JP2005077891A - Projection type image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projection type image display device which can remove dust sticking to light valves. <P>SOLUTION: Each fun device 21 is disposed so that an air current created by rotation of a fun is blown upwards through an opening 21a. The liquid crystal light valves 31, 32, and 33 are disposed above the respective openings 21a such that polarizer plates on the incoming side, panels, and polarizer plates on the outgoing side are separated from one another. Thereby, air current is blown onto the exposed faces of the polarizer plates and the exposed faces of the panels. The rotating speed of the motor which drives the fans are controlled by a motor driver (drive IC) such that first rotating speed (rotation in a cooling period) and second rotating speed (rotation higher than the rotation in the cooling period) are available. Dust sticking to the liquid crystal light valves are blown off with the second rotating speed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a projection display apparatus such as a liquid crystal projector.

  A projection display apparatus includes a light source such as a lamp, an illumination optical system that uniformly and efficiently collects a light beam from the light source, a light valve that optically modulates light collected by the illumination optical system, A projection lens for enlarging and projecting image light obtained through the light valve. In the configuration for performing color display, there are a single plate method using one light valve and a three plate method using three light valves corresponding to three colors of red, green, and blue.

  Since the light valve used in such a projection display apparatus is made of a material having poor heat resistance, the light valve takes in air from the outside using a cooling fan, and circulates the air inside the apparatus housing. Try to lower the temperature. Further, when a liquid crystal display panel is used as a light valve, polarizing plates are required on the light incident side and the light emitting side, and this polarizing plate is also inferior in heat resistance, so cooling is necessary.

  By the way, when air from outside is taken in for cooling as described above, dust in the air enters the optical system in the housing and circulates. When dust circulating in the optical system adheres to the light valve, the dust is enlarged and projected on the screen, which may cause deterioration in image quality.

Therefore, as a technique for suppressing such dust intrusion, a technique for performing fan drive control so as to keep the inside of the casing in a positive pressure state is known (see Patent Document 1). There is also a method using a fine eye filter in order to prevent dust in the outside air from entering the housing.
JP 2001-242434 A

  However, the conventional technique described above is a technique for preventing dust in the outside air from entering the casing, and does not provide a solution when the dust that has entered the light valve adheres to the light valve.

  In view of the above circumstances, an object of the present invention is to provide a projection display apparatus that can remove dust attached to a light valve.

  In order to solve the above-described problem, the projection display apparatus of the present invention generates an air flow in the projection display apparatus for projecting an image by modulating light emitted from a light source with a light valve. An air flow generating means for blowing on the light valve, and a control means for increasing the wind speed of the air flow output from the air flow generating means when the dust removal mode is set, compared to during cooling. .

  If it is said structure, the dust adhering to a light valve will be removed with the airflow of the wind speed raised rather than the time of cooling.

  It is preferable to provide a throttle means for adjusting the area of the air outlet of the air flow generation means so that the area is narrower than that during cooling when the dust removal mode is set. According to this, the flow velocity of the air flow can be further increased by the restriction, and the dust removing ability is improved.

  The surface of the light valve against which the airflow is blown may be water repellent. This water repellent treatment weakens the adhesion of dust and facilitates the blowing of dust by an air flow.

  It is preferable that the surface of the light valve on which the airflow blows is subjected to antistatic treatment. This antistatic treatment weakens the adhesion of charged dust and facilitates the blowing of dust by airflow.

  An air suction port may be formed on the side opposite to the air blowing port across the light valve, and a discharge unit that discharges air sucked from the air suction port to the outside of the housing may be provided. According to this, it is possible to reduce the dust blown off by the air flow from recirculating through the housing and adhering to the light valve again.

  As described above, according to the present invention, the dust attached to the light valve is removed by the air flow at a higher wind speed than that for cooling, and the image quality deterioration due to the dust attachment can be prevented.

  A liquid crystal projector according to an embodiment of the present invention will be described below with reference to FIGS.

  FIG. 1 is a diagram showing an optical system of a three-plate liquid crystal projector of this embodiment. The light emitting part in the light source 1 is composed of an ultra-high pressure mercury lamp, a metal halide lamp, a xenon lamp or the like, and the irradiation light is emitted as parallel light by a parabolic reflector and guided to the integrator lens 4.

