JP6028440B2 - Image display device and light source control method - Google Patents

Description

  The present invention relates to an image display device that generates an image by spatially modulating incident illumination light, and a control method for a light source included in the image display device.

  In recent years, liquid crystal display devices and projection display devices (projectors) have become widespread as image display devices that spatially modulate incident light to produce images. A general liquid crystal display device includes a backlight unit that emits planar illumination light, and a liquid crystal display panel that is a transmissive spatial light modulator that generates an image by spatially modulating the illumination light in units of pixels. And have. In recent backlight units, a light emitting diode (LED) light source or a semiconductor laser light source is used in place of a conventional white lamp light source such as a halogen lamp.

  As a method of adjusting the white chromaticity of the illumination light regardless of the temperature change in the vicinity of the light source in this type of image display device, light of three different wavelength ranges (for example, red, green, and blue) is emitted 3 For illumination light emitted from illumination means including two light sources, a color sensor for detecting a color detection value related to the chromaticity of the illumination light, a temperature detection means for detecting a temperature in the vicinity of the light source, and the detected temperature There is a method of controlling the light emission of each light source based on the color detection value (see, for example, Patent Document 1).

JP 2010-66465 A (page 4-5, FIG. 1)

  However, the method as in Patent Document 1 is a method of adjusting the white chromaticity of illumination light with respect to three different wavelength ranges, and the illumination light is used when a plurality of light sources including the same wavelength range are used. A method for adjusting the white chromaticity of the image is not disclosed. Therefore, in an image display apparatus using a plurality of light sources including the same wavelength region, control is performed on each light source so that the white chromaticity of the illumination light is accurately maintained in response to changes in the light emission characteristics of each light source. It was difficult to do.

  The present invention has been made in order to solve the above-described problems. In an image display apparatus using a plurality of light sources including the same wavelength region, the white color of the illumination light even if the light emission characteristics of each light source change. An image display device that maintains chromaticity accurately is obtained.

In the image display device according to the present invention, a spatial light modulation element that spatially modulates illumination light to generate a display image, a first light source that emits light in a first wavelength region, and the first wavelength region A second light source comprising a laser light source that emits light in a second wavelength range that is included, and two types of light emitted from the first light source and the second light source, respectively, A light mixing unit that generates illumination light, emits the illumination light to the spatial light modulator, and receives a part of the illumination light, and detects a light component in a wavelength region different from the second wavelength region; A light amount detection unit that outputs a first light amount detection value, detects a light component in the second wavelength range, and outputs a second light amount detection value, and individually drives the first light source and the second light source. Based on the light source driving unit, the first light quantity detection value, and the second light quantity detection value A light source controller for adjusting the chromaticity of the illumination light by controlling the light source driving unit, a temperature detector for detecting the temperature of the second light source near the second based on the temperature of the second light source near A correction unit that calculates a shift amount of the light emission wavelength of the light source and corrects a light source light amount value of the second light source using the shift amount of the light emission wavelength, and the light source control unit includes the first light amount detection value. Is used to control the emission intensity of the first light source, and the emission intensity of the second light source is controlled using both the first light quantity detection value and the second light quantity detection value, and the correction unit corrects the emission intensity. The emitted light intensity of the second light source is controlled using the light source light amount value of the second light source .

  The present invention includes a first light source that emits light in a first wavelength range, and a second light source that emits light in a second wavelength range that is a wavelength range included in the first wavelength range. A part of illumination light generated by mixing two kinds of light respectively emitted from the two light sources is received, a light component in a wavelength region different from the second wavelength region is detected, and a first light amount detection value is obtained. A light amount detection unit that outputs a second light amount detection value by detecting a light component in the second wavelength range, and an emission intensity of the first light source driven by the light source control unit using the first light amount detection value And a light source control unit that controls the emission intensity of the second light source that is driven by the light source control unit using both the first light quantity detection value and the second light quantity detection value. In an image display device using a plurality of light sources including the white chromaticity of illumination light even if the light emission characteristics of each light source change It is possible to maintain accurately.

