JP6061360B2 - Image display device and dimming control method - Google Patents

Description

  The present invention relates to an image display apparatus that projects an image using light from a light source, and more particularly to a technique for shielding light from a light source.

  In a projector that projects an image using light from a light source, a method of adjusting the amount of light with an optical aperture is known as a method for increasing the contrast of the image (see, for example, Patent Document 1).

  FIG. 1 is a diagram illustrating an example of a projector that adjusts the amount of light using an optical aperture.

  As shown in FIG. 1, the projector according to this example includes a lamp 11 serving as a light source, an optical aperture unit 21, a video display device 31, and a projection lens 50. The projector also includes a lamp lighting power source 12, a lamp power control unit 13, a motor 22, a motor control unit 23, a dimming control unit 24, a video signal processing unit 32, a signal level detection unit 33, and a fan. A control unit 43, cooling fans 42a and 42b, ducts 41a and 41b, and a device control unit 60 are provided.

  When the device control unit 60 receives a mode switching instruction by a user operation for operating the projector in either the rated power mode or the power saving mode, the device control unit 60 sends a signal indicating the mode according to the mode switching instruction to the lamp power control unit 13. And notifies the fan control unit 43.

  The lamp power control unit 13 performs control to supply power from the lamp lighting power source 12 to the lamp 11 according to the mode notified from the device control unit 60. When it is notified from the device control unit 60 that it is the rated power mode, the lamp lighting power source 12 is controlled to supply the rated power of the lamp 11 to the lamp 11, and the device control unit 60 performs the power saving mode. When notified that there is, the lamp lighting power source 12 is controlled to supply the lamp 11 with power lower than the rated power of the lamp 11.

  The lamp lighting power source 12 supplies power to the lamp 11 according to the mode in accordance with the mode switching instruction under the control of the lamp power control unit 13. In the rated power mode, the rated power of the lamp 11 is supplied to the lamp 11, and in the power saving mode, power lower than the rated power of the lamp 11 is supplied to the lamp 11.

  The lamp 11 emits illumination light by the power supplied from the lamp lighting power source 12. In the rated power mode, the lamp 11 is lit at the rated power, and in the power saving mode, the lamp 11 is lit at a power lower than the rated power of the lamp 11. That is, in the power saving mode, the amount of illumination light emitted from the lamp 11 is smaller than in the rated power mode.

  The fan control unit 43 controls the cooling fans 42 a and 42 b to rotate at a rotation speed corresponding to the mode notified from the device control unit 60. When the mode notified from the device control unit 60 is the rated power mode, the cooling fans 42a and 42b rotate at a higher rotation speed than when the mode notified from the device control unit 60 is the power saving mode. Control.

  The cooling fans 42a and 42b rotate under the control of the fan control unit 43, and blow cool air to the optical diaphragm unit 21 and the video display device 31 through the ducts 41a and 41b, respectively. Accordingly, the cooling fans 42 a and 42 b operate as a cooling unit that cools the optical aperture unit 21 and the video display device 31.

  The signal level detection unit 33 detects the signal level of the video signal that is input to the projector and forms an image projected from the projection lens 50.

  The video signal processing unit 32 converts the video signal input to the projector into a signal format corresponding to the video display device 31 and outputs the signal format.

  The video display device 31 is composed of, for example, a liquid crystal panel, and forms a video corresponding to the video signal output from the video signal processing unit 32.

  The dimming control unit 24 calculates the aperture amount of the optical aperture unit 21 according to the signal level detected by the signal level detection unit 33. In the dimming control unit 24, how much light is applied to the video display device 31 according to the signal level of the video signal input to the projector so that the contrast of the video projected from the projection lens 50 becomes a predetermined one. It is decided whether or not it is necessary to irradiate the light. Then, the aperture amount of the optical aperture unit 21 for irradiating the image display device 31 with the light amount is calculated according to the signal level of the image signal.

  The motor control unit 23 controls the motor 22 according to the aperture amount of the optical aperture unit 21 calculated by the dimming control unit 24.

