JP2005055760A - Projection display device and method for controlling the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projection display device and a method for controlling the same, which can maintain the quality of a picture to be displayed, even when the characteristics of a dimmer element or a light valve are varied, due to the variation with the lapse of time. <P>SOLUTION: The projection display device, which includes a light source, optical modulation means 36, 37, and 38 for modulating the light from the light source, a projection means for projecting the light modulated by the optical modulation means 36, 37, and 38, and the dimmer means for adjusting the amount of the light projected by the projection means on the basis of an image signal, is provided with a calibration means 60 for automatically calibrating the dimmer means. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a projection display device and a control method for the projection display device.

In recent years, as one form of display device, a projection type device (liquid crystal projector) that enlarges and projects an image emitted from an optical system using a liquid crystal light valve onto a screen through a projection lens has been developed. This apparatus has been proposed to adjust not only the amount of light transmitted through the liquid crystal light valve in accordance with the image to be displayed but also the amount of light emitted from the light source.
For example, as the above-described projection type display device, one that controls the amount of lamp light incident on a liquid crystal light valve according to the level of an input video signal is known (for example, Patent Document 1).
Japanese Patent Laid-Open No. 03-179886 (page 3-4, FIG. 1)

  As described above, in the conventional projection display device, the display characteristics of the light valve may change due to changes over time, and the brightness of the set image may not be obtained. In particular, in a display device that changes the brightness of a video in accordance with the video, there is a problem that the quality of the video may be impaired.

In addition, in the projection type display device provided with a light control element that adjusts the amount of light in addition to the light source and the light valve, there is a possibility that the brightness of the image set at the time of manufacture cannot be obtained due to the change over time of the light control element. .
In particular, when an optical diaphragm is used as the light control element, the brightness of the set image is displayed due to a control signal for controlling the optical diaphragm, an error of a mechanical part that drives the optical diaphragm, in addition to a change with time. There was a risk that the state of the video would be different during video display. Due to these factors, there is a problem that the quality of the video may be impaired.

  The present invention has been made to solve the above-described problem, and is a projection type capable of maintaining the quality of a displayed image even when the characteristics of a light control element, a light valve, and the like change due to changes over time. It is an object of the present invention to provide a display device and a control method for a projection display device.

  In order to achieve the above object, a projection display device according to the present invention includes a light source, a light modulation unit that modulates light from the light source, a projection unit that projects light modulated by the light modulation unit, and an image. A projection-type display device comprising: a dimming unit that adjusts the amount of light projected from the projection unit based on a signal; and a calibration unit that automatically calibrates the dimming unit. To do.

  That is, the projection display device of the present invention includes the calibration unit even if the light amount adjusted by the light control unit changes from the set light amount due to, for example, a change over time of the light control unit. The amount of light adjusted by the means can be calibrated, and the quality of the displayed image can be maintained.

In order to realize the above configuration, the calibration unit may include an optical detection unit that measures the amount of light adjusted by the light control unit, and the light control unit may be automatically calibrated based on the output of the optical detection unit.
According to this configuration, since the calibration unit includes the optical detection unit, it is possible to more reliably detect a change in the amount of light adjusted by the dimming unit. Therefore, it is possible to reliably calibrate the amount of light adjusted by the light control means, and it is easy to maintain the quality of the displayed image.

In order to realize the above-described configuration, more specifically, the light amount adjusted by the light control unit may be measured by detecting the brightness of the image projected from the projection unit by the optical detection unit.
According to this configuration, since the optical detection unit measures the light amount adjusted by the dimming unit by detecting the brightness of the image, the change in the light amount adjusted by the dimming unit can be detected and displayed. The quality of the recorded video can be maintained. In addition to the change in the amount of light adjusted by the light control means, it is also possible to detect a change in the brightness of the surroundings of the projection display device, and an image displayed by performing calibration according to the change in the brightness of the surroundings Can keep the quality.
The light control unit may adjust the amount of light incident on the light modulation unit, may adjust the amount of light transmitted through the light modulation unit, or may adjust the amount of light modulated by the light modulation unit. May be.