1 is a functional block diagram schematically showing a basic configuration of an image display apparatus according to Embodiment 1 of the present invention. It is a figure which shows an example of a blue-green LED light source. It is the schematic which shows an example of the image display apparatus comprised as a transmissive liquid crystal display device. It is a top view which shows schematic structure of the light guide diffusion plate of a transmissive liquid crystal display device. It is a top view which shows schematic structure of the other light guide diffusing plate of a transmissive liquid crystal display device. It is the schematic which shows an example of the waveform of the drive current which concerns on Embodiment 1 of this invention. It is a functional block diagram which shows schematic structure of the calculating part of Embodiment 1 of this invention. It is a flowchart which shows roughly the procedure of the chromaticity control process which concerns on Embodiment 1 of this invention. It is a functional block diagram which shows roughly the basic composition of the image display apparatus which concerns on Embodiment 2 of this invention. It is a functional block diagram which shows schematic structure of the correction | amendment part of Embodiment 2 of this invention. It is a graph which shows roughly an example of the correspondence of detection temperature value Tr and shift amount dw. It is a graph which shows roughly an example of the correspondence of shift amount dw and correction coefficient γ.

Embodiment 1 FIG.
FIG. 1 is a functional block diagram schematically showing a basic configuration of an image display device 10 according to Embodiment 1 for carrying out the present invention. In FIG. 1, the image display device 10 includes a first light source 31 that emits light CL in a first wavelength range, and a second light source that emits light RL in a second wavelength range that is a wavelength range included in the first wavelength range. 32, a light mixing unit 33 for generating illumination light ML by mixing two kinds of light respectively emitted from the first light source 31 and the second light source 32, and the illumination light ML spatially (two-dimensionally) in pixel units. The spatial light modulation element 13 that modulates the target (three-dimensionally or three-dimensionally) to generate a display image, and a light amount detection unit that receives a part of the illumination light ML and outputs a first light amount detection value and a second light amount detection value 34, the light source drive unit 24 that individually drives the first light source 31 and the second light source 32, the light source control unit 20 that controls the light source drive unit 24, and the element drive unit 12 that drives the spatial light modulation element 13. And an image control unit 11 for controlling the element driving unit 12. Here, for example, the light CL in the first wavelength region is cyan light, and the light RL in the second wavelength region is red light. In the present embodiment, light in the first wavelength range is described as cyan light CL, and light in the second wavelength range is described as red light RL.

  The first light source 31 is composed of a group of blue-green LED light sources 35 (blue-green light emitting diode group) that emits cyan light CL. Here, the cyan light CL is light having a spectrum having a peak intensity in the red wavelength range in addition to the blue wavelength range and the green wavelength range, and pure cyan having a peak intensity only in the blue wavelength range and the green wavelength range. Compared with colored light, the color is light and whitish cyan.

  FIG. 2 is a diagram illustrating an example of the blue-green LED light source 35. As shown in FIG. 2, the blue-green LED light source 35 absorbs a part of the emitted light from the blue LED light source 36, which is a semiconductor light emitting element that emits light in the blue wavelength range, and the blue LED light source 36 as excitation light. It has a green and red mixed phosphor 37 that emits light. By mixing the emitted light of the blue LED light source 36 and the emitted light of the mixed phosphor 37, light blue-green (cyan) light CL is generated. The amounts of the green phosphor and the red phosphor in the mixed phosphor are adjusted so that the cyan light CL becomes light cyan light and is combined with the red light from the second light source to become white light. Yes. Further, a blue laser light source may be used instead of the blue LED light source 36.

  On the other hand, the second light source 32 is composed of a group of red laser light sources 38. By using the red laser light source group, it is possible to realize a high-purity red color and a wide color reproduction range in the display image.

  Using a blue-green LED light source 35 that also uses a red phosphor as the first light source 31, two types of light of the first light source and the second light source 32 that is a group of 31 red laser light sources are mixed to generate illumination light ML. Thus, the total amount of light output of the red light emitted from the second light source 32 that is the red laser light source group can be suppressed, and the output from each light source can be suppressed, or the number of light sources can be suppressed. The laser light source generally has a narrower operating temperature range at a higher temperature than the LED light source, but the light output from the red laser light source 38 can be suppressed by using a configuration in which a red phosphor is used together. Since the amount of heat generated by the red laser light source 38 can be suppressed, the environmental temperature range in which the image display device operates can be expanded. The red laser light source 38 has a light emitting efficiency that decreases as the temperature increases, and the amount of heat generation increases, so that the cooling structure tends to be large. However, the use of a red phosphor together reduces the size of the light source cooling structure. It is also possible to make it easier. Furthermore, a decrease in luminous efficiency of the red laser light source 38 at a high temperature leads to a decrease in display luminance or an increase in power consumption at a high temperature, but these can also be reduced by using a red phosphor together. It becomes.

