JP2001174775A - Projector device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a device which can sufficiently display an image of medium gradation with high luminance while decreasing the number of parts. SOLUTION: The light of three colors resolved (divided) by a color wheel 24 enters a polarizing beam splitter 25 and exits in the two directions as polarized light. The light emitted in the two directions is modulated by two reflection type liquid crystal panels 26, 27 into the image light divided into a plurality of gradations, and then the light is synthesized in the polarization beam splitter 25 and projected. When the two reflection type liquid crystal panels 26, 27 have the maximum gradations n, m respectively, the maximum gradation in the projected image is n+m-1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projector suitable for use in a reflection type liquid crystal projector using a color wheel, and more particularly to a projector using a reflection type liquid crystal panel as a spatial light modulator. It belongs to the technical field.

[0002]

2. Description of the Related Art Conventionally, as an example of an image display device,
There is a projector device (also referred to as a projection type image display device) using a projection lens. This projector device does not directly observe a light emitting unit that displays an image (video), but uses intensity-modulated (light is modulated by an applied image signal) image light on a screen such as a screen by a projection lens. By projecting the image on the screen, an image is displayed and observed on the screen, and the screen can be enlarged to an arbitrary size, which is suitable for enlargement of the screen.

The principle of this projector apparatus will be described with reference to FIG.
And a spatial light modulator 2 having no light emitting function by itself. Then, while illuminating the spatial light modulator 2 with the white light L1 emitted from the light source 1, an image signal is applied to the spatial light modulator 2 and the white light L1 is intensity-modulated into image light L2 in accordance with an applied image signal, and the phase-modulated image light L2 is projected onto a screen 4 such as a screen by the projection lens 3.
The image is displayed by projecting the image upward.

There are various methods for modulating the intensity of the spatial light modulator 2 used in the projector device. For example, the polarization of light is controlled using a liquid crystal panel (also referred to as a liquid crystal light valve). And a device that controls the emission direction of image light for each pixel by using a movable fine mirror. In general, a liquid crystal material called twisted nematic (hereinafter, referred to as TN) is often used as a liquid crystal material of a liquid crystal panel.

This liquid crystal panel can be classified into two types, a transmission type and a reflection type, from the viewpoint of input and output directions. The transmission type liquid crystal panel 6 shown in FIG. The white light L1 is phase-modulated into image light L2 by an image signal applied, and is emitted from the emission surface 6b opposite to the incidence surface 6a in the same direction as the incident direction. The reflection type liquid crystal panel 7 shown in FIG. 9 has a reflection layer 7b provided inside, and after white light L1 incident on the incident surface 7a is phase-modulated into image light L2 by an image signal applied thereto, The light is reflected by the internal reflection layer 7b and emitted from the incident surface 7a in the direction opposite to the incident direction.

The reflection type liquid crystal panel shown in FIG. 9 has the following advantages as compared with the transmission type liquid crystal panel 6 shown in FIG. That is, the transmissive liquid crystal panel 6
Since the image light L2 is blocked at the wiring portion of each pixel wired inside, the transmission area of the image light L2 decreases as the number of pixels increases or as the size of the transmissive liquid crystal panel 6 decreases. And the available image light L2
Utilization rate decreases. On the other hand, the reflection type liquid crystal panel 7 reflects the image light L2 on the reflection layer 7b and emits the image light L2 from the incident surface 7a.
b can be arranged on the back surface 7c side opposite to the incident surface 7a. Therefore, in the reflective liquid crystal panel 7, the image light L2 is not blocked by the wiring portion, and even if the area of the wiring portion increases, the light utilization rate of the image light L2 does not decrease, and the reflective liquid crystal panel 7 has high brightness. A projector device can be realized.

Here, in a projector device that projects a full-color image, three primary colors of light, red light (hereinafter referred to as R), green light (hereinafter referred to as G), and blue light (hereinafter referred to as B). ) Is phase-modulated with a corresponding image signal and synthesized on a screen such as a screen to display a full-color image. In a full-color projector device using a reflection type liquid crystal panel, three liquid crystal panels for R, G, and B are used, and phase modulation of image light of three colors of R, G, and B is performed for each liquid crystal. The three-panel system, which is performed independently on the panel, and the R,
There are two single-panel systems that sequentially perform phase modulation of the three colors of G and B image light.