  The motor 22 sets the aperture amount of the optical aperture section 21 under the control of the motor control section 23.

  The optical diaphragm 21 is configured such that the diaphragm amount is variable by the motor 22, and the illumination light emitted from the lamp 11 is shielded / passed by the diaphragm amount set by the motor 22.

  Hereinafter, the operation of the projector configured as described above will be described.

  When any one of the rated power mode and the power saving mode is designated by the user operation via the device control unit 60, a signal indicating the designated mode is notified to the lamp power control unit 13 and the fan control unit 43. The

  The lamp power control unit 13 performs control to supply power corresponding to the mode notified from the device control unit 60 from the lamp lighting power source 12 to the lamp 11. As a result, power corresponding to the mode designated by the user operation is supplied from the lamp lighting power source 12 to the lamp 11 and the lamp 11 is lit. When the rated power mode is designated by the user operation, the lamp 11 is lit at the rated power, and when the power saving mode is designated by the user operation, the lamp 11 is lit at a power lower than the rated power. Thus, in the lamp power control unit 13, the power supplied to the lamp 11 is switched according to the mode designated by the user operation.

  In the fan control unit 43, the cooling fans 42 a and 42 b are controlled to rotate at the number of rotations corresponding to the mode notified from the device control unit 60. Thereby, the cooling fans 42a and 42b rotate at the number of rotations corresponding to the mode specified by the user operation. When the power saving mode is designated by the user operation, the amount of light emitted from the lamp 11 is smaller than when the rated power mode is designated, so that the optical diaphragm unit 21 and the image display device 31 are irradiated. Less light is generated and less heat is generated. Therefore, when the power saving mode is designated by a user operation, the fan control unit 43 performs control so that the rotational speeds of the cooling fans 42a and 42b are lower than when the rated power mode is designated.

  Note that the rotation speeds of the cooling fans 42a and 42b in the rated power mode and the power saving mode respectively correspond to the heat generation amount or temperature of the optical aperture unit 21 and the video display device 31 in the rated power mode and the power saving mode, respectively. Is set. When the cooling fans 42a and 42b rotate, the cold air generated by the rotation of the cooling fan 42a is applied to the optical diaphragm 21 via the duct 41a, and the cold air generated by the rotation of the cooling fan 42b is applied via the duct 41b. To. As described above, since the rotation speed of the cooling fans 42a and 42b is lower in the power saving mode than in the rated power mode, the cold air applied to the optical aperture unit 21 and the video display device 31 is rated power. It becomes weaker in the power saving mode than in the mode.

  In the signal level detection unit 33, when a video signal is input, the signal level of the video signal is detected and output to the dimming control unit 24. The video signal input to the signal level detection unit 33 is input to the video signal processing unit 32, and the input video signal is converted into a signal format corresponding to the video display device 31 in the video signal processing unit 32. Is output.

  In the video display device 31, a video is formed based on the video signal output from the video signal processing unit 32.

  Further, in the dimming control unit 24, when the signal level of the video signal detected by the signal level detection unit 23 is input, the optical diaphragm unit 21 according to the signal level detected by the signal level detection unit 33. The aperture amount is calculated. As described above, in the dimming control unit 24, the video display device 31 is set according to the signal level of the video signal input to the projector so that the contrast of the video projected from the projection lens 50 becomes a predetermined contrast. It is determined how much light should be irradiated. Then, the aperture amount of the optical aperture section 21 for irradiating the image display device 31 with the light amount is calculated according to the signal level of the image signal.

  In the motor control unit 23, the motor 22 is controlled according to the aperture amount of the optical aperture unit 21 calculated by the dimming control unit 24. Then, the aperture amount of the optical aperture unit 21 is set by the motor 22 to the value calculated by the dimming control unit 24. Thereby, the aperture amount of the optical aperture section 21 is in accordance with the signal level of the video signal input to the projector.

