JP2816060B2 - Reflective LCD projector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a light guide whose impedance changes with writing light and a twisted nematic liquid crystal whose twist structure changes due to a change in the impedance of the light guide to change the polarization state of read light. The present invention relates to a reflective liquid crystal projector that includes a reflective liquid crystal and displays information of writing light by reading light.

[0002]

2. Description of the Related Art As shown in FIGS. 4 and 5, a conventional reflection type liquid crystal projector of this type is provided on an optical axis 3 connecting a reading light source 1 for emitting reading light and a writing light source 2 for emitting writing light. A condenser lens 4 for condensing the reading light, a condenser lens 5 for condensing the writing light, and only the S wave of a component orthogonal to the P wave on the separation surface inclined at 45 ° with respect to the optical axis 3 And a polarization beam splitter (hereinafter referred to as P.S.
B. S) 6, a transmission type liquid crystal 7 for transmitting or blocking the writing light condensed by the condenser lens 5 according to image information to be displayed, and an irradiation amount of the writing light transmitted through the transmission type liquid crystal 7 ( The strength of the photoconductor 8 is a light guide whose impedance at the illuminated portion changes due to the change in the applied voltage due to the change in the impedance of the photoconductor 8. B. A twisted nematic liquid crystal (hereinafter, referred to as a liquid crystal) that changes the polarization state of the P wave separated in S6.
9) and a reflective liquid crystal 11 composed of a reflective mirror 10 for reflecting light transmitted through the TN liquid crystal 9. Further, after being reflected by the reflective mirror 10, the TN liquid crystal 9 is retransmitted. Out of the light emitted by B.
A condenser lens 13 for condensing the S-wave separated at S6 on the projection lens 12, B. And a polarizing plate 14 for removing P-waves that could not be separated in S6.

In the above structure, the transmission type liquid crystal 7 and the reflection type liquid crystal 11 are in close contact with each other. B. It is arranged opposite to the P-wave emission surface of S6.

A certain voltage is applied between the photoconductor 8 of the reflection type liquid crystal 11 and the TN liquid crystal 9, and the impedance of the photoconductor 8 and the impedance of the TN liquid crystal 9 are applied to the TN liquid crystal 9. And the divided voltage is applied.

The TN liquid crystal 9 has a 45-degree optical rotation when no voltage is applied, and rotates the wavefront of the incident light by 45 degrees. Thus, the optical rotation at 45 ° is degraded.

The operation of the reflection type liquid crystal projector constructed as described above will be described. Light emitted from the readout light source 1 is condensed by the condenser lens 4 and is condensed by the P.V. B. S6. B. At S6, the readout light is separated by reflecting the S wave of the readout light and transmitting only the P wave. On the other hand, the writing light emitted from the writing light source 2 is condensed by the condenser lens 5 and applied to the transmission type liquid crystal 7 for transmitting and blocking light corresponding to image information to be displayed.

The writing light transmitted through the transmission type liquid crystal 7 in accordance with the image information to be displayed is irradiated on the photoconductor 8 of the reflection type liquid crystal 11, and the impedance of the irradiated portion of the photoconductor 8 changes according to the irradiation amount. Let
Therefore, the voltage applied to the TN liquid crystal 9 also changes, and P.P. B. S6, the polarization state of the P wave separated is changed to B. The light is emitted to S6.

Here, when no voltage is applied to the TN liquid crystal 9, the P-wave incident on the TN liquid crystal 9 rotates by 45 ° while passing through the liquid crystal layer, is reflected by the reflection mirror 10, and is again reflected by the reflection mirror 10. The liquid crystal layer of the TN liquid crystal 9 rotates in the opposite direction by 45 °, that is, the P wave incident on the TN liquid crystal 9 becomes a P. B. S6 and the P.S. B. Since the light is transmitted through S6, it does not go to the projection lens 12, and therefore, a black image is displayed without any projection image.

