JP2007240858A - Lighting device, video display device, and video signal control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lighting device, a video display device, and a video signal control method that can provide an image having a high contrast ratio while suppressing deterioration in an image like a level difference in luminance and variance in light emission efficiency of a light source small. <P>SOLUTION: The lighting device 100 is constituted by arraying at least one or more lighting means 30 each having a short-wavelength light source 40 emitting short-wavelength light and a wavelength converting means 50 of emitting visible light in response to the short-wavelength light as exciting light corresponding to a plurality of lighting regions. Then the lighting device 100 irradiates an optical modulating element adjusting the quantity of light according to a video signal with the visible light as illumination light. Further, the lighting device 100 includes a frequency distribution calculating means 10 of calculating frequency distributions of luminance of the video signal by the plurality of lighting regions based upon luminance information of the video signal and a lighting modulating means 20 of modulating the quantity of the short-wavelength light emitted by the short-wavelength light sources of the one or more lighting means 30 according to the calculated frequency distributions. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an illumination device that illuminates a light modulation element or the like, a video display device that displays an image by modulating the light modulation element according to a video signal and adjusting a transmission amount of illumination light from the illumination device, and an image The present invention relates to a video signal control method used in a display device.

  Unlike CRT (Cathode Ray Tube) and PDP (Plasma Display Panel), a video display device typified by a liquid crystal display or the like is a non-luminous display device, and includes a light modulation element that adjusts the amount of light according to an image signal. And an illumination device for illuminating the light modulation element.

  The light modulation elements are classified into a transmission type light modulation element that adjusts the amount of transmitted light and a reflection type light modulation element that adjusts the amount of reflected light. In particular, a liquid crystal image display device in which a transmissive liquid crystal element (generally called a liquid crystal panel) is used as the former light modulation element and an illuminating device (generally called a backlight) is arranged on the back thereof is generally used as a liquid crystal display. Widely used in society.

  A self-luminous display device typified by a CRT can reduce power consumption in a black display or dark image of an image signal because pixels forming the image of the display device do not emit light or emit a small amount of light. In black display, since no light is emitted, the contrast ratio in the dark room is 10000: 1 or more, and good image quality with black tightening can be obtained.

  On the other hand, the liquid crystal display, unlike the self-luminous type, adjusts the amount of light with the light modulation element, so that the backlight is always lit even in the black display of the image signal. Therefore, since the liquid crystal display consumes the same power as that of white display even in a black display or a dark image, the power consumption cannot be reduced.

  Further, in the black display of the image signal, since the light modulation element has insufficient capability, there is a problem that a part of the backlight light leaks and the black display is not sufficiently darkened. In particular, the contrast ratio in a dark room is generally about 500: 1, and this lack of contrast ratio is one of the problems in improving the image quality of a liquid crystal display.

  In order to improve such a contrast ratio deficiency, a video display device has been proposed in which an illumination area is divided finely and the luminance of a backlight is adjusted (see, for example, Patent Document 1). In Patent Document 1, LEDs (Light Emitting Diodes) serving as a light source of illumination light that irradiates a liquid crystal panel are arranged in a plurality of divided regions, and illumination light is irradiated only on a necessary screen region according to a video signal. LED is controlled per division area.

JP 2001-142409 A (first page, FIG. 1)

  However, the prior art has the following problems. In the conventional backlight for illuminating the divided area, when only a part of the image is bright and the periphery thereof is dark, there is a problem that an undesirable luminance level difference occurs at the boundary of the divided area and the image is deteriorated. .

  Moreover, in order to satisfy uniform illumination, as a premise, it is necessary that the light quantity variation of each light source is within a certain range. However, for example, when an LED is used as a light source, there is a problem that the current LED has a large individual difference in light emission efficiency. For this reason, it takes time and effort to dimm individual LEDs to make adjustments so that they are uniform, or to select only LEDs that generate the same amount of light.

  Even if the light source is adjusted, the light source generates light at the same time as generating light, so that a problem of temperature dependency of luminous efficiency newly occurs. The luminous efficiency of an LED strongly depends on the temperature, and generally, the luminous efficiency tends to decrease as the temperature increases. Especially, since the temperature dependence of the light emission efficiency differs for each color, there is a problem that the color tone changes as the temperature increases. In order to correct this, it is conceivable to arrange an optical sensor in the backlight and adjust the light quantity of the light source for each color in accordance with the temperature, but this causes problems such as an increase in the number of components and control.

  The present invention has been made to solve the above-described problems, and illumination that can provide an image with a high contrast ratio while suppressing image deterioration such as a luminance step and variation in light emission efficiency of a light source. An object is to obtain a device, a video display device, and a video signal control method.

  An illumination device according to the present invention includes at least one illumination unit including a short wavelength light source that emits short wavelength light and a wavelength conversion unit that emits visible light using the short wavelength light as excitation light. In a lighting device that emits visible light as illumination light to a light modulation element that is arranged in accordance with the video signal and adjusts the amount of light according to the video signal, the video signal for each of the plurality of illumination areas based on the luminance information of the video signal Frequency distribution calculating means for calculating the frequency distribution of the brightness of the light source, and illumination modulation means for modulating the light quantity of the short wavelength light emitted from the short wavelength light source of one or more illumination means according to the calculated frequency distribution. It is a thing.

  A video display device according to the present invention includes a lighting device, a video signal modulating unit that modulates a video signal according to a frequency distribution of luminance of the video signal calculated by a frequency distribution calculating unit in the lighting device, and a video And a light modulation element that changes the transmitted light amount of the illumination light from the illuminating device based on the video signal modulated by the signal modulation means and forms an image.

  Furthermore, the video signal control method according to the present invention adjusts the transmitted light amount of the illumination light output from the illumination device having at least one illumination means arranged corresponding to the plurality of illumination areas according to the video signal. A video signal control method for realizing display according to a video signal, the step of calculating a frequency distribution of luminance of the video signal for each of a plurality of illumination areas, and a plurality of illumination means according to the calculated frequency distribution A step of modulating the amount of illumination light output from the light source, a step of reverse correcting the luminance distribution of the video signal using a response function stored in advance as the luminance distribution of the illuminated surface illuminated by the illuminating device, and a reverse correction And a step of modulating the transmitted video signal according to the frequency distribution and adjusting the amount of transmitted light.

  According to the present invention, by modulating and controlling the short wavelength light source according to the luminance frequency distribution of the video signal for each of the plurality of illumination regions, it is possible to suppress degradation of the image due to the luminance step and variation in the light emission efficiency of the light source, An illumination device, a video display device, and a video signal control method that can provide an image with a high contrast ratio can be obtained.

