JPH0895515A - Projector device - Google Patents

Abstract

(57) [Abstract] [Purpose] A projector device capable of displaying a color image using a spatial light modulator can easily be made compact and lightweight, and simplifies the adjustment work by eliminating the need for registration adjustment and the like. Plan. [Structure] According to the writing light by the image light of the CRT 1,
In the projector device configured to output the light supplied from the light source 6 as the reading light by the spatial light modulator 40 and project the display image formed based on the reading light, the surface to be supplied to the CRT 1 A liquid crystal shutter 20 is provided in the path of the light emitted from the light source 6 so that the R, G, and B colors of the transmitted light are selected according to the timing of the field frequency of the sequential video signal. As a result, a color image can be displayed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projector device, and more particularly to a projection type projector constructed by using a spatial light modulator.

[0002]

2. Description of the Related Art As a projection type projector device, a system using a CRT as an image receiving device and a system using an LCD (liquid crystal display) are known.
Due to the characteristics of CDs, it is difficult to achieve both high brightness and high resolution in any of the systems while meeting the demand for a large screen. Therefore, as a projector device that can obtain both the high brightness and the high resolution, a projector device including a spatial light modulator has been developed.

FIG. 5 is a cross-sectional view showing an example of the structure of the spatial light modulation element. In the spatial light modulation element 40 of this figure, 41 is enclosed inside, and the read light is modulated according to the applied voltage. Indicates a liquid crystal. Reference numeral 42 denotes a dielectric mirror, which reflects almost 100% of the light from the light source that has passed through the liquid crystal 41 as shown by the arrow in the figure, and emits it as read light. Reference numeral 43 denotes a light-shielding film, which is provided to prevent the reading light from affecting the high-sensitivity photoconductive layer 44 and to obtain output light with higher power. Reference numeral 44 denotes a photoconductive layer made of, for example, amorphous silicon, which performs photoelectric conversion in response to weak writing light incident from the direction shown by the arrow in the figure. This conversion action causes a gap between both ends of the liquid crystal 41. Control the voltage. Further, 45 and 46 provided so as to sandwich the liquid crystal 41, the dielectric mirror 42, the light shielding film 43, and the photoconductive layer 44 are transparent electrodes, and an AC bias 49 is applied to these transparent electrodes 45 and 46 as shown in the figure.
Is applied. And 47 and 48 are glass substrates,
The glass substrate 47 for the layer formed as described above,
The spatial light modulation element 40 is configured by providing 48 so as to sandwich this. The spatial light modulator 4
No processing such as fine processing for pixel division is performed on 0.

The spatial light modulator 40 having such a structure is
Writing light enters from the left side of the figure through the glass substrate 47 and the transparent electrode 45. Then, impedance change occurs due to photoelectric conversion of the photoconductive layer 44 according to the write light amount, and thereby the voltage across the liquid crystal 41 is controlled. The light from the light source, which is incident from the right side through the glass substrate 48, passes through the liquid crystal 41, is reflected by the dielectric mirror 42, and is emitted again as read light. As it passes through, it is optically modulated, that is, polarized. In such a spatial light modulator, the interference between the writing light and the reading light is eliminated by the dielectric mirror 42, whereby the writing light and the reading light can be treated as independent from each other.

In a projector device, an image is displayed by using such a spatial light modulator as an image amplifier. Therefore, the operation principle of the spatial light modulator when the spatial light modulator is applied as an image amplifier will be described with reference to FIG.

In this figure, reference numeral 40 is the spatial light modulator shown in FIG. Further, 3 provided on the reading system side of the spatial light modulator 40 is a polarization beam splitter (P
BS) and separates the natural light from the light source 6 into a p-wave and an s-wave in a polarization direction orthogonal to the p-wave. Further, in this case, only the s wave is reflected at the interface of the polarization beam splitter 3,
The waves are designed to go straight. A light source 6 emits natural light that is not polarized in the polarization direction.

Natural light incident on the polarization beam splitter 3 from the light source 6 is separated into p-wave and s-wave, and the p-wave travels straight as shown in the figure, but the s-wave is reflected at the interface and is a spatial light modulator. 40 incidents. The s wave is reflected by the dielectric mirror 42 via the liquid crystal 41 and returns again via the liquid crystal 41, and this light is used as the reading light.

