JP2006343365A - Projection type video display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projection type video display device having a plurality of light sources and constituted so that the number of the light sources to be lit can be selected, and capable of always displaying a stable picture. <P>SOLUTION: The projection type video display device projecting light emitted from the plurality of light sources through a liquid crystal panel and constituted so that the number of the light sources to be lit can be selected is equipped with: a polarizing plate arranged at a position where it is opposed to the liquid crystal panel relative to an optical axis; a cooling mechanism cooling the polarizing plate; a lit state detection means detecting the number of the lit light sources; and a control means controlling the cooling mechanism based on output from the lit state detection means so that the temperature of the polarizing plate may be nearly constant. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a projection display apparatus that includes a plurality of light sources and is configured so that the number of light sources to be lit is variable.

  The following is known as a projection display apparatus that cools a polarizing plate on which light transmitted through a liquid crystal panel is incident to a substantially constant temperature.

That is, when a black signal included in the video signal or a signal whose luminance level is close to black (black level signal) is detected, and the integrated value of the black level signal detected at a predetermined time exceeds a threshold value, the cooling fan The cooling speed of the polarizing plate is increased by accelerating the cooling of the polarizing plate, and when the integrated value of the black level signal detected at a predetermined time is equal to or lower than the threshold value, the cooling fan is turned down to suppress the overcooling of the polarizing plate. (See, for example, Patent Document 1).
JP 2001-92015 A

  In the above configuration, the integrated value of the black level signal detected at a predetermined time exceeds the threshold value, that is, the state where the temperature of the polarizing plate rises due to an increase in the amount of light absorbed by the polarizing plate, In the state where the integral value of the black level signal detected at a predetermined time is equal to or lower than the threshold value, that is, the state where the temperature of the polarizing plate is lowered due to a decrease in the amount of light absorbed by the polarizing plate, These polarizing films have different shrinkage ratios due to heat.

  For this reason, the distribution of the phase difference variation due to the thermal contraction of the polarizing film is also changed, and the slight display unevenness generated in the black display is also changed, which may cause the display quality to be deteriorated.

Therefore, the rotation speed of the cooling fan is controlled in a state where the integrated value of the black level signal detected at the predetermined time exceeds the threshold value and in a state where the integrated value of the black level signal detected at the predetermined time is equal to or less than the threshold value. Accordingly, the display quality is lowered by keeping the temperature of the polarizing plate substantially constant.

  However, in a projection display apparatus having a plurality of light sources and the number of light sources to be lit can be selected, the thermal effect on the polarizing plate due to the number of light sources to be lit is more influenced by the integrated value of the black level signal. Therefore, even if the temperature of the polarizing plate is controlled based on the integrated value of the black level signal as in the background art, there is a drawback that the display quality is deteriorated.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a projection display apparatus that has a plurality of light sources and can display a stable image at all times in a projection display apparatus that can select the number of light sources to be lit. To do.

  A first means for solving the above problem is a projection display apparatus configured to project light emitted from a plurality of light sources through a liquid crystal panel and to select the number of light sources to be lit. A polarizing plate disposed at a position facing the liquid crystal panel with respect to the optical axis, a cooling mechanism for cooling the polarizing plate, a lighting state detection means for detecting the number of light sources that are lit, and an output of the lighting state detection means And a control means for controlling the cooling mechanism so that the temperature of the polarizing plate becomes substantially constant.

  In the first means for solving the above problem, the cooling mechanism further has a function of cooling the liquid crystal panel, and the cooling is performed so that the temperature of the liquid crystal panel becomes substantially constant based on the output of the lighting state detecting means. Control means for controlling the mechanism may be provided.

  The projection display apparatus further includes a retardation plate and a retardation compensation optical element, and the cooling mechanism further includes a function of cooling the retardation plate and the retardation compensation optical element, Control means for controlling the cooling mechanism so that the temperatures of the phase difference plate and the phase difference compensation optical element become substantially constant based on the output of the lighting state detection means may be provided.

