JP2008107575A - Display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display apparatus capable of keeping a good white balance also in a black side area of image information although the display apparatus is of energy-saving. <P>SOLUTION: The display apparatus is provided with: two or more light source devices 3; a light quantity controller 5 for controlling a light quantity of illumination light emitted from these light source devices 3; a signal processor 7 for generating a modulated signal of which the signal strength reflects the brightness information of each color contained in a color video signal; a modulator 9 for controlling the light intensity of the illumination light emitted from each light source device 3 based on the signal strength of the modulated signal; and a maximum value detection device for detecting a 1st color in maximum brightness from the color video signal and a signal strength corresponding to the maximum value of the brightness. The signal processor 7 is so configured as to increase the signal strength of the modulated signal by a 1st modulation amount and also as to decrease the light quantity of the light source devices 3 emitting the illumination light of the 1st color by a 1st controlled variable according to the 1st modulation amount by controlling the operation of the light quantity controller 5. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a display device having a plurality of light sources having different emission wavelengths and modulation elements that respectively modulate light emitted from the light sources.

As such a display device, for example, a display device described in Patent Document 1 described below is known.
This display device is a field-sequential system that performs display by synchronizing sequential switching of light of a plurality of colors incident on a display element and light control on the display element by display data of each color corresponding to a display image Display device.

The display device includes a detecting unit that detects a gradation level of display data, and an adjusting unit that adjusts the intensity of light incident on the display element and a light control amount in the display element based on a detection result of the detecting unit. And.
The detection means detects the gradation level of the maximum brightness of the display data in a predetermined period, and when obtaining the maximum brightness, the adjustment means maximizes the transmittance or reflectance of incident light in the display element. Thus, the light control amount in the display element is adjusted, and the intensity of incident light is adjusted in accordance with the adjusted light control amount.
Thereby, it is possible to save energy by suppressing the brightness of the light source device without reducing the brightness of the image.

JP 2004-233555 A

In this display device, the light control amount of the display element corresponding to the light source and the intensity of light incident on the display element are adjusted individually for each color light.
Further, in this display device, the adjustment of the light control amount is performed by adjusting the light control amount in the display element and adjusting the intensity of light incident on the display element based on the gradation level of the maximum brightness of the display data. It is carried out.

In the simplest adjustment of the light control amount, the display element is configured so that the relationship between the intensity of the input control signal and the transmittance or reflectance of the incident light is monotonously increased, and the adjustment means is displayed. A control signal having an intensity proportional to the gradation level of the display data is input to the element, and the maximum intensity of the control signal is the input saturation signal value of the display element at the gradation level of the maximum brightness of the display data. In addition, the control signal can be realized by amplifying at a constant amplification factor.
In this method, in the brightest region of the display data, the light amount of the color for which the light amount control is performed does not change before and after the color light amount control, and the brightness balance with respect to the light of other colors is maintained. That is, white balance is maintained in the brightest area in the display data.

However, in this method, since the amplification factor of the control signal by the adjusting means is constant, the white balance is lost in the area where the brightness is low (black area) in the display data.
Specifically, since the intensity of the original control signal is small in a region where the brightness gradation level is small in the display data, the amplification width of the control signal by the adjusting means is small compared to the brightest region.
For this reason, as the brightness of the display data is smaller, the light amount of the color for which the light amount control is performed decreases after the color light amount control, and the white balance is lost.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a display device that can maintain a good white balance even in a black region of image information while saving energy.

In order to achieve the above object, the present invention provides the following means.
The present invention is a display device that displays multicolor image information based on a color video signal in which luminance information for each color is reflected in signal intensity, and a plurality of light source devices that emit illumination light of different colors; A light amount control device for individually controlling the amount of illumination light emitted from each of these light source devices, and for each color included in the color video signal by performing signal processing on the color video signal having an intensity equal to or less than an input saturation signal value A signal processing device that generates a modulation signal in which the luminance information is reflected in the signal intensity, and the intensity of the illumination light emitted from each light source device is individually controlled based on the signal intensity of the modulation signal, and the luminance for each color A modulation device that generates projection light in which information is reflected; a first color that has a maximum luminance from luminance information for each color included in the color video signal; and a maximum luminance of the first color Signal strength corresponding to the value And a saturation determination for determining whether the signal intensity corresponding to the maximum value of the luminance of the first color detected by the maximum value detection device has reached the input saturation signal value of the signal processing device. And when the saturation determination device determines that the maximum value of the detection value of the maximum value detection device has not reached the input saturation signal value, the saturation determination device. As a result, the signal intensity of the modulation signal is increased by a first modulation amount as compared with the case where the maximum value of the detection value of the maximum value detection device has reached the input saturation signal value. The first color corresponding to the first modulation amount is set so that the luminance of the first color of the light is equal to the luminance determined by the luminance information of the first color included in the color video signal. The first color illumination light is controlled by a controlled amount. To provide a display device that is configured to reduce the intensity of the light source device for morphism.