Here, when there is no writing light to the spatial light modulator 40, the voltage across the liquid crystal 41 becomes a certain threshold value or less, and in this state, the long axis of the liquid crystal molecules and the passing optical axis are aligned. No birefringence effect occurs. by this,
The incident s-wave light passes through the liquid crystal 41 and the dielectric mirror 42.
The light is reflected by and is again obtained as the read light through the liquid crystal 41 as it is with the s wave. The s-wave read light is reflected by the interface of the polarization beam splitter 3 and returns to the light source. That is, if there is no writing light, the detection light that the reading light goes straight through the polarization beam splitter 3 cannot be obtained.

Further, when writing light is applied to the spatial light modulator 40, a voltage is generated across the liquid crystal 41, and in this state, the alignment of the liquid crystal molecules is twisted, and the long axis and the passing optical axis thereof are generated. The double refraction effect occurs because the two intersect. At this time, the polarization form determines the degree of modulation depending on the level of the writing light, but in the case of maximum modulation, the incident s-wave travels through the route of liquid crystal 41 → reflection by dielectric mirror 42 → liquid crystal 41. It is modulated by 90 ° and polarized by 90 °,
The light is output as p-wave reading light. Therefore, when such read-out light of the p-wave component is incident on the polarization beam splitter, it goes straight on and is emitted as detection light.

In this way, the spatial light modulator 40 operates as a light amplifier, but as described above, the photoconductive layer 4 is used.
4 also reacts to weak writing light, and the dielectric mirror 42 reflects light at almost 100%, so that its heat absorption is extremely small. Therefore, it is possible to use a high-intensity lamp as a light source, and thereby a very high optical amplification factor, that is, high brightness can be obtained. Further, each layer of the spatial light modulator 40 is very thin and suppresses the occurrence of light diffusion, and since it is not subjected to pixel division processing, high resolution can be obtained.

FIG. 7 is a conceptual diagram showing the basic construction of a projector device using the spatial light modulation element 40 as a light amplification element. The same parts already shown in FIG. To do. In this case, the CRT 1 is used as a device that outputs the writing image light.
When a CRT is used at low brightness, for example, the beam diameter becomes small and a high resolution can be obtained. In addition, a CRT has an emission wavelength corresponding to the photosensitivity of the photoconductive layer required for writing image light, variable scan compatibility, and high stability. Since it can be obtained, it is suitable as a writing device. As the light source 6, a light source with high brightness such as a xenon lamp is used. Further, 2 is a writing lens provided between the CRT 1 and the spatial light modulator 40, 4 is a projection lens which magnifies the detection light from the polarization beam splitter 3 and projects it on the screen 5, and 7 is emitted from the light source 6. It is a condenser lens that condenses the generated light.

In this case, an image is displayed on the display screen by the video signal input from the CRT 1, and this display image is written as writing light into the spatial light modulator 40 through the writing lens 2. Then, in the reading system, one of the lights which is incident on the polarization beam splitter 3 from the light source 6 through the condenser lens 7 and is separated by the polarization direction as described with reference to FIG. It is incident on 40. The light incident on the spatial light modulator 40 reciprocates through the liquid crystal 41 while being reflected by the dielectric mirror 42 and emitted as read light as described above, and at this time, is modulated in the liquid crystal 41 according to the write light amount. Is output. That is, the image light of the CRT 1 is amplified on the read side of the spatial light modulator 40 and is output as read light. The read light is magnified through the projection lens 4 and projected on the screen 5. In this way, the image of the video signal input to the CRT 1 is displayed on the screen 5 with high brightness and high resolution. become.

When a color image is displayed by the system using the spatial light modulator 40 as an optical amplifier, the projector device has a structure as shown in the external view of FIG. 8, for example. The same components as those in FIG. 6 are designated by the same reference numerals. As can be seen from this figure, three sets of the CRT 1, the writing lens 2, the spatial light modulator 40, the polarization beam splitter 3, and the projection lens 4 are provided for each of the R, G, and B optical systems. In this case, all three CRTs 1 are black and white type using the same phosphor. In this case, cold mirrors M ₁ , M ₂ and M ₃ are provided to form the path of the white light emitted from the light source 6, and a dichroic filter (DF (B) for B reflection and DF for R reflection in this case) is formed.
(Denoted as (R)), R, G, and B are provided to the respective polarization beam splitters 3 corresponding to the colors R, G, and B, respectively.
Light of the separated color is made incident on G and B,
Therefore, the read light from each spatial light modulator 40 is R,
Light of each color of G and B is obtained respectively. Note that C _IR indicates a circuit section.