  The integrator lens 4 is composed of a pair of lens groups (fly eye lenses) 4a and 4b, and each lens portion guides light emitted from the light source 1 to the entire surface of a liquid crystal light valve to be described later. The partial luminance unevenness existing in the light source 1 is averaged, and the light amount difference between the center of the screen and the peripheral portion is reduced. The light passing through the integrator lens 4 is guided to the first dichroic mirror 7 after passing through the polarization conversion device 5 and the condenser lens 6.

  The polarization conversion device 5 is configured by a polarization beam splitter array (hereinafter referred to as a PBS array). The PBS array includes a polarization separation film and a phase difference plate (1 / 2λ plate). Each polarization separation film of the PBS array passes, for example, P-polarized light out of the light from the integrator lens 4 and changes the optical path of S-polarized light by 90 °. The optically polarized S-polarized light is reflected by the adjacent polarization separation film and emitted as it is. On the other hand, the P-polarized light transmitted through the polarization separation film is converted into S-polarized light by the retardation plate provided on the front side (light emitting side) and emitted. That is, in this case, almost all light is converted to S-polarized light.

  The first dichroic mirror 7 transmits light in the red wavelength band and reflects light in the cyan (green + blue) wavelength band. The light in the red wavelength band that has passed through the first dichroic mirror 7 is reflected by the reflection mirror 8 to change the optical path. The red light reflected by the reflection mirror 8 is light-modulated by passing through a lens 9 and a transmissive liquid crystal light valve 31 for red light. On the other hand, the light in the cyan wavelength band reflected by the first dichroic mirror 7 is guided to the second dichroic mirror 10.

  The second dichroic mirror 10 transmits light in the blue wavelength band and reflects light in the green wavelength band. The light in the green wavelength band reflected by the second dichroic mirror 10 is guided to the transmissive liquid crystal light valve 32 for green light through the lens 11 and is modulated by being transmitted therethrough. The light in the blue wavelength band that has passed through the second dichroic mirror 10 is guided to the blue-light transmissive liquid crystal light valve 33 through the total reflection mirror 12, total reflection mirror 13, and lens 14, and is transmitted therethrough. It is optically modulated.

  Each of the liquid crystal light valves 31, 32, 33 includes a panel portion 31b, in which liquid crystal is sealed between an incident-side polarizing plate 31a, 32a, 33a and a pair of glass substrates (with pixel electrodes and alignment films formed). 32b, 33b and output side polarizing plates 31c, 32c, 33c.

  The modulated light (each color video light) modulated by passing through the liquid crystal light valves 31, 32, 33 is synthesized by the cross dichroic prism 15 to become color video light. The color image light is enlarged and projected by the projection lens 16, and is projected and displayed on a screen (not shown).

  FIG. 2 is a perspective view showing fan devices 21A, 21B, and 21C (hereinafter, when a specific fan device is not represented, reference numeral 21 is added), and FIG. It is the perspective view which showed the arrangement | positioning relationship with an expansion projection system. The fan device 21A is responsible for cooling the liquid crystal light valve 31, the fan device 21B is responsible for cooling the liquid crystal light valve 32, and the fan device 21C is responsible for cooling the liquid crystal light valve 33.

  Each fan device 21 is arranged and configured to blow an airflow generated by the rotation of the fan upward from the upward opening 21a. On each opening 21a, liquid crystal light valves 31, 32, 33 are disposed such that the incident side polarizing plate, the panel portion, and the outgoing side polarizing plate are spaced apart from each other, and the exposure surface of the polarizing plate and the exposure of the panel portion are arranged. Airflow is blown over the surface. The number of rotations of the motor that drives the fan is controlled by a motor driver (drive IC). The rotational speed control is performed by, for example, PWM control or phase control, so that a first rotational speed state (rotation during cooling) and a second rotational speed state (higher rotational speed than rotation during cooling) are formed. Yes.

  A microcomputer (not shown) performs various controls in the liquid crystal projector and gives a first rotation command and a second rotation command to the motor driver. In the case of PWM control, a signal indicating a predetermined ON duty ratio is given as a first rotation command, and a signal indicating an ON duty ratio longer than the ON duty ratio is given as a second rotation command for a predetermined time or until a stop operation is performed. Give it. The microcomputer gives a first rotation command to the motor driver when the power is turned on or when a temperature sensor (not shown) detects that the liquid crystal light valve or the like has exceeded a predetermined temperature, and the dust removal mode is set. When requested, a second rotation command is given to the motor driver. For example, the microcomputer determines that the dust removal mode is requested when a remote control transmitter (not shown) or a key labeled “cleaning” on the operation panel is operated.