  The light mixing unit 33 mixes two types of light emitted from the first light source 31 and the second light source 32 to generate illumination light ML. Next, the light mixing unit 33 will be described separately for the case where the image display device 10 is configured as a projection display and the case where the image display device 10 is configured as a transmissive liquid crystal display device.

  When the image display device 10 is configured as a projection display, the light mixing unit 33 includes an optical system that guides the illumination light ML to the spatial light modulator 13. The image display apparatus 10 further includes a projection optical system that projects the light modulated by the spatial light modulator 13 onto a screen (not shown).

  On the other hand, when the image display device 10 is configured as a transmissive liquid crystal display device, the light mixing unit 33 includes a light guide plate that guides and mixes the cyan light CL and the red light RL. FIG. 3 is a schematic diagram illustrating an example of the image display device 10 configured as a transmissive liquid crystal display device. The transmissive liquid crystal display device of FIG. 3 is incident on the inside from a spatial light modulation element 13 configured as a transmissive liquid crystal display element, a first optical sheet 51, a second optical sheet 52, and a blue-green LED light source 35. The light guide diffusion plate 53 that guides the cyan light CL, the light guide diffusion plate 54 that guides the red light RL incident inside from the red laser light source 38, and the light reflection sheet 60 are provided. The spatial light modulation element 13, the first optical sheet 51, the second optical sheet 52, the light guide diffusion plate 53, the light guide diffusion plate 54, and the light reflection sheet 60 are perpendicular to the image display surface 13 f of the spatial light modulation element 13. They are stacked along the Z-axis direction.

  The light guide diffusion plates 53 and 54 are made of an optical material such as a glass material or a translucent resin material. The light guide diffusing plate 53 has a function of converting a plurality of light beams incident inside from the side end surfaces 53ea and 53eb of the light guide diffusing plate 53 into a planar cyan light CL and radiating it in the direction of the spatial light modulation element 13. Have A micro optical element 53 d is formed on the bottom surface of the light guide diffusion plate 53. Similarly, a fine optical element 54 d is formed on the bottom surface of the light guide diffusion plate 54.

  FIG. 4 is a plan view illustrating a schematic configuration of the light guide diffusion plate 53 when viewed from the image display surface 13 f side of the spatial light modulator 13. As shown in FIG. 4, the shape of the light guide diffusion plate 53 is a rectangle. A large number of blue-green LED light sources 35 are arranged so as to face the side end faces 53ea and 53eb of the light guide diffusion plate 53. A plurality of light beams incident on the inside from the side end faces 53ea and 53eb travel through the light guide diffusion plate 53, and the fine optical element 53d formed on the bottom surface of the light guide diffusion plate 53 causes the spatial light modulator 13 to Total internal reflection in the direction. Thereby, planar cyan light CL is radiated from the front surface of the light guide diffusion plate 53 (surface on the spatial light modulation element 13 side).

  A light reflecting film is formed on the other side end faces 53ec and 53ed of the light guide diffusion plate 53 except for a part of the area. As shown in FIG. 4, the light amount detection unit 34 can be arranged to face the side end face 53 ec. The light quantity detection unit 34 can receive light leaking from a region of the side end face 53ec where the light reflecting film is not formed.

  On the other hand, the light guide diffusing plate 54 has a function of converting a plurality of light beams incident inside from the side end surfaces 54ea and 54eb of the light guide diffusing plate 54 into a planar red light RL and radiating it to the light guide diffusing plate 53. Have