In the display device configured in this way, the signal strength corresponding to the maximum value of the luminance of the first color, which is the color with the maximum luminance, does not reach the input saturation signal value of the signal processing device by the saturation determination device. When the signal processing device determines that the signal intensity of the modulation signal is equal to the first modulation amount compared to the case where the saturation determination device has detected that the maximum value of the detection value of the maximum value detection device has reached the input saturation signal value. Only increase.
Thereby, the modulation device increases the intensity after modulation of the illumination light emitted from all the light source devices.

Here, as the modulation device, a filter (for example, a transmissive LCD (Liquid Crystal Display)) that controls the transmission amount of illumination light emitted from each light source device to the projection position, and illumination light emitted from each light source device A reflection device (for example, a reflective LCD or DMD (Digital Micromirror Device, registered trademark)) is used to reflect the light toward the projection position.
In such a modulation device, the intensity of the illumination light after modulation can be increased by increasing the transmittance or reflectance of the illumination light.
Further, by configuring the modulation device to set the first modulation amount so that the intensity of the modulation signal is equal to the input saturation signal value, the loss amount of the first color light by the modulation device is minimized. In addition, since the light amount of the light source device that emits the illumination light of the first color can be minimized, energy consumption can be minimized.

On the other hand, the light amount control device reduces the light amount of the light source device that emits the illumination light of the first color by the first control amount corresponding to the first modulation amount.
As a result, the luminance of the first color in the projection light becomes equal to the luminance determined by the luminance information of the first color included in the color video signal.
Thus, in this display device, when the signal intensity corresponding to the maximum value of the luminance of the first color, which is the color having the maximum luminance, does not reach the input saturation signal value of the signal processing device, the first It is possible to save energy by reducing the light amount of the light source device that emits the illumination light of the first color without reducing the luminance of the first color.

In this display device, the light amount control device reduces the light amount only for the light source device that emits the illumination light of the first color, whereas the signal processing device controls the signal intensity itself of the modulation signal. That is, the modulation device increases the intensity of the illumination light emitted from all the light source devices.
For this reason, in this display device, the white balance of the image information is maintained not only in the vicinity of the maximum luminance but also in a low luminance region (black side region).
Further, in this display device, the saturation determination device determines that the signal intensity corresponding to the maximum luminance value of the first color, which is the color with the maximum luminance, has not reached the input saturation signal value of the signal processing device. In this case, the temporal contrast of the display image can be increased by reducing only the black level (brightness) without destroying the white balance.

Here, the modulation device is a filter that controls a transmission amount of the illumination light emitted from each of the light source devices to a projection position, and the first processing amount is an input signal intensity to the signal processing device. X1, the output signal strength from the signal processing device is X1 ′, the maximum value of the signal strength detected by the maximum value detection device is a, and the input saturation signal value of the signal processing device is A,
X1 '= A / a × X1
And the first control amount is defined as T1 for the transmittance of the modulation device for the first color, and this transmittance is T1 =
Let L1o be the light amount before the light amount control of the light source device that has the modulation characteristic of f1 (X1 ′) and emit the illumination light of the first color, and let L1a be the light amount after the light amount control corresponding to the detection value a. ,
L1a = L1o × f1 (a) / f1 (A)
It can be.

In the signal processing device, when the saturation determination device has reached the signal intensity corresponding to at least the maximum value of the luminance of the first color among the color video signals to the input saturation signal value of the signal processing device. When it is determined, the light intensity control is performed for each color n whose luminance information signal intensity does not reach the input saturation signal value of the signal processing apparatus. In this light intensity control, the input signal to the signal processing apparatus is Xn, when the output signal from the signal processing device is Xn ′, the maximum value of the signal intensity detected by the maximum value detection device is a, and the input signal saturation value of the signal processing device is A, the modulation device Tn is the transmittance for the nth color, and this transmittance is Tn =
When the modulation characteristic is fn (Xn ′), the first processing amount Xn ′
= hn (Xn) is
Xn '= hn (Xn) = fn ^-1 (fn (A) / fn (a) × fn (Xn))
And
The first control amount is Lno as the light amount before the light amount control of the color n, and Lna as the light source light amount corresponding to the detection value a.
Lna = Lno × fn (a) / fn (A)
It may be.
In this case, even when the signal intensity corresponding to the maximum luminance value for some colors reaches the input saturation signal value of the signal processing device, the white balance on the black side should be kept good while saving energy. Can do.