  The illumination light emitted from the lamp 11 is shielded by the optical diaphragm unit 21 by the diaphragm amount corresponding to the video signal, and only the light that has passed through the optical diaphragm unit 21 is passed through the video display device 31 to the projection lens 50. It will be incident on.

  When the light that has passed through the optical diaphragm 21 enters the projection lens 50 via the video display device 31, the video formed by the video display device 31 is enlarged and projected onto the screen.

  Thus, in the projector of this example, the aperture amount of the optical aperture section 21 is set according to the signal level of the input video signal, and the illumination light emitted from the lamp 11 is shielded / passed by the aperture amount. By doing so, the contrast of the image enlarged and projected from the projection lens 50 onto the screen is increased.

  In the projector shown in FIG. 1, in the power saving mode, the lamp 11 is lit at a power lower than the rated power. Therefore, the lamp 11 also generates heat at the optical aperture unit 21 and the video display device 31. Compared to when it is lit at Therefore, in the power saving mode, the noise caused by the rotation of the cooling fans 42a and 42b can be reduced by rotating the cooling fans 42a and 42b at a low rotational speed. Thereby, the power saving mode also functions as a silent mode with low noise at the same time.

  FIG. 2 is a diagram illustrating another example of a projector that adjusts the amount of light using an optical aperture.

  As shown in FIG. 2, the projector of this example has one cooling fan 42 as compared with the projector shown in FIG. 1, and the cool air generated by the cooling fan 42 is transmitted through two ducts 41a and 41b to an optical aperture section. 21 and the video display device 31 are different from each other only.

  Also in the projector of this example, the aperture amount of the optical aperture section 21 is set according to the signal level of the input video signal, and the illumination light emitted from the lamp 11 is blocked / passed by the aperture amount, The contrast of the image enlarged and projected from the projection lens 50 onto the screen is increased.

Japanese Patent Laid-Open No. 2002-23106

  In an image display device such as the projector described above, the optical diaphragm unit generates heat because the optical diaphragm unit shields illumination light emitted from the lamp. The amount of heat generated by the optical diaphragm increases with the amount of light shielded by the optical diaphragm, and raises the temperature of the optical diaphragm. At this time, when an optical diaphragm part made of resin is used, or when parts made of resin are arranged around the optical diaphragm part, problems such as failure or deterioration of parts occur in terms of reliability. End up. Therefore, as described above, it is conceivable to cool the optical diaphragm unit together with the video display device by the cooling fan.

  In parts such as video display devices, the amount of heat generated decreases as the amount of illumination light radiated decreases. Therefore, even if the cooling capacity of the cooling fan is kept low in the power saving mode as described above, the temperature of the parts is extremely high. It won't get expensive. On the other hand, since it is necessary to arrange | position the optical aperture part in the front | former stage of a video display device, it will be arrange | positioned in the vicinity of a lamp | ramp. Therefore, the calorific value of the optical diaphragm is affected not only by the amount of light blocked by the optical diaphragm but also by the radiant heat from the lamp. In general, the temperature of the lamp is controlled so as to be kept substantially constant regardless of the rated power mode or the power saving mode. Therefore, even if the amount of illumination light emitted from the lamp in the power saving mode decreases, the influence of radiant heat from the lamp hardly changes. For this reason, if the cooling capacity of the cooling fan is kept low as the amount of illumination light emitted from the lamp decreases in the power saving mode, the temperature of the optical aperture section may increase.

As described above, the ratio of the cooling fan air volume required in the rated power mode and the cooling fan air volume required in the power saving mode, and the rated power in the optical aperture section, for parts such as video display devices. The ratio of the air flow required for the cooling fan in the mode and the air flow required for the cooling fan in the power saving mode are different. Therefore, for example, as shown in FIG. 2, when cooling air from one cooling fan is applied to each of the components such as the optical aperture unit and the image display device, the cooling fan is cooled in the power saving mode. If the capacity is set in accordance with the heat generation amount or temperature of a component such as a video display device, the temperature of the optical aperture section will increase . In addition, when the cooling capacity of the cooling fan in the power saving mode is set according to the heat generation amount or temperature of the optical aperture section, for example, the temperature of the video display device is increased as the cooling capacity of the cooling fan is increased. It becomes too low, causing image quality degradation and noise.