  Further, the lighting state detection means may comprise a power consumption detection unit that detects power consumption of a light source that is lit.

  Further, the lighting state detection means may comprise an illuminance sensor that detects the illuminance of light projected from the projection display apparatus.

  A second means for solving the above problem is a projection display apparatus configured to project light emitted from a plurality of light sources through a liquid crystal panel and to select the number of light sources to be lit. A polarizing plate disposed at a position facing the liquid crystal panel with respect to the optical axis, a cooling mechanism for cooling the polarizing plate, a power consumption detection unit for detecting power consumption of a light source that is lit, and a projection display And an illuminance sensor for detecting the illuminance of the light projected from the light source, and a control means for controlling the cooling mechanism so that the temperature of the polarizing plate becomes substantially constant based on the output of the power consumption detector and the illuminance sensor. Features.

  According to the configuration of claim 1 of the present invention, since the cooling mechanism can be controlled according to the number of light sources to be lit, the amount of heat shrinkage of the polarizing film of the polarizing plate due to the number of light sources to be lit varies. It is possible to prevent such an effect that the display quality can be stabilized.

  According to the configuration of the second aspect of the present invention, since the liquid crystal panel can be cooled in accordance with the amount of heat generated from the light source simultaneously with the polarizing plate, the display quality of the liquid crystal panel can be stabilized. Play.

  According to the configuration of the third aspect of the present invention, the retardation plate and the retardation compensation optical element can be cooled according to the amount of heat generated from the light source. The effect is that the quality can be stabilized.

  According to the configuration of claim 4 of the present invention, since the cooling mechanism can be controlled by the power consumption detector according to the number of light sources to be lit, the amount of heat shrinkage of the polarizing film of the polarizing plate according to the number of light sources to be lit In addition, it is possible to prevent the occurrence of fluctuations, to stabilize the display quality, and to detect the presence of a light source that is not lit due to the lifetime, etc. Play.

  According to the configuration of the fifth aspect of the present invention, since the cooling mechanism can be controlled by the illuminance sensor according to the number of light sources to be lit, the amount of heat shrinkage of the polarizing film of the polarizing plate due to the number of light sources to be lit varies. Can be prevented, the display quality can be stabilized, and it is possible to detect the presence of a light source that is not lit due to the lifetime or the like. .

  According to the configuration of claim 6 of the present invention, since the cooling mechanism can be controlled according to the number of light sources to be lit, the amount of heat shrinkage of the polarizing film of the polarizing plate due to the number of light sources to be lit varies. It is possible to prevent this, stabilize the display quality, and detect the presence of a light source that is not lit due to its lifetime. In addition, even when the illuminance decreases due to the life of the light source, etc., it is possible to prevent variations in the amount of heat shrinkage of the polarizing film of the polarizing plate due to the decrease in the illuminance of the light source, and to stabilize the display quality. There are effects such as being able to.

(First embodiment)
A first embodiment of the present invention will be described in detail below with reference to FIGS.

  FIG. 1 is a diagram showing an optical system and a lighting control system of a four-lamp three-plate liquid crystal projector of this embodiment. The illumination device 1 includes two light sources 1a and 1b arranged opposite to each other, two light sources 1c and 1d arranged opposite to each other, an optical path changing member 2 arranged between the light sources 1a and 1b, and the light sources 1c and 1d. The optical path changing member 3 is arranged. Each of the light sources 1a, 1b, 1c, and 1d includes an ultrahigh pressure mercury lamp, a metal halide lamp, a xenon lamp, and 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, and each lens portion guides light emitted from the light sources 1a, 1b, 1c, and 1d to the entire surface of a liquid crystal light valve to be described later. 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 change conversion device 5 is composed of a plurality of polarization beam splitter arrays (hereinafter referred to as PBS arrays). The PBS array includes a reflection film, a polarization separation film, and a phase difference plate (1 / 2λ plate) (all not shown). The polarization separation film is located corresponding to the lens center of the lens group 4 b in the integrator lens 4. The PBS array passes, for example, P-polarized light out of the light from the integrator lens 4, changes the optical path of S-polarized light by 90 °, reflects the reflected light by the reflective film, and emits it.