  Hereinafter, preferred embodiments of a lighting device, a video display device, and a video signal control method according to the present invention will be described with reference to the drawings.

Embodiment 1 FIG.
FIG. 1 is an overall configuration diagram of a video display apparatus according to Embodiment 1 of the present invention. The video display device 200 includes an illumination device 100, a video signal correction unit 110, and a video signal modulation unit 120.

  The illumination device 100 includes a frequency distribution calculation unit 10, an illumination modulation unit 20, and M (M is an integer of 1 or more) illumination units 30 (1) to 30 (M). Further, each of the M illumination means 30 (1) to 30 (M) includes a short wavelength light source 40 and a wavelength conversion means 50.

  The illumination device 100 includes a plurality of illumination means 30 (1) to 30 (M) that illuminate the entire illumination area for each of a plurality of divided areas. And the illumination light from these several illumination means 30 (1) -30 (M) will be irradiated toward the liquid crystal panel by which transmitted light amount is adjusted according to a video signal.

  Here, the frequency distribution calculating means 10 in the lighting apparatus 100 of the present invention obtains the luminance frequency distribution of the video signal for each of the plurality of divided regions. Further, the illumination modulation unit 20 performs modulation control on the illumination light output from the plurality of illumination units 30 (1) to 30 (M) based on the frequency distribution for each divided region calculated by the frequency distribution calculation unit 10. . Details of the plurality of illumination means 30 (1) to 30 (M) will be described later.

  On the other hand, the video signal correction unit 110 in the video display device 200 stores in advance the luminance distribution of the illuminated surface illuminated by the plurality of illumination units 30 (1) to 30 (M) as a response function. Then, the video signal correcting unit 110 reversely corrects the luminance distribution of the video signal using a response function stored in advance, and generates a corrected video signal.

  Furthermore, the video signal modulation unit 120 is configured to display liquid crystal on the basis of the frequency distribution for each divided region calculated by the frequency distribution calculation unit 10 in the lighting device 100 and the corrected video signal generated by the video signal correction unit 110. By modulating and controlling the amount of light transmitted through the panel, an image corresponding to the video signal is displayed.

  Next, FIG. 2 is a specific explanatory diagram of the video display apparatus according to Embodiment 1 of the present invention. In FIG. 2, the plurality of illumination means 30 (1) to 30 (M) are arranged on the illumination mounting plate 60. The illumination modulation unit 20 performs modulation control on the drive circuits 21 and 22 based on the frequency distribution calculated by the frequency distribution calculation unit 10, thereby outputting from the plurality of illumination units 30 (1) to 30 (M). Control the illumination light.

  Illumination light output from the plurality of illumination means 30 (1) to 30 (M) is irradiated toward the light modulation element 130 corresponding to the liquid crystal panel. The video signal modulation unit 120 then drives the drive circuits 121 and 122 based on the frequency distribution for each divided region calculated by the frequency distribution calculation unit 10 and the corrected video signal generated by the video signal correction unit 110. By controlling the modulation, the amount of light transmitted through the light modulation element 130 is controlled. As a result, a display image corresponding to the video signal is obtained.

  In FIG. 2, the light diffusing unit 140, the air blowing unit 70, and the waste heat unit 80 are described as other components, and details thereof will be described later.

  Next, the illumination means 30 included in the illumination device 100 will be described. FIG. 3 is a cross-sectional view of the illumination unit 30 according to Embodiment 1 of the present invention. FIG. 4 is a perspective view of the illumination unit 30 according to Embodiment 1 of the present invention. The illumination means 30 is roughly composed of a short wavelength light source 40 and a wavelength conversion means 50.

  Here, the short wavelength light source 40 includes an LED mounting substrate 41, an LED element 42, a mold lens 43, and an LED package substrate 44. LED elements 42 (not shown) that are sources of short-wavelength light are mounted on the LED mounting substrate 41 in a plurality of units. Further, the LED package substrate 44 is formed by covering a plurality of units of LEDs on the LED mounting substrate 41 with a mold lens 43 made of a transparent mold material. Details of this configuration will be described later with reference to FIG.

  On the other hand, the wavelength converting means 50 is provided on the concave surface inside the housing 51. The LED package substrate 44 is attached to the housing side plate 51a and fixed to the housing body 51b, and irradiates the wavelength conversion means 50 with short wavelength light. The short wavelength light irradiated in this way is converted into white light by the wavelength conversion means 50.

  FIG. 5 is a diagram illustrating a spectral distribution of light of the illumination device 100 according to Embodiment 1 of the present invention. In FIG. 5, the horizontal axis indicates the wavelength and the vertical axis indicates the relative intensity. The LED element 42 emits short-wavelength light having a peak in the near ultraviolet region, as indicated by the broken line in FIG.

  On the other hand, the wavelength conversion means 50 provided in the concave surface portion of the casing 51 shown in FIGS. 3 and 4 is light-distributed by a mold lens 43 covering the LED element 42 (not shown in FIG. 3). Using the short-wavelength light as excitation light, white light mixed with a blue emission spectrum, a green emission spectrum, and a red emission spectrum as shown in FIG. 5 is emitted.

  The wavelength converting means 50 is composed of a plurality of phosphors typified by red, green, and blue as described above, and is mixed in consideration of light emission efficiency and color rendering properties. Specifically, a phosphor may be filled in silicone, and a silver reflective sheet (not shown) may be disposed on the back surface in order to efficiently reflect short wavelength light.

  Thus, LED elements that emit single colors of blue, green, and red are not used as light sources, but short wavelength light is used as an excitation light source, and wavelength conversion means 50 emits white light, thereby adjusting LED elements having a large individual difference. Can be simplified. In addition, the luminous efficiency of the LED element that emits a single color varies depending on the temperature for each color, so that the color mixture ratio of blue, green, and red changes with temperature, and the color tone changes as it is.

  On the other hand, in the first embodiment, it is possible to reduce the temperature dependence of the color tone by causing the wavelength conversion unit 50 to emit white light with an excitation light source of short wavelength light. That is, an object is to suppress variations in the most upstream light source by combining a plurality of LED elements having large variations in luminous efficiency due to temperature or the like into a single excitation light source and mixing phosphors in advance to emit white light.

  FIG. 6 is a diagram showing the arrangement of the LED elements 42 for suppressing light source variations in the first embodiment of the present invention. Since the LED element 42 has a large variation in light emission efficiency due to individual differences, a plurality of (three in FIG. 6) LED elements 42 are collectively covered with the mold lens 43 on the LED mounting substrate 41, thereby improving the light emission efficiency. Average the variation. Furthermore, an LED package substrate 44 having a plurality of components (five in FIG. 6) covered with a mold lens is used as a short wavelength light source. This has the effect of reducing the variation in luminous efficiency due to individual differences. In the first embodiment, the number of LED elements in one mold lens 43 is three and the number of mold lenses 43 is five.