  Therefore, it is conceivable to provide a cooling fan for cooling the optical aperture section separately from the other cooling fans and to control them independently. However, in that case, there are problems such as an increase in cost and noise as in the above case.

  An object of the present invention is to provide an image display device and a dimming control method capable of solving the problems of the above-described technology.

In order to achieve the above object, the present invention provides:
A light source having a plurality of modes in which the amount of illumination light emitted is different from each other;
Video forming means for forming video according to the video signal;
A light shielding means for shielding the illumination light;
Projecting means for projecting the image formed by the image forming means using the illumination light that has passed through the light shielding means,
The light shielding means and the required cooling capacity are different from each other for each of the plurality of modes, and the cooling parts required for each of the plurality of modes are different from those of the light shielding means. Cooling means for cooling with a corresponding cooling capacity;
Light shielding control means for changing a light shielding rate in the light shielding means according to the video signal,
The light shielding control unit independently sets a range in which the light shielding rate is changed for each of the plurality of modes.

Further, the light source is formed by a light source having a plurality of modes in which the amount of illumination light to be emitted is different from each other, an image forming unit that forms an image according to an image signal, a light shielding unit that blocks the illumination light, and the image forming unit The projection unit that projects the projected image using the illumination light that has passed through the light blocking unit, the light blocking unit, and the required cooling capacity are different for each of the plurality of modes, and for each of the plurality of modes. The light shielding means having different cooling capacity required is a cooling means for cooling a component with a cooling capacity corresponding to the plurality of modes, and a light shielding control for changing a light shielding rate in the light shielding means according to the video signal. A dimming control method in a video display device comprising:
The light shielding control unit sets a range in which the light shielding rate is changed independently for each of the plurality of modes, and sets the light shielding rate according to the mode and the video signal.

  According to the present invention, the temperature of the light shielding unit can be appropriately adjusted in the plurality of modes.

It is a figure which shows an example of the projector which adjusts light quantity with an optical aperture. It is a figure which shows the other example of the projector which adjusts light quantity with an optical aperture. It is a figure which shows one Embodiment of the video display apparatus of this invention. It is a graph which shows the relationship between the signal level by the table which the light control part shown in FIG. 3 has, and the aperture amount of an optical aperture part.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 3 is a diagram showing an embodiment of the video display device of the present invention.

  As shown in FIG. 3, the present embodiment is a projector having a lamp 11 serving as a light source, an optical aperture 21 serving as a light shielding unit, a video display device 31 serving as a video forming unit, and a projection lens 50 serving as a projection unit. is there. Further, the projector includes a lamp lighting power source 12, a lamp power control unit 13, a motor 22, a motor control unit 23, a dimming control unit 124, a video signal processing unit 32, a signal level detection unit 33, and a fan. A control unit 43, a cooling fan 42 serving as a cooling means, a first duct 41a and a second duct 41b, and an apparatus control unit 160 are provided. The motor 22, the motor control unit 23, and the dimming control unit 124 constitute the light shielding control means of the present invention.

  3 that are given the same reference numerals as those shown in FIG. 1 and FIG. 2 are the same as the operations of the components shown in FIG. 1 and FIG. To work.

  When the apparatus control unit 160 receives a mode switching instruction by a user operation for operating the projector in either the rated power mode or the power saving mode, the apparatus control unit 160 displays a signal indicating the mode according to the mode switching instruction. 13. Notify the fan control unit 43 and the dimming control unit 124.

