JP2007072208A - Projector device, lamp drive control device, lamp drive control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control luminance corresponding to a picture signal, reduce power consumption, and stabilize lamp drive power in a projector device which uses a high-pressure discharge lamp, such as HID lamp as the light source. <P>SOLUTION: A fixed luminance control for controlling the lamp drive power so that the luminance is kept fixed based on the sample value of the lamp drive voltage, and the luminance reduction control for reducing the amount of emission of the lamp corresponding to the luminance information of the picture signal are performed, in a time-sharing manner. Since the luminance reduction control according to the picture signal can be performed by adjusting the amount of emission of the lamp itself, the power consumption can be reduced by the corresponding amount required for the adjustment carried out. Also, since the conventional fixed luminance control of the lamp, based on the sample value, can be maintained, the lamp drive power can be kept at a level more stable than when the fixed luminance control such as this is not carried out. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  INDUSTRIAL APPLICABILITY The present invention is suitable for being applied to a projector device that modulates light from a light source by a light modulation element such as a liquid crystal panel according to a video signal, and projects this as a video image on a screen or the like. The present invention relates to a lamp drive control device and a lamp drive control method.

2. Description of the Related Art Conventionally, projector apparatuses that use a high-pressure discharge lamp such as an HID (High Intensity Discharge) lamp as a light source have been widely used.
Thus, in a projector apparatus using a high-pressure discharge lamp as a light source, control is performed so that lamp power is always emitted under constant power control.
FIG. 5 shows an example of such lamp constant power control.
As shown in the “lamp driving waveform” in this figure, high-pressure discharge lamps such as HID are driven by alternating current. In this case, in the lamp constant power control, the lamp driving voltage value is sampled at a sample timing of a predetermined cycle shown in the drawing, and based on the difference between this sample value and a preset target value, the sample value = target value. To control the drive power level. Accordingly, the lamp is controlled so as to always have a constant light emission amount.

At this time, a value corresponding to the rated voltage value of the lamp is set as the target value, and the lamp is driven so as to be always constant at the rated power. As a result, deterioration of the lamp light emission performance and the like are prevented, and a stable light emission operation is obtained.
Further, by keeping the drive power stable in this way, the operation of the power supply circuit to the lamp drive circuit is also kept stable.

By the way, in various image display apparatuses including a projector apparatus, it is required to increase the contrast of a display image.
In order to meet such a demand, particularly in an image display device that is not a self-luminous type, as shown in so-called APL (average luminance) control, when the display image is entirely dark, the light from the light source is further darkened. Control is to be done. That is, by performing such control, for example, the contrast ratio of a bright image: dark image is usually 500: 1, but the contrast ratio is 5000: It can be expanded to 1.

  However, in the projector device, the lamp is always controlled to emit light with a constant luminance as described above. As a configuration for achieving such high contrast, for example, in the optical path A liquid crystal shutter, an iris (iris) diaphragm, and the like are inserted. That is, as long as the light quantity of the light source is always constant, the light transmittance must be adjusted by the liquid crystal shutter and the diaphragm in order to reduce the light.

Note that the following patent document describes a technique for adjusting the amount of light using a liquid crystal shutter.
JP-A-8-21977

However, when a mechanical device such as an iris diaphragm is used, there is a problem in the response speed of the light amount adjustment, which is limited in this respect. Further, when a liquid crystal shutter is used, it is difficult to ensure reliability because the amount of light of projection is large.
In any case, when these methods are adopted, power for driving a device separately provided for light amount adjustment is required, and power consumption cannot be reduced correspondingly. Arise.

Therefore, in the present invention, in view of the above problems, the projector apparatus is configured as follows.
That is, a lamp as a light source, a projection light generating means for obtaining projection light for performing video display by modulating light emitted from the lamp according to a video signal, and a lamp for performing light emission drive control of the lamp Drive control means.
Then, the lamp drive control means controls the brightness of the lamp so that the light emission amount of the lamp becomes constant based on the sample value of the drive voltage of the lamp, and the light emission amount of the lamp as a video. The luminance reduction control for reducing the luminance information according to the signal luminance information is performed in a time-sharing manner.