On the other hand, a discharge lamp having high luminous efficiency is often used as a light source to emit white light. For this reason, in a three-plate system full-color projector device,
The white light emitted from the discharge lamp is divided into R, G, and B temporally different frequency bands by a photodecomposer (light splitter).
The three color lights of R, G, and B are respectively incident on three liquid crystal panels, and the three colors of R, G, and B applied to the three liquid crystal panels, respectively. Is spatially modulated into three colors of image light of R, G, and B by the image signal. Then, the spatially modulated R, G, and B color image lights are combined and projected on a screen. Therefore, this full-color projector apparatus has a problem that the optical system becomes large and the number of parts increases.

On the other hand, in a single-panel type full-color projector device, white light emitted from a discharge lamp is divided into three color lights of R, G, and B having different frequency bands in time by a photo-decomposing means (light dividing means). The three color lights of R, G, and B are sequentially incident on one liquid crystal panel, and the image signals of the three colors of R, G, and B are incident on the single liquid crystal panel. By sequentially applying the light in synchronization with the incidence, the one liquid crystal panel sequentially modulates the image light into three colors of R, G, and B. Then, the modulated R, G, and B image lights are sequentially projected onto a screen or the like, and the R, G, and B image lights are subjected to photolysis and modulation at a high speed. The three colors of image light appear to be integrated as if they were superimposed on human eyes (afterimage phenomenon), so that a full-color image can be displayed.

Means for rapidly decomposing white light into three color lights of R, G, and B having different temporal frequency bands include:
For example, transmissive color wheels are the most common,
As shown in FIG. 10, the color wheel 9 has three color filters RF (red filter), GF (green filter), and BF (blue filter) formed on the outer periphery of the rotating shaft 10. . Therefore, in a state where the color wheel 9 is rotated at a high speed by a motor (not shown) for driving the rotating shaft 10, three color filters RF, G of R, G, B are provided.
By injecting and transmitting white light into one of the rotation regions of F and BF, the white light is decomposed into three color lights of R, G, and B having different frequency bands in time, and is incident on the liquid crystal panel. It is configured to:

A conventional full-color projector using a single-panel reflective liquid crystal panel will be described with reference to FIG. 11. White light L11 emitted from a discharge lamp 12 is condensed into a spot light by a condenser lens 13. The light is then incident on the color wheel 14 and passes through the three color filters of the color wheel 14 to be decomposed into three-color light L12 of R, G, and B having different temporal frequency bands. Then, the decomposed three-color light L of R, G, and B
12 enter the polarization beam splitter 15, and the respective P-polarized lights in the three-color light L12 pass through the polarization separation surface 15a and sequentially enter one reflection type liquid crystal panel 16, and S
The polarized light is reflected by the polarization splitting surface 15a and is discarded as unnecessary light. Then, in synchronism with the P-polarized light of the three-color light L12 sequentially incident on the reflective liquid crystal panel 16, R, G, and B
Color image signals are sequentially applied and phase-modulated (the polarization direction of P-polarized light is modulated to S-polarized light according to the image signal). Then, the phase-modulated R becomes S-polarized light,
The image light L13 of three colors of G and B is reflected by the reflection layer in the reflection type liquid crystal panel 16 and reenters the polarization beam splitter 15. At this time, the image light L1 of three colors of R, G and B is obtained.
3, since the polarization direction is already modulated to S-polarization,
The three colors of image light L13 are reflected by the polarization separation surface 15a, are incident on the projection lens 17, and are projected on a screen such as a screen. Here, the polarizing beam splitter 15 has a function of an analyzing element, and selects only the S-polarized light phase-modulated by the reflective liquid crystal panel 16 to enter the projection lens 17. In FIG. 11, the P-polarized light of the three-color light L12 of R, G, and B as viewed from the polarization splitting surface 15a of the polarization beam splitter 15 is configured to be incident on the reflective liquid crystal panel 16. As shown in FIG. 12, the reflective liquid crystal panel 16 with respect to the polarizing beam splitter 15
Of the polarization splitting surface 15 by changing the arrangement of
As viewed from a, the S-polarized light of the three-color light L12 of R, G, and B is incident on the reflective liquid crystal panel 16.