  The P-polarized light that has passed through the PBS array is converted into S-polarized light by the phase difference plate provided on the front side (light emitting side) and emitted. That is, 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 passes through the concave lens 8 and is reflected by the reflecting mirror 9 to change the optical path. The red light reflected by the reflection mirror 9 is light-modulated by passing through the lens 10 and the 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 12 through the concave lens 11.

  The second dichroic mirror 12 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 12 is guided through the lens 13 to the transmissive liquid crystal light valve 32 for green light, and is modulated by being transmitted therethrough. The light in the blue wavelength band transmitted through the second dichroic mirror 12 passes through the relay lens 14, the total reflection mirror 15, the relay lens 16, the reflection mirror 17, and the relay lens 18, and is a transmissive liquid crystal light valve for blue light. The light is modulated by being guided to 33 and transmitted therethrough.

  Each of the liquid crystal light valves 31, 32, 33 includes a liquid crystal panel 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. In the first embodiment, the incident-side polarizing plates 31a, 32a, and 33a absorb P-polarized light and transmit S-polarized light.

  The modulated light (each color video light) modulated by passing through the liquid crystal light valves 31, 32, 33 is synthesized by the dichroic prism 19 to become color video light. The color image light is enlarged and projected by the projection lens 20 and is projected and displayed on the screen 21.

  The energization controller 37 controls the light source based on the operation of a changeover switch (not shown) that is operated when all four lights of the light sources 1a, 1b, 1c, and 1d are turned on and when only two of the four lights are turned on. The current to be energized is controlled. The power consumption detection unit 36 monitors the power consumption state of the light source, and can detect the number of light sources that are lit based on the detected power consumption.

  Cooling air is supplied from the cooling fan 40 to the liquid crystal light valves 31, 32, and 33 via the cooling channel 41 (see FIG. 2). The cooling fan 40 is set so that the liquid crystal light valves 31, 32, and 33 are optimally cooled in a state where all four lights of the light sources 1a, 1b, 1c, and 1d are turned on. Therefore, when the two-lamp lighting is selected by operating a changeover switch (not shown), the liquid crystal light valves 31, 32, 33 are overcooled, and the polarizing plates 31a, 32a, 33a, 31c. , 32c, and 33c, the amount of shrinkage due to heat is reduced, so that the distribution of phase difference variation is also changed, and the slight display unevenness that has occurred in black display also fluctuates, which may cause deterioration in display quality. there were.

  Therefore, in the first embodiment of the present invention, the above-described disadvantages are solved by performing the following control.

  FIG. 3 shows a block diagram of the first embodiment of the present invention. Signals from the power consumption detection unit 36 and the energization control unit 37 are input to the control unit 42 that controls the projection display apparatus, and the operation of the cooling fan 40 is controlled.

  Next, specific control of the cooling fan 40 by the control unit 42 will be described in detail based on the flowchart shown in FIG.

  After the power is turned on, the power consumption detection unit 36 detects the power consumption state of the light source, and the control unit 42 determines in S1 whether or not the detected value is equal to or higher than the A level corresponding to the power consumption of the four lights. In the case of YES in S1, that is, when all four lights of the light source are turned on, the respective polarizing plates 31a, 32a, 33a, 31c, and 32c that are heated to a high temperature by the strong operation of the cooling fan 40 and heated from the four lights. , 33c and the liquid crystal panels 31b, 32b, 33b are accelerated (S2).

  When the detection value of the power consumption detection unit 36 is equal to or higher than the B level corresponding to the power consumption of three lamps (NO in S1 → YES in S3), it is determined that one lamp is not lit due to its lifetime or the like. In S4, the light source replacement warning is generated and the cooling fan 40 is operated in the middle so that the optimum polarizing plates 31a, 32a, 33a, 31c, 32c, 33c and the respective liquid crystals accompanying the decrease in the amount of heat generated from the light source are obtained. The panels 31b, 32b and 33b are cooled (S5).