In this structure, the three CRTs 1 are supplied with the video signals corresponding to the respective colors of R, G and B, and the spatial light modulators 40 are displayed by the images displayed by these video signals.
Are written to. Then, R, G, B obtained in each R, G, B system by this writing light
The read-out lights of the colors of R and R are respectively transmitted through the projection lens 4.
The G and B color images are simultaneously projected on the screen 5. Then, a color image is obtained by combining the images of these three colors on the screen.

[0015]

However, as shown in FIG. 8, when a projector apparatus capable of displaying a color image is constructed by using the spatial light modulation element 40 as an optical amplifier element, the writing system of the CRT 1 and the writing lens 2 is formed. The spatial light modulator 40 which is an optical amplifier, the polarization beam splitter 3, and the reading system of the projection lens 4 are required to have three systems corresponding to the respective colors of R, G, and B. As a result, the number of parts that make up the device increases, and there is a problem in that the size and weight of the entire device cannot be avoided. Also, it is disadvantageous in terms of cost. Furthermore, in the system having the configuration shown in FIG. 8, R,
Since the G and B color images are combined to obtain one color image, it is necessary to adjust the registration, and it is preferable to reduce such adjustment items as much as possible.

[0016]

Therefore, the present invention configures a projector device capable of displaying a color image with a writing system, a spatial light modulator, and a reading system of one system, thereby reducing the size and weight of the device. It is an object of the present invention to realize easily and to simplify the adjustment work by eliminating the need for registration adjustment and the like.

Therefore, a spatial light modulator is provided which is capable of emitting image light from the image receiving device as writing light and emitting read light obtained by modulating the light supplied from the light source in accordance with the writing light. In a projector device capable of projecting a display image formed on the basis of light, the R, G, and B of transmitted light can be determined based on the timing of the field frequency of a video signal of a frame sequential type supplied to an image receiving device. By providing a liquid crystal shutter for color selection with respect to the path of the light emitted from the light source, a color image can be displayed. The drive signal for driving the liquid crystal shutters is an alternate signal whose polarity changes at a frequency that is ½ of the field frequency of the video signal, and at the same time, between field screens of the same color for each field and each frame period, The pattern is formed so that the polarity of the signal turned on is reversed. A CRT is used as the image receiving device. The spatial light modulator includes a liquid crystal in which a predetermined alignment direction is set, a photoconductive layer that varies the voltage across the liquid crystal according to the amount of writing light that is incident, and a light source that is incident on the liquid crystal. It is decided to use an element configured as a device having a mirror layer that reflects light and emits it as read-out light again through the liquid crystal. Further, the liquid crystal shutter is provided with a color filter having a polarization direction capable of transmitting a specific color among the three primary colors of RGB, and a predetermined alignment direction to which a drive signal is applied. It was decided to use one configured by combining with a liquid crystal cell to be applied.

[0018]

According to the projector apparatus having the above-mentioned structure, the display image of the CRT or the like of the frame sequential type is used as the writing light, and the color of the reading light is selected by the liquid crystal shutter at the timing corresponding to the field cycle of the display image. Therefore, it is possible to display a color image with one writing system, spatial light modulator, and reading system.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the projector apparatus of the present invention will be described below. By the way, in the projector apparatus of the present embodiment, a liquid crystal shutter (hereinafter referred to as LCS) for color selection of the read light of the spatial light modulator is described later.
Will be also referred to as)). First, an outline of the liquid crystal shutter will be described. Since a direct-view type display device using such a liquid crystal shutter is known (US Pat. No. 4,635,051),
The liquid crystal shutter will be described by taking such a display device as an example.