In order to realize the above configuration, more specifically, even if the light control means adjusts the amount of light incident on the light modulation means, and the optical detection means measures the light amount of light incident on the light modulation means. Good.
According to this configuration, since the amount of light incident on the light modulation unit is measured, a change in the amount of light adjusted by the dimming unit can be detected more reliably. Therefore, it is possible to reliably calibrate the amount of light adjusted by the light control means, and it is easy to maintain the quality of the displayed image.

In order to realize the above configuration, more specifically, the optical detection unit may be disposed on the light source side of the light modulation unit, and the amount of light reflected from the light modulation unit may be measured.
According to this configuration, since the optical detection unit measures the amount of light reflected from the light modulation unit, the optical detection unit does not block light incident on the light modulation unit. Therefore, the quality of the displayed video can be easily maintained without being affected by the provision of the optical detection means.

In order to realize the above configuration, more specifically, the calibration unit may automatically calibrate the light control unit when the apparatus is started.
According to this configuration, in general, the projection display device takes time to start up, and the light adjustment means is automatically calibrated every time this start-up is performed. Therefore, the calibration of the light adjustment means is completed when an image is projected. Therefore, the quality of the image displayed after starting the projection display device can be maintained.
Further, since the light control means is automatically calibrated at the time of activation, it is not necessary to interrupt the projection of the image in order to calibrate the light control means.

In order to realize the above configuration, more specifically, the calibration unit may automatically calibrate the light control unit when the image signal is switched.
According to this configuration, since the dimming means is automatically calibrated using the period when the image signal is switched and the image is interrupted, the calibration of the dimming means is completed when the next image is projected. Therefore, the quality of the video displayed after the image signal is switched can be maintained.
Further, since the light control means is automatically calibrated using the time when the image signal is switched, it is not necessary to interrupt the projection of the image in order to calibrate the light control means.

More specifically, in order to realize the above configuration, a calibration instruction unit that instructs the calibration unit to perform calibration is provided, and the calibration unit calibrates the light control unit based on an instruction from the calibration instruction unit. May be.
According to this configuration, since the dimming means is calibrated by the calibration means based on an instruction from the calibration instruction section, the dimming means can be calibrated at a desired timing.

In order to realize the above-described configuration, more specifically, the calibration means includes environmental brightness detection means for detecting the ambient brightness of the projection display device, and the ambient brightness detected by the environmental brightness detection means. The calibration means may automatically calibrate the dimming means when the brightness changes.
According to this configuration, since it is possible to detect a change in ambient brightness of the projection display device, the dimming unit is calibrated according to the change in ambient brightness to maintain the quality of the displayed image. be able to.

In order to realize the above configuration, more specifically, the optical detection unit may also serve as the environmental brightness detection unit.
According to this configuration, since the optical detection unit also serves as the environmental brightness detection unit, the measurement of the amount of light adjusted by the dimming unit and the detection of a change in ambient brightness of the projection display device can be performed simultaneously. . Therefore, calibration with respect to the change in the amount of light adjusted by the light control means and calibration with respect to the change in ambient brightness can be performed at the same time, and the quality of the displayed image can be more easily maintained.

In order to realize the above configuration, the dimming unit is an optical diaphragm, and the calibration unit includes an opening degree detecting unit that detects that the opening degree of the optical diaphragm has reached a predetermined opening degree. When the degree is controlled to a predetermined opening, the opening of the optical diaphragm may be controlled and the opening of the optical diaphragm may be calibrated based on the output of the opening detection means.
According to this configuration, when the opening of the optical diaphragm is controlled to a predetermined opening, the opening of the optical diaphragm is controlled based on the output of the opening detection means, and the opening of the optical diaphragm is calibrated. Yes. Therefore, the opening of the optical aperture can be reliably calibrated without being affected by the error of the control signal of the light control means and the error of the mechanical parts, and the quality of the displayed image can be maintained.
In addition, since the opening of the optical diaphragm is detected and calibrated by the opening detection means, the opening of the optical diaphragm can be calibrated without interrupting the display of the image.

A control method for a projection display apparatus according to the present invention includes a light source, a light modulation unit that modulates light from the light source, and a projection unit that projects light modulated by the light modulation unit, and is based on an image signal. A control method for a projection display apparatus in which the amount of light projected from the projection unit is adjusted, wherein the adjustment amount of the amount of light projected from the projection unit is automatically calibrated.
According to this configuration, even if the adjustment amount of the light amount projected from the projection unit is changed from the set light amount, it is automatically calibrated, so that the quality of the displayed image can be maintained.