  Further, in the signal processing device, a numerical value obtained by putting each variable in an arithmetic expression for calculating the first processing amount and an arithmetic expression for calculating the first control amount in advance is stored in a table format. A storage device is further provided, and the signal processing device calls and calls the value of the first processing amount and the value of the first control amount corresponding to the current signal information from the first storage device. The modulation signal may be generated based on the value of the first processing amount and the value of the first control amount.

  In this case, since the modulation signal is generated based on the first processing amount and the first control amount that are calculated in advance, the time for calculating the first processing amount and the first control amount is determined. This eliminates the need for the modulation signal generation process.

  The signal processing device further includes a second storage device that stores an arithmetic expression for calculating the first processing amount and an arithmetic expression for calculating the first control amount, and the signal processing device The first storage device is called up from the second storage device to obtain the first processing amount and the first control amount under a plurality of different conditions by using the calculation equations. After that, the first processing amount that is called from the first storage device by calling the value of the first processing amount and the value of the first control amount corresponding to the current signal information is called. The modulation signal may be generated based on a value of the amount and a value of the first control amount.

In the present invention, the first storage device may store the first processing amount and the first control amount corresponding to all of the detection values that can be detected by the maximum value detection device.
In this case, the calculation amount of the signal processing device can be minimized. That is, since a high calculation performance is not required for the signal processing device, an inexpensive signal processing device can be used.

  According to the present invention, it is possible to provide a display device that can maintain a good white balance on the black side while saving energy. Further, the contrast of the display image can be increased depending on the range of the input signal.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First embodiment]
Hereinafter, the display device 1 according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 15. In this embodiment, an example in which the present invention is applied to a liquid crystal projector is shown. The present invention may be applied to a DMD (registered trademark) projector.

The display device 1 displays multicolor image information based on a color video signal in which luminance information for each color is reflected in signal intensity.
The display device 1 includes a plurality of light source devices 3 that emit illumination lights of different colors, a light amount control device 5 that individually controls the amount of illumination light emitted by each of the light source devices 3, and an input saturation signal value or less. A signal processing device 7 that performs signal processing on each of the color video signals R, G, and B of intensity and generates a modulation signal Y in which luminance information for each color included in these color video signals is reflected in the signal intensity; A modulation device 9 that individually controls the intensity of illumination light emitted from the light source device 3 based on the signal intensity of the modulation signal and generates projection light in which luminance information for each color is reflected.

In the present embodiment, a red (R) LED (Light Emitting Diode) 3R, a green (G) LED 3G, and a blue (B) LED 3B are used as the light source device 3.
The light quantity control device 5 is individually provided on the power supply line for each of the LEDs 3R, 3G, and 3B, and controls the light quantity of the LED by independently controlling the current supplied to the corresponding LED. It has current control units 5R, 5G, and 5B and a control device C that controls the operation of these constant current control units 5R, 5G, and 5B.

In the present embodiment, transmissive LCDs 9R, 9G, and 9B that control the transmittance of illumination light emitted from the corresponding light source device 3 are used as the modulation device 9. Each transmissive LCD has pixels that are arranged in a matrix and whose transmittance can be controlled, and by controlling the transmittance individually for each pixel, a luminance distribution is generated in the projection light. .
In other words, the modulation device 9 generates projection light reflecting the luminance information for each color by individually controlling the transmittance of the illumination light emitted from each light source device 3 based on the signal intensity of the modulation signal Y. It is configured.
Here, as the modulation device 9, a reflective type LCD such as a reflective LCD that controls the amount of reflected light or a DMD (registered trademark) that controls the amount of reflected light by controlling the direction of a minute mirror may be used. .

In this embodiment, as the signal processing device 7, signal processing devices 7 R, 7 G, and 7 B are provided on the transmission paths of the color video signals R, G, and B to the modulation elements 9.
Here, as shown in FIG. 2, the LCD used as the modulation device 9 of the present embodiment has a relationship between the intensity of the input signal and the transmittance (V-T characteristics) due to its operating principle. The relationship between the intensity of the input signal and the transmittance is nonlinear in other cases (when the transmittance is in the vicinity of the minimum value and the maximum value). It has characteristics. In FIG. 2, the VT characteristic of the modulation device 9G corresponding to the color video signal G is shown as the VT characteristic of the modulation device 9, but it corresponds to the color video signals B and R of light of other colors. The same applies to the VT characteristics of the modulating devices 9B and 9R.