  The dimming control unit 124 calculates the aperture amount of the optical aperture unit 21 according to the signal level detected by the signal level detection unit 33 and the mode notified from the device control unit 160. The aperture amount of the optical aperture section 21 in this embodiment corresponds to the light blocking rate of the present invention. When the aperture amount of the optical aperture section 21 is the largest and the light emitted from the lamp 11 does not pass at all, the light blocking ratio is 100%, and the aperture amount of the optical aperture section 21 is In the case where the light emitted from the lamp 11 is the smallest and all light passes therethrough, the light shielding rate is 0%.

  The dimming control unit 124 determines in advance how much light should be irradiated to the video display device 31 in order to make the contrast of the video projected from the projection lens 50 predetermined. Yes. This is determined according to the signal level of the video signal input to the projector for each of the rated power mode and the power saving mode. The dimming control unit 124 is a table (LUT: Look) in which the aperture amount of the optical aperture unit 21 for setting the light amount of the illumination light irradiated to the video display device 31 to the determined light amount is set according to the signal level. Up Table). The table is provided for each of the rated power mode and the power saving mode. Then, the dimming control unit 124 calculates the aperture amount of the optical aperture unit 21 according to the signal level detected by the signal level detection unit 33 and the mode notified from the device control unit 160 based on the table. To do.

  The ducts 41a and 41b are formed based on the heat generation amount or temperature of the optical aperture section 21 and the video display device 31 in the rated power mode.

  The rotation speed of the cooling fan 42 is set according to the heat generation amount or temperature of the video display device 31 in each of the rated power mode and the power saving mode.

  Hereinafter, the operation of the projector configured as described above will be described.

  When any one of the rated power mode and the power saving mode is specified by the user operation through the device control unit 160, a signal indicating the specified mode is transmitted to the lamp power control unit 13, the fan control unit 43, and the dimming. The control unit 124 is notified.

  The lamp power control unit 13 performs control to supply power corresponding to the mode notified from the device control unit 160 from the lamp lighting power source 12 to the lamp 11. As a result, power corresponding to the mode designated by the user operation is supplied from the lamp lighting power source 12 to the lamp 11 and the lamp 11 is lit. When the rated power mode is designated by the user operation, the lamp 11 is lit at the rated power, and when the power saving mode is designated by the user operation, the lamp 11 is lit at a power lower than the rated power. Thus, in the lamp power control unit 13, the power supplied to the lamp 11 is switched according to the mode designated by the user operation.

  In the fan control unit 43, the cooling fan 42 is controlled to rotate at the number of rotations corresponding to the mode notified from the device control unit 160. Thereby, the cooling fan 42 rotates at the number of rotations corresponding to the mode designated by the user operation. When the power saving mode is designated by the user operation, the amount of light emitted from the lamp 11 is smaller than when the rated power mode is designated, so that the optical diaphragm unit 21 and the image display device 31 are irradiated. Less light is generated and less heat is generated. Therefore, the fan control unit 43 performs control so that the rotation speed of the cooling fan 42 is lower when the power saving mode is specified by a user operation than when the rated power mode is specified. Note that the rotation speed of the cooling fan 42 in each of the rated power mode and the power saving mode is set according to the amount of heat generated or the temperature of the video display device 31 in each of the rated power mode and the power saving mode. When the cooling fan 42 rotates, cold air generated by the rotation of the cooling fan 42 is applied to the optical aperture unit 21 through the duct 41a and applied to the video display device 31 through the duct 41b. As described above, since the rotation speed of the cooling fan 42 is lower in the power saving mode than in the rated power mode, the cold air applied to the optical aperture unit 21 and the video display device 31 is in the rated power mode. It is weaker when in power saving mode than when it is.

  In the signal level detection unit 33, when a video signal is input, the signal level of the video signal is detected and output to the dimming control unit 24. Specifically, the signal level detection unit 33 first detects a histogram indicating the relationship between the signal level (gradation) of each pixel for one frame of the input video signal and the number of pixels. Then, the signal level detection unit 33 detects the gradation indicating the peak value of the number of pixels of the detected histogram as the peak class, and outputs the peak class signal level (gradation). In the detected histogram, the number of pixels is detected for each gradation here, but all gradations are divided into, for example, every four gradations or every eight gradations, and divided gradations are obtained. The number of pixels included in the range may be detected. In this case, the output signal level (gradation) of the peak class may be, for example, a minimum value, a maximum value, or a substantially intermediate value in the gradation range. The video signal input to the signal level detection unit 33 is input to the video signal processing unit 32, and the input video signal is converted into a signal format corresponding to the video display device 31 in the video signal processing unit 32. Is output.