On the other hand, when a certain voltage is applied to the TN liquid crystal 9, the alignment of the liquid crystal changes according to the voltage level. For example, if the TN liquid crystal 9 loses the optical rotation of 45 ° at all, the linearly polarized P wave Is 90 due to the birefringence effect of the liquid crystal.
° in a rotated state, that is, P. B. S6 and the P.S. B. The light is reflected by the separation surface of S6, is directed to the projection lens 12, and is collected by the condenser lens 13,
The P.I. B. After removing the P-wave component that could not be separated in S6, the image is projected from the projection lens 12, so that the projected image is displayed in white.

As described above, an image is displayed by the reading light in accordance with the intensity of the writing light transmitted through the transmission type liquid crystal 7.

In the case of a reflection type liquid crystal projector having the above-mentioned reflection type liquid crystal, readout light is blocked by a TFT disposed in a TFT liquid crystal layer, as compared with a transmission type liquid crystal projector using a TFT liquid crystal. Therefore, there is an advantage that the transmittance of the liquid crystal for the readout light is large, and thus a very bright projected image can be obtained.

[0012]

However, the conventional reflection type liquid crystal projector described above has a problem that two light sources, a reading light source and a writing light source, are required, and the maximum brightness of the projected image is high. Since the luminance (luminance) is deteriorated due to the deterioration due to the life of the reading light source and the life of the writing light source, there is a problem that the deterioration is fast.

[0013]

A reflection type liquid crystal projector according to the present invention separates light emitted from a light source into light waves of components orthogonal to each other, and uses one light wave as read light and writes the other light wave. It is provided with spectroscopic means for converting the light into light and adjusting means for adjusting the amount of the writing light to a constant value.

[0014]

The reflection type liquid crystal projector according to the present invention comprises:
The light emitted from the light source is separated into light waves of components orthogonal to each other by the spectral means, one light wave is used as read light, the other light wave is used as write light, and the light amount of the write light is kept constant by the adjusting means. In order to perform the adjustment, the reading light and the writing light can be emitted by one light source, and the lifetime of the luminance of the projected image can be extended.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a reflection type liquid crystal projector according to the present invention will be described below with reference to FIGS. 1 and 2. The same reference numerals are used for the same parts as those in the conventional example.

The reflection type liquid crystal projector of the present invention comprises a light source 21, a condenser lens 4 for condensing the light emitted from the light source 21, and a P-wave as the reading light for condensing the light condensed by the condenser lens 4. And S as writing light
Polarization beam splitter (hereinafter referred to as P.B.
S) 6 and the P.S. B. The torsional structure changes due to the photoconductor 8 which is a light guide whose impedance changes at the P-wave emission side of S6 depending on the irradiation amount (strong or weak) of light, and the applied voltage due to the change in the impedance of the photoconductor 8. , Of the reading light, B. Twisted nematic liquid crystal (hereinafter referred to as TN liquid crystal) that changes the polarization state of the P wave separated in S6
9 and a reflective liquid crystal 11 comprising a reflective mirror 10 for reflecting light transmitted through the TN liquid crystal 9; and a transmissive liquid crystal 7 for transmitting or blocking light according to image information to be displayed.
The P.S. B. The P.S. B. Adjusting means 22 for adjusting the light amount of the S-wave separated at S6 to a constant value, a half mirror 23 for reflecting light transmitted through the adjusting means 22 at 45 ° with respect to the emission direction, and reflected by the half mirror 23 A condenser lens 25 for condensing light at an entrance of the optical fiber 24; and a condenser lens 5 for condensing light guided by the optical fiber 24 and irradiating the transmission liquid crystal 7 as writing light. Further, of the emitted light reflected by the reflection mirror 10 of the reflective liquid crystal 11 and retransmitted through the TN liquid crystal 9 and emitted, the P.I. B. Condenser lens 13 for condensing S wave separated in S6 on projection lens 12
And P. B. And a polarizing plate 14 for removing P-waves that could not be separated in S6.