  As described above, the LED package substrate 44 in which a plurality of LEDs are molded together is used as the illumination unit 30 on the LED mounting substrate 41. However, the wiring required for the labor and arrangement of wiring is necessary. It arranges on the flexible substrate 45 which gave. FIG. 7 is a diagram showing a specific example of the flexible substrate 45 in the first embodiment of the present invention. In FIG. 7, a resistor 46 is arranged with respect to the LED package substrate 44 mounted on the flexible substrate 45 in order to reduce the variation in the light emission efficiency due to the individual difference due to the light source.

  An illumination light source group in which at least one of these illumination means 30 is arranged corresponding to a plurality of illumination areas is used as a backlight. FIG. 8 is a diagram showing a first arrangement example of the illumination means 30 according to Embodiment 1 of the present invention, and illustrates an example in which the illumination means 30 are arranged in an arrangement of 11 × 9. The first embodiment is not limited to this number of arrangements. In FIG. 8, since the illumination means 30 are arranged side by side in the horizontal direction so that the concave shape of the casing 51 is in the vertical direction (vertical direction), the light distribution of the illumination means 30 is narrow in the vertical direction, It has wide characteristics in the horizontal direction (left-right direction) perpendicular to it.

  That is, light sources that are long in the horizontal direction are arranged in a plurality of rows in the vertical direction. By the way, in a tubular (for example, straight tube or U-shaped tube) light source such as a cold cathode tube that is generally used as a conventional backlight, long tubes are arranged in the horizontal direction at intervals in the vertical direction. There are many cases. This means that light sources that are long in the horizontal direction are arranged in the vertical direction.

  That is, in FIG. 8, since the concave shape of the casing 51 is arranged in the horizontal direction with no gaps so as to be in the vertical direction (vertical direction), the configuration is close to a backlight typified by a conventional cold cathode tube. As a result, the conventional backlight can be easily replaced.

  Further, FIG. 8 shows an example in which the illumination means 30 arranged side by side with no gap in the horizontal direction are arranged with no gap in the vertical direction. However, it goes without saying that, for example, the illumination means 30 arranged side by side with no gap in the horizontal direction may be arranged with a gap in the vertical direction. FIG. 9 is a diagram showing a second arrangement example of the illumination means 30 according to the first embodiment of the present invention, and shows an example in which a gap is formed in the vertical direction.

  Moreover, FIG. 10 is a figure which shows the 3rd example of an arrangement | sequence of the illumination means 30 in Embodiment 1 of this invention. Further, FIG. 11 is a diagram showing a fourth arrangement example of the illumination means 30 in the first embodiment of the present invention. Thus, even if it arrange | positions in a checkered pattern, you may arrange | position with a clearance gap in both the horizontal and vertical directions.

  9 to 11 show only the arrangement of the illuminating means 30 for the sake of easy understanding. However, since each illuminating means 30 is configured as shown in FIG. 4, a part of the short wavelength light reaches the wavelength converting means 50. Without spreading from the side of the casing 51 to the outside of the casing 51. Specifically, using FIG. 4, among the short wavelength light in FIG. 4, the short wavelength light indicated by the dotted arrow in the back and the middle of the figure reaches the wavelength conversion means 50 and emits white light. . However, the dotted-line arrow on the near side does not reach the wavelength conversion means 50 and escapes from the front side surface of the casing 51 to the outside.

  Therefore, when there is actually a vacancy in the horizontal direction (for example, corresponding to the arrangement shown in FIGS. 10 and 11), the casing 51 including the wavelength conversion means 50 (that is, the illumination means 30 to the short wavelength light source). (Equivalent to a configuration obtained by removing the configuration of 40) is arranged in a free area. FIG. 12 is a diagram showing a fifth arrangement example of the illumination means 30 according to the first embodiment of the present invention, which is an arrangement example in which the space portion of FIG. 10 is filled. FIG. 13 is a diagram showing a sixth arrangement example of the illumination means 30 according to the first embodiment of the present invention, which is an arrangement example in which the space portion of FIG. 11 is filled. As a result, the short wavelength light that does not reach the wavelength conversion means 50 is fluorescently converted by the adjacent wavelength conversion means 50, so that the effect of improving the light conversion efficiency can be expected.

  Moreover, FIG. 14 is a figure which shows the 7th example of an arrangement | sequence of the illumination means 30 in Embodiment 1 of this invention. For example, as shown in FIG. 9 or FIG. 11, when a single row of vacancy is created in the vertical method, the diffusing reflector 52 is provided in the vacant region as shown in FIG. 13 or FIG. 14. As a result, white light can be diffusely reflected in the direction of the illuminated surface, and an improvement in the illumination efficiency of the illuminated surface can be expected.

  When these illumination means 30 are not spread, the interval of the illumination means 30 is widened in the vertical direction or both in the horizontal and vertical directions. When illuminating the light modulation element 130 with the backlight configured by such an arrangement of the illumination means 30, the surface illuminated by the illumination means 30 from the illumination means 30 (here, the surface of the light modulation element 130). If the interval is not set appropriately, there is a problem that uniform illumination is not performed.

  Here, when the interval between the illumination units 30 is p, where h is the larger interval in the horizontal or vertical direction, and h is the interval from the illumination unit 30 to the light modulation element 130, h is 0.8 to 3 times p. Uniform illumination can be obtained when it is set to fall within the range (that is, 0.8 <h / p <3.0 is satisfied). FIG. 15 is a cross-sectional view of the video display device 200 according to Embodiment 1 of the present invention, and shows h and p. Hereinafter, conditions for obtaining this uniform illumination will be described in detail.

Consider the horizontal illuminance of a surface to be illuminated (hereinafter referred to as an illuminated surface) at a distance h under the condition that the same type of light sources are periodically arranged. FIG. 16 is a schematic diagram for explaining conditions for obtaining uniform illumination in Embodiment 1 of the present invention. Here, consider a case where light sources having a luminous intensity I ₀ are periodically arranged at a pitch p.

Since the illuminance decreases in proportion to the inverse square of the distance, for the sake of simplicity, the case of the two closest light sources (corresponding to the first light source and the second light source in FIG. 16) having the greatest influence will be considered. From FIG. 16, it can be easily imagined that the illuminance at the characteristic position is directly above the light source E _c and the midpoint E ₀ of the light source. When both illuminances are equal, that is, E _c = E ₀ , the illuminance of the illuminated surface is expected to be approximately closest to uniformity.