  According to the above configuration, the conventional constant luminance control of the lamp based on the sample value and the luminance reduction control for reducing (decreasing) the light emission amount of the lamp according to the luminance information of the video signal are performed in a time-sharing manner. . According to this, the luminance can be reduced by the lamp emission amount itself according to the video signal, and the constant luminance control based on the conventional sample value can also be maintained.

In this way, according to the present invention, the luminance adjustment according to the video signal can be performed by adjusting the light amount of the lamp itself. For example, the light amount adjustment is performed by a diaphragm or a liquid crystal shutter separately provided in the optical path. In addition, it is possible to eliminate the need for power for driving the device for adjusting the amount of light. In this respect, power consumption can be reduced.
In addition, since the constant luminance control based on the conventional sample value can be maintained, the lamp driving power can be at a more stable level as compared with the case where the constant luminance control based on the sample value is not performed. it can. By stabilizing the lamp driving power in this way, it is possible to suppress deterioration of the lamp light emission performance and obtain a more stable light emission operation. Furthermore, if the lamp driving power is stabilized in this way, the operation of the power supply circuit that supplies power to the lamp driving circuit can be kept stable.

  Furthermore, if the luminance reduction control can be performed as described above, the lamp driving power can be reduced as compared with a case where this is not performed (a case where constant luminance control is always performed). For example, in the configuration using the above-described diaphragm, liquid crystal shutter, or the like as a configuration for performing brightness adjustment according to the same video signal, the lamp light amount itself is constantly controlled to be constant. Although not shown, according to the present invention, by adjusting the brightness, the lamp driving power can be reduced at the same time.

Hereinafter, the best mode for carrying out the invention (hereinafter referred to as an embodiment) will be described.
FIG. 1 is a block diagram showing an internal configuration of a projector 1 as a projector apparatus according to an embodiment.
The projector 1 is a rear projection type projector apparatus. Further, a transmissive liquid crystal panel is adopted as a light modulation element that modulates light from a light source according to a video signal, and three transmissive liquid crystal panels corresponding to three primary colors of R, G, and B are used. A so-called 3LCD (Liquid Crystal Display) type configuration is provided.

In FIG. 1, the projector 1 is provided with a video input terminal tVin for inputting a video signal. The video signal input from the video input terminal tVin is input to the video signal input / processing unit 2.
In this case, the input video signal is a video signal according to the NTSC (National Television System Committee) system, and the frame rate is 60 Hz.

The video signal input / processing unit 2 comprehensively shows a video signal input system and a video signal processing system.
This video signal input / processing unit 2 performs various video signal processing such as contour correction processing on the input video signal, as well as Y-C separation, R, G, B signal generation, and vertical / horizontal synchronization signal detection. Do.
The generated R signal is supplied to the R-LCD drive circuit 3R, the G signal is supplied to the G-LCD drive circuit 3G, and the B signal is supplied to the B-LCD drive circuit 3B. The R-LCD drive circuit 3R, G-LCD drive circuit 3G, and B-LCD drive circuit 3B are also supplied with vertical / horizontal synchronization signals detected by the video signal input / processing unit 2 as described above. The
Further, the video signal input / processing unit 2 supplies the luminance signal separated from the video signal as described above to the controller 4.
The controller 4 will be described later.

  The R-LCD drive circuit 3R, the G-LCD drive circuit 3G, and the B-LCD drive circuit 3B are respectively supplied with an R signal, a B signal, a G signal, and a vertical / horizontal synchronization signal supplied from the video signal input / processing unit 2. Based on this, a drive signal for driving an R-LCD 27R, a G-LCD 27G, and a B-LCD 27B provided in a liquid crystal / optical block 9 described later is generated.

In addition, the projector 1 includes a down chopper circuit 6 and an AC circuit 7 as a light emission drive system for driving the illustrated lamp 8 to emit light.
The down chopper circuit 6 generates a DC output voltage Vout obtained by stepping down the DC power supply voltage Vin supplied from the illustrated power supply circuit 5 to a predetermined voltage level. In this case, the down chopper circuit 6 is configured to vary the level of the DC output voltage Vout according to the value of the output level control signal supplied from the controller 4 as described later.
Further, the AC circuit 7 converts the DC output voltage Vout from the down chopper circuit 6 into an AC based on an AC signal supplied from the controller 4 as described later, and generates a lamp driving voltage Vld.
For convenience of explanation, the output of the power supply circuit 5 shows only one system of only the DC power supply voltage Vin to the down chopper circuit 6, but actually the power supply voltage to each part in the projector 1 is also shown. It is configured to supply.