FIG. 2 schematically shows a structural example of a display device (direct view type) having the above-mentioned liquid crystal shutter.
In this figure, 1 indicates a CRT, in which case R,
A video signal of a field-sequential type (field-sequential type) in which the screen for each of G and B is one field is supplied. A liquid crystal shutter 20 is provided on the front surface of the display surface of the CRT 1. Here, the liquid crystal shutter is disassembled and shown by the constituent parts as shown in the drawing. In this liquid crystal shutter 20,
Reference numerals 21, 22, and 23 denote color filters, respectively. Further, in the color filter 21, the horizontal polarization axis 21a is set to the three primary colors C ₁ , C ₂ , C ₃ (actually R, G, B
Of color C ₃ of either to become corresponding that respectively)
The state where only the light of ( ₃ ) is transmitted is obtained, and the state where the three primary colors C ₁ , C ₂ , and C ₃ (that is, white light) is transmitted through the vertical polarization axis 21b is obtained. Further, in the color filter 22, the horizontal polarization axis 22a is set to a state in which the three primary colors C ₁ , C ₂ and C ₃ are transmitted, and the vertical polarization axis 22b is set to be in a state in which only the color C ₂ is transmitted. ing. Further, the color filter 23
In the horizontal polarization axis 23a, the three primary colors C ₁ , C ₂ , C
_The vertical polarization axis 23b is set so that only the color C ₁ is transmitted.

Reference numeral 24 provided between the color filters 21 and 22 and reference numeral 25 provided between the color filters 22 and 23 denote liquid crystal cells. For example, in this case, the liquid crystal cells 24 and 25 each use the birefringence of the nematic liquid crystal to give a delay of 0 or a half wavelength to a specific wavelength, so that the liquid crystal cells are driven in advance when they are turned off. Only one of the selected three primary colors C ₁ , C ₂ and C ₃ is polarized by 90 °, while the light is incident when it is turned on. The light is transmitted as it is. Therefore, by changing the combination of the on / off states of the liquid crystal cells 24 and 25, the liquid crystal shutter 20 selects and transmits only one of the three primary colors C ₁ , C ₂ and C _3. It is possible to switch to. In addition,
For convenience of description, the liquid crystal cells 24 and 25 are the A cell and the liquid crystal 25, respectively, as shown in parentheses.
Will also be referred to as B cell.

Reference numeral 31 denotes a control circuit capable of performing control so that color selection of the liquid crystal shutter 20 is performed at a predetermined timing based on at least the input field synchronization signal. Reference numeral 32 denotes control of the control circuit 31. Due to
The LCS drive circuit generates a drive signal for performing on / off control of the liquid crystal cells 24 and 25. The structure of the liquid crystal shutter 20 shown in this figure is an example, and the structure is not limited to this as long as the color selection is performed based on the drive signal from the control circuit side. .

In the display device having the above-described structure, for example, as shown in FIG. 3, the liquid crystal shutter 20 transmits R light when the A cell (liquid crystal cell 24) is on and the B cell (liquid crystal cell 25) is off. It is assumed that the G light is transmitted when the A cell is off and the B cell is on, and the B light is transmitted when both the A cell and the B cell are on. Then, the operation for actually displaying a color image by the frame sequential method using the liquid crystal shutter 20 is performed as described below.

Here, the video signal supplied to the CRT 1 consists of 3 fields per frame, and each field period is formed by the luminance signal of the field image corresponding to G, B, and R in this order. Therefore, on the CRT 1, field images corresponding to the respective colors are displayed in the order of G, B, and R within one frame period. Therefore, in the first field period within one frame period, the control circuit 31 outputs the drive signal for turning off the A cell and turning on the B cell in the liquid crystal shutter 20 so that the light of G color is transmitted. LC
The S drive circuit 32 is controlled. As a result, the field image actually represented by the color G is obtained. Then, in the next field period, the drive signal is A cell
By performing switching control so that both B cells are turned on,
In this field period, the field image of B color is displayed. Further, by switching the A cell to be on and the B cell to be off in the last field period within one frame period, a field image of R color is displayed. The drive signal applied to the A cell and the B cell is an alternate signal (AC) having a predetermined frequency. This is because, as is well known, the liquid crystal has a property of deteriorating when a direct current is continuously applied.

As described above, the drive signal applied to the A cell and the B cell is switched on / off for each field period within one frame period to select the color of light transmitted through the liquid crystal shutter 20. There is. As a result, in the case of the present embodiment, one frame is formed by the three field screens displayed in the order of G, B, and R, and these field screens are visually combined by the afterimage phenomenon. A color image for one sheet is represented. Then, the operation of the liquid crystal shutter 20 as described above is repeated every frame period,
A full-color frame screen including G, B, and R field screens that are sequentially displayed is sequentially obtained, and a moving image can be expressed.