Here, the horizontal illuminances E _c and E ₀ of characteristic points are obtained. The horizontal illuminance E of the illuminated surface is generally represented by the following formula (1).

First, determine the horizontal plane illuminance E _c of light right above light source. This is expressed by the superposition of the horizontal illuminance E _c1 by the nearest first light source and the horizontal illuminance E _c2 by the second light source, which are separated by the pitch p, and is expressed by the following equation (2).

Similarly, the horizontal illuminance E ₀ at the midpoint is obtained. This is also expressed by the superposition of the horizontal illuminance E ₀₁ by the first light source and the horizontal illuminance E ₀₂ by the second light source, and therefore, the following expression (3) is obtained.

Here, cos θ _c in the above equation (2) becomes the following equation (4), and cos θ ₀ in the above equation (3) becomes the following equation (5), both of which are expressed by a “ratio” of h and p. That is, h and p are not independent.

  Here, if the ratio between the light source interval p and the illuminated surface distance h is defined as x≡p / h, the above equations (1) and (2) become the following equations (6) and (7), respectively.

However, (theta) _c is set to the following Formula (8), and (theta) ₀ is set to the following Formula (9).

When these two characteristic horizontal plane illuminances are equal to E _c = E ₀ (that is, when E ₀ / E _c = 1), the illuminance of the illuminated surface is expected to be uniformly closest. From the above, it is only necessary to obtain x for which the following expression (10) is 1.

  The above equation (10) is a function that is determined only by the ratio x between the light source pitch and the illuminated surface distance if the light distribution I (θ) is determined.

  In the case of a planar light source parallel to the illuminated surface, the illuminance decreases in proportion to the fourth power of cos θ. Therefore, considering the generality, the light distribution can be set to the Nth power of cos θ, and the function type can be approximated by the characteristic parameter N. Assume that Here, FIG. 17 is an exemplary diagram of the light distribution I (θ; N) in the first embodiment of the present invention. The light distribution I (θ; N) is expressed by the following formula (11) in consideration of generality.

For example, N = 3 for a cylindrical light source, N = 4 for a planar light source, and if the light distribution is narrower than the planar light source, N> 4 may be effectively set. The four types of broken lines in FIG. 17 indicate light distributions normalized by I ₀ = 1 when N is changed, and it can be seen that the light distribution becomes narrower as N increases.

On the other hand, there is a backlight light source that emits light in the lateral direction for the purpose of reducing the depth. A solid line in FIG. 17 is an example of a lateral irradiation type light source, and shows a distribution spread in the horizontal direction. In this solid line, I ₀ is not 1 in order to compare spread distributions. Such a lateral illumination type light source is outside the scope of this configuration.

  Here, h / p = 1 / x where the illuminance ratio in the above equation (10) is f (x; N) = 1 is obtained as a function of the general light distribution N. Actually, numerical calculation was performed for arbitrary N. FIG. 18 is a diagram showing the relationship of h / p with respect to the illuminance distribution N in Embodiment 1 of the present invention, where the horizontal axis represents the illuminance distribution N and the vertical axis represents h / p. For example, when N = 3, h / p = 0.833, and when N = 4, h / p = 0.944. Since h / p and N can be well approximated by a power function, when an optimum value is obtained, the following equation (12) is obtained.

  From FIG. 18, in any light distribution of N> 3 (strictly 3 <N ≦ 40), the illumination intensity on the illuminated surface is approximately uniform if 0.8 <h / p <3.0 is satisfied. Will be the closest.

  Actually, the illumination light from the illumination means 30 illuminates the light modulation element 130, but the light modulation element 130 has polarization dependency. Therefore, as it is, about half of the illumination light from the illumination means 30 does not pass through the light modulation element 130 and is lost. Therefore, as shown in FIG. 15, the polarization selection unit 150 is disposed between the illumination unit 30 and the light modulation element 130 (here, directly below the light modulation element 130), and selectively transmits the target polarized light. Is reflected on the light source side.

  Further, as shown in FIG. 15, by diffusing the reflection plate 52 in the space formed by the illumination means 30 and the light modulation element 130, the return light from the light modulation element 130 is reflected again at a wide angle. This reflected light is selectively transmitted again by the polarization selection means 150, so that the illumination light finally transmitted through the light modulation element 130 can be increased.

  Further, by arranging the polarization selection unit 150 and the diffuse reflection plate 52 in this way, the light reflected to the light source side by the polarization selection unit 150 is reflected again by the diffusion reflection plate 52 and reenters the polarization selection unit 150. Therefore, the distribution of the illumination light by the illumination means 30 is practically widened, and illumination unevenness can be reduced.

  Actually, even if the approximate condition described above is satisfied, if the light modulation element 130 serving as the illuminated surface is directly illuminated for illumination in each of the plurality of divided regions by the plurality of illumination means 30, the adjacent divided regions remain as they are. Light unevenness occurs at the boundary. Therefore, in order to reduce illumination unevenness, at least one or more light diffusion means 140 may be arranged between the light modulation element 130 and the illumination means 30 (see FIG. 15).

  In order to reduce the deflection, the light diffusing means 140 has a thickness of the order of several millimeters, and a light diffusion means of the order of several hundred microns that enables fine adjustment of the light diffusion. Or you may use both in combination. As described above, by disposing at least one light diffusing unit 140 between the light modulation element 130 and the illumination unit 30, the distribution of the illumination light by the illumination unit 30 is substantially widened, and uneven illumination can be reduced. It becomes possible.

  As described above, the illumination unit 30 uses the LED element 42 as a short wavelength light source and is converted into white light by the wavelength conversion unit 50. The light conversion efficiency depends on the phosphor constituting the wavelength conversion means 50, the concave shape of the casing 51, the shape of the mold lens 43, and the like. The light conversion efficiency from short-wavelength light to white light by the wavelength conversion means 50 is about 0.5 to 0.6, and in order to effectively produce white light as illumination light, an improvement in light conversion efficiency is required. Is done.

  Further, by mixing the short wavelength light that is not fluorescently converted and the blue, green, and red light converted by the wavelength conversion means 50, the short wavelength component of the white light is increased, resulting in a strong blue tone. . In particular, when a part of short wavelength light transmitted from the LED element 42 through the mold lens 43 leaks directly from the housing 51 without passing through the wavelength conversion means 50, a part of the illuminated surface is illuminated by the short wavelength light. For this reason, there arises a problem of a strong blue tone.

