JP4729911B2 - Image display method and projector - Google Patents

Description

  The present invention relates to an image display method and a projector.

  A projector is known in which light emitted from a light source is incident on light modulation means such as a liquid crystal light valve, and image light emitted from the light modulation means is enlarged and projected onto a screen by a projection lens or the like. Among them, a three-plate projector is widely used in which light of the three primary colors emitted from a light source is incident on separate light modulation means, and image display is performed by combining image light emitted from each light modulation means. . Since this three-plate projector does not use a color filter, it is a high-intensity projector with excellent light source light utilization efficiency.

  Projectors are required to have higher brightness and wider color gamut. Widening the color gamut corresponds to expanding the central triangle in the chromaticity diagram of FIG. In order to realize a wide color gamut, it is necessary to increase the saturation (high color purity) by moving the light of the three primary colors emitted from the light source to the outside of the chromaticity diagram. However, high-saturation light is generally composed of light in the vicinity of a specific wavelength, and thus generally has low luminance. In addition, high-luminance light generally includes low saturation because it includes light of various wavelengths. As described above, it is said that there is a trade-off between increasing the luminance and increasing the color gamut.

Therefore, a technique for switching between a display state in which priority is given to color reproducibility and a display state in which priority is given to brightness by switching the color selection optical element (dichroic filter) with respect to the optical path with a single device. It is disclosed in Patent Document 1. In the technique of this patent document 1, the user can insert / remove the color selection optical element into / from the optical path by operating a knob or switching an electrical switch. By changing the control format of the image display element (light modulation means) according to the insertion / removal of the color selection optical element, it is possible to provide a display device in which the image quality is less deteriorated than before.
JP 2000-347292 A

In general, an image requiring a wide color gamut and an image requiring high luminance are mixed in one program. In one image, an area requiring a wide color gamut and an area requiring high luminance are mixed.
However, in the technique of Patent Document 1, image display is performed by selecting one of a display state in which color reproducibility is prioritized or a display state in which brightness is prioritized. Therefore, there is a problem that it is impossible to achieve both high brightness and wide color gamut throughout the program and the entire screen.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an image display method capable of achieving both high luminance and wide color gamut.
Another object is to provide a projector with excellent display quality.

In order to achieve the above object, one image display method according to the present invention is a method of generating a plurality of image lights by modulating different color lights, and performing image display by synthesizing the respective image lights. One image light is generated by a first spectrum generated by a first filter that transmits light in a first wavelength band and a second filter that transmits light in a second wavelength band included in the first wavelength band. The second spectrum is sequentially switched, and the switching between the first spectrum and the second spectrum is performed within the frame of the input image signal.
In order to achieve the above object, an image display method of the present invention is a method of generating a plurality of image lights by modulating different color lights, and performing image display by synthesizing the image lights. The image light is characterized by sequentially switching a plurality of lights having different spectral characteristics.
Further, at least one of the image lights is formed by sequentially switching a pair of lights having different spectral characteristics every unit time, and one of the pair of lights having different spectral characteristics has higher luminance than the other light. It is desirable that the other light has higher saturation than the one light.
According to this configuration, a bright image in a program can be displayed with high luminance, and a dark image can be displayed in a wide color gamut. Further, a bright area in the image can be displayed with high luminance, and a dark area can be displayed in a wide color gamut. Therefore, both high luminance and wide color gamut can be achieved.

The modulation is preferably performed by converting the gradation signal of the image into a drive signal for the modulation means, and the content of the conversion is varied according to the spectral characteristics.
The modulation is preferably performed by expanding the gradation signal of the image to a different gradation signal, and the content of the expansion varies according to the spectral characteristics.
According to this configuration, it becomes possible to display a bright image with extremely high luminance and a dark image with an extremely wide color gamut according to the gradation signal of the image, and the high luminance and wide color gamut can be displayed at a high level. It can be made compatible.

The modulation is preferably performed by multiplying the frame frequency of the input image signal by an integral multiple, and the plurality of lights having different spectral characteristics are sequentially switched for each frame multiplied by the integral multiple.
According to this configuration, discontinuity caused by switching a plurality of lights having different spectral characteristics can be reduced.