The lamp 8 is a high-pressure discharge lamp such as an HID (High Intensity Discharge) lamp, and is provided as a light source of the projector 1. The light from the lamp 8 undergoes modulation according to the video signal through a liquid crystal / optical block 9 described below, and is enlarged and projected onto a screen 10 shown in the figure.
The lamp 8 is provided with an igniter circuit (not shown) for starting the lamp lighting, and the lamp 8 starts lighting when a high voltage of about several kilos to several tens of kilovolts is applied by the igniter circuit. Has been.

FIG. 2 shows the internal configuration of the liquid crystal / optical block 9 shown in FIG.
2 also shows the R-LCD drive circuit 3R, G-LCD drive circuit 3G, B-LCD drive circuit 3B, lamp 8, and screen 10 shown in FIG.
First, as the liquid crystal / optical block 9 in this case, after the light from the lamp 8 is condensed by the light source optical system 20 via the IR / UV cut filter in accordance with the adoption of the 3LCD type configuration. A configuration for color separation is adopted.
The light source optical system 20 is composed of two microlens arrays 21 a and 21 b that are a collection of microlenses, a polarization beam splitter (P / S integrator) 22 that aligns the polarization plane of light, and a condenser lens 23.

  The light beam (white light) that has passed through the light source optical system 20 first enters the dichroic mirror 24 that transmits the red light R. Here, the red light R is transmitted and the green light G and the blue light B are reflected. The red light R that has passed through the dichroic mirror 24 is guided to the R-LCD 27R through the field lens 26R after the traveling direction is bent by, for example, 90 ° by the mirror 25 shown in the drawing.

On the other hand, the green light G and the blue light B reflected by the dichroic mirror 24 are separated by the dichroic mirror 28 that transmits the blue light.
That is, the green light G is reflected by the dichroic mirror 28 to bend its traveling direction by 90 °, for example, and guided to the G-LCD 27G via the field lens 26G. The blue light B passes through the dichroic mirror 28 and travels straight, and is guided to the B-LCD 27B via the relay lens 29 → mirror 30 → relay lens 31 → mirror 32 → field lens 26B.

The liquid crystal panels of the R-LCD 27R, G-LCD 27G, and B-LCD 27B are transmissive liquid crystal panels, and drive signals from the R-LCD drive circuit 3R, G-LCD drive circuit 3G, and B-LCD drive circuit 3B, respectively. Are driven individually. That is, the R-LCD 27R is driven by the R-LCD drive circuit 3R, so that an image corresponding to the R component of the input video signal can be obtained. Similarly, the G-LCD 27G is driven by the G-LCD drive circuit 3G, and the B-LCD 27B is driven by the B-LCD drive circuit 3B, so that images corresponding to the G component and B component of the input video signal can be obtained. It has come to be obtained.
These R-LCD 27R, G-LCD 27G, and B-LCD 27B function as light modulation elements whose transmittance changes in accordance with the obtained images.

  The R, G, and B color lights that have been light-modulated through the R-LCD 27R, G-LCD 27G, and B-LCD 27B are incident on a cross dichroic prism 33 serving as light combining means, and are spatially combined. . That is, the red light R is reflected by the reflecting surface 33a and the blue light B is reflected by the reflecting surface 33b in the direction in which the projection lens 34 is disposed. The green light G passes through the reflecting surfaces 33a and 33b, so that the three-color light is combined on one optical axis.

  The synthesized light thus obtained is projected onto the flat screen 10 by the projection lens 34, whereby a color image is enlarged and projected on the screen 10.

Returning to FIG.
The controller 4 is provided to control the operation of the lamp light emission drive system by the down chopper circuit 6-AC circuit 7 described above, and is constituted by a microcomputer including a CPU (Central Processing Unit), ROM, and RAM.
The controller 4 supplies an alternating signal to the alternating circuit 7, thereby generating an alternating voltage with a predetermined period as the lamp driving voltage Vld. In this case, one cycle of the AC signal is set to 60 Hz, for example.

  Further, the controller 4 calculates an APL (average luminance) value for each frame image of the video signal based on the luminance signal supplied from the video signal input / processing unit 2 as described above. Although such an APL value calculation operation is actually realized by software processing, it is shown here as one functional block as the APL calculation unit 4a shown in the figure for convenience.