  FIG. 19 is a diagram showing a first example of a structure for preventing leakage of short wavelength light in the first exemplary embodiment of the present invention. As shown in FIG. 19, a light shielding plate 53 is arranged in a part of the casing 51, specifically, directly above the LED mounting substrate 41 on which the LED element 42 is mounted, so that the short wavelength light is directly transmitted to the casing. It is good to prevent leakage from 51. This not only shields the short wavelength light leaking directly from the casing 51 without going through the wavelength converting means 50 from the outside, but also confines it inside the casing 51, thereby improving the light conversion efficiency. Also have.

  FIG. 20 is a diagram showing a second example of a structure for preventing leakage of short wavelength light in the first exemplary embodiment of the present invention. As illustrated in FIG. 20, a wavelength selection element 161 may be disposed as the short wavelength light leakage prevention unit 160 so as to cover the opening of the housing 51. The wavelength selection element 161 includes the substrate 44 transparent substrate 161b and an optical functional film 161a on one or both sides thereof. If the optical function film 161a is configured to reflect the short wavelength light into the housing 51, the short wavelength light is converted into white light by the wavelength conversion means 50, and the light conversion efficiency is improved.

  If the optical function film 161 a is configured to absorb short wavelength light, the short wavelength light is absorbed by the optical function film 161 a when the short wavelength light goes out of the case 51, and the short wavelength light is absorbed by the case 51. Can be prevented from leaking out.

  FIG. 21 is a diagram showing a third example of the structure for preventing leakage of short wavelength light in the first exemplary embodiment of the present invention. As shown in FIG. 21, as the short wavelength light leakage prevention means 160, a diffusion sheet 162 may be disposed so as to cover the opening of the housing 51. The diffusion sheet 162 has a surface on which irregularities of several to several hundred microns are randomly formed, or a mixture of fillers having a refractive index of several to several hundreds of microns in the form of spherical or non-spherical beads. In addition, there are those coated on the surface, etc., which have the effect of changing the light traveling direction and widening the light distribution.

  The reason why the air is blue although it is transparent is because of the light scattering, blue light having a shorter wavelength than red is widely scattered in inverse proportion to the fourth power of the wavelength. Similarly, as for the light passing through the diffusion sheet 162, blue light is spread more than red light due to ray scattering, that is, light returning to the direction of the casing 51 is more blue light than red light. As described above, the short wavelength light returning in the direction of the casing 51 is converted into white light by the wavelength conversion means 50, so that the light conversion efficiency is improved.

  FIG. 22 is an illustration of the relationship between the wavelength and the relative intensity in the first embodiment of the present invention, where the horizontal axis indicates the wavelength and the vertical axis indicates the relative intensity. Here, the broken line indicates the spectrum of the short wavelength light, and the solid line indicates the ratio of the white light in the case where the diffusion sheet 162 covering the opening of the housing 51 is not disposed. From the solid line, it can be seen that the long wavelength component is relatively large and the short wavelength light component is relatively small.

  FIG. 23 is a diagram showing a fourth example of the structure for preventing leakage of short wavelength light in the first exemplary embodiment of the present invention. As shown in FIG. 23, a prism sheet 163 may be disposed as the short wavelength light leakage prevention means 160 so as to cover the opening of the housing 51. The prism sheet 163 has a triangular, polygonal, or curved surface regularly formed on the surface of several microns to several hundreds of microns, and has an effect of selectively transmitting light. As described above, the short wavelength light returning in the direction of the casing 51 is converted into white light by the wavelength conversion means 50, so that the light conversion efficiency is improved.

  By the way, as described above, the light emission efficiency of the LED element depends on the temperature, and generally, the light conversion efficiency decreases as the temperature increases. Therefore, as described above, even if it is configured to improve the light conversion efficiency, if the heat generated from the LED element 42 is not appropriately exhausted to the external heat bath, the effect is diminished.

  Therefore, it is considered that the heat generated by the LED element 42 and the resistor 46 is exhausted to the illumination mounting plate 60 using the housing 51 as a heat conducting means. As a specific example for enhancing the waste heat effect, a medium having a high thermal conductivity may be used, for example, the casing 51 is made of a metal such as aluminum or copper.

  FIG. 24 is a diagram showing a configuration for enhancing the waste heat effect in the first embodiment of the present invention. As shown in FIG. 24, when the heat conduction from the housing 51 to the illumination mounting plate 60 is not sufficient, a heat conduction tube 54 is disposed in the vicinity of the LED package substrate 44 on which the LED elements 42 as heat sources are disposed. May be.

  Further, since heat is proportional to the thermal conductivity and the surface area, the back surface of the LED package substrate 44 on which the LED mounting substrate 41 on which a plurality of LED elements 42 are mounted is disposed on the housing 51 with a heat conductive adhesive or heat. By adhering to the casing 51 with a conductive double-sided tape, the area that becomes the path of heat can be used effectively. Actually, since the cost and weight of the material are also important, the entire casing 51 is not made of metal, and only the casing 51a that is in contact with the LED package substrate 44 that is a path for heat is made of metal. The remaining casing 51b may be made of resin or the like.

  If the waste heat is not sufficient, the heat may be wasted from the lighting mounting plate 60 using the waste heat means 80 (see FIG. 15). Specifically, as the waste heat means 80, fins for heat dissipation are arranged side by side on the illumination mounting plate 60. If further waste heat is required, the air blowing means 70 may be used (see FIG. 2). In this case, the air blowing means 70 is disposed on the side surface of the lighting attachment plate 60 or the back surface of the waste heat means 80 on the back surface of the lighting attachment plate 60 in order to blow air to the waste heat means 80. Here, since the housing | casing 51 is carrying out the concave shape, when it arranges without a gap | interval in a horizontal line, it can also be used especially as an air guide means.

  By configuring as described above, the heat generated from the LED element 42 can be efficiently wasted into an external heat bath, and the temperature rise can be suppressed to a low level. Thereby, it has the effect that it becomes possible to suppress reduction of the luminous efficiency of an LED element few.

  An illumination light source group in which at least one or more of these illumination means 30 are arranged corresponding to a plurality of illumination areas is used as a backlight, and thereby the light modulation element 130 is illuminated. The light modulation element 130 is, for example, a transmissive liquid crystal element, and has a function of forming an image by adjusting the amount of transmitted light according to the image signal.

  Next, the contrast ratio improving effect in the present invention will be described. The frequency distribution calculating means 10 takes in the video signal, calculates the frequency distribution (histogram) of the luminance of the video signal for each of the plurality of divided areas, and determines the magnitude of the luminance of the desired divided area. Specifically, the frequency distribution calculating unit 10 determines the luminance level of the video signal in each divided region by comparing the magnitude relationship between the sum or average value of the luminance for each divided region and a predetermined value. it can.