[0012]

As described above, the single-panel type full-color projector using the color wheel 14 and one reflective liquid crystal panel is replaced with a three-panel full-color projector using three liquid crystal panels. The number of parts can be reduced in comparison with this, but on the other hand,
There were also the following problems. That is, the reflective liquid crystal panel 16 using TN as the liquid crystal material has a low response speed, and is not suitable for high-speed light modulation. On the other hand, when the three color lights L12 of R, G, and B decomposed by the color wheel 14 are sequentially modulated by the single reflective liquid crystal panel 12 into the image lights L13 of three colors of R, G, and B, the reflective liquid crystal panel Requires fast modulation.

That is, in the case of a three-panel type full-color projector device, the phase modulation of the image light of three colors R, G, and B can be separately performed by the three liquid crystal panels. Only one phase modulation per unit time is required. However, in a single-panel type full-color projector device, the unit time for image switching is R, G, B.
And the phase modulation must be performed sequentially. Therefore, a modulation speed three times faster than that of the reflective liquid crystal panel 16 is required as compared with a three-panel type full color projector. Furthermore, if the modulation speed is slow,
The projection interval time of the image light of three colors of R, G, and B becomes slow,
From the relationship with the integration time (afterimage time) of the human eye, on a screen such as a screen, R, G,
The three colors B of image light L13 appear to be shifted in time, causing a so-called screen flicker phenomenon.
Therefore, by increasing the rotation speed of the color wheel, R,
It is necessary to shorten the switching time of the three color lights of G and B, and to increase the phase modulation speed of the image light of three colors of R, G and B of the reflective liquid crystal panel.

However, a reflection type liquid crystal panel using TN as a liquid crystal material cannot realize such high-speed phase modulation. Therefore, it is conceivable to use a ferroelectric liquid crystal material (hereinafter, referred to as FLC) capable of high-speed phase modulation as a liquid crystal material of the reflective liquid crystal panel.
However, in a reflection type liquid crystal panel using this FLC,
A new problem arises in that it is difficult to display intermediate gradations of image light.

That is, in the case of a reflection type liquid crystal panel using a general material such as TN as a liquid crystal material, although the phase modulation speed is low, as shown in FIG. The light output can be easily modulated in an analog manner, and the intermediate gradation can be easily displayed.
On the other hand, in the reflection type liquid crystal panel using FLC as the liquid crystal material, the image signal is a digital signal because only the modulation of “0” or “1” can be performed. Since the response of the optical output to the signal voltage is steep and cannot be modulated in an analog manner, and the modulation speed is high, the intermediate voltage cannot be applied.
There is a problem that a halftone cannot be displayed by a simple voltage application method.

On the other hand, pulse width modulation is considered as a switching method for displaying intermediate gradations of R, G and B image light in a reflection type liquid crystal panel using FLC as a liquid crystal material. Can be This switching method is a method of dividing a unit image display time by a digital signal for phase modulation applied to one reflection type liquid crystal panel into a desired number of gradations, and performing switching corresponding to the number of gradations. For example, 8
If the image is divided into gradations (levels 0 to 7), the unit image display time is divided into seven, and switching is performed seven times.
When the level is 0, it is turned off seven times, and when the level is 8, it is all turned on.

A switching method for displaying an intermediate gradation in the case of using a reflection type liquid crystal panel using FLC as a liquid crystal material in a single-panel type full color projector device using a color wheel will be described with reference to FIG. First, the unit image display time of one reflective liquid crystal panel is divided into R, G, and B, and three color lights of R, G, and B are sequentially incident on the single reflective liquid crystal panel by a color wheel. I do. Then, the switching operation is performed by dividing the image signal into a desired number of tones within each unit image display time of the one reflective liquid crystal panel divided into R, G, and B.