Further, the time mixing ratio of the plurality of lights having different spectral characteristics may be varied according to the characteristics of the input image signal.
The at least one image light is configured by sequentially switching a pair of lights having different spectral characteristics, and one of the pair of lights having different spectral characteristics is higher in luminance than the other light. The other light is higher in saturation than the one light, and it is desirable that the time mixing ratio of the one light and the other light is made different according to the luminance of the input image signal.
Even with this configuration, a bright image can be displayed with high luminance and a dark image can be displayed with a wide color gamut, and both high luminance and wide color gamut can be achieved.

The plurality of lights having different spectral characteristics are preferably generated through filters having different spectral transmittances.
According to this configuration, it is possible to easily generate a plurality of lights having different spectral characteristics.

On the other hand, a projector according to the present invention is characterized in that an image is displayed using the image display method described above.
According to this configuration, it is possible to achieve both high luminance and wide color gamut, and thus it is possible to provide a projector with excellent display quality.

(First embodiment)
Embodiments of the present invention will be described below with reference to the drawings. In each drawing used for the following description, the scale of each member is appropriately changed to make each member a recognizable size.

(projector)
FIG. 1 is a schematic configuration diagram showing a main part of the projector. In FIG. 1, 810 is a light source, 813 and 814 are dichroic mirrors, 815, 816 and 817 are reflection mirrors, 822, 823 and 824 are light modulation means comprising a liquid crystal device, 825 is a cross dichroic prism, and 826 is a projection lens. . The light source 810 includes a lamp 811 such as a metal halide and a reflector 812 that reflects the light of the lamp. The white light emitted from the lamp 811 includes light in the entire visible light range.

  The dichroic mirror 813 transmits red light contained in white light from the light source 810 and reflects blue light and green light. The transmitted red light is reflected by the reflection mirror 817 and is incident on the light modulation means 822 for red light. The green light reflected by the dichroic mirror 813 is reflected by the dichroic mirror 814 and enters the light modulating means 823 for green light. Further, the blue light reflected by the dichroic mirror 813 passes through the dichroic mirror 814, is reflected by the reflection mirrors 815 and 816, and enters the blue light light modulation means 824.

  In each of the light modulation units 822, 823, and 824, the incident three primary color lights are modulated based on the image signal, and the three primary color image lights are generated. Image light emitted from each of the light modulation units 822, 823, and 824 is incident on the cross dichroic prism 825. The cross dichroic prism 825 is formed by bonding four right-angle prisms. A dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are formed in an X shape at the interface. Yes. These dielectric multilayer films combine the three primary colors of image light to form light representing a color image. The synthesized light is projected onto the screen 827 by the projection lens 826 which is a projection optical system, and the image is enlarged and displayed.

Here, rotary spectral filters 832, 833, and 834 are provided on the light source side of the light modulators 822, 823, and 824, respectively.
FIG. 2 is a front view of the rotary spectral filter. In the following, the case of the rotating spectral filter 833 for green light will be described as an example. The rotary spectral filter 833 is rotatable about the central axis 840 and is disposed in the projector so that light from the light source passes through the side portion 845 of the central axis 840.

In the rotary spectral filter 833, two types of spectral filters (high color purity filters) having different spectral transmittances are arranged in the circumferential direction (first filter 841 and second filter 842).
FIG. 3 shows the spectral transmittance of each filter constituting the rotary spectral filter. The spectral transmittance of the first filter shown in FIG. 3A shows a transmittance of 100% in a wide band centered around the wavelength of 550 nm. Therefore, the first spectrum from the first filter is configured to include light of various wavelengths, and has high luminance but low spectral characteristics. On the other hand, the spectral transmittance of the second filter shown in FIG. 3B shows a transmittance of 100% only in a narrow band centered around the wavelength of 550 nm. Therefore, the second spectrum from the second filter is configured to include only light having a wavelength near 550 nm, and has a spectral characteristic of high saturation but low luminance. As a result, the first spectrum has higher luminance than the second spectrum, and the second spectrum has higher saturation than the first spectrum.