  FIG. 25 is an explanatory diagram of the effect of improving the contrast ratio in the first embodiment of the present invention. The left half of FIG. 25 shows a conventional lighting device and video signal control method, and the right half of the present invention 2 shows an illumination device and a video signal control method. Further, FIG. 25 shows a) input signal, b) illumination means, c) video signal, c ′) video signal after reverse correction, d) transmitted light, e) visual characteristics, and f) recognition image. Yes.

  First, the problem of the recognition image by the conventional lighting device will be described. For example, consider a case where the luminance of the input signal is partially large (a1 in FIG. 25) and the other luminance is small (a2 in FIG. 25). The conventional illumination device emits constant illumination light regardless of the area (b1 in FIG. 25). At this time, the luminance distribution of the video signal c1 is large only in part and small in other parts as with the input signal. In general, the transmitted light d1 that has passed through the light modulation element 130 may not be sufficiently dark because a part of the black display light leaks because the light blocking ability of the light modulation element 130 is not sufficient. Needless to say, since the contrast ratio is lowered when such a black float is present, a good image cannot be obtained (e1 in FIG. 25).

  On the other hand, in the illumination device 100 of the present method, the frequency distribution calculation means 10 calculates the frequency distribution (histogram) of the luminance of the video signal input for each of the plurality of divided regions, and calculates the magnitude of the luminance for each divided region. to decide. The illumination modulation unit 20 adjusts the illumination unit 30 corresponding to the area with high luminance so as to increase the amount of light (b2 in FIG. 25), and adjusts the illumination unit 30 corresponding to the area with low luminance. Then, adjustment is made so that the amount of light is further reduced (b3 in FIG. 25).

  When an image is formed by the light modulation element 130 in combination with the illumination light b2 and b3 that have been dimmed for each divided region by the illumination unit 30 in this way and the video signal c1, transmission through the light modulation element 130 is transmitted. Light is brighter in bright areas and darker in dark areas. In particular, it is possible to reduce black float that does not sufficiently darken due to partial leakage of black display light. These improve the contrast ratio. However, if the light amount adjustment based on the frequency distribution is excessively applied, there is a problem that an undesirable luminance step is generated at the boundary between the divided regions.

  Therefore, the video signal correcting unit 110 reduces the luminance distribution of the video signal in the region determined by the frequency distribution calculating unit 10 to brighten the illumination (b2 in FIG. 25) (c2 in FIG. 25), and darkens the illumination ( The luminance distribution of the video signal in the area determined to be b3) in FIG. 25 is increased (c3 in FIG. 25). At this time, if the product of the brightness of the modulated illumination means 30 and the brightness of the modulated video signal is equal to the product of the brightness of the original illumination means 30 and the brightness of the original video signal, light and dark Linearity can be maintained.

  However, as described above, when the bright part is brighter and the dark part is darker, the contrast ratio is emphasized and the image becomes sharp. Therefore, it is not always necessary to maintain the linearity of light and dark.

  The illumination modulation means 20 can adjust the amount of light by, for example, a method of modulating the current or voltage to the illumination means 30 or a method of modulating the lighting time width (pulse width modulation). When the lighting device 100 is used as a backlight for the video display device 200, if the backlight is always turned on, an image created by the light modulation element 130 based on the video signal is displayed until the next video signal is input. Therefore, this is generally recognized as a retinal afterimage, and there is a problem that the moving image is blurred.

  In order to avoid this, it can be considered that the backlight is repeatedly turned on and off according to the input time of the video signal. Specifically, a black image is displayed (black insertion) until the next video signal is input.

  The modulation of the illumination means 30 for each divided region is preferably in the range of 0.3 to 1.2, where 1 is the time when no modulation is performed for each divided region. The lower limit of 0.3 to the upper limit of 1.2 corresponds to a range in which the contrast ratio can be enhanced while avoiding an undesirable luminance step at the boundary of the divided areas, that is, a problem of image deterioration. In addition, when the lighting time is increased, in addition to the luminance step at the boundary between the divided areas, there is a problem that the above black insertion cannot be performed.

  As described above, the video signal and the illumination unit 30 are modulated for each divided region. The light modulation element 130 illuminated by the illumination unit 30 is different from the light distribution characteristics of the illumination unit 30 and the illumination unit 30 and the light modulation element. Depending on the distance to 130, the distance between adjacent illumination means 30, and the like, the illumination is not necessarily uniform and has a certain distribution.

  For example, in the conventional case in which illumination is not performed for each divided region, the distribution of illumination light from the light source (b1 in FIG. 25) overlaps with adjacent illumination light and is averaged so that the illumination distribution approaches uniformly. However, in the case of illuminating each divided region, the distribution of illumination light from adjacent light sources (b2 and b3 with respect to b4 in FIG. 25) is modulated to have a distribution, so that illumination unevenness is caused as it is.

  This is the origin of contrast ratio emphasis that makes bright areas brighter and dark areas darker, but an undesired luminance step occurs at the boundary of the divided areas. Therefore, the video signal correction unit 110 stores in advance the luminance distribution of the transmitted light of the light modulation element 130 illuminated by the illumination unit 30 as a response function, and inversely corrects the luminance distribution of the video signal with the response function (see FIG. 25 c′1). The transmitted light d2 obtained in this way can remove undesirable luminance steps at the boundaries of the divided areas.

  Actually, a human observes the transmitted light d2 of the light modulation element 130. However, because of human visual characteristics, for example, a bright / dark boundary surface is emphasized and perceived (Mach effect). Yes (f1 in FIG. 25). Therefore, when the video signal is corrected by the video signal correction unit 110, the image is not necessarily output accurately, and the image is displayed so that humans feel comfortable when viewing the video in consideration of visual characteristics. May be corrected.

  As described above, according to the first embodiment, the brightness of the illumination unit is modulated according to the frequency distribution of the luminance of the video signal for each of the plurality of illumination areas, thereby suppressing image degradation due to the luminance step. An illumination device for providing an image with a high contrast ratio can be obtained. Furthermore, by causing the short-wavelength excitation light source to emit white light by wavelength conversion, it is possible to obtain an illumination device that suppresses a change in color tone due to temperature and a decrease in light emission efficiency. Further, in terms of structure, an illumination device that can be easily replaced with a conventional backlight can be obtained.

  In addition, an image that can generate an image with a good contrast ratio by adjusting the transmitted light amount of the light modulation element by modulating the brightness of the video signal according to the frequency distribution of the luminance of the video signal in combination with the lighting device A display device and a video signal control method can be obtained.