  Here, the controller 4 itself is configured to perform APL calculation. However, it is also possible to adopt a configuration in which an APL value calculated outside the controller 4 is input.

Furthermore, the controller 4 is configured to be able to perform the operations described below as the lamp power control unit 4b illustrated. The operation of the lamp power control unit 4b is actually realized by software processing, but is shown as one functional block for convenience.
First, the lamp power control unit 4b detects the level of the DC output voltage Vout from the down chopper circuit 6 at a predetermined sampling period (sample value in the figure), and this sample value and a preset target value inside. Based on the above, an output level control signal for causing the DC output voltage Vout to be the target value is supplied to the down chopper circuit 6.
In other words, in this case, as the target value, for example, the rated voltage value of the lamp 8 is set, so that the lamp power control unit 4b allows the level of the DC output voltage Vout from the down chopper circuit 6 to be the rated voltage level of the lamp 8. It is possible to control so that

Further, the lamp power control unit 4b controls the level of the DC output voltage Vout of the down chopper circuit 6 also based on the APL value calculated by the APL calculation unit 4a in the frame period.
That is, the lamp light amount can be controlled according to the luminance information of the video signal.

Here, as a technique for controlling the lamp light amount according to the luminance information of the video signal in this case, a technique that follows so-called APL control is adopted.
As described above, the APL control referred to here is to set the lamp light amount to a darker value when the calculated APL value is less than a predetermined value and the display image is generally dark. It is. That is, by performing such control, for example, the contrast ratio of a bright image: dark image is usually 500: 1, but the contrast ratio is 5000: It can be expanded to 1.

In the present embodiment, this APL control technique is further developed, and the definition of “entirely dark image” is divided into two stages. That is, two values of the first threshold value and the second threshold value are defined as threshold values for the APL value, and the lamp light amount is decreased by one step for a frame image whose APL value is lower than the first threshold value. Further, for the frame image whose APL value is lower than the second threshold, the lamp light amount is decreased by two steps.
In this case, for a frame image whose APL value does not fall below any of these threshold values (that is, an image that is bright overall that does not require APL control), the lamp light quantity is not reduced, that is, the light is emitted at the rated level. To do.

In order to realize such APL control, the first threshold value and the second threshold value are preset in the controller 4 in this case.
Further, information on how much the level of the DC output voltage Vout is reduced when the APL value falls below each threshold is also stored in advance. Here, the level to be reduced when it falls below the first threshold value is assumed to be level Lv-1. Further, the level to be reduced when it falls below the second threshold value is assumed to be level Lv-2.

The lamp power control unit 4b determines whether or not the APL value calculated by the APL calculation unit 4a is greater than or equal to the first threshold value. When the APL value is greater than or equal to the first threshold, there is no need for APL control, so “0” is selected as the level to be reduced.
If the APL value is not less than or equal to the first threshold value (APL value <first threshold value), it is determined whether or not the APL value is less than the second threshold value.
When it is not less than the second threshold (that is, when the second threshold ≦ the APL value <the first threshold), the level Lv−1 is selected as the level to be reduced. On the other hand, if it is below the second threshold, the level Lv-2 is selected.
The lamp power control unit 4b supplies an output level control signal to the down chopper circuit 6 for reducing the level of the DC output voltage Vout by the level selected according to the APL value in this way. . Thus, control can be performed so that the DC output voltage Vout is reduced by a selected level.

Here, as the projector 1 according to the present embodiment shown in FIG. 1, the luminance constant control based on the sample value and the target value described above and the luminance reduction control based on the APL value are performed in a time-sharing manner. It is characterized by the fact that it was made to be performed.
The specific operation will be described with reference to FIG.

FIG. 3 is obtained based on the lamp drive waveform at 100% output (at the rated level) (FIG. 3A), the sample timing for the DC output voltage Vout (FIG. 3B), and the control of this example. It shows about the relationship with the lamp electric power waveform (FIG.3 (c)).
First, as shown in FIG. 3A, one period of the lamp driving voltage Vld in this case is set to 60 Hz in correspondence with the frame period of the input video signal.
As a matter of course, the sampling period in this case is a period earlier than the period of the lamp driving voltage Vld, as can be seen by comparing this lamp driving period and the sample timing in FIG.