  Similarly, the rotary spectral filter 832 for red light shown in FIG. 1 includes two types of filters that exhibit a transmittance of 100% near a wavelength of 440 nm. Further, the rotating spectral filter 834 for blue light includes two types of filters that exhibit a transmittance of 100% near a wavelength of 700 nm. In FIG. 1, the rotary spectral filters 832, 833, and 834 are disposed on the light source side of the light modulators 822, 823, and 824. In the present embodiment, the spectral transmittance of the first filter of the rotary spectral filter 833 for green light is approximately 100% over the wavelength range of 500 nm to 600 nm. However, each primary color light is accurately separated by the dichroic mirror. In this case, the spectral transmittance of the first filter may be approximately 100% (transparent) in the entire wavelength range. The same applies to the rotating spectral filter 832 for red light and the rotating spectral filter 834 for blue light.

(Image display method)
Next, an image display system and an image display method in the projector described above will be described.
FIG. 4 is a block diagram of the image display system according to the first embodiment. The image display system according to the present embodiment mainly includes a light modulation unit 823 and a display control circuit 290. The light modulation means 823 is mainly provided with the liquid crystal panel 110 and its drive circuit 110D. The display control circuit 290 is mainly provided with a frame converter 12, an expansion processing unit 14, an LUT conversion unit 16, and a filter switching unit 20.

  In this embodiment, first, an image signal and a vertical synchronization signal (VSync) are input to the frame converter 12. In general, an image signal is generated for each frame serving as an image display unit, and the frame frequency is 60 Hz. Corresponding to this frame frequency, a vertical synchronizing signal of 60 Hz is generated. In this embodiment, image display is performed with the frame frequency doubled. Therefore, the frame converter 12 converts the vertical synchronization signal to 120 Hz and generates an image signal corresponding to the increased frame. The new image signal may be generated by copying the previous input image signal, or may be generated by averaging the previous and next input image signals.

Next, the converted image signal and vertical synchronization signal are input to the expansion processing unit 14. The image signal represents the brightness of each pixel by a gradation signal, and is used after being converted into an applied voltage to each pixel electrode of the liquid crystal panel. As is well known, since the transmittance-voltage curve (TV curve) of the liquid crystal panel shows non-linearity, there is a case where a part of the gradation signal corresponding to the applied voltage should be expanded. The expansion processing unit 14 performs such gradation signal expansion processing as necessary.
FIG. 5A is a graph of an extension curve according to the first embodiment. In the present embodiment, a case where an image signal is expressed by a gradation signal having 256 gradations will be described as an example. The extension curve in FIG. 5A is composed of a straight line with an inclination of 1. In this case, the gradation signal input to the expansion processing unit is converted to the same gradation and output. That is, in this embodiment, the gradation signal is not expanded.

Next, the converted image signal and vertical synchronization signal are input to the LUT converter 16 shown in FIG. The LUT converter 16 converts the gradation signal constituting the image signal into a drive level signal (signal corresponding to the applied voltage) of the liquid crystal panel based on the LUT (Look Up Table).
FIG. 5B is a graph of the LUT according to the first embodiment. In the present embodiment, two types of LUTs are used in order to individually modulate the first spectrum and the second spectrum from the rotary spectral filter described above. In FIG. 5B, the LUT 91 corresponding to the first spectrum is indicated by a solid line, and the LUT 92 corresponding to the second spectrum is indicated by a broken line. The LUT 91 corresponding to the high-intensity first light beam has a small drive level increase rate at a low gradation and a high drive level increase rate at a high gradation. On the other hand, the LUT 92 corresponding to the high-chroma second spectrum has a large drive level increase rate in the low gradation and a low drive level increase rate in the high gradation (or the increase rate is 0).

  Next, the converted image signal and vertical synchronizing signal are output to the drive circuit 110D of the light modulation means 823 shown in FIG. In the drive circuit 110D, the image signal converted into the drive level signal is supplied to the liquid crystal panel 110 based on the vertical synchronization signal. As a result, an image for light modulation is displayed on the liquid crystal panel 110.

  On the other hand, the vertical synchronization signal output from the frame converter 12 described above is input to the filter switching unit 20. The filter switching unit 20 sequentially switches the first filter and the second filter of the rotary spectral filter based on the doubled frame frequency in the vertical synchronization signal.