  Further, the luminance distribution of the illuminated surface illuminated by the illumination device is stored in advance as a response function, and the video signal is inversely corrected with the response function, thereby effectively removing the luminance step generated at the boundary of the divided areas of the illumination. Therefore, it is possible to obtain a video display device and a video signal control method that can generate an image with a better contrast ratio.

  If the contrast ratio is not emphasized, or if the contrast ratio is excessively emphasized in a very special image, the conventional control is not used according to the user's preference without using such a video signal control method. It is preferable to return to the method. Therefore, the distinction as to whether the control method is used may be displayed on the light modulation element 130 so that the use of the control method can be selected based on a modulation ON / OFF signal by external setting.

  In the first embodiment described above, the case where reverse correction is performed by the video signal correction unit 110 has been described. However, the video display device and the video signal control method of the present invention are not limited to this. A video display device capable of generating an image with a good contrast ratio by modulating a video signal that has not been corrected in accordance with the frequency distribution of the luminance of the video signal in a simple configuration without the video signal correction means 110 And a video signal control method can be obtained.

Embodiment 2. FIG.
In the first embodiment, a case has been described in which a plurality of illumination units 30 are arranged immediately below the light modulation element 130 in order to illuminate the light modulation element 130. In the second embodiment, a case will be described in which the illumination unit 30 is not disposed directly below the light modulation element 130 but has a light guide unit. FIG. 26 is a specific explanatory diagram of the video display apparatus according to Embodiment 2 of the present invention. As shown in FIG. 26, the light guide means 90 is arranged for each divided area, and a plurality of illumination means 30 are arranged on the side surface of the light guide means 90 to adjust the light, thereby enabling illumination for each divided area. You can also

  FIG. 27 is a perspective view of the illumination unit 30 and the light guide unit 90 in Embodiment 2 of the present invention. A plurality of illumination means 30 are arranged on the side surface of the light guide means 90. The short wavelength light emitted from the LED element 42 on the LED package substrate 44 is light distribution controlled by the mold lens 43, and white light is excited by the wavelength conversion means 50.

  The excited white light is propagated to a wide spatial range by total reflection using the refractive index difference between the light guide unit 90 and the atmosphere. In order to extract light uniformly from the light guide unit 90, the light distribution control unit 91 is regularly arranged on the lower surface or the upper surface of the light guide unit 90 according to the distance from the illumination unit 30. The light distribution control means 91 plays a role of scattering light from the illumination means 30, for example.

  As shown in FIG. 27, the light distribution control means 91 is regularly arranged because when a large amount of light is extracted in the vicinity of the illuminating means 30, light cannot be extracted in the distance, and conversely, only a small amount of light is extracted in the distance. This is because the light is not used effectively. As described above, the light distribution control means 91 is regularly arranged according to the distance from the illumination means 30, but specifically depends on the surface density of the light distribution control means 91.

  In other words, the size of the light distribution control means 91 is increased according to the distance from the illumination means 30, or the number of the light distribution control means 91 is increased according to the distance from the illumination means 30, etc. The surface density of the light distribution control means 91 may be increased according to the distance.

  In this way, a plurality of illumination means 30 including the light guide means 90 as shown in FIG. 27 are arranged immediately below the light modulation element 130 (5 in the vertical direction and 3 in the horizontal direction in FIG. 26). The second embodiment is not limited to this number of arrangements. FIG. 28 is a cross-sectional view of the video display apparatus according to Embodiment 2 of the present invention. As shown in FIG. 28, a diffuse reflection plate 52 is further arranged on the illumination mounting plate 60 in order to effectively reuse the white light from the illumination means 30 leaking downward.

  Further, when the illumination unit 30 is configured on the side surface of the light guide unit 90 as described above, the waste heat unit 80 can be directly disposed on the back surface of the casing 51 of the illumination unit 30 as shown in FIG. For example, as shown in FIG. 26, when a plurality of illumination means 30 including the light guide means 90 are arranged immediately below the light modulation element 130, the illumination means 30 are arranged in a row, so The concave surface can be used as a wind guide means. Therefore, as shown in FIG. 26, by disposing the air blowing means 70 in front of and behind the lighting means 30 (up and down when used as a video display device), waste heat can be efficiently made.

  Of course, as shown in FIG. 15 of the first embodiment, the waste heat means 80 may be provided on the back surface of the illumination mounting plate 60. FIG. 29 is another cross-sectional view of the video display device according to Embodiment 2 of the present invention, and shows a case where the waste heat means 80 is provided on the back surface of the illumination mounting plate 60. In FIG. 29, the LED element 42 serving as a heat source is disposed farther from the light modulation element 130, and the casing 51 is closely attached to the illumination mounting plate 60 and the waste heat means 80 provided on the illumination mounting plate 60. Deploy. Thus, by disposing the heat source in the vicinity of the waste heat means 80, it becomes possible to efficiently waste heat.

  As described above, according to the second embodiment, by using the light guide unit disposed immediately below the light modulation element, the illumination device is disposed not on the light modulation element but on the side surface of the light guide unit. In addition, the same effect as in the first embodiment can be obtained. Furthermore, it becomes possible to arrange | position the LED element used as a heat source away from a light modulation element, and can aim at the improvement of waste heat efficiency.

  In the above example, the illumination unit 30 is arranged from the back to the front (up and down when used as a video display device), but naturally the top and bottom and the left and right are interchanged, that is, rotated 90 degrees. Needless to say.