In the present embodiment, luminance constant control based on sample values is performed only in the period before and after each sample timing shown in FIG.
That is, in this case, for example, a predetermined period before and after each sample timing is set as the period before and after the sample (colored portion in the figure). Only in the period before and after the sample, brightness constant control based on the sample value is performed.

Here, the luminance constant control based on the sample value will be described. First, the controller 4 (lamp drive control unit 4b) detects the level of the DC output voltage Vout at each sample timing, and the sample value and the above-described explanation. Processing for determining the value of the output level control signal to be supplied to the down chopper circuit 6 according to the difference from the target value is performed (first processing). That is, by performing such first processing, at each sample timing shown in FIG. 3B, the level of the DC output voltage Vout = target according to the difference between the sample value of the DC output voltage Vout and the target value. The value of the output level control signal for setting the value (that is, the absolute value level of the lamp driving voltage Vld = the target value) is determined.
In addition, as a second process in parallel with this, the controller 4 (lamp power control unit 4b) uses the value determined by the first process at the immediately preceding sample timing according to the period before and after the sample. Processing for supplying the output level control signal to the down chopper circuit 6 is performed.
By the two processes of the first process and the second process, for example, according to the start of the period before and after the sample in the period t1-t2 shown in FIG. 3, the sample value at the sample timing immediately before the time t1 (not shown) An output level control signal having a value determined according to the difference from the target value is supplied to the down chopper circuit 6, and thereby, control is performed so that the absolute value level of the lamp driving voltage Vld = the target value.
Also, depending on the start of the period before and after the sample in the next period t3-t4, the value depends on the difference between the sample value and the target value at the immediately preceding sample timing between the immediately preceding time point t1 and time point t2. The output level control signal is supplied to the down chopper circuit 6, and similarly, the control is performed so that the absolute value level of the lamp driving voltage Vld = the target value.

  In this manner, the absolute value level of the lamp driving voltage Vld is controlled to be constant at the rated level as the target value in the period before and after the sample. That is, this controls the lamp light amount (that is, luminance) to be constant at 100% in the period before and after the sample.

In addition, in the present embodiment, the above-described time-division control is performed by performing the luminance reduction control based on the APL value between the periods before and after the sample in which the control to be constant at 100% luminance is performed. Is supposed to be realized.
In FIG. 3C, the level Lv-1 is selected according to the APL value of the first frame image, and the level Lv-2 is selected according to the APL value of the next frame image. The lamp drive waveform is illustrated.

In this case, in the first first frame, every time it is outside the pre-sample period, the level reduced by the selected level Lv−1 from the level of the lamp drive voltage Vld output in the pre-sample period (that is, the rated level). The lamp driving voltage Vld is output.
That is, in this first frame, the controller 4 (lamp power control unit 4b) outputs an output level control signal to be supplied to the down chopper circuit 6 every time outside the pre-sample period. A value obtained by subtracting the value of the output level control signal that has been output by an amount corresponding to the level Lv−1 is output.

In the next second frame, every time it is outside the pre-sample period, the lamp drive voltage Vld is output at a level reduced by the level Lv-2 selected from the level of the lamp drive voltage Vld output in the pre-sample period. To do.
That is, in this second frame, every time the controller 4 (lamp power control unit 4b) goes out of the pre-sample period, the controller 4 (lamp power control unit 4b) outputs a level from the value of the output level control signal output in the pre-sample period. A value obtained by subtracting an amount corresponding to Lv-2 is output.

As described above, according to the lamp driving power control as the present embodiment, there is a conventional constant luminance control based on the sample value and a luminance reduction control for reducing the light amount of the lamp itself according to the luminance information of the video signal. Performed in a time-sharing manner.
Since the brightness adjustment according to the video signal can be performed by adjusting the light amount of the lamp itself, the device for adjusting the light amount is driven, for example, when adjusting the light amount with a diaphragm or liquid crystal shutter separately provided in the optical path. The electric power for doing so can be made unnecessary, and the power consumption can be reduced in this respect.
In addition, since the constant luminance control based on the conventional sample value can be maintained, the lamp driving power can be at a more stable level as compared with the case where the constant luminance control based on the sample value is not performed. it can. By stabilizing the lamp driving power, it is possible to suppress the deterioration of the lamp light emission performance and obtain a more stable light emission operation. Furthermore, if the lamp driving power is stabilized in this way, the operation of the power supply circuit for supplying power to the lamp driving circuit can be kept stable.