In the above arrangement, the adjusting means 22
The twisted structure changes according to the applied voltage. B. A twisted nematic liquid crystal (hereinafter, referred to as a TN liquid crystal) 26 that changes the polarization state of the S wave separated in S6, B. S
An analyzer 27 arranged perpendicular to the outgoing wavefront of the S-wave separated at 6; a photosensor 28 as a detection unit for measuring and detecting the amount of light transmitted through the half mirror 23;
A liquid crystal control unit 29 is a control unit that controls the voltage applied to the TN liquid crystal 26 by changing the voltage applied to the TN liquid crystal 26 according to the amount of light measured by the photosensor 28. .

In the reflection type liquid crystal projector configured as described above, the light emitted from the light source 21 is condensed by the condenser lens 4 and B. S6.
B. At S6, the S wave is reflected and only the P wave is transmitted and separated. The P.S. B. The S wave separated in S6 is adjusted in the light amount by the adjusting means 22 and reflected by the half mirror 23, then condensed by the condenser lens 25 at the entrance of the optical fiber 24, and further condensed by the optical fiber 24. The guided light is condensed by a condenser lens 5 and is applied to a transmission type liquid crystal 7 which transmits and blocks light corresponding to image information to be displayed as writing light.

The writing light transmitted through the transmission type liquid crystal 7 according to the image information to be displayed is reflected by the reflection type liquid crystal 11.
And the impedance of the illuminated portion of the photoconductor 8 is changed in accordance with the amount of irradiation, so that the voltage applied to the TN liquid crystal 9 is also changed.
Out of the light emitted from B. The polarization state of the P-wave as the read light separated in S6 is changed to B.
The light is emitted to S6.

Here, when no voltage is applied to the TN liquid crystal 9, the P-wave incident on the TN liquid crystal 9 rotates by 45 ° while passing through the liquid crystal layer, is reflected by the reflection mirror 10, and is again reflected by the reflection mirror 10. The liquid crystal layer of the TN liquid crystal 9 rotates in the opposite direction by 45 °, that is, the P wave incident on the TN liquid crystal 9 becomes a P. B. S6 and the P.S. B. Since the light is transmitted through S6, it does not go to the projection lens 12, and therefore, a black image is displayed without any projection image.

On the other hand, when a certain voltage is applied to the TN liquid crystal 9, the arrangement of the liquid crystal changes according to the voltage level. Is 90 due to the birefringence effect of the liquid crystal.
° in a rotated state, that is, P. B. S6 and the P.S. B. The light is reflected by the separation surface of S6, is directed to the projection lens 12, and is collected by the condenser lens 13,
The P.I. B. After removing the P-wave component that could not be separated in S6, the image is projected from the projection lens 12, so that the projected image is displayed in white.

As described above, an image is displayed by the reading light according to the intensity of the writing light transmitted through the transmission type liquid crystal 7.

In the above operation, the adjusting means 22
When no voltage is applied to the TN liquid crystal 26, the incident S wave is rotated by 90 ° while passing through the liquid crystal layer due to the molecular arrangement of the TN liquid crystal 26, and can pass through the analyzer 27. Is applied, the arrangement of the liquid crystal changes according to the voltage level, and the S wave incident on the TN liquid crystal 26 has a 90 ° twisting effect reduced by the birefringence function of the liquid crystal. When the amount of light measured by the photo sensor 28 is smaller than a specified value, the liquid crystal controller 29 performs TN.
The amount of light transmitted through the analyzer 27 is increased by controlling the voltage applied to the liquid crystal 26 to be small. When the amount of light measured by the photo sensor 28 is larger than a prescribed value, the liquid crystal The control is performed so that the applied voltage is increased to reduce the amount of light transmitted through the analyzer 27, thereby adjusting the amount of writing light.