  FIG. 5 is a plan view showing a schematic configuration of the light guide diffusion plate 54 when viewed from the image display surface 13 f side of the spatial light modulator 13. As shown in FIG. 5, the shape of the light guide diffusion plate 54 is a rectangle. A number of red laser light sources 38 are arranged so as to face the side end faces 54ea and 54eb of the light guide diffusion plate 54. A plurality of light beams incident on the inside from the side end faces 54ea and 54eb travel inside the light guide diffusion plate 54, and are formed on the light guide diffusion plate 53 by the micro optical element 54d formed on the bottom surface of the light guide diffusion plate 54. Total internal reflection in the direction. Thereby, planar red light RL is radiated from the front surface (surface on the spatial light modulation element 13 side) of the light guide diffusion plate 54. A light reflecting film is formed on the other side end faces 54ec and 54ed of the light guide diffusion plate 54 except for a part of the area. As shown in FIG. 5, the light quantity detection unit 34 can be arranged to face the side end face 54 ec. The light quantity detector 34 can receive light leaking from a region of the side end face 54ec where the light reflecting film is not formed.

  Since the red light RL emitted from the surface of the light guide diffusion plate 54 is mixed with the cyan light CL when passing through the light guide diffusion plate 53, the illumination light ML is emitted from the light guide diffusion plate 53. The illumination light ML passes through the second optical sheet 52 and the first optical sheet 51 in order, and irradiates the back surface 13b of the spatial light modulator 13. Conversely, the light emitted from the back surface of the light guide diffusion plate 54 is reflected by the light reflecting sheet 60 in the direction of the spatial light modulator 13.

  A part of the illumination light ML radiated from the light mixing unit 33 is received by the light amount detection unit 34 without being modulated by the spatial light modulator 13. The light amount detection unit 34 converts an optical sensor having a red color filter, an optical sensor having a blue color filter, an optical sensor having a green color filter, and three outputs of these optical sensors into three digital signals. A color sensor including an A / D converter. As illustrated in FIG. 1, the light amount detection unit 34 includes a digital signal indicating a light amount detection value Rd that is a detection result of a light component in the red wavelength region and a light amount detection value Gd that is a detection result of the light component in the green wavelength region. And a digital signal indicating a light quantity detection value Bd, which is a detection result of the light component in the blue wavelength region, are output in parallel to the calculation unit 40 provided in the light source control unit 20. The light quantity detection unit 34 may output a value obtained by normalizing the light quantity detection values Rd, Gd, and Bd to the calculation unit 40 while maintaining the ratio of the light quantity detection values Rd, Gd, and Bd. The calculation unit 40 will be described later.

  The image control unit 11 performs image processing on a digital or analog input image signal (video signal) to generate a control signal, and supplies the control signal to the element driving unit 12. The element driving unit 12 gives an element driving signal MD to the spatial light modulation element 13 in accordance with the control signal supplied from the image control unit 11. The spatial light modulator 13 can generate a display image by spatially (two-dimensionally or three-dimensionally) modulating the illumination light ML in units of pixels in accordance with the element drive signal MD.

  The spatial light modulator 13 is a transmissive spatial light modulator that spatially modulates the incident illumination light ML and then transmits it, or a reflective spatial modulation that reflects the incident illumination light ML after spatially modulating it. If it is a vessel. Spatial modulation of the illumination light ML can be performed by modulating the intensity and phase of the illumination light ML in units of pixels.

  As the transmissive spatial light modulator, for example, a liquid crystal display panel that operates in an active matrix system can be employed. On the other hand, as the reflective spatial light modulator, for example, a DMD (Digital Micro-mirror Device) or LCOS (Liquid Crystal On Silicon) spatial light modulator can be used. When the image display device 10 is configured as a direct view display, a transmissive spatial light modulator can be used. On the other hand, when the image display apparatus 10 is configured as a projection display (projector), a reflective spatial light modulator can be used.

  The light source drive unit 24 supplies a drive current Ic to the blue LED light source group of the first light source 31 to drive the first light source 31, and a drive current Ir to the red laser light source group of the second light source 32. And a second drive circuit 26 for driving the second light source 32. FIG. 6 is a schematic diagram illustrating an example of the waveform of the drive current Ic or Ir. Here, the horizontal axis represents time t and the vertical axis represents the amount of current. Here, the drive current is indicated by a pulse waveform, Wd indicates the pulse width in a state where the current value of the drive current is high (H), and Ad indicates the amplitude. The first drive circuit 25 supplies a drive current Ic that has been subjected to pulse width modulation based on the pulse width Wd for the first light source 31 and amplitude modulated based on the amplitude Ad. Similarly, the second drive circuit 25 supplies a drive current Ir that has been subjected to pulse width modulation based on the pulse width Wd for the second light source 32 and amplitude modulated based on the amplitude Ad. If the cycle period of the pulse waveform is determined by a predetermined period, the duty ratio of the pulse waveform is determined by the cycle period and the pulse width Wd. The brightness of the light emitted from the light source becomes brighter as the state where the current value of the drive current is higher is longer. That is, the first light source 31 and the second light source 32 emit light with brightness according to the duty ratios and amplitudes of the drive signals Ic and Ir, respectively.