1 is an overall configuration diagram of a video display device in Embodiment 1 of the present invention. It is a specific explanatory view of the video display device in Embodiment 1 of the present invention. It is sectional drawing of the illumination means in Embodiment 1 of this invention. It is a perspective view of the illumination means in Embodiment 1 of this invention. It is the figure which showed the spectral distribution of the light of the illuminating device in Embodiment 1 of this invention. It is the figure which showed arrangement | positioning of the LED element for suppressing the light source variation in Embodiment 1 of this invention. It is the figure which showed the specific example of the flexible substrate in Embodiment 1 of this invention. It is a figure which shows the 1st example of an arrangement | sequence of the illumination means in Embodiment 1 of this invention. It is a figure which shows the 2nd example of an arrangement | sequence of the illumination means in Embodiment 1 of this invention. It is a figure which shows the 3rd example of an arrangement | sequence of the illumination means in Embodiment 1 of this invention. It is a figure which shows the 4th example of arrangement | sequence of the illumination means in Embodiment 1 of this invention. It is a figure which shows the 5th example of arrangement | sequence of the illumination means in Embodiment 1 of this invention. It is a figure which shows the 6th example of arrangement | sequence of the illumination means in Embodiment 1 of this invention. It is a figure which shows the 7th example of an arrangement | sequence of the illumination means in Embodiment 1 of this invention. It is sectional drawing of the video display apparatus in Embodiment 1 of this invention. It is a schematic diagram for demonstrating the conditions which obtain the uniform illumination in Embodiment 1 of this invention. It is an illustration figure of the light distribution I ((theta); N) in Embodiment 1 of this invention. It is the figure which showed the relationship of h / p with respect to the illumination distribution N in Embodiment 1 of this invention. It is a figure which shows the 1st example of the structure which prevents the leakage of the short wavelength light in Embodiment 1 of this invention. It is a figure which shows the 2nd example of the structure which prevents the leakage of the short wavelength light in Embodiment 1 of this invention. It is a figure which shows the 3rd example of the structure which prevents the leakage of the short wavelength light in Embodiment 1 of this invention. It is an illustration figure of the relationship between the wavelength and relative intensity in Embodiment 1 of this invention. It is a figure which shows the 4th example of the structure which prevents the leakage of the short wavelength light in Embodiment 1 of this invention. It is the figure which showed the structure for improving the waste heat effect in Embodiment 1 of this invention. It is explanatory drawing of the contrast ratio improvement effect in Embodiment 1 of this invention. It is a specific explanatory view of a video display device in Embodiment 2 of the present invention. It is a perspective view of the illumination means and light guide means in Embodiment 2 of this invention. It is sectional drawing of the video display apparatus in Embodiment 2 of this invention. It is another sectional view of the video display device in Embodiment 2 of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Frequency distribution calculation means, 20 Illumination modulation means, 30 Illumination means, 40 Short wavelength light source, 41 LED mounting board, 42 LED element, 43 Mold lens, 44 LED package board, 45 Flexible board, 46 Resistance, 50 Wavelength conversion means, 51, 51a, 51b Case, 52 Diffuse reflection plate, 53 Light shielding plate, 54 Heat conduction tube, 60 Illumination mounting plate, 70 Blower unit, 80 Waste heat unit, 90 Light guide unit, 91 Light distribution control unit, 100 Illumination device 110 Video signal correction means, 120 Video signal modulation means, 130 Light modulation element, 140 Light diffusion means, 150 Polarization selection means, 160 Short wavelength light leakage prevention means, 161 Wavelength selection element, 161a Optical functional film, 161b Transparent substrate, 162 diffusion sheet, 163 prism sheet, 200 video display device.

Claims (18)

At least one or more illumination means including a short wavelength light source that emits short wavelength light and a wavelength conversion means that emits visible light using the short wavelength light as excitation light is arranged corresponding to a plurality of illumination regions, In an illumination device that irradiates the visible light as illumination light to a light modulation element that adjusts the light amount according to a video signal
Frequency distribution calculating means for calculating a frequency distribution of luminance of the video signal for each of the plurality of illumination areas based on luminance information of the video signal;
An illumination device further comprising: an illumination modulation unit that modulates a light amount of the short wavelength light emitted from the short wavelength light source of the one or more illumination units according to the calculated frequency distribution. The lighting device according to claim 1.
The short wavelength light source is a light emitting diode that emits ultraviolet rays or near ultraviolet rays. The lighting device according to claim 1 or 2,
The said wavelength conversion means is formed with the wavelength conversion element provided in the concave reflective surface, The illuminating device characterized by the above-mentioned. The lighting device according to claim 3.
The illumination device is characterized in that the light intensity is subjected to pulse width modulation control in accordance with the frequency distribution. The lighting device according to claim 4.
The illumination device characterized in that the illumination modulation means performs pulse width modulation control so that the amount of light is 0.3 to 1.2 times when the amount of light when not modulated is 1. In the illuminating device of any one of Claim 1 thru | or 5,
A plurality of the short wavelength light sources are mounted on a substrate attached to a housing serving as a heat conducting means. The lighting device according to claim 6.
An illuminating device, further comprising a heat dissipating unit that wastes heat generated from the short wavelength light source on either the back surface or the side surface of the housing. The lighting device according to claim 3.
An illuminating device further comprising an air guide unit formed by arranging the illuminating units having the concave-shaped reflecting surfaces. The lighting device according to claim 8.
An illuminating device further comprising a blowing unit provided on either the back surface or the side surface of the air guiding unit. The lighting device according to any one of claims 1 to 9,
Video signal modulating means for modulating the video signal according to the frequency distribution of luminance of the video signal calculated by the frequency distribution calculating means in the lighting device;
An image display device comprising: a light modulation element that changes the amount of transmitted illumination light from the illumination device based on the image signal modulated by the image signal modulation means, and forms an image. The video display device according to claim 10, wherein
A luminance distribution of the illuminated surface illuminated by the illuminating device is stored in advance as a response function, further comprising a video signal correction means for reversely correcting the luminance distribution of the video signal using the response function,
The video signal modulating means modulates the video signal reversely corrected by the video signal correcting means according to the frequency distribution of luminance of the video signal calculated by the frequency distribution calculating means in the lighting device. Video display device. The video display device according to claim 10 or 11,
An image display device, further comprising at least one light diffusing unit between the light modulation element and the illumination device. The video display device according to any one of claims 10 to 12,
An image display device further comprising at least one short-wavelength light leakage prevention unit directly above the illumination device. The video display device according to any one of claims 10 to 13,
The illumination device switches on / off the modulation control of the light amount based on the modulation ON / OFF signal from the outside,
The video signal modulation means switches on / off of modulation control of the video signal based on the modulation ON / OFF signal from the outside, and displays the modulation ON / OFF state by the light modulation element. Video display device. The video display device according to any one of claims 10 to 14,
The video display device, wherein the light modulation element is a transmissive liquid crystal element. The video display device according to any one of claims 10 to 15,
The video display device, wherein the illumination device is disposed immediately below the light modulation element. The video display device according to any one of claims 10 to 15,
Further comprising a light guide means disposed immediately below the illumination modulation means,
The video display device, wherein the illuminating device is disposed on at least one of top and bottom and left and right of the light guide unit. An image that realizes display according to the video signal by adjusting the transmitted light amount of the illumination light output from the illumination device having at least one illumination means arranged corresponding to the plurality of illumination areas according to the video signal A signal control method comprising:
Calculating a luminance frequency distribution of the video signal for each of the plurality of illumination regions;
Modulating the amount of illumination light output from the plurality of illumination means according to the calculated frequency distribution;
Using the response function stored in advance as the luminance distribution of the illuminated surface illuminated by the illumination device, reverse correcting the luminance distribution of the video signal;
Modulating the inversely corrected video signal in accordance with the frequency distribution and adjusting the amount of transmitted light.

Images