Here, in FIG. 15, the number of gradations of the image signal in each unit image display time divided into three is divided into three to enable four gradation display. The image signal switching operation within the unit image display time is displayed. On the left side of FIG. 15 showing the first switching operation, all gradations are ON (R: 3 /
3, G: 3/3, B: 3/3), and R, G,
This shows a state in which the light outputs of the three color B image lights all have the maximum luminance. On the right side of FIG. 15 showing the second switching operation, the light output of the image light is R = 1.
/ 3, G is ／, and B is ／.

If the required image is of high quality, it is necessary to finely divide the unit image display time of the image signal into more gradations. Even with a reflective liquid crystal panel, it becomes difficult to divide the liquid crystal panel beyond a certain number of gradations. Explaining with a specific example, the response speed (light modulation speed) of a general FLC is about 35.
μs, and the unit image display time of the image signal is 33.3 m.
This is s seconds (30 sheets per second). Therefore, 33.3 ms
/ 35 μs = 951, and each image light can have about 300 gradations when divided into RG and B. But,
In order to avoid the above-described screen flicker phenomenon, there is a case where a rotation speed of the color wheel that is twice or more the unit image display time is required, and when the rotation speed of the color wheel is set to twice the unit image display time, In this case, the gradation of each of the R, G, and B image lights is reduced to about 150 gradations, and high-quality image cannot be obtained.

In a single-panel type full-color projector using a color wheel, as shown in FIG. 16, three color filters RF (red filter), GF (green filter) of R, G, and B of the color wheel 14 are provided. ), BF
(Blue filter) three borders RGP, GBP, BRP
At the timing when the spotlight of white light is incident so as to straddle the image signal, it is necessary to adjust the image signal so as not to operate the reflective liquid crystal panel in order to prevent mixing of colors on the screen. For this reason, the time during which the actual phase modulation can be performed is shorter than the above-described unit image display time.
The gradation of the image light of the three colors G and B is further reduced.

As described above, in the conventional single-panel type full-color projector device using a color wheel, the phase modulation speed is slow in a reflection type liquid crystal panel using TN as a liquid crystal material, and the modulation cannot be performed in time. In addition, F
In a reflective liquid crystal panel using LC, there is a problem that a sufficient gradation cannot be obtained and a high-quality image cannot be obtained.

The present invention has been made in order to solve the above-described problem, and has a small number of parts.
It is an object of the present invention to provide a projector device that can obtain a high-quality image with high luminance and sufficient display of intermediate gradations.

[0023]

In order to achieve the above object, a projector apparatus according to the present invention is characterized in that light emitted from a light source is polarized in two directions by a polarizing beam splitter and emitted, and emitted in the two directions. The emitted light is incident on two reflective liquid crystal panels and is modulated into image light divided into a plurality of gradations by an image signal applied thereto, reflected in two directions, and reflected in the two directions. The tone of light is synthesized by the polarizing beam splitter and projected on a screen by a projection lens.

In the projector device of the present invention configured as described above, the light emitted in two directions from the polarizing beam splitter is incident on two reflective liquid crystal panels, respectively, and these two reflective liquid crystal panels are used. The image light is divided into a plurality of gradations by a panel, and the modulated gradations of the image light are combined by the polarization beam splitter and projected on a screen by a projection lens. An image obtained by synthesizing the gradations of the image light by the reflective liquid crystal panels can be obtained.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a reflection type liquid crystal projector using a color wheel to which the present invention is applied will be described below with reference to FIGS.

First, the basic structure and operating principle of a two-panel reflective liquid crystal projector using two reflective liquid crystal panels will be described with reference to FIG.
1, R, G,
The three-color light B is emitted, and the three-color light enters the polarization beam splitter 25. Then, each S-polarized light in the three color lights is converted into a polarization splitting surface 25a of the polarization beam splitter 25.
And is incident on the first reflective liquid crystal panel 26 from the first direction, while the respective P-polarized light in the three-color light is transmitted through the polarization splitting surface 25a as it is to the second reflective liquid crystal panel 27. Light is incident from the second direction. Then, the incident light emitted from these two directions is phase-modulated into R, G, and B image lights by the first and second reflective liquid crystal panels 26 and 27, respectively, and reflected by the internal reflection layer. Then, these image lights are emitted from the same surfaces as the incident surfaces 26a and 27a of the first and second reflective liquid crystal panels 26 and 27, and are incident on the polarization beam splitter 25 again in two directions.