[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a schematic diagram of a projection display device 10 according to the present embodiment.
As shown in FIG. 1, the projection display device 10 according to the present embodiment includes an illumination device 11 and dichroic mirrors 31 and 32 that split white light emitted from the illumination device 11 into red light, green light, and blue light. Liquid crystal light valves (light modulation means) 36, 37, 38 for modulating each color light, a cross dichroic prism 39 for synthesizing each modulated color light, and a projection lens (projection) for enlarging and projecting the synthesized image on the screen S Means) 40 and a controller 70 that controls the illumination device 11 and the liquid crystal light valves 36, 37, and 38 based on the horizontal / vertical synchronization signal and the image signal.

The illuminating device 11 includes a light source 12, fly-eye lenses 13 and 14, and a light shielding unit (light control means) 20. The light source 12 includes a lamp 15 such as a high-pressure mercury lamp and a reflector 16 that reflects light from the lamp 15. It is configured.
Further, on the optical axis of the light source 12, a first fly eye lens 13 and a second fly eye lens 14 in which a plurality of lenses are arranged in a plane are sequentially installed.
The light shielding unit 20 includes light shielding plates (optical diaphragms) 21 and 21, rotating shafts 22 and 22 extending in a direction parallel to the surface of the light shielding plate 21, and stepping motors 23 and 23 provided on the rotating shaft 22. It consists of and. The light shielding unit 20 is disposed in the vicinity of the second fly-eye lens 14 between the first fly-eye lens 13 and the second fly-eye lens 14.

The dichroic mirrors 31 and 32 are arranged in the order of the dichroic mirror 31 and the dichroic mirror 32 from the side closer to the illumination device 11. The dichroic mirror 31 transmits red light and reflects blue / green light toward the dichroic mirror 32, and the dichroic mirror 32 transmits blue light and reflects green light.
Further, between the dichroic mirrors 31 and 32 and the liquid crystal light valves 36, 37, and 38, the respective color lights dispersed by the dichroic mirrors 31 and 32 are guided to the corresponding liquid crystal light valves 36, 37, and 38, respectively. Reflection mirrors 33, 34, and 35 and relay lenses 41, 42, and 43 are arranged.

The liquid crystal light valves 36, 37, and 38 use TN (Twisted Nematic) mode active matrix type transmissive liquid crystal cells using thin film transistors (hereinafter abbreviated as TFTs) as pixel switching elements. Yes.
In the cross dichroic prism 39, four right angle prisms are bonded, and a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are formed in a cross shape on the inner surface thereof.

FIG. 2 is a block diagram illustrating signal processing in the control unit 70 of the present embodiment, and FIG. 3 is a block diagram illustrating in detail the inside of the image analysis unit 51 of the dimming unit 50.
As shown in FIG. 2, the control unit 70 controls the stepping motor 23 and the liquid crystal light valves 36, 37, and 38 in accordance with the input horizontal / vertical synchronization signal and image signal. And a calibration unit (calibration means) 60 that calibrates the light control unit 50.
The dimming unit 50 analyzes an input horizontal / vertical synchronization signal and an image signal to determine a dimming coefficient and an image processing coefficient, an image processing unit 52 that performs an expansion process on the image signal, Liquid crystal light valve converters 36b, 37b, and 38b that convert the output of the image processing unit 52, a stepping motor converter 23b that converts the output of the image analysis unit 51, and liquid crystal that drives and controls the liquid crystal light valves 36, 37, and 38. The light valve drivers 36a, 37a, and 38a and a stepping motor driver 23a that drives and controls the stepping motor 23 are configured.
The liquid crystal light valve conversion units 36b, 37b, and 38b receive the liquid crystal light valve control table calibrated and generated by the liquid crystal light valve calibration unit 62 described later, and output from the image processing unit 52 according to the liquid crystal light valve control table. Has been converted. The stepping motor conversion unit 23b receives a stepping motor control table calibrated and generated by a stepping motor calibration unit 63, which will be described later, and converts the output of the image analysis unit 51 according to the stepping motor control table.