  Furthermore, if the luminance reduction control by adjusting the lamp light amount can be performed as described above, the lamp driving power can be reduced as compared with the case where this is not performed (when constant luminance control is always performed). For example, in a configuration that uses the above-described diaphragm, liquid crystal shutter, or the like as a configuration that performs luminance adjustment according to the same video signal, the lamp light amount itself is constantly controlled to be constant. Although not shown, according to this example, the luminance adjustment is performed, and at the same time, the lamp driving power can be reduced.

  Further, since the luminance control is to control the lamp driving power, there is no disadvantage in terms of responsiveness as in the case of performing luminance control (light quantity control) using a mechanical device such as an iris diaphragm.

Here, for the sake of confirmation, as the luminance reduction control of this example, as in the APL control described above, the luminance of an image that is totally dark is further reduced to achieve high contrast. However, it is human beings to experience such a high contrast effect. Therefore, the level Lv-1 and the level Lv-2 that define the reduction range of the luminance are detected by the human luminance difference. It is important to select a level that takes into account the ability. That is, if the values of the level Lv-1 and the level Lv-2 are set to be large, the luminance difference can be easily recognized, and the visual effect can be easily obtained accordingly.
However, on the other hand, it is known that high-pressure discharge lamps such as HID cause blackening of the lamp and the like, and the lamp life tends to decrease if the light emission continues at a level lower than the rated voltage. In consideration of this, the values set as the level Lv-1 and the level Lv-2 are as small as possible so as not to have a great influence on the lamp life within the range where the luminance difference is visually recognized. It is preferable that it is set.

FIG. 4 is a flowchart showing the processing operation to be executed by the controller 4 shown in FIG. 1 in order to realize the lamp driving power control operation as the present embodiment described above.
The processing operation shown in this figure is executed by the controller 4 based on a program stored in, for example, an internal ROM.
Although not shown, the controller 4 (lamp drive control unit 4b) performs the DC output voltage Vout at each sample timing as described above as the first process as a process parallel to the processing operation shown in FIG. The level of the output level control signal is determined according to the difference between the sample value and the target value.

  Further, the processing operation shown in this figure is performed in response to the start of the input of the video signal. In this case, in a state before the start of video signal input, the lamp 8 is driven so as to be constantly constant at the rated level. That is, during this period, the controller 4 performs control so that the lamp light amount is constantly constant based on the value of the output level control signal determined in the first process.

In FIG. 4, first, in step S101, an APL value is referred to. That is, the APL value calculated as the operation of the APL calculation unit 4a shown in FIG. 1 is referred to.
In step S102, the level Lv corresponding to the APL value is selected.
As described above, the level Lv is selected based on the first threshold value and the second threshold value that are set in advance as the threshold value of the APL value. That is, first, it is determined whether or not the APL value is greater than or equal to the first threshold value. When the APL value is greater than or equal to the first threshold, there is no need for APL control, so “0” is selected as the level to be reduced.
If the APL value is not equal to or less than the first threshold value (APL value <first threshold value), it is determined whether the APL value is less than the second threshold value. When the APL value is not less than the second threshold (that is, when the second threshold ≦ the APL value <the first threshold), the level Lv−1 is selected as the level to be reduced. On the other hand, if it is below the second threshold, the level Lv-2 is selected.

In a succeeding step S103, a determination process is performed as to whether or not the period is before and after the sample.
If an affirmative result is obtained that the period is before and after the sample, the process proceeds to step S104, and the value of the output level control signal is switched to a value determined according to the difference between the sample value and the target value. That is, as the second process described with reference to FIG. 3, the value of the output level control signal to be supplied to the down chopper circuit 6 is obtained by calculating the sample value detected at the immediately preceding sample timing by the first process and the target value. The value is switched according to the difference.
According to the processing of steps S101 → S102 → S103 → S104 so far, the luminance constant control based on the sample value is performed when the start time of the first frame period is the period before and after the sample.

If a negative result is obtained in step S103 that the period is not before or after the sample, the value of the output level control signal is switched to a value obtained by subtraction according to the selected level Lv in step S107.
As a result of the processing in steps S101 → S102 → S103 → S107, the luminance reduction control based on the APL value of the frame image is performed when the start time of the first frame period is outside the period before and after the sample. .