At this time, the image light phase-modulated and reflected by the first reflective liquid crystal panel 26 contains a P-polarized component, and passes through the polarization splitting surface 25 a of the polarization beam splitter 25 as it is. On the other hand, the image light that is phase-modulated and reflected by the second reflective liquid crystal panel 27 contains an S-polarized component, is reflected by the polarization splitting surface 25a of the polarization beam splitter 25, and
The light is combined with the P-polarized light component reflected by the first reflective liquid crystal panel 26 and transmitted through the polarization splitting surface 25 a of the polarization beam splitter 25. Then, the combined image light is emitted from the polarizing beam splitter 25 and is incident on the projection lens 28, and is projected on a screen such as a screen by the projection lens 28.

Here, the first and second reflective liquid crystal panels 2
The first and second reflection type liquid crystal panels 26 and 27 are switched by the switching means 29 from the entire image signal (input video signal) A, which is phase-modulated in synchronization with the incident light incident on the light receiving panels 6 and 27.
Are divided into two image signals (divided video signals) B and C to be applied independently. At this time, the gradation of the entire image signal A is set to n + m−1, and the gradation of the image signal B applied to the first reflective liquid crystal panel 26 is set to n.
And the image signal C applied to the second reflective liquid crystal panel 24
Is divided into m and the divided image signals B and C
Are synthesized and projected on the screen, the maximum gray scale of the screen in which the P-polarized light and the S-polarized light of the image light projected on the screen are synthesized is n + m−1.

That is, in the conventional single-panel reflective liquid crystal projector described with reference to FIGS. 11 and 12, the three-color light of R, G, and B split by the color wheel 14 and incident on the polarizing beam splitter 15 is used. Only one of the P-polarized light and the S-polarized light is phase-modulated into image light and is incident on the projection lens 17 so as to be projected on a screen such as a screen.
One of the S-polarized light or the P-polarized light in the three color lights of R, G, and B was discarded as unnecessary light, so the light use efficiency was low, the luminance was low, and the screen display was low in gradation, The intermediate gradation could not be displayed sufficiently. However, according to the two-panel reflective liquid crystal projector of the present invention described with reference to FIG. 1, the P-polarized light in the three colors of R, G, and B emitted from the light source means 21 and entered the polarization beam splitter 25. , And S-polarized light are phase-modulated into image light by the two reflective liquid crystal panels 26 and 27, respectively.
Since the polarized light is synthesized by the polarization beam splitter 22 and can be incident on the projection lens 25 and projected on a screen such as a screen, the light use efficiency of the P-polarized light and the S-polarized light is significantly increased, and the brightness is high. Since a multi-gradation screen can be displayed, a sufficient intermediate gradation can be displayed.

Next, the specific structure of a two-panel reflective liquid crystal projector using the color wheel of the present invention will be described with reference to FIGS. 2 to 5. First, as shown in FIG. The first and second reflective liquid crystal panels 26, which are two reflective liquid crystal panels in which a color wheel 24 is used as a light decomposing means (light dividing means) in 21 and a liquid crystal material is FLC, 27 are arranged at right angles to the two emission directions of the polarization beam splitter 25.