  The light source control unit 20 includes a light emission luminance control unit 21 that performs pulse width modulation control on each of the drive currents Ic and Ir, and a chromaticity control unit 22 that executes amplitude modulation control on the drive currents Ic and Ir. The light emission luminance control unit 21 can variably control the pulse widths Wd of the drive currents Ic and Ir, and the chromaticity control unit 22 can variably control the amplitudes Ad of the pulse waveforms of the drive currents Ic and Ir. it can. As a result, the first light source 31 and the second light source 32 are driven by the light source controller 20 based on the pulse width Wd and the amplitude Ad that are variably controlled for the first light source 31 and the second light source 32, respectively. Driven by. That is, the light source control unit 20 can individually control the brightness of the first light source 31 and the second light source 32. The light source controller 20 may supply not the pulse width Wd but information on the duty ratio to the light source driver 24.

  The light emission luminance control unit 21 has a function of adjusting the luminance of the illumination light ML based on the image information Lu supplied from the image control unit 11. For example, when the average luminance or peak luminance of the input image data is supplied as the image information Lu, the emission luminance control unit 21 can appropriately adjust the emission luminance according to the magnitude of the average luminance or peak luminance. Thereby, the contrast of the display image can be improved.

  The light source control unit 20 includes a calculation unit 40 that calculates the first light source light amount value Cs and the second light source light amount value Rs from the light amount detection values Rd, Gd, and Bd from the light amount detection unit 34. FIG. 7 is a functional block diagram illustrating a schematic configuration of the calculation unit 40 of the present embodiment. As illustrated in FIG. 7, the calculation unit 40 includes a color detection unit 41, a first light source light amount calculation unit 42, and a second light source light amount calculation unit 43.

  The color detection unit 41 has a function of calculating a blue-green (cyan) light amount detection value Cd from the green and blue light amount detection values Gd and Bd. Specifically, for example, the sum or average value of the light quantity detection values Gd and Bd may be calculated as the light quantity detection value Cd. Further, the light amount detection value Cd can be set with either the light amount detection value Gd or Bd as a representative value. The light amount detection value Cd calculated here is a detection value of a light component that does not include the red wavelength region in the illumination light from the first light source.

  The first light source light amount calculation unit 42 calculates a first light source light amount value Cs that is a value representing the light emission intensity of the first light source 31 from the light amount detection value Cd. The first light source light amount value Cs is calculated by multiplying the light amount detection value Cd by a predetermined coefficient. The predetermined coefficient is determined by the ratio of blue light, green light, and red light included in the cyan light CL emitted from the first light source 31, and can be determined in advance by measurement or the like. On the other hand, the second light source light amount calculation unit 43 calculates a second light source light amount value Rs that is a value representing the light emission intensity of the second light source 32 from the light amount detection values Rd and Cd. Specifically, the second light source light amount value Rs is calculated by subtracting a value obtained by multiplying the light amount detection value Cd by a predetermined coefficient from the light amount detection value Rd. The predetermined coefficient is also determined by the ratio of blue light, green light and red light contained in the cyan light CL emitted from the first light source 31, and can be determined in advance by measurement or the like.

  The relationship between the first light source light amount value Cs and the second light source light amount value Rs and the light amount detection values Rd and Cd can be expressed by the following equation (1).