The calibration unit 60 includes an optical sensor (optical detection means) 61 formed of a photodiode, a liquid crystal light valve calibration unit 62 that calibrates and generates a liquid crystal light valve control table based on the output of the optical sensor 61, and an output of the optical sensor 61. The stepping motor calibration unit 63 calibrates and generates the stepping motor control table based on the above.
The optical sensor 61 is arranged toward the screen S so as to detect the brightness of the image projected on the screen S (see FIG. 1). The liquid crystal light valve calibration unit 62 outputs the calibrated / generated liquid crystal light valve control table to the liquid crystal light valve conversion units 36b, 37b, and 38b, and controls the driving of the liquid crystal light valves 36, 37, and 38 during the calibration operation. Signals are output to the liquid crystal light valve drivers 36a, 37a, and 38a. Similarly, the stepping motor calibration unit 63 outputs the calibrated / generated stepping motor control table to the stepping motor conversion unit 23b and also outputs the drive control signal of the stepping motor 23 during the calibration operation to the stepping motor driver 23a. Yes.

Here, the stepping motor control table is a table in which the relationship of the rotation angle of the stepping motor 23 to the output of the image analysis unit 51 is stored. In other words, the opening of the light shielding plate 21 with respect to the output of the image analysis unit 51 is stored. It is a table that stores the relationship with degrees.
The liquid crystal light valve control table is a table in which the relationship of the driving voltages of the liquid crystal light valves 36, 37, and 38 with respect to the output of the image processing unit 52 is stored.

As shown in FIG. 3, the image analysis unit 51 similarly creates a histogram creation unit 53 that creates a brightness histogram from an image signal, and a dimming coefficient determination unit 54 that decides a dimming coefficient from the created histogram. The image processing coefficient determination unit 55 determines an image processing coefficient from the histogram.
The dimming coefficient determined by the dimming coefficient determination unit 54 is output to the stepping motor conversion unit 23b, and the image processing coefficient determined by the image processing coefficient determination unit 55 is output to the image processing unit 52.

Next, the operation of the projection display device 10 having the above configuration will be described.
As shown in FIG. 1, the white light emitted from the lamp 15 is reflected directly or reflected by the reflector 16 and is incident on the first fly-eye lens 13, and is collected and incident on the second fly-eye lens 14. . Immediately before entering the second fly's eye lens 14, the white light is driven to a predetermined position by the stepping motor 23 based on a dimming coefficient from the control unit 70 (to be described later). Is done. White light emitted from the second fly-eye lens 14 is incident on the dichroic mirror 31, together with the red light L _R in the white light is transmitted, and the blue light L _B and the green light L _G is reflected .

The red light _{LR that} has passed through the dichroic mirror 31 is reflected by the reflection mirror 35 and enters the liquid crystal light valve 36. Meanwhile, the color light reflected by the dichroic mirror 31 is incident on the dichroic mirror 32, the green light L _G is reflected by the dichroic mirror 32, is incident on the liquid crystal light valve 37. On the other hand, the dichroic mirror 32 the blue light L _B transmitted through the relay lens 41, reflecting mirror 33, a relay lens 42, reflecting mirror 34, is incident on the liquid crystal light valve 38 through a relay system 45 comprising a relay lens 43.

  The three color lights are respectively incident on the corresponding liquid crystal light valves 36, 37, and 38, modulated based on an image signal from a control unit 70 described later, and emitted toward the cross dichroic prism 39. The three color lights incident on the cross dichroic prism 39 are combined here to form light representing a color image. The synthesized light is projected on the screen S by the projection lens 40 which is a projection optical system, and an enlarged image is displayed.

Next, the effect | action in the light control part 50 is demonstrated.
As shown in FIG. 2, the dimming unit 50 receives the horizontal / vertical synchronization signal and the image signal, and branches to the image analysis unit 51 and the image processing unit 52, respectively.
As shown in FIG. 3, the horizontal / vertical synchronization signal and the image signal input to the image analysis unit 51 are first input to the histogram generation unit 53 to generate a histogram used for analysis of the image signal. The histogram shows the gradation distribution included in the image, the vertical axis represents the frequency of appearance of the display gradation on the screen, and the horizontal axis represents the gradation. The histogram creation unit 53 extracts a brightness parameter characterizing the brightness of the image from the created histogram. As an extraction method, for example, a method in which the frequency is checked from the bright side and a gradation that has a certain size for the first time can be selected.
In the dimming coefficient determination unit 54, the dimming coefficient is determined from the characteristics of the actual light shielding unit by using a look-up table (Look Up Table; hereinafter referred to as LUT) from the brightness parameter. Similarly, the image processing determination unit 55 determines the image processing coefficient from the brightness parameter and the characteristics of the liquid crystal light valve.