Therefore, in the present embodiment, the signal processing device 7 generates primary modulation signals R ′ and G′B ′ having signal intensity proportional to the luminance of each color included in the color video signal from the input color video signal. As shown in FIG. 3, the light quantity function processing unit 11 that performs the primary modulation signal generated by the light quantity function processing unit 11 is used as an inverse function of the function that represents the relationship between the intensity and transmittance of the input signal in the modulation device 9. And a VT correction unit 13 for conversion.
Thereby, as shown in FIG. 4, the relationship between the primary modulation signal G ′ and the light quantity E of the projection light transmitted through the modulation device 9 becomes substantially linear. 3 and 4, the green light primary modulation signal G ′ has been described as the primary modulation signal, but the same applies to the primary modulation signals B ′ and R ′ of light of other colors.

Here, the light quantity function processing unit 11 generates a primary modulation signal having a signal intensity proportional to the luminance of the light by performing function processing on the luminance of the corresponding light.
Further, the VT characteristic of the VT correction unit 13 is appropriately set according to the VT characteristic of the modulation device 9. For example, when the VT characteristic of the modulation device 9 exhibits an exponential characteristic as shown in FIG. 5, the VT correction unit 13 serves as the VT characteristic of the modulation device 9 as shown in FIG. 6. Those having a logarithmic VT characteristic that is an inverse function of the characteristic are used.
In the present embodiment, the VT correction unit 13 has a VT correction table in which an input value and an output value corresponding to the input value are recorded. Based on the VT correction table, a primary order is obtained. The modulation signal is converted into the modulation signal Y.

The control device C detects the signal intensity corresponding to the maximum luminance value of each color from the luminance information for each color included in the color video signal, and sets the maximum luminance value detected by each image analysis unit 21. And a control unit (saturation determination device) 23 for determining whether the corresponding signal intensity has reached the input saturation signal value of the signal processing device 7. In the present embodiment, as the image analysis unit 21, image analysis units 21R, 21G, and 12B are provided corresponding to the color video signals of light of each color.
The image analysis unit 21 and the control unit 23 obtain the first color that is the maximum luminance from the luminance information for each color included in the color video signal and the signal intensity corresponding to the maximum luminance value of the first color. The maximum value detecting device is detected.

When the control unit 23 determines that the maximum value of the detection values of all the image detection units 21 has not reached the input saturation signal value, the signal processing device 7, as shown in the graph of FIG. Compared with the case where the maximum value of the detection value of the image analysis unit 21 reaches the input saturation signal value (shown by a broken line in FIG. 7), the signal intensity of the modulation signal is increased as shown by the broken line in FIG. It is configured to increase by one modulation amount. In FIG. 7, the primary modulation signal G ′ of green light is used as the primary modulation signal, but the same applies to the primary modulation signals B ′ and R ′ of light of other colors.
In the light amount control device 5, the light amount control device corresponding to the first color is determined by the luminance information of the first color included in the color video signal in the luminance of the first color of the projection light. The light amount of the light source device 3 that emits the illumination light of the first color is reduced by the first control amount corresponding to the first modulation amount so as to be equal to the luminance.

In the display device 1 configured as described above, as illustrated in FIG. 8, the control unit 23 sets the maximum value of the luminance of the first color that is the color having the maximum luminance (R (red) in FIG. 8). When it is determined that the corresponding signal intensity has not reached the input saturation signal value of the signal processing device 7, the signal processing device 7 detects the detected value of the color video signal detected by the control unit 23 as shown in FIG. The primary modulation signal is generated by increasing the signal intensity of the modulation signal by the first modulation amount as compared with the case where the maximum value of the signal reaches the input saturation signal value.
Thereby, each modulation device 9 increases the intensity after modulation of the illumination light emitted from the corresponding light source device 3. In the present embodiment, each modulation device 9 increases the intensity of the modulated illumination light emitted from the corresponding light source device 3 by improving the transmittance of each pixel.

On the other hand, the light amount control device 5 reduces the light amount of the light source device 3 (LED 3R in this example) that emits the illumination light of the first color by a first control amount corresponding to the first modulation amount.
As a result, the luminance of the first color in the projection light becomes equal to the luminance determined by the luminance information of the first color included in the color video signal.
Thus, in this display device 1, when the signal intensity corresponding to the maximum value of the luminance of the first color, which is the color with the maximum luminance, does not reach the input saturation signal value of the signal processing device 7, Since the light amount of the light source device 3 that emits the illumination light of the first color is reduced without reducing the luminance of the first color, energy saving can be achieved.

In the display device 1, the light amount control device 5 reduces the light amount only for the light source device 3 that emits the illumination light of the first color, whereas all the signal processing devices 7 have their respective modulation signals. Control the signal strength. That is, all the modulation devices 9 increase the intensity of the illumination light emitted from the corresponding light source device 3.
Therefore, in this display device 1, the intensity balance of each light is maintained, and the white balance of the image information is maintained not only in the vicinity of the maximum luminance but also in the low luminance region (black side region). It is.