  When the detected value of the power consumption detector 36 is equal to or higher than the C level corresponding to the power consumption of the two lamps (NO in S3 → YES in S6), the cooling fan 40 is operated weakly to increase the heat generation amount from the two lamps. The corresponding polarizing plates 31a, 32a, 33a, 31c, 32c, 33c and the liquid crystal panels 31b, 32b, 33b are cooled (S7).

  When the detection value of the power consumption detection unit 36 is less than the C level (NO in S6), it is determined that one lamp is not lit due to the life or the like, and a light source replacement warning is generated in S8. By operating the cooling fan 40 weakly, the respective polarizing plates 31a, 32a, 33a, 31c, 32c, 33c and the liquid crystal panels 31b, 32b, 33b are cooled in accordance with a decrease in the amount of heat generated from the light source (S9). ).

  In this way, since the operating state of the cooling fan 40 can be controlled according to the number of light sources to be lit, the polarizing films of the polarizing plates 31a, 32a, 33a and 31c, 32c, 33c according to the number of light sources to be lit. It is possible to prevent variation in the amount of heat shrinkage and to stabilize the display quality.

  In addition, the power consumption detection unit 36 can detect the presence of a light source that is not lit due to a lifetime or the like, and can also allow the user to recognize the necessity of light source replacement by a warning. .

  In addition, since each of the liquid crystal panels 31b, 32b, and 33b can be cooled according to the amount of heat generated from the light source at the same time as each of the polarizing plates 31a, 32a, 33a and 31c, 32c, and 33c, each of the liquid crystal panels 31b, 32b, It is also possible to stabilize the display quality of 33b.

  The experimental results of such control will be described in detail below.

  In a state where all four lights of the light source are lit, the cooling fan 40 is operated strongly so that the distribution of the phase difference variation due to the thermal contraction of the polarizing film of the polarizing plate does not change.

  In the state where all four lights of the light source are lit, the illuminance is 9700 lm, and the temperatures of the polarizing plates 31c, 32c, 33c on the respective emission sides of R, G, B at this time are 70 ° C., 77 ° C., respectively. It was 71 ° C. At this time, as a result of measuring the CIE chromaticity on the black screen when projected onto the screen, the in-plane variation (Δx, Δy) of the (x, y) value was (0.025, 0.064). It was.

  If the two lamps of the light source are turned off without changing the strong operation state of the cooling fan 40, and the two lamps are turned on, the brightness becomes 4900 lm, and the polarizing plate 31c on each of the R, G, and B emission sides at this time , 32c, and 33c were 64 ° C, 70 ° C, and 63 ° C, respectively. At this time, as a result of measuring the CIE chromaticity on the black screen when projected onto the screen, the in-plane variation (Δx, Δy) of the (x, y) value increased to (0.029, 0.078). did.

  This is because the temperature of the polarizing films of the polarizing plates 31c, 32c, and 33c is decreased by changing the light source from the four-lighting state to the two-lighting state while the cooling fan 40 is in a strong operation state.

  Therefore, when the cooling fan 40 is switched to a weak operation in order to make the temperature of the polarizing films of the polarizing plates 31c, 32c, and 33c substantially constant in a state where the light source is changed from the four-lamp lighting state to the two-lamp lighting state, , G, and B have temperatures of 69 ° C., 76 ° C., and 71 ° C., respectively, on the output side polarizing plates 31c, 32c, and 33c. At this time, as a result of measuring the CIE chromaticity on the black screen when projected on the screen, the in-plane variation (Δx, Δy) of the (x, y) value is (0.026, 0.059). It was.

  In this way, when the light source is switched from four-lamp lighting to two-lamp lighting, the number of rotations of the cooling fan 40 is reduced so that the temperature of the polarizing film of the polarizing plates 31c, 32c, 33c becomes substantially constant. As a result, the display unevenness does not fluctuate in the black display, and the deterioration of the display quality can be prevented.