  The dimming coefficient determined by the image analysis unit 51 is input to the stepping motor conversion unit 23b as shown in FIG. In the stepping motor conversion unit 23b, the rotation angle of the stepping motor 23 corresponding to the dimming coefficient is obtained from the stepping motor control table and output to the stepping motor driver 23a. The stepping motor driver 23a controls the stepping motor 23 so that the rotation angle of the stepping motor 23 becomes the input value.

  The image processing coefficient determined by the image analysis unit 51 is input to the image processing unit 52, and the image signal is subjected to expansion processing according to the image processing coefficient in the image processing unit 52 to generate an image signal that is modulated. The The modulated image signal is input to the liquid crystal light valve converters 36b, 37b, and 38b, and the driving voltages of the liquid crystal light valves 36, 37, and 38 corresponding to the image signal modulated by the liquid crystal light valve control table are obtained. It is output to the liquid crystal light valve drivers 36a, 37a, 38a. The liquid crystal light valve drivers 36a, 37a, and 38a control the liquid crystal light valves 36, 37, and 38 with the above driving voltage.

Next, the operation of the calibration unit 60, which is a feature of the present invention, will be described.
First, when the projection display device 10 is activated, the liquid crystal light valve calibration unit 62 instructs the liquid crystal light valve drivers 36a, 37a, and 38a to display a calibration pattern. As the calibration pattern, for example, the logo of the manufacturer of the projection display device 10 or the logo of the product can be used. The brightness of at least a part of the displayed image can be detected by the optical sensor 61 and used for calibration. Anything is possible.
When the calibration pattern is displayed, the stepping motor calibration unit 63 instructs the stepping motor driver 23a to fully open the light shielding plate 21. When the light shielding plate 21 is fully opened and the calibration pattern becomes bright, the stepping motor calibration unit 63 gradually closes the light shielding plate 21 while measuring the brightness of at least a part of the calibration pattern using the optical sensor 61. go.
Based on the measurement result, the stepping motor calibration unit 63 calibrates the relationship between the opening of the light shielding plate 21 and the brightness of the calibration pattern in the stepping motor control table, and converts the calibrated stepping motor control table into a stepping motor conversion. To the unit 23b. When the output of the stepping motor control table is finished, the stepping motor calibration unit 63 instructs the stepping motor driver 23a to fully open the light shielding plate 21.

Next, the liquid crystal light valve calibration unit 62 uses the optical sensor 61 to measure the brightness of the calibration pattern while the liquid crystal light valve drivers 36 a, 37 a, and 38 a use the calibration pattern in the liquid crystal light valves 36, 37, and 38. An instruction is given to change the display gradations in order.
Based on the measurement result, the liquid crystal light valve calibration unit 62 calibrates the relationship between the display gradation in the liquid crystal light valve control table and the brightness of the calibration pattern, and the calibrated liquid crystal light valve control table is used as the liquid crystal light valve. The data is output to the conversion units 36b, 37b, and 38b.
Thus, the calibration by the calibration unit 60 is completed, and thereafter, the projection display apparatus 10 displays an image on the screen S based on the input horizontal / vertical synchronization signal and video signal.

  The calibration of each control table by the calibration unit 60 described above is performed when the input video signal and the horizontal / vertical synchronization signal are switched, for example, the video signal input from the VTR is converted into the video signal input from the PC. It may be performed at a cut edge to be switched. Then, since the calibration of each control table is completed when the next image whose input signal is switched is projected, the quality of the video displayed after the input signal is switched can be maintained. Further, since each control table is automatically calibrated by using a break where the input signal is switched, the projection of the image is not interrupted in order to calibrate the light control means.