  FIG. 6 is an explanatory diagram of image display. FIG. 6A shows an initial image signal input to the frame converter of FIG. 4, and a scale is written on the horizontal axis according to the initial frame frequency (60 Hz). FIG. 6B shows an image display example based on the doubled frame frequency (120 Hz). In the present embodiment, a frame obtained by doubling the first image 41 (41a, 41b) by the first spectrum from the rotary spectral filter described above and the second image 42 (42a, 42b) by the second spectrum. Switch to display each. When the first image 41 is displayed, the first spectrum 841 of the rotary spectral filter 833 shown in FIG. The light modulating means modulates the first spectrum using the image signal converted by the LUT 91 in FIG. And the 1st image 41 shown in FIG.6 (b) is displayed by the emitted light from the light modulation means. On the other hand, when displaying the 2nd image 42, the 2nd spectrum is made to enter into a light modulation means using the 2nd filter 842 of the rotation type spectral filter 833 shown in FIG. In the light modulation means, the second spectral modulation is performed using the image signal converted by the LUT 92 of FIG. And the 2nd image 42 shown in FIG.6 (b) is displayed by the emitted light from the light modulation means.

  Here, the A part of the image signal in FIG. 6A is composed of a high gradation signal in order to display a bright image. If this high gradation signal is converted by the LUT 92 in FIG. 5B, the drive level of the light modulation means can be kept low. Therefore, the transmittance of the second spectrum with low luminance (high saturation) is lowered, and the second image 42a shown in FIG. 6B is dark. However, if the high gradation signal described above is converted by the LUT 91 in FIG. 5B, the drive level of the light modulation means increases. Thereby, the transmittance of the first spectrum with high luminance (low saturation) is increased, and the first image 41a shown in FIG. 6B is extremely bright. By displaying the image by sequentially switching the first image 41a and the second image 42a as described above, the observer can recognize a high-luminance image. Further, since the frame frequency is doubled, discontinuity due to switching between the first image 41a and the second image 42a can be reduced.

  On the other hand, the B portion of the image signal in FIG. 6A is composed of a low gradation signal so as to display a dark image. If this low gradation signal is converted by the LUT 91 in FIG. 5B, the drive level of the light modulation means can be kept low. Therefore, the transmittance of the first spectrum with low saturation (high luminance) becomes low, the first image 41b shown in FIG. 6B becomes dark, and the decrease in saturation is suppressed. On the other hand, if the low gradation signal described above is converted by the LUT 92 in FIG. 5B, the drive level of the light modulation means increases. Thereby, the transmittance of the second spectrum with high saturation (low luminance) is increased, and the second image 42b shown in FIG. 6B has extremely high saturation. By displaying the image by sequentially switching the first image 41b and the second image 42b as described above, the observer can recognize an image with high saturation. Further, since the frame frequency is doubled, discontinuity due to switching between the first image 41b and the second image 42b can be reduced.

  As described above, the image display method according to the present embodiment is configured to sequentially switch and display the first image based on the first spectrum with high luminance and the second image based on the second spectrum with high saturation. Accordingly, a bright image in a program can be displayed with high luminance and a dark image can be displayed in a wide color gamut without requiring a user to perform mode switching or the like. Further, a bright area in the image can be displayed with high luminance, and a dark area can be displayed in a wide color gamut. Therefore, both high luminance and wide color gamut can be achieved.

  In addition, in the case of a high gradation signal, the transmittance of the first spectrum with high luminance is increased, and in the case of a low gradation signal, the transmittance of the second spectrum with high saturation is increased, so that the first having different spectral characteristics. The configuration is such that the spectrum and the second spectrum are modulated. This makes it possible to display a bright image with extremely high luminance and a dark image with an extremely wide color gamut, and achieve both high luminance and wide color gamut at a high level.

(Modification)
FIG. 7A is a graph of an extension curve according to a modification of the first embodiment. In this modification, two types of extension curves are used to individually modulate the first and second beams from the rotary spectral filter described above. In FIG. 7A, the extension curve 81 corresponding to the first spectrum is indicated by a solid line, and the extension curve 82 corresponding to the second spectrum is indicated by a broken line. The expansion curve 81 corresponding to the high-intensity first spectrum has a small inclination at the low gradation and a large inclination at the high gradation. On the other hand, the expansion curve 82 corresponding to the second chroma with high saturation has a large gradient at the low gradation and a small gradient at the high gradation (or the gradient is 0).

  FIG. 7B is a graph of an LUT according to a modification of the first embodiment. Here, the graph of the LUT corresponding to the first spectrum matches the graph of the LUT corresponding to the second spectrum. The LUT graph employs a gamma correction curve (γ = 2.2).