Hereinafter, an example of a specific operation of the display device 1 will be described. Below, it demonstrates paying attention to light quantity control of green (G) illumination light.
First, it is assumed that the relationship between the primary modulation signal G ′ and the light quantity E of the projection light transmitted through the modulation device 9 is corrected by the VT correction unit 13 to be substantially linear, and a color video signal is input. The bit width on the circuit is a saturation gradation A, and the maximum value of the gradation to be displayed in a certain video scene is a.

Then, the transmittance Tg of the modulation device 9G corresponding to the green light is
Tg = α × G '+ β
(Α and β are constants determined by the characteristics of the modulation device 9G, respectively).
In addition, since G = G ′ when the modulation processing by the signal processing device 7G is not performed,
Tg = α × G + β
It becomes.
On the other hand, when the modulation processing by the signal processing device 7G is performed, (A / a) × G = G ′,
Tg = α × (A / a) × G + β
It becomes.

When the light source light amount of the LED 3G when the light amount control is not performed is Lg0, and the light source light amount when the light amount control is performed is Lga,
Lga = Lg0 × (α × a + β) / (α × A + β)
It becomes.

Next, the projection light quantity of green light before and after the light quantity control is compared.
Eg0 is the amount of green light projected when the amount of light is not controlled, and Ega is the amount of green light projected when the amount of light is controlled.
Eg0 = Lg0 x α x G + β) (1)
Ega = Lga × (α × (A / a) × G + β) (2)
In the graph of FIG. 9, equation (1) is indicated by a broken line and equation (2) is indicated by a solid line.

As can be seen from FIG. 9, in equations (1) and (2), the amount of projection light is the same when G = a, but when G = 0, the ratio of the constant term appears as a difference.
For this reason, when the light amount control according to the present invention is not performed, a desired brightness is not obtained in the dark part of the image information, and the white balance on the dark side is lost.

Therefore, when the saturation gradation is 255 and the maximum gradation is 200, the transmittance Tg of the modulation device 9G is defined by the following equation:
Tg = fg (G ')
The light intensity function of G is defined by
G '= hg (G)
If the light source light amount of the LED 3G when the light source control is not performed is defined as Lgo and the light source light amount controlled by the light source is defined as Lga, the following formula is established because the maximum brightness does not change regardless of the presence or absence of the light source control.
Lga × fg (255) = Lgo × fg (200)
Further, the amount of green light projected from the LED 3G when the light source is not controlled is expressed by the following equation (3) (because G ′ = G).
fg (G) x Lg ₀ (3)
The amount of light projected by the LED 3G when the light source is controlled is expressed by the following equation (4).
fg (hg (G)) × Lga (4)
Therefore, hg (G) satisfying Expression (3) = Expression (4) may be applied to the light quantity function.

As a result, the following equations (5) and (6) are obtained.
Lga = Lgo × fg (200) /
fg (255) (5)
G ′ = hg (G) = fg ⁻¹ (Lgo / Lga × fg (G)) (6)
The processing satisfying the above equations (5) and (6) (control of the modulation amount of the modulation device 9) and the light source light amount control are performed for green light, and the modulation devices 9 corresponding to the remaining colors are also converted to green light. By increasing the modulation amount (transmission amount of each pixel) by the same amount as the corresponding modulation device 9, it is possible to obtain the same projection light amount as in the case where the light amount control is not performed in all gradations, and it is possible to reduce the power consumption of each LED. , Can keep white balance.

Here, in the following, when the relationship between the primary modulation signal G ′ and the light quantity E of the projection light transmitted through the modulation device 9 is substantially linear by VT correction by the VT correction unit 13, that is, the following expression (7 A case where Tg is expressed by a linear function will be described.
Tg = fg (G ′) = α × G ′ + β (7)

In this case, if the light source light amount of the LED 3G when the light source control is not performed is Lgo and the light source light amount controlled by the light source is Lga, the maximum brightness does not change regardless of the presence or absence of the light source control. , (9), (10) must be established.
Lga x fg (A) = Lgo x fg (a) (8)
Lga × (α × A + β) = Lgo × (α × a + β) (9)
Lga = Lgo × (α × a + β) / (α × A + β) (10)

Under the condition that the projected light quantity does not change before and after the light source control, the light quantity function is expressed by a linear function as shown in the following equation (11).
fg (G) × Lg ₀
= fg (G ') x Lga (11)
By transforming equation (11),
(α × G + β) × Lgo = (α × G '+ β) × Lga
Further deformation,
G ′ = (Lgo / Lga) × G + β / α × (Lgo / Lga-1)… (12)
Therefore, the light quantity function is expressed by a linear function as shown in Expression (12).