  In the video display device 31, a video is formed based on the video signal output from the video signal processing unit 32.

  In the dimming control unit 124, when the signal level of the video signal output from the signal level detection unit 23 is input, the signal level output from the signal level detection unit 33 based on the above-described table, The aperture amount of the optical aperture unit 21 corresponding to the mode notified from the device control unit 160 is calculated and output.

  The contrast of the image projected from the projection lens 50 can be adjusted by the amount of light emitted to the image display device 31. A predetermined contrast can be obtained by performing the adjustment in accordance with the signal level of the video signal. Therefore, as described above, the dimming control unit 124 controls the video display device according to the signal level of the video signal input to the projector so that the contrast of the video projected from the projection lens 50 becomes a predetermined level. It is determined how much light should be irradiated to the image 31, and the aperture amount of the optical aperture section 21 for setting the light amount irradiated to the image display device 31 to the determined light amount is a signal. It has a table set according to the level. In addition, the dimming control unit 124 according to the present embodiment has a table in which the aperture amount of the optical aperture unit 21 is set according to the signal level in each of the rated power mode and the power saving mode.

  FIG. 4 is a graph showing the relationship between the signal level by the table included in the dimming control unit 124 shown in FIG. 3 and the aperture amount of the optical aperture unit 21.

  As described above, in order to adjust the contrast of the image projected from the projection lens 50 according to the amount of light emitted to the image display device 31, the dimming control unit 124 uses the light emitted to the image display device 31. A table in which the aperture amount of the optical aperture section 21 is set in accordance with the signal level.

  Therefore, as shown in FIG. 4, the aperture amount of the optical aperture section 21 calculated by the dimming control section 124 changes according to the signal level output from the signal level detection section 33. The aperture amount is calculated according to the signal level output from the signal level detection unit 33 within a range between the aperture amount when the signal level is the smallest and the aperture amount when the signal level is the highest. It will be. Further, as described above, the dimming control unit 124 has a table in which the aperture amount of the optical aperture unit 21 is set according to the signal level for each of the rated power mode and the power saving mode. As shown in FIG. 4, the aperture amount of the optical aperture section 21 corresponding to the signal level is set for each of the rated power mode and the power saving mode. Thereby, the aperture of the optical diaphragm unit 21 according to the range between the diaphragm amount when the signal level is the smallest and the diaphragm amount when the signal level is the largest, that is, the signal level output from the signal level detector 33. The range in which the amount is changed is set independently for each of the rated power mode and the power saving mode.

  Here, the aperture amount of the optical aperture section 21 in the rated power mode and the power saving mode will be described.

  The optical diaphragm unit 21 receives a large amount of light when the diaphragm amount is large and the light shielding rate is high, and the amount of heat generated is increased. On the other hand, when the aperture amount is small and the light blocking ratio is low, the amount of light received is reduced and the amount of heat generated is reduced. By the way, since the cooling fan 42 has a lower rotational speed in the power saving mode than in the rated power mode, the cooling air applied to the optical aperture 21 is less in the power saving mode than in the rated power mode. Is weaker. Therefore, the dimming control unit 124 is set so that the aperture amount of the optical aperture unit 21 is smaller in the power saving mode than in the rated power mode for the same signal level. As a result, the amount of heat generated in the optical diaphragm 21 is reduced in the power saving mode where the cold air applied to the optical diaphragm 21 is weak.