  Part A of the image signal in FIG. 6A is composed of a high gradation signal in order to display a bright image. If this high gradation signal is converted by the extension curve 82 in FIG. 7A, the drive level of the light modulation means can be kept low. Therefore, the transmittance of the second spectrum with low luminance (high saturation) is lowered, and the second image 42a shown in FIG. 6B is dark. However, if the above-described high gradation signal is converted by the expansion curve 81 in FIG. 7A, the drive level of the light modulation means increases. Thereby, the transmittance of the first spectrum with high luminance (low saturation) is increased, and the first image 41a shown in FIG. 6B is extremely bright.

  Further, the B part of the image signal in FIG. 6A is composed of a low gradation signal so as to display a dark image. If this low gradation signal is converted by the expansion curve 81 in FIG. 7A, the drive level of the light modulation means can be kept low. Therefore, the transmittance of the first spectrum with low saturation (high luminance) becomes low, the first image 41b shown in FIG. 6B becomes dark, and the decrease in saturation is suppressed. On the other hand, if the low gradation signal described above is converted by the expansion curve 82 in FIG. 7A, the drive level of the light modulation means increases. Thereby, the transmittance of the second spectrum with high saturation (low luminance) is increased, and the second image 42b shown in FIG. 6B has extremely high saturation.

  As described above, also in the modification of the first embodiment, it is possible to display a bright image with extremely high luminance and a dark image with an extremely wide color gamut, and achieve high luminance and wide color gamut at a high level. Both can be achieved.

(Second Embodiment)
Next, an image display system and an image display method according to the second embodiment will be described. The image display method according to the second embodiment is a first implementation of switching every unit time in that the time mixture ratio of the first image by the high-brightness first spectrum and the second image by the high-chroma second spectrum is different. It is different from the form. Note that detailed description of portions having the same configuration as in the first embodiment is omitted.

  FIG. 8 is a block diagram of an image display system according to the second embodiment. Also in the second embodiment, the image signal and the vertical synchronization signal are input to the frame converter 12 to double the frame frequency.

Next, the converted image signal and vertical synchronization signal are sequentially input to the expansion processing unit 14 and the LUT conversion unit 16.
FIG. 9A is a graph of an extension curve according to the second embodiment, and FIG. 9B is a graph of an LUT. In the second embodiment, modulation is performed uniformly without distinguishing between the first and second light beams having different spectral characteristics. Therefore, one type of extension curve and LUT are used. Note that a straight line having an inclination of 1 is adopted as the expansion curve in FIG. 9A, and the expansion processing is not performed. In addition, a gamma correction curve (γ = 2.2) is adopted for the LUT in FIG.

On the other hand, in the second embodiment, the image signal and the vertical synchronization signal output from the frame converter 12 illustrated in FIG. 8 are input to the image analysis unit 22.
FIG. 10 is an explanatory diagram of image analysis. The image analysis unit analyzes the gradation signal of each pixel included in the input image signal and performs histogram processing. Then, a peak gradation or a gradation in the vicinity thereof is set in the illumination control signal. In the histogram of FIG. 10, since there is a peak near the 170th gradation, the 170th gradation is used as the illumination control signal.

Next, the image analysis unit obtains the usage time ratio of the first filter and the second filter in the rotary spectral filter based on the illumination control signal.
FIG. 11 is a graph showing the relationship between the illumination control signal and the usage time ratio of each filter. This graph is composed of, for example, a gamma curve (γ = 2.2), and the length ratio of the top and bottom of the graph in a certain illumination control signal indicates the usage time ratio of the first filter 841 and the second filter 842. For example, in the case of the illumination control signal (170 gradations) obtained in FIG. 10, the usage time ratio of the first filter 841 and the second filter 842 according to FIG. 11 is about 45:55. Then, the image analysis unit 22 illustrated in FIG. 8 generates a rotation spectral filter switching control signal within one frame based on the obtained usage time ratio, and outputs the generated signal to the filter switching unit 20. The filter switching unit 20 switches the rotary spectral filter based on the input control signal.