Next, in the above-described embodiment, a description has been given of an apparatus using a TN liquid crystal as an adjusting means. Hereinafter, another embodiment of a reflection type liquid crystal projector according to the present invention will be described in which a polarizing plate is used as an adjusting means. Will be described with reference to FIG.

The same parts as those in the above-mentioned embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

In the reflection type liquid crystal projector of the present invention, P. B. A polarizing plate 33 that, on the S-wave emission side of S6, blocks light by arranging it in a direction perpendicular to the plane of polarization with respect to linearly polarized light, and transmits light by arranging it in a direction parallel to the plane of polarization; Half mirror 23
And a motor drive control unit 35 which is a driving unit that rotates the polarizing plate rotating motor 34 by the light amount measured by the photo sensor 28. It is provided with.

The adjusting means 32 in the reflection type liquid crystal projector configured as described above rotates the polarizing plate rotating motor 34 by the motor drive control unit 35 when the light amount measured by the photo sensor 28 is smaller than a specified value. Then, the rotation angle of the polarizing plate 33 is controlled so as to increase the amount of light transmitted through the polarizing plate 33, and when the amount of light measured by the photo sensor 28 is larger than a specified value, the polarizing plate is controlled by the motor drive control unit 35. The rotation motor 34 is rotated in the reverse direction to control the rotation angle of the polarizing plate 33 so as to reduce the amount of light transmitted through the polarizing plate 33, thereby adjusting the amount of writing light.

[0028]

The reflection type liquid crystal projector of the present invention is
Because of the above configuration, the light emitted from the light source is separated into light waves of components orthogonal to each other by the spectroscopic means, one light wave is used as read light, and the other light wave is used as write light, and the adjusting means In order to adjust the light amount of the writing light to be constant, a single light source can emit the reading light and the writing light, and it is possible to obtain a stable writing light. Can be extended.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing one embodiment of a reflection type liquid crystal projector of the present invention.

FIG. 2 is a schematic explanatory view of a reflective liquid crystal in one embodiment of the reflective liquid crystal projector of the present invention.

FIG. 3 is a schematic explanatory view showing another embodiment of the reflection type liquid crystal projector of the present invention.

FIG. 4 is a schematic explanatory view showing a conventional reflection type liquid crystal projector.

FIG. 5 is a schematic explanatory view of a reflective liquid crystal in a conventional reflective liquid crystal projector.

[Explanation of symbols]

 6P. B. S 8 Photoconductor 9 TN liquid crystal 11 Reflective liquid crystal 22 Adjusting means 26 TN liquid crystal 27 Analyzer 28 Photosensor 29 Liquid crystal control unit 32 Adjusting means 33 Polarizing plate 35 Motor drive control unit

Claims (3)

(57) [Claims] 1. A reflection type liquid crystal having a light guide whose impedance changes by writing light, and a twisted nematic liquid crystal whose twist structure changes due to a change in impedance of the light guide to change a polarization state of reading light, In a reflection type liquid crystal projector that displays information of writing light by reading light, light emitted from a light source is separated into light waves of components orthogonal to each other, one light wave is used as reading light, and the other light wave is used as writing light. A reflection type liquid crystal projector comprising: a spectral unit; and an adjusting unit that adjusts a light amount of the writing light to be constant. 2. The adjusting means according to claim 1, wherein the adjusting twisted nematic liquid crystal whose twisted structure is changed by an applied voltage, an analyzer which transmits only a light wave of a predetermined component, and a light which transmits the analyzer. A detection unit for detecting the amount of light of
A reflection type liquid crystal projector, comprising: a control unit that controls a voltage applied to the twisted nematic liquid crystal for adjustment based on a detection result of the detection unit. 3. The adjusting means according to claim 1, wherein the adjusting means comprises a polarizing plate rotatably disposed with respect to the spectral means, a detecting unit for detecting the amount of light transmitted through the polarizing plate, and the detecting unit. And a driving section for rotating the polarizing plate based on the detection result of (1).