  In the first embodiment of the present invention, the temperatures of the polarizing plates 31c, 32c, and 33c on the output side of the liquid crystal panels 31a, 32a, and 33a were measured. However, the polarizing plates 31a and 32a on the incident side of the liquid crystal panels 31a, 32a, and 33a were measured. , 33a are not measured because they have the same amount of temperature change.

  In the first embodiment of the present invention, the polarizing plates 31a, 32a, 33a and 31c, 32c, 33c are arranged on the incident side and the outgoing side of the liquid crystal panels 31a, 32a, 33a, respectively. It is not limited. The polarizing plates 31c, 32c, and 33c may be arranged only on the emission side of the liquid crystal panels 31a, 32a, and 33a.

Further, in the first embodiment of the present invention, as shown in FIG. 5, the phase difference that aligns the polarization direction of light on the incident surface side of the polarizing plates 31a, 32a, 33a on the incident side of the liquid crystal panels 31a, 32a, 33a. A phase difference compensating optical element 44 for increasing the contrast is disposed between the liquid crystal panels 31a, 32a, 33a and the polarizing plates 31a, 32a, 33a on the incident side of the plate 43 and the liquid crystal panels 31a, 32a, 33a. The phase difference plate 43 and the phase difference compensation optical element 44 may also be controlled by the cooling fan 40 so that the temperature becomes substantially constant according to the lighting state of the light source. With this configuration, the quality of the phase difference plate 43 and the phase difference compensation optical element 44 can be stabilized.
(Second Embodiment)
6 to 8 show a second embodiment of the present invention. In addition, about the same component as 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted. In the first embodiment, the number of light sources that are lit is detected by the power consumption detection unit 36, but in the second embodiment, the illuminance sensor 45 that detects the illuminance of the image projected on the screen 21 is provided on the main body case 46. The number of light sources that are lit is detected on the basis of the detection value of the illuminance sensor 45 provided on the front surface.

  FIG. 7 shows a block diagram of a second embodiment of the present invention. Signals from the illuminance sensor 45 and the energization control unit 37 are input to the control unit 42a that controls the projection display apparatus, and the operation of the cooling fan 40 is controlled.

  Next, specific control of the cooling fan 40 by the controller 42a will be described in detail based on the flowchart shown in FIG.

  After the power is turned on, the illuminance sensor 45 detects the illuminance of the image projected on the screen 21, and the control unit 42a determines in S21 whether or not the detected value is equal to or higher than the α level corresponding to the illuminance when the four lamps are lit. to decide. In the case of YES in S21, that is, when all four lamps of the light source are lit, the polarizing plates 31a, 32a, 33a and 31c, 32c, which are heated to a high temperature by the strong operation of the cooling fan 40 and heated from the four lamps, The cooling of 33c is promoted (S22).

  If the detected value of the illuminance sensor 45 is equal to or higher than the β level corresponding to lighting of three lamps (NO in S21 → YES in S23), it is determined that one lamp is not lit due to the life or the like, and in S24 By generating a light source replacement warning and operating the cooling fan 40 in the middle, the optimal polarizing plates 31a, 32a, 33a and 31c, 32c, 33c are cooled in accordance with a decrease in the amount of heat generated from the light source (S25).

  When the detected value of the illuminance sensor 45 is equal to or higher than the γ level corresponding to lighting of two lights (NO in S23 → YES in S26), the cooling fan 40 is operated weakly to correspond to the heat generation amount when the two lights are lit. The polarizing plates 31a, 32a, 33a and 31c, 32c, 33c are cooled (S27).

  If the detection value of the illuminance sensor 45 is less than the γ level (NO in S26), it is determined that one lamp is not lit due to its life or the like, and a light source replacement warning is generated (S28) and cooling is performed. The fan 40 is operated weakly to cool the polarizing plates 31a, 32a, 33a and 31c, 32c, 33c optimally with a decrease in the amount of heat generated from the light source (S29).