  FIG. 12 is an explanatory diagram of image display in the second embodiment. FIG. 12A shows an initial image signal input to the frame converter of FIG. 8, and a scale is written on the horizontal axis according to the initial frame frequency (60 Hz). FIG. 12B is an image display example of the present embodiment. In the present embodiment, the first image 41 (41a, 41b) based on the first spectrum with high luminance and the second image 42 (42a, 42b) based on the second spectrum with high saturation are switched at a predetermined time ratio for each frame. To display the image.

  The A part of the image signal in FIG. 12A is composed of a high gradation signal so as to display a bright image. In this case, since the illumination control signal becomes high, the usage time ratio of the first filter 841 is larger than the usage time ratio of the second filter 842 according to the graph of FIG. Therefore, as shown in FIG. 12B, the time mixing ratio of the first image 41a by the first spectrum with high luminance (low saturation) is the time of the second image 42a by the second spectrum with low luminance (high saturation). It becomes larger than the mixing ratio. Thereby, the observer mainly recognizes the first image 41a with high luminance.

  On the other hand, the B portion of the image signal in FIG. 12A is composed of a low gradation signal so as to display a dark image. In this case, since the illumination control signal is low, the usage time ratio of the second filter 842 is larger than the usage time ratio of the first filter 841 according to the graph of FIG. Therefore, as shown in FIG. 12B, the time mixing ratio of the second image 42b by the second spectrum with high saturation (low luminance) is the time of the first image 41b by the first spectrum with low saturation (high luminance). It becomes larger than the mixing ratio. Thereby, the observer mainly recognizes the second image 42b with high saturation.

  Then, as shown in FIG. 12A, as the gradation changes from the A part to the B part of the image signal, as shown in FIG. 12B, the time mixing of the first image 41 by the first spectrum is performed. The ratio and the temporal mixing ratio of the second image 42 obtained by the second spectroscopy continuously change. Accordingly, a bright image in a program can be displayed with high luminance and a dark image can be displayed in a wide color gamut without requiring a user to perform mode switching or the like. Further, a bright area in the image can be displayed with high luminance, and a dark area can be displayed in a wide color gamut. Therefore, as in the first embodiment, both high luminance and wide color gamut can be achieved.

  It should be noted that the technical scope of the present invention is not limited to the above-described embodiments, but includes those in which various modifications are made to each embodiment without departing from the spirit of the present invention. That is, the specific materials and configurations described in the embodiments are merely examples, and can be changed as appropriate. For example, in each of the above embodiments, the frame frequency is doubled and the image display is performed. However, the image may be displayed as an integer multiple of three or more, and conversely, the image display may be performed with the original frame frequency.

  Moreover, in each embodiment, although this invention was applied to the projection type display apparatus, it is also possible to apply this invention to a direct view type display apparatus. In each embodiment, the present invention is applied to a three-plate projector, but the present invention can also be applied to a single-plate projector. A single-plate projector for simultaneous display of each color includes a white light source and a color filter. In a single-plate projector of time sequential display, each color light source and light modulation means are driven in time sequential. It is possible to apply.

  In each embodiment, the light having different spectral characteristics is sequentially switched for all the three primary color image lights. However, the structure of the present invention can be achieved by simply switching light having different spectral characteristics for at least one image light. Part of the effect can be achieved. In particular, it is desirable to sequentially switch light having different spectral characteristics for green or red image light having high human visibility. However, in these cases, it is necessary to pay attention to ensuring white balance. In each embodiment, a pair of lights having different spectral characteristics are sequentially switched. However, a structure in which three or more types of light are sequentially switched may be used.

  FIG. 13 is a schematic configuration diagram of a projector that switches between a plurality of light sources. In FIG. 13, the case of green light is described as an example. In each embodiment, the rotary spectral filter is rotated to switch the first filter and the second filter having different spectral transmittances, thereby generating the first spectral and the second spectral. Instead, in FIG. 13, a plurality of light sources 810a and 810b having different spectral characteristics are used. For example, the first light source 810a is a high brightness light source, and the second light source 810b is a high chroma light source. By switching between these light sources 810a and 810b, the same effects as those of the above embodiments can be obtained. If both light sources are turned on at the same time, light with higher luminance can be obtained.