  Thus, when the dust removal mode is requested, the second rotation command is given to the motor driver of the fan device 21, and the fan rotates at a higher rotational speed than during cooling, which is higher than that for cooling. The air flow with the high wind speed is blown against the liquid crystal light valves 31, 32, 33, and dust adhering to the polarizing plate and the panel portion is removed.

  As shown in FIG. 2, each aperture 21 a of each fan device 21 may be provided with a diaphragm plate 22 that adjusts the air flow blowing area. The diaphragm plate 22 adjusts the blowing area of the air flow by linearly moving or swinging by an actuator (not shown) (for example, an electromagnetic solenoid, a motor, etc.). The actuator is controlled by a microcomputer. When the dust removal mode is requested, the microcomputer controls the actuator so as to narrow the airflow blowing area. According to this, each opening 21a is narrowed and the flow rate of the airflow which blows off from each opening 21a can be raised, and dust removal capability improves.

  Further, as shown in FIG. 3, the air suction hood is located above the cross dichroic prism 15 (the side opposite to the opening 21a across the liquid crystal light valves 31, 32, 33: the downstream side of the air flow). 23 and an intake fan (not shown) may be provided, and when the dust removal mode is requested, the intake fan may be rotated to perform exhaust processing. According to this, it is possible to reduce the dust blown off by the air flow from recirculating in the casing and adhering to the liquid crystal light valves 31, 32, 33 again. Note that an adhesive portion may be formed at a location downstream of the air flow (such as the hood 23), and dust may be fixed to the adhesive portion to prevent dust from being recirculated. It is preferable that the adhesive portion is replaceable.

  The surfaces of the liquid crystal light valves 31, 32, and 33 where the incident-side polarizing plates 31 a, 32 a, and 33 a, the panel portions 31 b, 32 b, and 33 b and the outgoing-side polarizing plates 31 c, 32 c, and 33 c are subjected to water repellent treatment. It is good to have. This water repellent treatment weakens the adhesion of dust and facilitates the blowing of dust by an air flow. For example, an antireflection layer (AR layer) is formed on the outermost surfaces of the panel portions 31b, 32b, and 33b. The antireflection film is composed of an organic material having an intermediate refractive index film, a high refractive index film, and a low refractive index film, and a low refractive index water repellent organic material is deposited on the low refractive index film, or the low refractive index film is formed. The refractive index film itself may be made of an organic material having water repellency.

  The surfaces of the liquid crystal light valves 31, 32, 33 on the incident side polarizing plates 31 a, 32 a, 33 a, the panel portions 31 b, 32 b, 33 b, and the outgoing side polarizing plates 31 c, 32 c, 33 c are subjected to antistatic treatment. It is good to have. This antistatic treatment weakens the adhesion of dust and facilitates the blowing of dust by airflow. As the antistatic treatment, a transparent conductive film (for example, ITO: indium tin oxide) may be formed and coated with, for example, magnesium fluoride (MgF2).

  In the above description, a projection display apparatus using a liquid crystal light valve is shown, but the present invention can also be applied to a configuration using other light valves.

1 is a configuration diagram showing an optical system of a liquid crystal projector of an embodiment of the present invention. It is a perspective view of a fan apparatus. It is the perspective view which showed the arrangement | positioning relationship between a fan apparatus, an image light composition system, and an expansion projection system.

Explanation of symbols

1 Light source 4 Integrator lens 4a and 4b Lens group (fly eye lens)
5 Polarization Conversion Device 21 Fan Device 21a Aperture 22 Aperture Plate 31, 32, 33 Liquid Crystal Light Valve

Claims (5)

In a projection display apparatus for projecting an image by modulating light emitted from a light source with a light valve, an air flow generating means for generating an air flow and spraying the light valve, and a dust removal mode are set. And a control means for increasing the wind speed of the airflow output from the airflow generation means more than that during cooling. 2. The projection display apparatus according to claim 1, further comprising a throttle means for adjusting an area of the air outlet of the air flow generating means so that the area is narrower than that during cooling when the dust removal mode is set. A projection-type image display device characterized by being configured as described above. 3. The projection display apparatus according to claim 1, wherein a surface of the light valve on which the air flow blows is subjected to a water repellent treatment. 4. 4. The projection display apparatus according to claim 1, wherein a surface of the light valve on which the air flow blows is subjected to antistatic treatment. 5. The projection type image display device according to claim 1, wherein an air suction port is formed on a side opposite to the air blowing port across the light valve, and is sucked from the air suction port. A projection-type image display device comprising discharge means for discharging the air out of the casing.

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