  Thus, since the illumination sensor 45 can control the operating state of the cooling fan 40 according to the number of light sources to be lit, there is variation in the amount of heat shrinkage of the polarizing film of the polarizing plate depending on the number of light sources to be lit. This can be prevented, and the display quality can be stabilized.

In addition, the illuminance sensor 45 can detect the presence of a light source that is not lit due to a lifetime or the like, and can make the user recognize the necessity of light source replacement by a warning.
(Third embodiment)
9 and 10 show a third embodiment of the present invention. In addition, about the same component as 1st Embodiment and 2nd Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted. In 3rd Embodiment, the power consumption detection part 36 and the illumination intensity sensor 45 are provided, and it has the structure which can control the cooling fan 40 corresponding to the illumination intensity fall of the light source accompanying a long-term use.

  FIG. 9 shows a block diagram of a third embodiment of the present invention. Signals from the power consumption detection unit 36, the energization control unit 37, and the illuminance sensor 45 are input to the control unit 42b that controls the projection display apparatus, and the operation of the cooling fan 40 is controlled.

  Next, specific control of the cooling fan 40 by the controller 42b will be described in detail based on the flowchart shown in FIG.

  After the power is turned on, the power consumption detection unit 36 detects the power consumption state of the light source, and the control unit 42b determines in S31 whether or not the detected value is equal to or higher than the A level corresponding to the power consumption of the four lights. If YES in S31, that is, if all four lights of the light source are lit, the illuminance of the light source lit in S32 is detected by the illuminance sensor 45, and the detected value of the illuminance sensor 45 is the value when the four lights are lit. If the level is equal to or higher than the α level corresponding to the illuminance (YES in S32), the cooling fan 40 is operated strongly to cool each of the polarizing plates 31a, 32a, 33a and 31c, 32c, 33c at a high temperature by the heat from the four lights. Promote (S33).

  In S32, if the detected value of the illuminance sensor 45 is less than the α level corresponding to the illuminance when the four lamps are lit (NO in S32), it is determined that the light source is in a dark state due to the lifetime, etc. In S34, a light source replacement warning is generated, and the cooling fan 40 is operated in the middle so that the optimum polarizing plates 31a, 32a, 33a and 31c, 32c, 33c are cooled as the heat generation amount from the light source decreases (S35). ).

  When the detection value of the power consumption detection unit 36 is equal to or higher than the B level corresponding to the power consumption of three lamps (NO in S31 → YES in S36), it is determined that one lamp is not lit due to its lifetime or the like. Then, a light source replacement warning is generated (S37) and the cooling fan 40 is operated in the middle to cool the respective polarizing plates 31a, 31b, 31c and 31c, 32c, 33c optimally with a decrease in the amount of heat generated from the light source. (S38).

  When the detection value of the power consumption detector 36 is equal to or higher than the C level corresponding to the power consumption of two lamps (NO in S36 → YES in S39), the illuminance sensor 45 detects the illuminance of the light source that is lit in S40. If the detected value of the illuminance sensor 45 is equal to or higher than the γ level corresponding to the illuminance when the two lamps are lit (YES in S40), the cooling fan 40 is operated weakly to correspond to the amount of heat generated from the two lamps. The polarizing plates 31a, 32a, 33a and 31c, 32c, 33c are cooled (S41).

  In S40, when the detection value of the illuminance sensor 45 is less than the γ level, it is determined that the light source is in a dark state due to the lifetime or the like, and a light source replacement warning is generated (S41). By causing the cooling fan 40 to be operated weakly, the optimal polarizing plates 31a, 32a, 33a and 31c, 32c, 33c are cooled in accordance with a decrease in the amount of heat generated from the light source (S42).

  In S39, if the detection value of the power consumption detection unit 36 is less than the C level, it is determined that one lamp has not been turned on due to the life or the like, and a light source replacement warning is generated (S43). The cooling fan 40 is operated weakly to optimally cool the polarizing plates 31a, 31b, 31c and 31c, 32c, 33c in accordance with a decrease in the amount of heat generated from the light source (S44).