  Further, a calibration instruction unit for instructing calibration of each control table may be provided in the calibration unit 60, and the user may perform calibration by pressing, for example, a button provided on the calibration instruction unit via the calibration instruction unit. According to this configuration, since each control table is calibrated based on an instruction from the calibration instruction unit, each control table can be calibrated at a desired timing.

  Further, when the optical sensor 61 constantly monitors the image projected on the screen S and detects a change in the brightness of the image due to a factor other than the projection display device 10, that is, the brightness of the environment changes (in the room Each of the control tables may be calibrated in the case where the illumination of the light is turned on / off. According to this configuration, since it is possible to detect a change in ambient brightness of the projection display device 10, each control table is calibrated according to the change in ambient brightness to maintain the quality of the displayed image. be able to. Note that the optical sensor (environmental brightness detection means) for detecting the change in the brightness of the environment may share the optical sensor 61 or may be provided with a dedicated optical sensor.

  According to the above configuration, the calibration unit 60 is provided even if the amount of light adjusted by the light blocking unit 20 and the liquid crystal light valves 36, 37, and 38 changes from the amount of light set at the time of manufacture due to change over time, for example. The amount of light adjusted by the light shielding unit 20 and the liquid crystal light valves 36, 37, and 38 can be calibrated, and the quality of the displayed image can be maintained.

  Since the calibration unit 60 includes the optical sensor 61, it is possible to more reliably detect a change in the amount of light adjusted by the light shielding unit 20 and the liquid crystal light valves 36, 37, and 38. Therefore, the amount of light adjusted by the light shielding unit 20 and the liquid crystal light valves 36, 37, and 38 can be reliably calibrated, and the quality of the displayed image can be easily maintained.

  The optical sensor 61 detects the brightness of the image projected on the screen S, and measures the amount of light adjusted by the light shielding unit 20 and the liquid crystal light valves 36, 37, and 38. Therefore, it is possible to detect a change in the amount of light adjusted by the light shielding unit 20 and the liquid crystal light valves 36, 37, and 38, and to maintain the quality of the displayed image. Further, not only the change in the amount of light adjusted by the light shielding unit 20 and the liquid crystal light valves 36, 37, and 38 but also the change in the surrounding brightness of the projection display device 10 can be detected. The quality of the displayed image can be maintained by performing the corresponding calibration.

Since each control table of the light shielding unit 20 and the liquid crystal light valves 36, 37, and 38 is automatically calibrated every time the projection display device 10 is activated, when the image is projected, the light shielding unit 20 and the liquid crystal light valves 36, 37, and 38 Calibration is complete. Therefore, the quality of the image displayed after starting up the projection display device 10 can be maintained.
In addition, since the light shielding unit 20 and the liquid crystal light valves 36, 37, and 38 are automatically calibrated at the time of activation, image projection is not interrupted for calibration.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG. 4 and FIG.
The basic configuration of the projection display apparatus according to the present embodiment is the same as that of the first embodiment, but the configuration of the calibration unit is different from that of the first embodiment. Therefore, in the present embodiment, only the periphery of the calibration unit will be described with reference to FIGS. 4 and 5, and the description of the projection display device main body and the like will be omitted.
FIG. 4 is a block diagram showing signal processing in the control unit 90 of the present embodiment.
As shown in FIG. 4, the control unit 90 includes a light control unit 50 that controls the stepping motor 23 and the liquid crystal light valves 36, 37, and 38 according to the input horizontal / vertical synchronization signal and image signal, and a light control unit. And a calibration unit (calibration means) 80 for calibrating 50.

FIG. 5 is a schematic diagram showing the arrangement of the photosensors in the present embodiment.
The calibration unit 80 includes an optical sensor (optical detection means) 81 formed of a photodiode and a stepping motor calibration unit 83 that calibrates and generates a stepping motor control table based on the output of the optical sensor 81.
As shown in FIG. 5, the optical sensor 81 reflects the light reflected from the liquid crystal light valves 36, 37, 38 at a position where the illumination light from the light source 12 on the light source 12 side of the liquid crystal light valves 36, 37, 38 is not blocked. Arranged to detect. The stepping motor calibration unit 83 outputs the calibrated / generated stepping motor control table to the stepping motor conversion unit 23b and also outputs a drive control signal for the stepping motor 23 during the calibration operation to the stepping motor driver 23a.