Then, in step S105 after executing the process of step S104, assuming that it is the pre-sample period, a determination process is performed as to whether the pre-sample period has ended.
If an affirmative result is obtained because the period before and after the sample has ended, the process proceeds to the previous step S107 to perform a process of switching the value of the output level control signal to a value subtracted according to the selected level Lv. With this process, according to the start of the period outside the pre- and post-sample periods, switching is performed from luminance constant control based on the sample value to luminance reduction control based on the APL value of the frame image.

If a negative result is obtained in step S105 that the period before and after the sample has not ended, a determination process is performed on whether or not one frame period has ended in step S106. If a negative result is obtained that one frame period has not ended, the process returns to the previous step S105, and the determination process for the end of the period before and after the sample is performed again. That is, a process of waiting for either the end of the pre-sample period or the end of one frame period is performed by the loop process of steps S105 → S106 → S105.
If an affirmative result is obtained in step S106 that one frame period has ended, the process returns to step S101, and processing for referring to the APL value is executed. As a result, the newly calculated APL value of the next frame image is referred to at the end of one frame period.

Subsequently, in step S108 after executing the process of step S107 described above as being outside the period before and after the sample, a determination process is performed as to whether or not the period before and after the sample is started.
If a positive result is obtained because the period before and after the sample has started, the process proceeds to step S104 described above, and the value of the output level control signal is switched to a value determined according to the difference between the sample value and the target value. To be. With this process, the luminance reduction control according to the selected level Lv is switched to the luminance constant control based on the sample value in accordance with the start of the period before and after the sample.

If a negative result is obtained in step S108 that the period before and after the sample has not started, a determination process is performed as to whether or not one frame period has ended in step S109. If a negative result is obtained that one frame period has not ended, the process returns to step S108 and the determination process for the start of the period before and after the sample is performed again. In other words, as in the loop processing from step S105 → S106 → S105, depending on the loop processing from step S108 → S109 → S108, the process waits for either the start of the period before and after the sample or the end of one frame period. Is done.
If a positive result is obtained in step S109 that one frame period has ended, the process returns to step S101, and processing for referring to the APL value is executed.

  Although illustration is omitted here, actually, as a process in parallel with the processing operation shown in this figure, the controller 4 turns off the lamp, for example, by giving an instruction to turn off the power of the projector 1. In accordance with the state to be performed, processing for ending the processing operation shown in this figure is performed.

Although the embodiments of the present invention have been described above, the present invention should not be limited to the embodiments described so far.
For example, in the embodiment, the configuration of the projector device using the 3LCD type is exemplified, but the present invention can also be suitably applied to a projector device using a single plate type (1LCD type) that uses only one transmissive liquid crystal panel.
Further, not only when a transmission type liquid crystal panel is used, but also when a DLP (Digital Light Processing: registered trademark) method using a DMD (Digital Micromirror Device) is adopted, or when a reflection type liquid crystal panel is used, SXRD (Silicon X-tal). The present invention can also be suitably applied to the case where the (crystal) Reflective Display (registered trademark) system is adopted.
Moreover, although the case where it applied to a rear projection type was illustrated, it can apply suitably also to a front projection type.

  The projector 1 according to the embodiment is configured to display only the video signal input from the video input terminal Vin. However, the projector 1 includes a tuner device that can receive and select a television broadcast signal. It can also be configured as a television receiver that projects and displays a station image on the screen 10.

In the embodiment, the case where the NTSC signal is input as the video signal has been exemplified. However, the present invention can be suitably applied to the case where another video signal such as a PAL system is input.
In this case, the frame period of the video signal may be other than 60 Hz. In that case, for example, when the luminance adjustment for one frame of the video signal is performed in one cycle of the lamp driving voltage as in the embodiment, If this is the case, one cycle of the lamp driving voltage may be set to coincide with the frame cycle of the video signal.

Further, one cycle of the lamp driving voltage does not necessarily need to coincide with the frame cycle.
For example, there may be a case where the lamp driving voltage cycle and the frame cycle cannot be matched for some reason. Even when the lamp drive voltage period and the frame period cannot be matched in this way, the luminance reduction control is performed according to the APL value of the frame image for each frame period as shown in FIG. By performing control so that the drive voltage is reduced by the selected level Lv, it is possible to perform luminance reduction control according to the APL value for each frame image.