  The aperture amount of the optical aperture section 21 is for adjusting the contrast of the image projected from the projection lens 50. Therefore, as described above, the aperture amount of the optical aperture section 21 differs for the same signal level. If this happens, the contrast of the image projected from the projection lens 50 may not be a predetermined one. In the dimming control unit 124 of this embodiment, the aperture amount of the optical aperture unit 21 in the rated power mode is set so that the contrast of the image projected from the projection lens 50 can obtain a predetermined contrast. The aperture amount of the optical aperture section 21 in the mode is set such that the contrast of the image projected from the projection lens 50 is slightly different from the predetermined contrast.

  When the light control unit 124 calculates the diaphragm amount of the optical diaphragm unit 21, the motor control unit 23 controls the motor 22 in accordance with the diaphragm amount of the optical diaphragm unit 21 calculated by the light control unit 124. Is done. Then, the aperture amount of the optical diaphragm unit 21 is set by the motor 22 to the value calculated by the light control unit 124.

  As a result, the light blocking rate according to the aperture amount of the optical aperture unit 21 is in accordance with the signal level of the video signal input to the projector. Then, the illumination light emitted from the lamp 11 is shielded by the optical diaphragm unit 21 at a light shielding rate according to the video signal, and only the light that has passed through the optical diaphragm unit 21 is projected via the video display device 31. It will be incident on. At this time, when the projector is operating in the power saving mode, the cooling fan 42 is rotated at a rotation speed corresponding to the heat generation amount or temperature of the video display device 31, so that the optical aperture is affected by the radiant heat of the lamp 11. In the part 21, the cooling capacity is insufficient. However, in the power saving mode, since the aperture amount of the optical aperture section 21 is small and the light shielding rate is set low, the heat generation amount of the optical aperture section 21 is reduced, and sufficient cooling is possible.

  When the light that has passed through the optical diaphragm 21 enters the projection lens 50 via the video display device 31, the video formed by the video display device 31 is enlarged and projected onto the screen.

  A predetermined contrast can be obtained by performing the control described above for each frame of the video signal. However, the control described above need not be performed for each frame, and may be performed based on the detection results of a plurality of frames. For example, the aperture amount of the optical aperture section 21 may be controlled to operate when a frame whose image has the same tendency in the histogram of one frame (for example, a dark image) continues for a predetermined number of times.

  As described above, in the present embodiment, since the range in which the light shielding rate in the light shielding unit is changed is set independently for each of the plurality of modes, even in a mode where the cooling capacity of the cooling unit such as the power saving mode is low. By setting a range in which the light shielding rate in the light shielding unit is reduced, the temperature of the light shielding unit is not significantly increased, and the temperature of the light shielding unit can be appropriately adjusted without increasing noise. Specifically, according to the amount of illumination light emitted from the lamp 11 and the cooling capacity of the cooling fan 42, the ranges in which the light blocking rate according to the aperture amount of the optical aperture section 21 is set are set to be different from each other. This ensures a balance between the amount of heat generated and the cooling capacity. Thus, even if the cooling fan that cools the optical aperture section 21 is shared with the cooling fan that cools other components, it is not necessary to increase the rotation speed of the cooling fan, and an inexpensive and low-noise projector is provided. Can do.

  In the present embodiment, the case where the mode in which the amount of illumination light emitted from the lamp 11 is different has two modes of the rated power mode and the power saving mode has been described as an example. The device mode is not limited to two. Three or more modes having different amounts of illumination light emitted from the lamp 11 may be used. Moreover, it is not necessary for one mode among the plurality of modes that the lamp 11 is lit at the rated power.

  In the present embodiment, the signal level detection unit 33 calculates the aperture amount of the optical aperture unit 21 according to the signal level of the peak class in the histogram of the video signal. However, the number of pixels in the histogram is 1 or more. Of the gradation (range), the aperture amount of the optical diaphragm unit 21 may be calculated according to the signal level of the maximum class indicating the maximum gradation (range) or the minimum class indicating the minimum gradation. Further, instead of calculating the aperture amount of the optical aperture unit 21 according to the signal level in the histogram, the maximum value, the average value, the minimum value, etc. of the signal level of each pixel for each frame of the video signal are detected. The aperture amount of the optical aperture section 21 may be calculated according to the signal level (detection result). Further, the detection of the video signal is performed in units of one frame, but may be performed in a plurality of frames.