Then, a projector device of this embodiment which is equipped with the liquid crystal shutter 20 and is capable of displaying a color image will be described with reference to the conceptual diagram of FIG. In this figure, the same components as those in FIG. 7 showing the projector device as the conventional example and FIG. 2 showing the liquid crystal shutter 20 are designated by the same reference numerals and the description thereof will be omitted. In this embodiment, as can be seen from this figure, C
Each of the RT1, the writing lens 2, the spatial light modulator 40, the polarization beam splitter 3, and the projection lens 4 constitutes one set. That is, the projector device is configured by the writing system, the optical amplifier (spatial light modulator 40), and the reading system of one system. The liquid crystal shutter 20 is provided for the light path of the reading system of the spatial light modulator 40 as shown in the figure. That is, in this case, it is provided so as to be interposed between the condenser lens 7 and the polarization beam splitter 3. Thereby, the light from the light source 6 is emitted from the liquid crystal shutter 2
Since only R, G, or B colors are selectively transmitted by 0 and then are incident on the polarization beam splitter 3, the spatial light modulator 40 to be the optical path of the subsequent readout system.
The read-out light from and the detection light traveling straight through the polarization beam splitter 3 are also lights of the color selected by the liquid crystal shutter 20.

Then, the projector device having the above-described configuration displays a color image by the operation described below. Also in the present embodiment, the liquid crystal shutter 20 has R, G, B according to the ON / OFF pattern of the drive signal shown in FIG.
It shall be possible to obtain a state in which each color of light can be transmitted. Further, it is assumed that the CRT 1 displays field images corresponding to the order of G, B, and R for each of the three field periods forming one frame by the supplied field sequential video signal (luminance signal).

For example, in the first field period within one frame period, a field image corresponding to G is displayed on the display screen of the CRT 1, and this is used as writing light and is incident on the spatial light modulator 40 via the writing lens 2. ing.
At this time, the control circuit 31 controls the LCS drive circuit 32 to turn off the A cell in the liquid crystal shutter 20,
A drive signal for turning on the cell is output. As a result, the light passing through the liquid crystal shutter 20 from the light source 6 becomes G
Therefore, only the color of P is transmitted and is incident on the polarization beam splitter 3. This G component light is modulated as read light by the spatial light modulator 40, and then is transmitted from the PSB 3 to the projection lens 4 as detection light. It is incident and projected on the screen 5. Therefore, in this field period, the field image of G color is actually displayed on the screen 5.

In the next field period, B is set by CRT1.
The image light corresponding to is written in the spatial light modulator 40.
Then, at this time, the LDS drive circuit 32 is controlled so as to apply drive signals for both the A cell and the B cell to be ON, so that the liquid crystal shutter 20 is in a state of transmitting only the color of B, and the light source 6 For light, only the B color component is transmitted and PS
It will be incident on B3. As a result, screen 5
A field image of color B is displayed on the top. Then, in the last field period within one frame period, the drive signal is switched and controlled so that the A cell is turned on and the B cell is turned off, so that the liquid crystal shutter 20 can pass only the R color. As a result, R is displayed on the screen 5.
The field image of the color of is displayed.

As described above, in the present embodiment, field images are displayed on the screen 5 in the order of G → B → R color screens within one frame period. However, these field images are visually observed due to the afterimage phenomenon. A full-color image is represented by being combined. That is, in the present embodiment, when a projector capable of displaying a color image is provided with the spatial light modulator 40, this is realized by only one system of spatial light modulators and a writing system and a reading system for the spatial light modulators. Further, as a result, there is only one system for projecting an image on the screen, so G, B, R
The display positions of the respective field images are always coincident with each other on the screen 5, and it is not necessary to perform registration adjustment or the like.

By the way, the drive signal for driving the liquid crystal shutter 20 is the alternate signal as described above, and the alternate frequency is, for example, CRT1.
Is set to the main deflection frequency (line scanning frequency) of the video signal supplied to. For example, normally using a liquid crystal display or the like, NTSC, PAL, SE
In the case of displaying a television system such as CAM, if the drive signal is alternated at the frequency of the main deflection, images in which the rising and falling patterns of the liquid crystal are inverted are alternately displayed, which causes an image. The fringes can be offset to reduce flicker. Even when an image is displayed by the frame-sequential method, the alternate signal at the main deflection frequency is used as a drive signal by applying this. However, if an alternate signal with a high frequency such as the main deflection frequency is used, the power consumption required for driving the liquid crystal increases, and for example, the LCS drive circuit 32 that generates and outputs the alternate signal will be burdened. Further, if the frequency of the alternate signal is appropriately set low considering only the reduction of power consumption, flicker becomes conspicuous because it is not synchronized with the image display timing.