式（１）において、係数ａは第１光源３１の発光強度と赤色の光量検出値Ｒｄを関連付ける係数、係数ｂは第２光源３２の発光強度と赤色Ｒｄの光量検出値を関連付ける係数、係数ｃは第１光源３１の発光強度と青緑色の光量検出値Ｃｄを関連付ける係数、係数ｄは第２光源３２の発光強度と青緑色の光量検出値Ｃｄを関連付ける係数である。係数ａ及び係数ｃは、第１光源３１から発せられるシアン色光ＣＬに含まれる青色光、緑色光及び赤色光の比率により決定され、測定などによりあらかじめ決定することができる。また、係数ｂ及び係数ｄは、第２光源３２から発せられる赤色光ＲＬに含まれる青色光と緑色光と赤色光との比率により決定され、測定などによりあらかじめ決定することができる。

In equation (1), coefficient a is a coefficient that associates the light emission intensity of the first light source 31 with the red light quantity detection value Rd, coefficient b is a coefficient that associates the light emission intensity of the second light source 32 and the light quantity detection value of red Rd, and coefficient c. Is a coefficient that associates the emission intensity of the first light source 31 with the blue-green light quantity detection value Cd, and the coefficient d is a coefficient that associates the emission intensity of the second light source 32 with the blue-green light quantity detection value Cd. The coefficient a and the coefficient c are determined by the ratio of blue light, green light, and red light included in the cyan light CL emitted from the first light source 31, and can be determined in advance by measurement or the like. The coefficient b and the coefficient d are determined by the ratio of blue light, green light, and red light included in the red light RL emitted from the second light source 32, and can be determined in advance by measurement or the like.

  The following formula (2) is derived from the formula (1).

ここで、第２光源３２は赤色光のみを発することから、係数ｄは０となる。したがって、第１光源３１の発光強度Ｙ１、第２光源３２の発光強度Ｙ２は下記の式（３）で表される。第１の光源光量演算部４２及び第２の光源光量演算部４３は、下記式（３）の演算を行うことで第１の光源光量値Ｃｓ及び第２の光源光量値Ｒｓを算出する。

Here, since the second light source 32 emits only red light, the coefficient d is zero. Therefore, the emission intensity Y1 of the first light source 31 and the emission intensity Y2 of the second light source 32 are expressed by the following formula (3). The first light source light amount calculation unit 42 and the second light source light amount calculation unit 43 calculate the first light source light amount value Cs and the second light source light amount value Rs by performing the calculation of the following equation (3).

色度制御部２２は、第１の光源光量値Ｃｓ及び第２の光源光量値Ｒｓに基づいて第１駆動回路２５及び第２駆動回路２６を個別に制御することにより照明光ＭＬの色度を調整する。色度制御部２２は、演算部４０から得られる第１の光源光量値Ｃｓと基準値Ｃｒとから、第１の光源光量値Ｃｓの基準値Ｃｒからのズレを示す差分ΔＣを算出する。同様に演算部４０から得られる第２の光源光量値Ｒｓと基準値Ｒｒとから、第２の光源光量値Ｒｓの基準値Ｒｒからのズレを示す差分ΔＲを算出する。差分ΔＣ及びΔＲは、次式（４）に従って算出される。ここで、基準値Ｃｒ及びＲｒについては、たとえば、画像表示装置１０の製造段階において、所定の基準温度下で分光放射輝度計などを用いた色調整を実行し、その直後に実測された色検出値を基準値Ｃｒ及びＲｒとして基準値記憶部２３に記憶することができる。

The chromaticity control unit 22 controls the chromaticity of the illumination light ML by individually controlling the first drive circuit 25 and the second drive circuit 26 based on the first light source light amount value Cs and the second light source light amount value Rs. adjust. The chromaticity control unit 22 calculates a difference ΔC indicating a deviation of the first light source light amount value Cs from the reference value Cr from the first light source light amount value Cs obtained from the calculation unit 40 and the reference value Cr. Similarly, a difference ΔR indicating a deviation of the second light source light amount value Rs from the reference value Rr is calculated from the second light source light amount value Rs obtained from the calculation unit 40 and the reference value Rr. The differences ΔC and ΔR are calculated according to the following equation (4). Here, with respect to the reference values Cr and Rr, for example, color adjustment using a spectral radiance meter or the like is performed under a predetermined reference temperature in the manufacturing stage of the image display device 10, and the color detection measured immediately thereafter is performed. Values can be stored in the reference value storage unit 23 as reference values Cr and Rr.