Further, as the luminance reduction control according to the embodiment, the case where two levels of reduction levels are set according to the APL value is illustrated, but for example, one level or three or more levels can be set.
However, when increasing the number of stages, it is necessary to consider the balance between the brightness difference sensing ability and the lamp life described above. In other words, when considering the brightness difference sensing ability, the width between the levels Lv needs to be increased accordingly. Therefore, when the number of stages is increased, the reduction range of the driving voltage tends to increase accordingly, and the lamp The possibility of being driven at a relatively low drive voltage level increases. As a result, there is a high possibility that the lamp life will be reduced.
Therefore, the number of levels Lv to be set in the luminance reduction control is not necessarily large, and should be set to an optimum number within a range that does not affect the lamp life.

  Further, in the embodiment, the case where the lamp drive control operation according to the present invention is realized based on the software processing of the microcomputer is exemplified, but the configuration realized by the hardware is realized by such software processing. Thus, the lamp drive control operation of the present invention can be realized only by hardware.

1 is a block diagram showing an internal configuration of a projector apparatus as an embodiment of the present invention. It is the block diagram shown about the structure of the liquid crystal and the optical block with which the projector apparatus of embodiment is provided. It is a figure for demonstrating the lamp drive control operation | movement as embodiment. It is a figure for demonstrating the processing operation which should be performed in order to implement | achieve the lamp drive control operation | movement as embodiment. It is a figure for demonstrating the conventional lamp drive control operation.

Explanation of symbols

  1 projector, 2 video signal input / processing unit, 3R R-LCD drive circuit, 3G G-LCD drive circuit, 3B B-LCD drive circuit, 4 controller, 4a APL calculation unit, 4b lamp drive control unit, 5 power supply circuit, 6 down chopper circuit, 7 AC circuit, 8 lamp, 9 liquid crystal / optical block, 10 screen, 20 light source optical system, 21a, 21b micro lens array, 22 polarizing beam splitter (P / S integrator), 23 condenser lens, 24 28, Dichroic mirror, 25, 30, 32 Mirror, 26R, 26G, 26B Field lens, 27R, R-LCD, 27G, G-LCD, 27B B-LCD, 29, 31 Relay lens, 33 Cross dichroic prism, 33a, 33b Reflecting surface, 34 projection lens

Claims (5)

A lamp as a light source;
Projection light generating means for obtaining projection light for modulating the light emitted from the lamp in accordance with a video signal and performing video display;
Lamp drive control means for performing light emission drive control of the lamp, and
The lamp drive control means includes
Constant luminance control for controlling lamp driving power so that the light emission amount of the lamp becomes constant based on a sample value of the lamp driving voltage, and luminance reduction for reducing the light emission amount of the lamp according to luminance information of the video signal It is configured to perform control and time division,
A projector device characterized by that. The lamp drive control means includes
The value of the drive voltage is sampled at a sampling timing with a predetermined cycle, and constant luminance control based on the sample value is performed only in the period before and after each sampling timing,
In a period outside the period before and after each sampling timing, luminance reduction control is performed according to the luminance information of the video signal.
The projector device according to claim 1. The lamp drive control means includes
The luminance reduction control is performed based on the average luminance information calculated for each frame image of the video signal.
The projector device according to claim 1. In a projector apparatus comprising: a lamp as a light source; and projection light generation means for obtaining projection light for performing video display by modulating light emitted from the lamp in accordance with a video signal, light emission drive control of the lamp A lamp drive control device for performing
Constant luminance control for controlling lamp driving power so that the light emission amount of the lamp becomes constant based on a sample value of the lamp driving voltage, and luminance reduction for reducing the light emission amount of the lamp according to luminance information of the video signal It is configured to perform control and time division,
A lamp drive control device characterized by that. As a lamp drive control method in a projector apparatus comprising: a lamp as a light source; and projection light generation means for obtaining projection light for performing video display by modulating light emitted from the lamp according to a video signal,
Constant luminance control for controlling lamp driving power so that the light emission amount of the lamp becomes constant based on a sample value of the lamp driving voltage, and luminance reduction for reducing the light emission amount of the lamp according to luminance information of the video signal Control was performed in a time-sharing manner,
And a lamp driving control method.

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