer 10 is interposed between the transistor substrate 6 in which the pixel electrode 5 of the thin film transistor 4 is formed and the liquid crystal substrate 9 in which the counter electrode 7 and the light shielding film 8 are formed. .

[0020] The liquid crystal panel 3 is intended to change the polarization state of the incident light, unnecessary Ri polarizing means der in its polarization state
The second polarizing plate 11 having a function of absorbing polarized light controls transmission and blocking, and projects the image on a screen by a projection unit (projection lens, see FIG. 5A). In this case, the second polarizing plate 11 is provided so as to be inclined with respect to the liquid crystal panel 3 at a predetermined angle (for example, 45 °). Thereby, the reflected light from the surface of the second polarizing plate 11 can be emitted to the outside of the liquid crystal panel. It should be noted that tilting the second polarizing plate 11 slightly shifts the optical axis that passes through the second polarizing plate 11, but this is not different from the case where the image itself is not tilted.

Next, FIG. 2 shows a diagram for explaining the operation of FIG. FIG. 2 shows a setting condition of the inclination angle of the second polarizing plate 11, whereby reflected light from the surface of the second polarizing plate 11 is reflected to the outside of the liquid crystal panel 3. In FIG. 2, the liquid crystal panel 3 includes a predetermined number of thin film transistors 4, pixel electrodes 5, counter electrodes 7, and light shielding films 8 for one pixel in FIG.

Therefore, the liquid crystal panel 3 and the second polarizing plate 11
Is L, the inclination angle of the second polarizing plate is K, and the image width of the liquid crystal panel 3 is W, if K is an inclination angle equal to or more than the value satisfying the expression (1), then the second polarization The reflected light from the surface of the plate 11 is emitted to the outside of the liquid crystal panel 3.

Tan2K = W / {L− (W / 2) tanK} (1) Here, the incident angle (reflection angle) θ is equal to K, and x in FIG. 2 is x = (W / 2) tanK. Represented.

Thus, with a simple structure in which the second polarizing plate 11 is tilted, the thin film transistor 4 of the liquid crystal panel 3 is irradiated with the reflected light from the surface of the second polarizing plate 11 on the projection means side (emission side). It is possible to prevent malfunction of the thin film transistor 4 without increasing the cost, and to reduce the cost.

Next, FIG. 3 shows a block diagram of a second embodiment of the present invention. 3 (A), (C), and (D) are obtained by changing the shape of the second polarizing plate, and other configurations are similar to those of FIG. 1 and the like. In FIG. 3 (A), is arranged to divide the second polarizing plate 11 to the four polarization section 15, the respective polarization section 15 is inclined at an angle K in the same direction Rutotomoni, alongside each polarizing section 15
It is configured to be . In this case, the tilt angle K satisfies the expression (2), so that the liquid crystal panel 3 due to the reflected light is reflected.
It is possible to prevent the adverse effect on the thin film transistor 4.

K ≧ (1/2) tan ⁻¹ (W / L) (2) As a result, malfunction of the thin film transistor 4 can be prevented, and the apparent thickness of the second polarizing plate 11 is small. Therefore, the installation space can be reduced.

The second polarizing plate 11 formed by the polarizing section 15 shown in FIG. 3A has a "J" shape as shown in FIG. 3B.
The same effect can be obtained even if it is configured by a letter-shaped integral polarizing plate.

In FIG. 3C, the four deflecting portions 15 in FIG. 3A are arranged side by side with a similar inclination angle ± K so as to form a V shape around the optical axis. 3 (D), the second polarizing plate 11 has a tilt angle of ± K.
It is formed integrally by being curved in a V shape.

As a result, by changing the tilting direction of the second polarizing plate 11 within one screen, the width when tilted as a whole can be made small, and the thickness can be reduced.

The polarizing portions 15 in FIGS. 3A and 3C may be attached at the upper and lower ends, respectively, or may be formed by adhering to a transparent plate.

Next, FIG. 4 shows a block diagram of a third embodiment of the present invention. 4A to 4C show the second polarizing plate 11 positioned in parallel with the liquid crystal panel 3 provided with a predetermined number of prisms of a predetermined shape.

In FIG. 4, four prisms 20a having an incident surface angle K expressed by the above equation (2) are provided in the second polarizing plate 11 with deflecting portions 20 in which the incident surfaces are inclined in the same direction. is there. The deflecting unit 20 may be a prism having an "J" -shaped entrance surface, as shown in FIG. 4B, and has the same effect.

Further, FIG. 4C shows the deflecting section 20 in which the prism 20a is disposed on the second polarizing plate 11 with the incident surface arranged in the opposite direction with respect to the optical axis. As shown in D), a prism may be used in which the incident surface is curved in a V shape, which has the same effect.

By configuring as shown in FIGS. 4A to 4D, it is possible to prevent malfunction of the thin film transistor 4 as in FIG. It can be easily formed on the surface of the polarizing plate 11, and the cost can be reduced.

[0035]

As described above, according to the present invention, the second polarizing means is provided so as to be inclined at a predetermined angle so that the reflected light from the second polarizing means is irradiated to the outside of the liquid crystal display section.
A malfunction of the thin film transistor due to reflected light can be prevented, and cost reduction can be achieved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a first embodiment of the present invention.

FIG. 2 is a diagram for explaining the operation of FIG.

FIG. 3 is a configuration diagram of a second embodiment of the present invention.

FIG. 4 is a configuration diagram of a third embodiment of the present invention.

FIG. 5 is a conceptual diagram of a conventional projection display device.

FIG. 6 is a configuration diagram of a liquid crystal panel on which a light shielding film is formed.

FIG. 7 is a diagram for explaining a liquid crystal panel in which measures are taken by reflected light.

[Description of Reference Signs] 1 light source 1a reflector 1b lamp 2 first polarizing plate 3 liquid crystal panel 4 thin film transistor 11 second polarizing plate 15 polarizing unit 20 deflecting unit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshinori Tanaka 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Within Fujitsu Limited (56) References JP 63-67979 (JP, A) JP 64-50037 (JP, A) JP-A-2-302726 (JP, A) JP-A-2-220040 (JP, A)

Claims (3)

(57) [Claims] 1. A liquid crystal display unit (3) disposed between first and second polarizing means (2, 11) and having a predetermined portion on the side of the first polarizing means (2) shielded from light. Transparent in units,
In a projection type display device which projects an image of which interruption is controlled by a projection means, the liquid crystal display section (3) has a thin film transistor (6).
And, of the projection means side and the second polarizing means (11) is for absorbing unwanted polarization, the second polarization means (11)
A projection type display device, wherein the projection type display device is provided so as to be tilted at a predetermined angle (K) for irradiating reflected light from the outside of the liquid crystal display unit (3). 2. The second polarizing means (11) is divided into a predetermined number of inclined polarizing parts (15), and the divided polarizing parts (15) are arranged in parallel. To
The projection display device according to claim 1 . 3. A liquid crystal display unit (3) arranged between first and second polarizing means (2, 11) and having a predetermined portion on the side of the first polarizing means (2) shielded from light. Transparent in units,
In a projection type display device which projects an image of which interruption is controlled by a projection means, the liquid crystal display section (3) has a thin film transistor (6).
And, of the projection means side and the second polarizing means (11) is for absorbing unwanted polarization, the second polarization means (11)
A predetermined number of polarizing parts (20) on the liquid crystal display part (3) side of
And the polarizing unit (20) is provided with a predetermined number of deflecting units (20) for irradiating the light reflected by the surface of the polarizing unit (20) to the outside of the liquid crystal display unit (3). Type display device.