Therefore, in this embodiment, for example, FIG.
The liquid crystal shutter 20 is driven by the drive signal with the timing as shown in FIG. This figure shows a field screen displayed for each of G, B, and R in this embodiment,
9 is a timing chart showing the output timing of the drive signal (the backplane is GND) applied from the LCS drive circuit 32 to the A cell and the B cell corresponding to this. By the way, actually, two electrodes are provided in the liquid crystal cell. Here, the common electrode on one side is referred to as a back plane, and the electrodes on the other non-common poles are respectively defined. According to the name of each cell, they are simply referred to as A cell and B cell. Also,
The liquid crystal shutter 20 here will be described as being configured so that color selection of transmitted light is performed by a combination of ON / OFF states of drive signals for the A cell and the B cell shown in FIG.

FIG. 4A shows a field screen of a color to be displayed for each field. As described above, one field is formed by three field screens which are successively displayed in the order of G, B and R. It is supposed to represent the full-color image of the frame. 1A and 1B show timings of drive signals applied to the A cell and the B cell, respectively. As can be seen from this figure, in this embodiment, A
The polarities of the drive signals applied to the cells and the B cells are changed in each field period according to a predetermined pattern. In other words, the alternate signal has a predetermined pattern with a frequency that is ½ of the field frequency.
For example, the application timing of the drive signal to the A cell shown in FIG. 4B is from the field period corresponding to R before the time point t ₁ to the field period corresponding to B after the time point t ₅ .
R: on (negative electrode) → G: off → B: on (negative electrode) → for each field period in a period of 6 fields
R: ON (positive electrode) → G: OFF (negative electrode) → B: ON (positive electrode). Further, the drive signal to the B cell shown in FIG. 4C is R for each field period in a period ranging from the field corresponding to R before t ₁ time to the field corresponding to B after t ₅ time. : Off →
G: ON (positive electrode) → B: OFF → R: OFF → G: ON (negative electrode) → B: ON (positive electrode). That is, the drive signals to the A cell and the B cell have different patterns of change, but have different polarities in each field period from positive electrode on, negative electrode on or off (0 level) different from the previous field. Is considered to be an alternate signal that changes. As described above, the drive signal to be applied to the A cell and the B cell is an alternate signal having a frequency of 1/2 of the field frequency, so that the power consumption required for driving the liquid crystal is higher than that when the alternate signal is the main deflection frequency. Will also be reduced.

Further, FIG. 4B is shown for each field period.
On / off of cell A and cell B respectively shown in (c)
Looking at the combination of OFF, the A cell is turned off and the B cell is turned on in the field corresponding to G, both the A cell and the B cell are turned on in the field corresponding to B, and the A cell is turned on in the field corresponding to R. , B cells are turned off so as to match the combinations for selecting the color of the transmitted light of the liquid crystal shutter 20 shown in FIG.

Regarding the drive voltage of such a pattern, looking at the signal turned on for each field period, in the present embodiment, the polarity is sequentially inverted for each successive field. I understand.
For example, in the field period corresponding to R before the time point t _{1, the} negative polarity of the A cell is turned on, while the following t ₁ to
In the field period corresponding to G in the t ₂ period, the drive signal of the B cell which is turned on is inverted to the positive polarity. Further, in contrast, in the field period corresponding to B in the next t ₂ to t ₃ , both the A cell and the B cell are turned on, but their polarities are both inverted to the negative polarity. By thus inverting the polarity of the ON drive signal for each field, the rise / fall of the liquid crystal in the liquid crystal cell is inverted for each field period, so that the bright and dark are canceled and the flicker is not noticeable. Will be done. Further, in the field period corresponding to R in the subsequent t _{3 to} t _4, the drive signal of the A cell that has been turned on is further inverted and becomes positive, and together with this, the drive signal for the t _{3 to} t ₄ period is turned on. When the drive signal of 1 is compared with the drive signal of ON in the field period corresponding to R before the time point t ₁ that is within the frame period immediately before, the polarities thereof are opposite to each other. That is, when the ON drive signal in the field period corresponding to the same color for each frame is viewed, the polarity is sequentially inverted for each frame. For this reason,
The rise / fall of the liquid crystal is also inverted between the fields of the same color for each frame, which also cancels the bright and dark for each field of the same color and makes the flicker inconspicuous.