次に、色度制御部２２は、差分ΔＣが次式（５）を満たす第１の許容範囲内に収まり、且つ、差分ΔＲが次式（６）を満たす第２の許容範囲内に収まるように制御する。また、第１の許容範囲の下限ＴＬ１及び上限ＴＵ１と第２の許容範囲の下限ＴＬ２及び上限ＴＵ２は、基準値記憶部２３などに記憶しておくこととしてもよい。

Next, the chromaticity control unit 22 makes the difference ΔC fall within the first allowable range that satisfies the following expression (5), and the difference ΔR falls within the second allowable range that satisfies the following expression (6). To control. The lower limit TL1 and upper limit TU1 of the first allowable range and the lower limit TL2 and upper limit TU2 of the second allowable range may be stored in the reference value storage unit 23 or the like.

  Next, a specific light source control method will be described below. FIG. 8 is a flowchart schematically showing a procedure of chromaticity control processing by the chromaticity control unit 22 according to Embodiment 1 of the present invention. First, the first light source light amount value Cs and the second light source light amount value Rs are acquired from the calculation unit 40 (step S21). Next, the first reference value Cr and the second reference value Rr stored in the reference value storage unit 23 are read out and referred to (step S22). Next, the difference ΔC according to the equation (4) from the first light source light amount value Cs and the second light source light amount value Rs acquired in step S21 and the first reference value Cr and second reference value Rr acquired in step S22. And ΔR are calculated (step S23).

  After calculating the differences ΔC and ΔR in step S23, if the calculated difference ΔC exceeds the upper limit TU1 of the first allowable range (YES in step S24), amplitude control is performed on the drive current Ic. When the emission intensity of the first light source 31 is reduced (step S26) and the difference ΔC is below the lower limit TL1 of the first allowable range (NO in step S24 and YES in step S25), the amplitude with respect to the drive current Ic Control is executed to increase the emission intensity of the first light source 31 (step S27). On the other hand, when the difference ΔC is within the first allowable range (NO in step S24 and NO in step S25), the chromaticity control unit 22 shifts the process to the next step S28.

  Further, when the difference ΔR exceeds the upper limit TU2 of the second allowable range (YES in Step S28), the chromaticity control unit 22 performs amplitude control on the drive current Ir and emits light from the second light source 32. When the intensity is decreased (step S30) and the difference ΔR is below the lower limit TL2 of the second allowable range (NO in step S28 and YES in step S29), amplitude control is performed on the drive current Ir to execute the first control. The light emission intensity of the two light sources 32 is increased (step S31). On the other hand, when the difference ΔR is within the second allowable range (NO in step S28 and NO in step S29), the chromaticity control unit 22 does not perform the process (YES in step S32), and after step S21. Is executed (NO in step S32).

  As described above, the chromaticity control unit 22 according to the present embodiment uses the first light source so that the chromaticity of the display image becomes substantially constant based on the light source light amount values Cs and Rs calculated by the calculation unit 40. 31 and the light emission intensity of the second light source 32 can be variably controlled (steps S21 to S31 in FIG. 13). In addition, even when the light emission characteristics of the first light source 31 and the second light source 32 change due to secular change or the like, the white chromaticity of the display image can be adjusted to be constant. Therefore, the quality of the display image can be improved.

  The preferred embodiments according to the present invention have been described above with reference to the drawings, but these are exemplifications of the present invention, and various forms other than the above can be adopted. For example, in the above embodiment, the first light source 31 is a blue-green LED light source that emits cyan light CL including a red component, and the second light source 32 is a red laser light source that emits red light RL. It is not limited.

Embodiment 2. FIG.
FIG. 9 is a functional block diagram schematically showing another configuration of the image display apparatus 10 according to the embodiment of the present invention. The image display apparatus 10 shown in FIG. 9 has the same configuration as that of FIG. 1 of the first embodiment except that the temperature detection unit 39 and the light source control unit 20 include a correction unit 70. The description of the operation of the same configuration is omitted.

  In the image display device 10 of the present embodiment, the temperature detection means 39 is provided in the vicinity of the second light source 32. The temperature detecting means 39 detects the temperature of the second light source 32 or a temperature in the vicinity thereof, and outputs a detected temperature value Tr. The detected temperature value Tr is input to the correction unit 70 provided in the light source control unit 20. The correction unit 70 also receives the second light source light amount value Rs output from the calculation unit 40.