  Here, the stepping motor control table is a table in which the relationship of the rotation angle of the stepping motor 23 with respect to the output of the image analysis unit 51 is stored. In other words, the opening degree of the light shielding plate 21 with respect to the output of the image analysis unit 51. It is a table that stores the relationship.

Next, the operation of the calibration unit 60, which is a feature of the present invention, will be described.
First, when the projection display device 10 is activated, the stepping motor calibration unit 83 instructs the stepping motor driver 23a to fully open the light shielding plate 21. When the light shielding plate 21 is fully opened, the stepping motor calibration unit 83 gradually closes the light shielding plate 21 while measuring the brightness of the reflected light from the liquid crystal light valves 36, 37, 38 using the optical sensor 81. Go.
Based on the measurement result, the stepping motor calibration unit 83 calibrates the relationship between the opening of the light shielding plate 21 and the brightness of the reflected light in the stepping motor control table, and converts the calibrated stepping motor control table into a stepping motor conversion. To the unit 23b.
Thus, the calibration by the calibration unit 80 is completed, and thereafter, the projection display apparatus 10 displays an image on the screen S based on the input horizontal / vertical synchronization signal and video signal.

According to the above configuration, since the optical sensor 81 measures the amount of light reflected from the liquid crystal light valves 36, 37, 38, the optical sensor 81 blocks light incident on the liquid crystal light valves 36, 37, 38. There is nothing. Therefore, the quality of the displayed image can be easily maintained without being affected by the provision of the optical sensor 81.
In addition, since the configuration of the calibration unit 80 is simpler than that of the first embodiment, the projection display device can be easily manufactured and can be manufactured at a lower cost.

[Third Embodiment]
Next, a third embodiment of the present invention will be described with reference to FIGS.
The basic configuration of the projection display apparatus according to the present embodiment is the same as that of the first embodiment, but the configuration of the calibration unit is different from that of the first embodiment. Therefore, in the present embodiment, only the periphery of the calibration unit will be described with reference to FIGS. 6 to 9, and description of the projection display device main body and the like will be omitted.
FIG. 6 is a block diagram showing signal processing in control unit 110 of the present embodiment. FIG. 7 is a schematic diagram showing the positional relationship between the light shielding plate and the position sensor when the aperture is 100%.
As shown in FIG. 6, the control unit 110 includes a light control unit 50 that controls the stepping motor 23 and the liquid crystal light valves 36, 37, and 38 according to the input horizontal / vertical synchronization signal and image signal, and a light control unit. And a calibration unit (calibration means) 100 for calibrating 50.
As shown in FIG. 7, the calibration unit 100 includes a position sensor (opening detection means) 101 disposed at a position in contact with the light shielding plate 21 when the aperture is 100%. The position sensor 101 is arranged so that its output is input to the stepping motor driver 23a.

Next, the operation of the control unit 110, which is a feature of the present invention, will be described.
FIG. 8 is a schematic diagram showing the positional relationship between the light shielding plate and the position sensor when the aperture is 70%. FIG. 9 is a schematic diagram showing the positional relationship between the light shielding plate and the position sensor when the aperture is 40%.
When a video signal and a horizontal / vertical signal are input to the control unit 110, the dimming coefficient is first determined in the image analysis unit 51 as shown in FIG. Then, the stepping motor converter 23b determines the stepping motor rotation angle corresponding to the dimming coefficient determined according to the stepping motor control table, that is, the aperture of the light shielding plate 21. When the throttle opening is determined, the stepping motor 23 is driven to have the rotation angle determined by the stepping motor driver 23a.
When the determined aperture is less than 100%, for example, when the aperture is 70% (see FIG. 7) or 40% (see FIG. 8), the control of the aperture is performed based only on the dimming coefficient. Yes.

  On the other hand, when the determined opening degree is 100%, the stepping motor driver 23a opens the stepping motor 23 until the position sensor 101 is in contact with the light shielding plate 21 and a signal output is input. Rotate in the direction. That is, in this case, the control of the throttle opening is performed based only on the output of the position sensor 101.