  Furthermore, in this display device 1, if the signal intensity corresponding to the maximum luminance value of the first color, which is the color with the maximum luminance, has not reached the input saturation signal value of the signal processing device 7 by the control unit 23. If it is determined, the temporal contrast of the display image can be increased by reducing only the black level (brightness) without destroying the white balance.

Hereinafter, the control for maintaining the white balance by reducing the black level while maintaining the maximum brightness under the conditions shown in FIG. 8 will be described.
In FIG. 8, the gradation width of each RGB color video signal is 8 bits (the minimum gradation is 0 and the maximum gradation is 255).
Among the RGB color video signals, in the R system with the highest maximum value, the light source light amount Lra when the light amount control is performed to maintain the maximum brightness before and after the light amount control is expressed by the following equation: .
Lra = Lro × fr (220) /
fr (255)
Further, when performing simple gain control so that the input value of the light quantity function processing unit 11 is 200 and the output value is 255,
R '= hr (R) = R x 255/220
The input signal R pair and the projection light amount Er ′ after the light amount control are
Er '= Lra × fr (R × 255/220)
It can be expressed as

FIG. 10 is a graph showing the change in the projected light amount due to the input signal depending on whether or not the light amount is controlled.
In the display device 1, it is necessary to perform light amount control in the G system and the B system so that the white balance is the same as that in the case where the light amount control is not performed with reference to the R system subjected to light amount control.
First, the same simple gain as the R system in the G system and B system light intensity function processing unit,
G '= hg (G) = G × 255/200
B '= hb (B) = B × 255/200
To maintain the maximum brightness,
Lga = Lgo × Lra / Lro
Lba = Lbo × Lra / Lro
By doing so, contrast enhancement and white balance are maintained while maintaining the maximum brightness.
That is, when the maximum value in the image analysis unit is less than the maximum bit width (255) for both RGB, the gain of the video signal and the light amount control are performed at the same ratio according to the highest value. Contrast emphasis mode is possible, and even when the maximum value in the image analysis unit is less than the maximum bit width (255), RGB is independent of the light source and video signal processing, and the energy saving emphasis mode is Is possible.

Here, a case has been described in which the maximum luminance value determined by the image analysis unit 21 is 255 or less (200) for all colors of light. However, when the maximum luminance value for any of RGB is the maximum bit width (255), it is possible to save energy by independently processing the light source and the video signal for each of RGB.
Hereinafter, a case where only the green light has a maximum luminance value of 255 or less (200) will be described.
As shown in FIG. 11 (a), the maximum value of the luminance of blue light is 255, and as shown in FIG. 11 (b), the maximum value of the luminance of green light is 200. As shown, when the maximum value of the luminance of red light is 255, the LED 3G is controlled so that the following expression (13) is established.
Lga = Lgo × fg (200) /
fg (255) (13)
Further, the green light component of the color video signal is processed by the light quantity function processing unit 11G so as to satisfy the following expression (14).
G '= fg ^-1 (Lgo / Lga × f (G))
= fg ^-1 (fg (255) / fg (200) x fg (G)) (14)
Note that light amount control is not performed for the red light component and the blue light component of the color video signal.

Here, when Tg = fg (G) is a linear function as shown in FIG. 9, the light quantity function is expressed by the above-described equation (12). In this case, since the calculation by the light quantity function processing unit 11 is only multiplication and addition, the light quantity function processing unit 11 can be configured with a very simple circuit.
In this case, if the level of each RGB video signal input to the image analysis unit 21 is equal to or lower than the saturation gradation (255 for 8 bits), it can be handled regardless of the stage. (Because it is not a table method).
In this case, for example, as shown in FIG. 12, the display device 1 is provided with a ROM 31 (first storage device) that stores an arithmetic expression used for light amount control, and the control unit 21 stores the arithmetic expression in the light amount function processing unit 11. It is possible to adopt a configuration in which information is sent and the light quantity function processing unit 11 processes a color video signal based on this arithmetic expression.

この場合には、光量関数処理部１１を構成する演算回路が複雑となる。そこで、図１３に示すように、ROM３１には演算式のみ格納しておき、装置起動時に制御部２３に設けられるCPU(図示せず)が、演算式を用いてそれぞれ各変数を入れて求めた第１の処理量及び第１の制御量をテーブルとして、制御部２３に設けられたRAM３２（第二記憶装置）上に生成し、このテーブルから現状に該当する第１の処理量及び第１の制御量を呼び出して利用するようにしてもよい。
この場合には、光量関数処理部１１は、予めRAM３２上に生成しておいた第１の処理量及び第１の制御量の情報に基づいて変調信号を生成するので、第１の処理量及び第１の制御量を算出するための時間が不要となり、変調信号の生成処理を迅速に行うことができる。 Also, as shown in FIG. 5, when the characteristics of the input signal and the LCD transmittance are expressed by a complicated function, other configurations can be adopted.
For example, the characteristics of the input signal and LCD transmittance are expressed by the following equation (15)
T = αG ' ^2.2
+ β (15)
GG ′ characteristic of the light quantity function processing unit is expressed by the following function.