Then, the white light L11 emitted from the discharge lamp 22 of the light source means 21 is condensed by the first condenser lens 23A, and the spot light of the white light L11 is incident on the color wheel 24 which is rotating at high speed. The color wheel 24 separates (divides) the light into three color lights L12 of R, G, and B having different frequency bands with respect to time and emits the light. Then, the emitted three-color light L12 is condensed by the next condensing lens 23B, and is incident on the polarization beam splitter 25. Here, the polarization beam splitter 2
5, the R, G, B three-color light L12 is non-polarized light (or a partially modified light beam), and each S-polarized light in the three-color light L12 is a polarization splitting surface 25a of the polarization beam splitter 25. And is emitted from a first direction and enters the first reflective liquid crystal panel 26 from the first direction. Then, each P-polarized light in the three-color light L12 passes through the polarization splitting surface 25a of the polarization beam splitter 25 as it is, is emitted from the second direction, and enters the second reflective liquid crystal panel 27 from the second direction. Is done. Then, the S-polarized light incident on the first reflective liquid crystal panel 26 is rotated by the image signal applied to the first reflective liquid crystal panel 26 to become P-polarized light, and is reflected by the internal reflective layer. The incident surface 26 of the first reflective liquid crystal panel 26
a is emitted in the direction opposite to the incident direction. Further, the P-polarized light incident on the second reflective liquid crystal panel 27
The polarization is rotated by the image signal applied to the reflection type liquid crystal panel 27 to become s-polarized light, reflected by the internal reflection layer, and the incident surface 27 a of the second reflection type liquid crystal panel 27.
Is emitted in the direction opposite to the incident direction.

That is, the P-polarized light of the R, G, and B image light phase-modulated by the first reflective liquid crystal panel 26 and the R, G, and B of the R, G, and B phase modulated by the second reflective liquid crystal panel 27. The S-polarized light of the image light is again incident on the polarization beam splitter 25 from two directions. Then, the incident P-polarized light passes through the polarization splitting surface 25a as it is and is emitted to the projection lens 28, and the S-polarized light is reflected by the polarization splitting surface 25a and is emitted to the projection lens 28. The polarization splitting surface 25a of the splitter 25 is a combined surface of the P-polarized light and the S-polarized light, and the P-polarized light and the S-polarized light of the R, G, and B image lights are combined on the polarized light separating surface 25a and output to the projection lens 28. Will be done. Then, the projection lens 28 projects the R, G, and B image light L13 in which the P-polarized light and the S-polarized light are combined onto a screen such as a screen to display a full-color image.

Here, as described above, the switching means 29 converts the image signal (input video signal) A of n + m-1 gradation applied to the entire first and second reflective liquid crystal panels 26 and 27 into the first signal. The n-gradation image signal B applied to the reflective liquid crystal panel 26 and the m-gradation image signal C applied to the second reflective liquid crystal panel 27 are divided and produced.
By applying the gradation image signal B and the m gradation image signal C to the first and second reflective liquid crystal panels 26 and 27, respectively, they are projected and displayed on a screen such as a screen by a projection lens. Can be expressed to a maximum of n + m-1 tones. Therefore, the brightness is high,
In addition, a so-called multi-gradation screen having a large number of gradations can be displayed, and a high-quality screen capable of sufficiently displaying intermediate gradations can be obtained.

A description will now be given, with reference to FIG. 3, of the manner in which the image signals to be printed on the first and second reflective liquid crystal panels 26 and 27 are divided. The three color lights of R, G, and B separated (divided) into the first and second reflective liquid crystal panels 26 and 27. Therefore, the gradation of the unit image display time of the image signal which is a digital signal is divided into, for example, nine, and the first and second reflective liquid crystal panels 26,
27. At this time, the first and second reflective liquid crystal panels 26 and 27 using FLC as a liquid crystal material are ON and O of whether or not to perform 100% of the phase modulation operation.
The digital operation of the FF will be performed. By dividing the gradation of the unit image display time of the image signal of the first and second reflection type liquid crystal panels 26 and 27 into nine, the first and second reflection type liquid crystal panels 26 and 27 become 0 respectively. ~ 9
Can be displayed up to 10 gradations. By combining the gradations of the image light of the first and second reflective liquid crystal panels 26 and 27 with the polarizing beam splitter 25, 0 gradations can be displayed.
It is possible to display multiple gradations from 19 to 18 gradations.

In FIG. 3, the gradation of the unit image display time of the R, G, and B image light separated (divided) by the color wheel 24 is divided into, for example, six, and is divided into seven gradations from 0 to 6. , And the final gradation of the light output of the image light is R: 5/6, G: 4/6, B:
It is 1/6.