According to the above configuration, when the aperture of the light shielding plate 21 is controlled to 100%, the aperture of the light shielding plate 21 is controlled based on the output of the position sensor 101 and the aperture of the light shielding plate 21 is opened. The degree can be calibrated. Therefore, the aperture of the light shielding plate 21 can be reliably calibrated without being affected by the signal error of the stepping motor driver 23a or the error of the parts of the stepping motor 23, and the quality of the displayed image can be maintained. Can do.
Further, since the position sensor 101 detects and calibrates the opening degree of the light shielding plate 21, the opening degree of the optical diaphragm can be calibrated without interrupting the display of the image.

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in the above-described embodiment, the description has been made by adapting to the three-plate projection display device, but the present invention is not limited to the one adapted to the three-plate projection display device, but a single-plate projection display device. The present invention can be applied to various other projection display devices.

It is the schematic which shows the projection type display apparatus of the 1st Embodiment of this invention. It is the block diagram which showed the signal processing in a control part similarly. FIG. 3 is a block diagram illustrating in detail the inside of an image analysis unit of the light control unit. It is the block diagram which showed the signal processing in the control part of 2nd Embodiment. It is the schematic which shows arrangement | positioning of a photosensor similarly. It is the block diagram which showed the signal processing in the control part of 3rd Embodiment. It is the schematic which shows the positional relationship of a light-shielding plate and a position sensor similarly. It is the schematic which shows the positional relationship of a light-shielding plate and a position sensor similarly. It is the schematic which shows the positional relationship of a light-shielding plate and a position sensor similarly.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Projection type display apparatus, 11 ... Illumination device, 12 ... Light source, 20 ... Light-shielding part (light control means), 21 ... Light-shielding plate (optical diaphragm), 36, 37, 38 ... Liquid crystal light valve (light modulation means), 40 ... Projection lens (projection means), 50 ... Light control section (light control means), 60, 80, 100 ... Calibration section (calibration means) 61, 81 ... Optical sensor (optical detection means), 101 ... Position sensor (opening detection means)

Claims (12)

A light source; a light modulating unit that modulates light from the light source; a projecting unit that projects light modulated by the light modulating unit; and an amount of light projected from the projecting unit based on an image signal. A projection type display device comprising a light control means,
A projection display device comprising calibration means for automatically calibrating the light control means. The calibration means comprises optical detection means for measuring the amount of light adjusted by the light control means,
A projection type display apparatus, wherein the light control means is automatically calibrated based on the output of the optical detection means.   3. The projection type display device according to claim 2, wherein the optical detection unit measures the light amount adjusted by the dimming unit by detecting the brightness of the image projected from the projection unit. The light control means adjusts the amount of light incident on the light modulation means;
3. The projection display device according to claim 2, wherein the optical detection unit measures the amount of light incident on the light modulation unit. The optical detection means is disposed closer to the light source than the light modulation means;
5. The projection display device according to claim 4, wherein the amount of light reflected from the light modulation means is measured.   5. The projection type display device according to claim 1, wherein the calibration means automatically calibrates the light control means when the apparatus is activated.   5. The projection display device according to claim 1, wherein the calibration unit automatically calibrates the light control unit when the image signal is switched. A calibration instruction unit is provided for instructing the calibration means to perform calibration;
5. The projection display device according to claim 1, wherein the calibration unit calibrates the light control unit based on an instruction from the calibration instruction unit. The calibration means includes environmental brightness detection means for detecting the brightness around the projection display device,
6. The projection type display according to claim 2, wherein when the ambient brightness detected by the ambient brightness detection means changes, the calibration means automatically calibrates the light control means. apparatus.   The projection display device according to claim 9, wherein the optical detection unit also serves as the environmental brightness detection unit. The light control means is an optical diaphragm,
The calibration means includes an opening degree detecting means for detecting that the opening degree of the optical diaphragm has reached a predetermined opening degree,
When controlling the opening of the optical aperture to the predetermined opening,
2. The projection type display device according to claim 1, wherein the opening of the optical diaphragm is controlled based on the output of the opening detecting means, and the opening of the optical diaphragm is calibrated. A light source, a light modulation unit that modulates light from the light source, and a projection unit that projects light modulated by the light modulation unit,
A method for controlling a projection display device in which the amount of light projected from the projection means is adjusted based on an image signal,
A control method for a projection display device, wherein an adjustment amount of a light amount projected from the projection means is automatically calibrated.

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