In this case, the arithmetic circuit constituting the light quantity function processing unit 11 becomes complicated. Therefore, as shown in FIG. 13, only the arithmetic expression is stored in the ROM 31, and a CPU (not shown) provided in the control unit 23 when the apparatus is activated is obtained by entering each variable using the arithmetic expression. The first processing amount and the first control amount are generated as a table on the RAM 32 (second storage device) provided in the control unit 23, and the first processing amount and the first corresponding to the current state are generated from this table. You may make it call and use a control amount.
In this case, the light quantity function processing unit 11 generates the modulation signal based on the information on the first processing amount and the first control amount generated in advance on the RAM 32. Time for calculating the first control amount is not required, and the modulation signal generation process can be performed quickly.

In addition, when the configuration in which the information on the first processing amount and the first control amount is held as a table in this way is adopted, the levels of the RGB video signals input to the image analysis unit 21 are saturated. The same value may be applied to a plurality of gradations in a tone (255 for 8 bits) or less. Specifically, the same value may be applied as the first processing amount and the first control amount when the luminance is 255 and when the luminance is 254.
As a result, it is not necessary to store information on the first processing amount and the first control amount for all gradations. Thereby, the capacity of the ROM can be reduced, and the manufacturing cost can be reduced.

  Further, without storing the arithmetic expression in the RAM 32, numerical values obtained by putting each variable in the arithmetic expression for calculating the first processing amount and the arithmetic expression for calculating the first control amount in advance are stored in a table format. Then, the signal processing device 7 calls the first processing amount value and the first control amount value corresponding to the current signal information from the RAM 32, and calls the first processing amount value and the first control amount value. The modulation signal may be generated based on the value of the control amount.

  In this case, since the signal processing device 7 generates the modulation signal based on the first processing amount and the first control amount calculated in advance, the first processing amount and the first control amount are set. Time for calculation is not required, and modulation signal generation processing can be performed quickly.

In the present invention, as shown in FIG. 14, the RAM 31 may store the first processing amount and the first control amount corresponding to all the detection values that can be detected by the maximum value detection device. .
In this case, the calculation amount of the signal processing device can be minimized. That is, since a high calculation performance is not required for the signal processing device, an inexpensive signal processing device can be used.
In addition, even when T = f (x) has a curve that cannot be expressed by a function, the corresponding first processing amount and first control amount can be obtained.
Here, if the capacity of the ROM 31 can be large, all tables corresponding to all values detected by the maximum value detecting means are provided.
If the capacity of the ROM 31 is not large enough, the same numerical value may be applied as a plurality of detected values of the maximum value detecting means.

It is a block diagram which shows schematic structure of the display apparatus which concerns on 1st embodiment of this invention. It is a graph which shows the VT characteristic of the modulation apparatus used for the display apparatus which concerns on 1st embodiment of this invention. It is a graph which shows the VT characteristic of the VT correction | amendment part provided in the signal processing apparatus used for the display apparatus which concerns on 1st embodiment of this invention. It is a graph which shows the relationship between the primary modulation | alteration signal of the display apparatus which concerns on 1st embodiment of this invention, and the light quantity of the projection light which permeate | transmitted the modulation apparatus. It is a graph which shows the other example of the VT characteristic of the modulation apparatus used for the display apparatus which concerns on 1st embodiment of this invention. It is a graph which shows the other example of the VT characteristic of the VT correction | amendment part provided in the signal processing apparatus used for the display apparatus which concerns on 1st embodiment of this invention. It is a graph which shows operation | movement of the signal processing apparatus used for the display apparatus which concerns on 1st embodiment of this invention. It is a graph which shows the luminance distribution (number of pixels which take each gradation) for every color. It is a graph which shows the difference of the projection light quantity of the green light when not performing light quantity control concerning this invention, and the projection light quantity of the green light when performing light quantity control. It is a graph which shows the difference of the projection light quantity of the red light when not performing light quantity control concerning this invention, and the projection light quantity of the red light when performing light quantity control. It is a graph which shows the luminance distribution (number of pixels which take each gradation) for every color. It is a block diagram which shows the other example of a display apparatus which concerns on this invention. It is a block diagram which shows the other example of a display apparatus which concerns on this invention. It is a block diagram which shows the other example of a display apparatus which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Display apparatus 3 Light source apparatus 5 Light quantity control apparatus 7 Signal processing apparatus 9 Modulation apparatus 21 Image analysis part (maximum value detection apparatus)
23 Control unit (maximum value detection device, saturation judgment device)
31 ROM (first storage device, second storage device)