Next, referring to FIG. 4, an image signal to be applied to the entire first and second reflective liquid crystal panels 26 and 27 is applied to the first liquid crystal panel 26, 27.
Reflective liquid crystal panel 26 and second reflective liquid crystal panel 27
First, as shown in the block diagram of FIG. 4, the entire image signal input from the image signal input circuit 31 to the A / D converter 32 will be described. The image is digitally converted into an entire image gradation sin, and is divided by the distributor 33 into two gradations Sa and Sb. Then, these two gradations Sa and Sb are applied to the first and second reflective liquid crystal panels 26 and 27 by drive circuits 34 and 35, respectively, are synthesized by the polarization beam splitter 25, and are projected by the projection lens 28 to a screen or the like. It is configured to be projected on the screen.

Here, Grayscale an in FIG.
As shown in d ON time duration,
Each gradation S when the entire gradation sin is set to 0 to 8 gradations
As a dividing operation of a and Sb, for example, when sin = 0, S
a = 0, Sb = 0 (Alloff), Sa = 0 and Sb = 1 when sin = 1, Sa = 1 when sin = 2,
Sb = 1 (Botbl), and when sin = 3, Sa =
1, Sb = 1 + 2, and sin = 4, Sa = 2, Sb
= 2 (Both2), and when sin = 5, Sa = 2, S
b = 1 + 2, and when sin = 6, Sa = 1 + 2 and Sb =
1 + 2, when sin = 7, Sa = 1 + 2, Sb = 4, and when sin = 8, Sa = 4, Sb = 4.

FIG. 5 shows an algorithm (algorism) for distributing an image signal (video signal). In the input image signal (input video signal), a gradation which is a signal level of a signal of a certain pixel is shown. Is sin, and when sin is an odd number, Sa = (sin−1) /
2, Sb = (sin-1) / 2 + 1 holds, and when sin is an even number, Sa = sin / 2 and Sb = sin / 2 hold. Then, the odd and even gradations Sa, Sb
Is an image signal (video signal) of a pixel to be applied to the two reflective liquid crystal panels 26 and 27, so that the divided gray scale Sa corresponding to each of the gray levels of 0 to 8 shown in FIG. , Sb from 0 to 4 can be obtained.

FIG. 6 shows a modification, in which WF, which is a white filter, is added to the color filters of the color wheel 24, and the color filters of the color wheel 24 are RF (red filter), GF ( Green filter), B
By dividing into F (blue filter) and WF (white filter), the brightness of the projected screen can be further improved.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and various modifications can be made based on the technical concept of the present invention.

[0041]

The projector device of the present invention configured as described above has the following effects. That is, the light emitted in two directions from the polarizing beam splitter is incident on two reflective liquid crystal panels, respectively, and is modulated into image light divided into a plurality of gradations by the two reflective liquid crystal panels. Then, the modulated image light gradation is synthesized by the polarizing beam splitter and projected onto the screen by the projection lens, so that the screen obtained by synthesizing the image light gradation by the two reflective liquid crystal panels is formed. So that you can get
Compared with a conventional three-plate type projector device, a small-sized, light-weight, inexpensive yet high-brightness full-color projector device can be realized. Also,
N + m− applied to the entire first and second reflective liquid crystal panels
By generating image signals of n and m gradations from an image signal of one gradation and applying these image signals of n and m gradations to the first and second reflective liquid crystal panels, a maximum of n + m Since a multi-tone image of -1 can be displayed, a high-quality screen capable of sufficiently displaying intermediate tones can be obtained. When a ferroelectric liquid crystal is used as the liquid crystal material,
High-speed modulation is possible, and it is possible to prevent flickering of the screen while sufficiently displaying the intermediate gradation. In particular, by combining with a color wheel, a full-color projector device can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating the basic configuration and operation principle of a two-panel reflective liquid crystal projector device to which the present invention is applied.

FIG. 2 is a schematic diagram illustrating a specific configuration of a two-panel reflective liquid crystal projector using a color wheel to which the present invention is applied.

FIG. 3 is a diagram illustrating the operation of the color wheel and the FLC liquid crystal panel of the reflection type liquid crystal projector of the present invention.