It is a schematic block diagram which shows the principal part of a projector. It is a front view of a rotary spectral filter. It is a spectral transmittance of each filter which comprises a rotation type spectral filter. 1 is a block diagram of an image display system according to a first embodiment. (A) is a graph of an extension curve according to the first embodiment, and (b) is a graph of an LUT. It is explanatory drawing of the image display in 1st Embodiment. (A) is a graph of an extension curve according to a modification of the first embodiment, and (b) is a graph of an LUT. It is a block diagram of the image display system concerning a 2nd embodiment. (A) is a graph of the expansion curve according to the second embodiment, and (b) is a graph of the LUT. It is explanatory drawing of image analysis. It is a graph showing the relationship between an illumination control signal and the usage rate of a rotary spectral filter. It is explanatory drawing of the image display in 2nd Embodiment. It is a schematic block diagram of the projector which switches and uses several light sources. It is a chromaticity diagram.

Explanation of symbols

  41a, 41b ... first image 42a, 42b ... second image

Claims (11)

A method of generating a plurality of image lights by modulating different color lights and combining the image lights to display an image,
At least one of the image lights is generated by a first spectrum generated by a first filter that transmits light in a first wavelength band and a second filter that transmits light in a second wavelength band included in the first wavelength band. and a second spectral produced, Ri Na sequentially switched,
Switching between said 1st spectroscopy and said 2nd spectroscopy is performed within the frame of the inputted image signal, The image display method characterized by the above-mentioned. At least one of the image lights is formed by sequentially switching the first spectrum and the second spectrum every unit time,
The image display method according to claim 1, wherein the first spectrum has higher luminance than the second spectrum , and the second spectrum has higher saturation than the first spectrum . The modulation is performed by converting the gradation signal of the image into a drive signal for the modulation means,
The image display method according to claim 1 , wherein the content of the conversion is made different between the first spectrum and the second spectrum .   The modulation is performed by converting the gradation signal of the image into a drive signal for the modulation means,
  The contents of the conversion are the first increase rate of the drive signal that modulates the first spectrum and the drive signal that modulates the second spectrum with respect to the increase rate of the drive signal as the gradation signal increases. Different from the second rate of increase,
  The first increase rate at a low gradation among the gradation signals of the image is smaller than the first increase rate at a high gradation among the gradation signals of the image,
  The image according to claim 3, wherein the second increase rate at a low gradation among the gradation signals of the image is larger than the second increase rate at a high gradation among the gradation signals of the image. Display method. The modulation is performed by expanding the first gradation signal of the image into the second gradation signal,
3. The image display method according to claim 1 , wherein the contents of the extension are different between the first spectrum and the second spectrum . 4.   The modulation is performed by expanding the first gradation signal of the image into a different second gradation signal, and then converting the second gradation signal into a driving signal for the modulation means,
  The content of the expansion is converted into the drive signal that modulates the first spectrum with respect to the increase rate of the second gradation signal with the increase of the first gradation signal. Differentiating between an increase rate and a second increase rate of the second gradation signal converted into the drive signal for modulating the second spectrum;
  The first increase rate at a low gradation among the gradation signals of the image is smaller than the first increase rate at a high gradation among the gradation signals of the image,
  The second increase rate at a low gradation among the gradation signals of the image is larger than the second increase rate at a high gradation among the gradation signals of the image. 6. The image display method according to 5. The modulation is performed by multiplying the frame frequency of the input image signal by an integral multiple,
Wherein said first spectral and switching between the second spectroscopy, image display method according to any one of claims 1 to 6, characterized in that for each frame that is an integer doubled. 2. The image display according to claim 1, wherein a time mixing ratio of the first spectrum and the second spectrum in a frame of the input image signal is made different in accordance with characteristics of the input image signal. Method. The first spectral is a high luminance than the second spectral, said second spectral image display method according to claim 8, characterized in that a high saturation than the first spectral.   In accordance with the characteristics of the input image signal, the time mixing ratio of the first spectrum and the second spectrum in the frame of the input image signal is varied,
  By analyzing the characteristics of the image signal, an illumination control signal is set according to the characteristics of the image signal. When the illumination control signal displays an image higher than a predetermined value, the temporal mixing ratio of the first spectrum Is made larger than the time mixture ratio of the second spectrum, and when displaying an image whose illumination control signal is lower than a predetermined value, the time mixture ratio of the second spectrum is made larger than the time mixture ratio of the first spectrum. The image display method according to claim 9, wherein: An image display is performed using the image display method according to any one of claims 1 to 10 .

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