The pattern of the alternate signal given to the A cell and the B cell as described above is the polarity of the drive signal which is alternately turned on for each field, in contrast to the field sequential system in which one frame is formed by three odd fields. Is obtained because the pattern is formed so as to be inverted. Therefore, the drive signal applied to the A cell and the B cell forms one alternate pattern in 6 fields corresponding to 2 frames.

The configuration described as the above embodiment can be modified within the scope of the gist of the present invention.
The correspondence between the on / off combination of the liquid crystal cells and the color of the transmitted light as shown in FIG. 3 is an example, and the liquid crystal shutter may be configured so that the combination is actually changed according to various conditions. Absent.

[0038]

As described above, the projector device using the spatial light modulator of the present invention as an optical amplifier corresponds to the field cycle of the display image by using the display image of the CRT of the frame sequential type as the writing light. By selecting the R, G, and B colors of the read light by the liquid crystal shutter at the timing of performing, it is possible to display a color image by the writing system, the spatial light modulator, and the reading system of one system. . As a result, it is possible to easily reduce the size and weight of the apparatus and further reduce the cost, and since registration adjustment and the like are not necessary, it is possible to simplify the adjustment work. Have an effect.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a configuration of a projector device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a liquid crystal shutter in the present embodiment.

FIG. 3 is a diagram showing correspondence between on / off combinations of liquid crystal cells and transmitted light of a liquid crystal shutter in the present embodiment.

FIG. 4 is a timing chart showing a drive signal applied to a liquid crystal cell in the present embodiment.

FIG. 5 is a cross-sectional view showing the structure of the spatial light modulator.

FIG. 6 is an explanatory diagram showing an operation of the spatial light modulator as an optical amplifier.

FIG. 7 is a conceptual diagram showing a configuration of a projector device as a conventional example.

FIG. 8 is an external view showing a projector device capable of displaying a color image as a conventional example.

[Explanation of symbols]

 1 CRT 2 Writing Lens 3 Polarizing Beam Splitter 4 Projection Lens 5 Screen 6 Light Source 7 Condensing Lens 20 Liquid Crystal Shutters 21, 22, 23 Color Filter 24 Liquid Crystal Cell (A Cell) 25 Liquid Crystal Cell (B Cell) 31 Control Circuit 32 LCS Drive Circuit 40 Spatial light modulator

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G09G 5/02 Z 9377-5H H04N 5/74 K 9/31 C

Claims (5)

[Claims] 1. The reading light is provided with a spatial light modulator that is capable of emitting reading light in which image light of an image receiving device is incident as writing light and light supplied from a light source is modulated according to the writing light. In a projector device capable of projecting a display image formed on the basis of R, G, and B of transmitted light, based on the timing of the field frequency of the video signal of the frame sequential type supplied to the image receiving device. A projector device characterized in that a color image can be displayed by providing a liquid crystal shutter unit for color selection with respect to a path of light emitted from the light source. 2. A drive signal for driving the liquid crystal shutter means is an alternate signal whose polarity changes at a frequency which is ½ of the field frequency of the video signal, and also for each field and each frame period. The projector device according to claim 1, wherein a pattern is formed so that the polarities of signals that are turned on are reversed between field screens of the same color. 3. The projector device according to claim 1, wherein a CRT is used as the image receiving device. 4. The spatial light modulator includes a liquid crystal having a predetermined alignment direction, a photoconductive layer for varying a voltage across the liquid crystal according to an incident write light amount, and a liquid crystal with respect to the liquid crystal. 4. A mirror layer configured to reflect light of a light source that has been made incident and to emit it as read-out light again through the liquid crystal, and is configured as an element, claim 1 or claim 2 or claim 3. The projector device according to. 5. The liquid crystal shutter means applies a drive signal with a color filter having a polarization direction capable of transmitting a specific color of the three primary colors of RGB and a predetermined alignment direction set. 5. The projector device according to claim 1, wherein the projector device is configured by being combined with a liquid crystal cell that is formed.