Claims (6)

A display device that displays multicolor image information based on a color video signal in which luminance information for each color is reflected in signal intensity,
A plurality of light source devices that emit illumination light of different colors;
A light amount control device for individually controlling the amount of illumination light emitted by each of these light source devices;
A signal processing device that performs signal processing on the color video signal having an intensity equal to or less than an input saturation signal value, and generates a modulation signal in which luminance information for each color included in the color video signal is reflected in the signal intensity;
A modulation device that individually controls the intensity of illumination light emitted from each light source device based on the signal intensity of the modulation signal, and generates projection light in which luminance information for each color is reflected;
Maximum value detection device for detecting a first color that is the color having the maximum luminance and a signal intensity corresponding to the maximum value of the luminance of the first color from the luminance information for each color included in the color video signal. And a saturation determination device that determines whether the signal intensity corresponding to the maximum value of the luminance of the first color detected by the maximum value detection device has reached the input saturation signal value of the signal processing device,
When the saturation determination device determines that the maximum value of the detection value of the maximum value detection device has not reached the input saturation signal value, the signal processing device uses the saturation determination device to detect the maximum value detection device. The signal intensity of the modulated signal is increased by a first modulation amount compared to the case where the maximum value of the detected value has reached the input saturation signal value,
The light amount control device is configured to control the first modulation so that the luminance of the first color in the projection light is equal to the luminance determined by the luminance information of the first color included in the color video signal. A display device configured to reduce a light amount of a light source device that emits illumination light of the first color by a first control amount corresponding to the amount. The display device according to claim 1,
The modulation device is a filter that controls a transmission amount of illumination light emitted from each light source device to a projection position;
The first throughput is
The input signal strength to the signal processing device is X1, the output signal strength from the signal processing device is X1 ′, the maximum value of the signal strength detected by the maximum value detection device is a, and the input saturation of the signal processing device If the signal value is A,
X1 '= A / a × X1
And
The first control amount is
The transmittance for the first color of the modulator is T1, and this transmittance is T1 =
Let L1o be the light amount before the light amount control of the light source device that has the modulation characteristic of f1 (X1 ′) and emit the illumination light of the first color, and let L1a be the light amount after the light amount control corresponding to the detection value a. ,
L1a = L1o × f1 (a) / f1 (A)
Display device. The display device according to claim 1,
In the signal processing device, it is determined by the saturation determination device that the signal intensity corresponding to at least the maximum luminance value of the first color among the color video signals has reached the input saturation signal value of the signal processing device. When
For each color n where the signal intensity of the luminance information does not reach the input saturation signal value of the signal processing device, the light amount control is performed,
In this light control,
The input signal to the signal processing device is Xn, the output signal from the signal processing device is Xn ′, the maximum value of the signal intensity detected by the maximum value detection device is a, and the input signal saturation value of the signal processing device Is A,
When the transmittance for the nth color of the modulator is Tn, and the transmittance has a modulation characteristic of Tn = fn (Xn ′),
Xn ′ = hn (Xn) which is the first processing amount is
Xn '= hn (Xn) = fn ^-1 (fn (A) / fn (a) × fn (Xn))
And
The first control amount is
When the light amount before the light amount control of the color n is Lno, and the light source light amount corresponding to the detection value a is Lna,
Lna = Lno × fn (a) / fn (A)
Is a display device. The display device according to claim 2 or 3,
A first storage device that stores, in a tabular form, numerical values obtained by putting each variable in an arithmetic expression for calculating the first processing amount and an arithmetic expression for calculating the first control amount in advance in the signal processing device. Further provided,
The signal processing device calls the first processing amount and the first processing amount value corresponding to the current signal information from the first storage device, and calls the first processing amount. A display device configured to generate the modulation signal based on the value of the first control amount and the value of the first control amount. The display device according to claim 4,
The signal processing device further includes a second storage device that stores an arithmetic expression for calculating the first processing amount and an arithmetic expression for calculating the first control amount,
The signal processing device calls each arithmetic expression from the second storage device at the start of operation, and uses the arithmetic expressions to perform the first processing amount and the first control under a plurality of different conditions. Determining the amount and storing it in the first storage device;
Thereafter, the first processing amount value and the first control amount value corresponding to the current signal information are called from the first storage device, and the called first processing amount value and A display device configured to generate the modulation signal based on a value of the first control amount. The display device according to claim 4,
The display device in which the first storage device stores the first processing amount and the first control amount corresponding to all of the detection values that can be detected by the maximum value detection device.

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