FIG. 4 is a block diagram illustrating a switching unit (circuit) for generating a gradation of an image signal applied to two reflective liquid crystal panels in FIG. 3 and a drawing illustrating a combination of the gradation.

FIG. 5 is an algorithm for explaining a method of distributing gradations of image signals applied to the two reflective liquid crystal panels of FIG. 5;

FIG. 6 shows R, G, and R which are modifications of the color wheel used in the two-panel reflective liquid crystal projector of the present invention.
It is the drawing which showed the B and W four-part color wheel.

FIG. 7 is a schematic diagram illustrating a configuration of a general projector device using a spatial light modulator.

FIG. 8 is a diagram illustrating a transmission type liquid crystal panel.

FIG. 9 is a diagram illustrating a reflective liquid crystal panel.

FIG. 10 is a drawing showing three color wheels of R, G and B.

FIG. 11 is a schematic diagram illustrating an example of a conventional single-panel reflective liquid crystal projector device.

FIG. 12 is a schematic diagram illustrating another example of a conventional single-panel reflective liquid crystal projector device.

FIG. 13 is a diagram illustrating characteristics of a reflective liquid crystal panel using TN as a liquid crystal material.

FIG. 14 is a diagram illustrating characteristics of a reflective liquid crystal panel using FLC as a liquid crystal material.

FIG. 15 is a diagram illustrating the operation of a color wheel and an FLC liquid crystal panel of a conventional single-panel reflective liquid crystal projector device.

FIG. 16 is a diagram illustrating a state in which light is incident on a boundary of a color filter of a color wheel.

[Explanation of symbols]

21 is a light source, 22 is a discharge lamp, 23A and 23B are condenser lenses, 24 is a color wheel as a photo-decomposing means, R
F, GF, BF, WF are color filters of the color wheel,
25 is a polarization beam splitter, 25a is a polarization separation surface, 2
6 is a first reflective liquid crystal panel, 27 is a second reflective liquid crystal panel, 26a and 27a are incident surfaces, 28 is a projection lens,
29 is a switching means.

Continued on the front page F term (reference) 2H088 EA14 EA15 EA16 HA06 HA12 HA20 HA24 JA05 MA06 MA13 MA16 2H091 FA10X FA26X FA41X FD26 GA11 HA07 LA15 LA16 LA30 MA07

Claims (8)

[Claims] 1. A light source means, a polarizing beam splitter which polarizes light emitted from the light source means and emits the light in two directions, and a reflection layer is formed inside the light source means. The emitted light is modulated into image light divided into a plurality of gradations by an applied image signal, reflected by the reflection layer, and incident on the polarizing beam splitter from two directions. First and second two reflective liquid crystal panels that combine the gradations of image light from different directions with the polarizing beam splitter, and display image light from the two directions combined with the gradations by the polarizing beam splitter on the screen. A projector device, comprising: a projection lens for projecting upward. 2. The maximum gradation number of an image signal applied to the entire first and second reflection type liquid crystal panels is A, and the maximum gradation number of an image signal divided and applied to the first reflection type liquid crystal panel. 2. The projector according to claim 1, wherein A ≦ B + C−1, where B is a number, and C is a maximum number of gradations of an image signal to be applied to the second reflective liquid crystal panel by dividing the number. apparatus. 3. The projector device according to claim 1, wherein said light source means includes means for generating light having a temporally different wavelength band. 4. The projector device according to claim 2, further comprising means for controlling the gradation of said first and second reflective liquid crystal panels in a time-division manner. 5. The projector according to claim 2, wherein said first and second reflective liquid crystal panels are made of a ferroelectric liquid crystal material. 6. The projector apparatus according to claim 3, wherein said light source means includes means for generating red light, green light, and blue light having different wavelength bands in time. 7. The projector apparatus according to claim 3, wherein said light source means includes means for generating red light, green light, blue light, and white light having different wavelength bands in time. 8. The light source means comprises a discharge lamp, and a color wheel for selecting incident light from the discharge lamp into light having a temporally different wavelength band and emitting the light. The projector device according to claim 3 or claim 6.