  Further, the cooling fan 42 for cooling the optical aperture section 21 is shared with the one for cooling the video display device 31, but the cooling fan 42 for cooling the optical aperture section 21 is other than the video display device. It may be configured to be shared with those which cool the parts.

  Further, the configuration shown in FIG. 3 may have two cooling fans 42a and 42b as shown in FIG. In that case, the ratio of the air volume required when the cooling fan 42a is in the rated power mode and the air volume required when in the power saving mode, and the air volume and power saving of the cooling fan required when the cooling fan 42b is in the rated power mode. Since the ratio of the cooling fan air volume required in the mode can be made the same, the control of the cooling means can be simplified, the cooling capacity of the cooling fan 42a can be suppressed, and the increase in noise is prevented. can do.

Claims (8)

A light source having a plurality of modes including at least a first mode in which the amount of emitted illumination light is a predetermined amount and a second mode in which the amount of emitted illumination light is less than the first mode ;
Video forming means for forming video according to the video signal;
A light shielding means for shielding the illumination light;
Projecting means for projecting the image formed by the image forming means using the illumination light that has passed through the light shielding means,
The light shielding means and the required cooling capacity are different from each other for each of the plurality of modes, and the cooling parts required for each of the plurality of modes are different from those of the light shielding means. Cooling means for cooling with a corresponding cooling capacity;
Light shielding control means for changing a light shielding rate in the light shielding means according to the video signal,
The light shielding control unit sets a range in which the light shielding rate is changed in the second mode to be narrower than a range in which the light shielding rate is changed in the first mode, and the second mode An image display device that sets a maximum value of a light shielding rate in the mode to be lower than a maximum value of the light shielding rate in the first mode . The video display device according to claim 1,
The video display apparatus in which the cooling capacity of the cooling means is set to be lower in the second mode than in the first mode. The video display device according to claim 2,
The video display device in which the cooling capacity of the cooling means is set according to the heat generation amount or temperature of the component in each of the plurality of modes. The video display device according to any one of claims 1 to 3,
The component is a video display device which is the video forming means. The video display device according to any one of claims 1 to 4,
Signal level detecting means for detecting a signal level of the video signal and outputting a detection result;
The image display device, wherein the light blocking control unit sets a light blocking rate in the light blocking unit according to a detection result output from the signal level detecting unit. The video display device according to any one of claims 1 to 5 ,
The cooling means cools the component parts and the light shielding means by a cooling fan,
The video display device
An electrically Ku first duct to said shielding means cold air by rotation of the cooling fan,
A video display device further have a a conductive Ku second duct to said component cold air by rotation of the cooling fan. The video display device according to any one of claims 1 to 6 ,
The cooling means is an image display device that cools the component parts and the light shielding means by a single cooling fan. A light source having a plurality of modes including at least a first mode in which the amount of emitted illumination light is a predetermined amount and a second mode in which the amount of emitted illumination light is less than the first mode; Image forming means for forming a corresponding image; light shielding means for shielding the illumination light; and projection means for projecting the image formed by the image forming means using the illumination light that has passed through the light shielding means; The light shielding means and the required cooling capacity are different from each other for each of the plurality of modes, and the cooling parts required for each of the plurality of modes are different from those of the light shielding means. A dimming control method for a video display device, comprising: a cooling unit that cools with a cooling capacity according to the video signal; and a light blocking control unit that changes a light blocking rate of the light blocking unit according to the video signal. ,
The light shielding control means, range, said set narrower than the range of changing the light blocking ratio in the first mode, and said second changing the light blocking ratio at the time of the second mode A light control ratio in which the maximum value of the light shielding rate in the mode is set lower than the maximum value of the light shielding rate in the first mode, and the light shielding rate is set according to the mode and the video signal. Control method.

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