  In this way, since the operating state of the cooling fan 40 can be controlled according to the number of light sources to be lit, the polarizing films of the polarizing plates 31a, 31b, 31c and 31c, 32c, 33c according to the number of light sources to be lit. It is possible to prevent variation in the amount of heat shrinkage and to stabilize the display quality.

  In addition, the power consumption detection unit 36 can detect the presence of a light source that is not lit due to a lifetime or the like, and can make a user recognize the necessity of light source replacement by a warning. .

  Furthermore, even when the illuminance decreases due to the life of the light source, etc., it can be detected by the power consumption detector 36 and the illuminance sensor 45, and the polarizing plates 31a, 32a, 33a and 31c, 32c, 33c due to the decrease in the illuminance of the light source. It is possible to prevent variations in the heat shrinkage of the polarizing film and to stabilize the display quality.

It is a top view which shows the optical system of the liquid crystal projector of 1st Embodiment of this invention. It is a sectional side view which shows the cooling structure of the polarizing plate. It is a block diagram which shows the control. It is a flowchart which shows the control. It is a sectional side view which shows the Example of the other cooling structure of the same polarizing plate. It is a perspective view which shows the external appearance of the liquid-crystal projector of 2nd Embodiment of this invention. It is a block diagram which shows the control. It is a flowchart which shows the control. It is a block diagram which shows control of the liquid crystal projector of 3rd Embodiment of this invention. It is a flowchart which shows the control.

Explanation of symbols

1a light source 1b light source 1c light source 1d light source 31a polarizing plate 32a polarizing plate 33a polarizing plate 31b liquid crystal panel 32b liquid crystal panel 33b liquid crystal panel 31c polarizing plate 32c polarizing plate 33c polarizing plate 36 power consumption detection unit (lighting state detection unit)
40 Cooling fan (cooling mechanism)
42 Control unit (control means)
42a Control unit (control means)
42b Control unit (control means)
43 Phase difference plate 44 Optical element 45 for phase difference compensation Illuminance sensor (lighting state detector)

Claims (6)

In a projection display device configured to project the light emitted from a plurality of light sources through a liquid crystal panel and select the number of light sources to be lit, it is disposed at a position facing the liquid crystal panel with respect to the optical axis. The polarizing plate, the cooling mechanism for cooling the polarizing plate, the lighting state detection means for detecting the number of light sources that are lit, and the temperature of the polarizing plate become substantially constant based on the output of the lighting state detection means And a control means for controlling the cooling mechanism. The cooling mechanism further includes a function of cooling the liquid crystal panel, and further includes control means for controlling the cooling mechanism so that the temperature of the liquid crystal panel becomes substantially constant based on the output of the lighting state detection means. The projection display apparatus according to claim 1. The projection display apparatus further includes a phase difference plate and a phase difference compensation optical element, and the cooling mechanism further includes a function of cooling the phase difference plate and the phase difference compensation optical element. 3. A control means for controlling the cooling mechanism so that the temperatures of the phase difference plate and the phase difference compensation optical element become substantially constant based on the output of the state detection means. Projection image display device. The projection image according to any one of claims 1 to 3, wherein the lighting state detection unit includes a power consumption detection unit that detects power consumption of a light source that is lit. Display device. 4. The projection according to claim 1, wherein the lighting state detection unit includes an illuminance sensor that detects an illuminance of light projected from the projection display apparatus. 5. Type image display device. In a projection display device configured to project the light emitted from a plurality of light sources through a liquid crystal panel and select the number of light sources to be lit, it is disposed at a position facing the liquid crystal panel with respect to the optical axis. A polarizing plate, a cooling mechanism for cooling the polarizing plate, a power consumption detection unit for detecting power consumption of a light source that is lit, and an illuminance sensor for detecting the illuminance of light projected from the projection display device And a control means for controlling the cooling mechanism so that the temperature of the polarizing plate becomes substantially constant based on the output of the power consumption detector and the illuminance sensor.