  FIG. 10 is a functional block diagram showing a schematic configuration of the correction unit 70 of the present embodiment. As illustrated in FIG. 10, the correction unit 70 includes a wavelength shift detection unit 71 and a correction calculation unit 72.

  The wavelength shift detection unit 71 has a function of calculating the shift amount (shift from the reference wavelength) dw of the emission wavelength of the second light source 32 based on the detected temperature value Tr. The correction calculation unit 72 corrects the red light source light amount value Rs using the shift amount dw, and outputs the corrected light source light amount value Rs. As illustrated in FIG. 10, the correction calculation unit 72 includes a correction coefficient calculation unit 73 and a weighting unit 74.

  The wavelength shift detector 71 samples the detected temperature value Tr and calculates the shift amount dw of the emission wavelength of the second light source 32 based on the sampled detected temperature value Tr. At this time, the wavelength shift detection unit 71 can estimate the shift amount dw corresponding to the detected temperature value Tr using a reference table or interpolation formula prepared in advance using the actual measurement values. FIG. 11 is a graph schematically showing an example of the correspondence relationship between the detected temperature value Tr and the shift amount dw. As shown in this graph, as the detected temperature value Tr deviates from the reference temperature T0 in the positive direction, the shift amount dw increases from zero, and conversely, the detected temperature value Tr decreases from the reference temperature T0 in the negative direction. The shift amount dw decreases from a zero value as it shifts. As described above, the second relationship based on the detected temperature value Tr sampled by preparing in advance a correspondence table between the detected temperature value Tr obtained from the actual measurement value and the shift amount dw by using a reference table or an interpolation formula. The shift amount dw of the light emission wavelength of the light source 32 can be calculated.

  Next, the correction coefficient calculation unit 73 calculates a correction coefficient γ based on the calculated shift amount dw. Next, the weighting unit 74 multiplies the light source light amount value Rs by the correction coefficient γ to calculate a corrected light source light amount value Rs2 (= γ × Rd). Here, the correction coefficient calculation unit 73 can calculate the positive correction coefficient γ corresponding to the shift amount dw using a reference table or an interpolation formula prepared in advance using the actual measurement values. FIG. 12 is a graph schematically showing an example of the correspondence relationship between the shift amount dw and the correction coefficient γ. As shown in this graph, as the shift amount dw increases from zero, the correction coefficient γ decreases from a value of 1.0. Conversely, as the shift amount dw decreases from zero, the correction coefficient γ becomes 1. Increase from 0. The corrected light source light amount value Rs2 is input to the chromaticity control unit 22 together with the light source light amount value Cs. Subsequent operations are the same as those in the first embodiment. In this way, a positive correction coefficient γ corresponding to the shift amount dw is calculated by preparing in advance a correspondence table between the shift amount dw obtained from the actual measurement value and the correction coefficient γ, which is represented by a reference table or an interpolation formula. can do.

  Incidentally, the spectral sensitivity of the light amount detector 34 is not uniform with respect to the wavelength of the illumination light ML, and the spectral sensitivity varies depending on the wavelength. That is, the spectral sensitivity of the light amount detector 34 has wavelength dependency. For this reason, even if the light amount detection value Rd of the red light component and the light source light amount value Rs calculated therefrom vary, the light emission intensity of the second light source 32 does not necessarily vary. The influence of the fluctuation of the emission wavelength due to the temperature change in the second light source 32 becomes larger as the color purity of the light emitted from the second light source 32 is higher, that is, as the energy is concentrated at the specific wavelength. In the present embodiment, since the light source light amount value Rs is corrected based on the detected temperature value Tr of the first light source 31, the light source light amount value Rs can be corrected to an appropriate value. In addition, the emission wavelength of the second light source 32 that emits red light has a temperature dependency higher than that of the first light source 31 and is more likely to fluctuate than the emission wavelength of the first light source 31. In the present embodiment, in particular, since the red light source light amount value Rs is corrected, the chromaticity of the display image can be accurately adjusted.

  DESCRIPTION OF SYMBOLS 10 Image display apparatus, 11 Image control part, 12 Element drive part, 13 Spatial light modulation element, 20 Light source control part, 21 Light emission luminance control part, 22 Chromaticity control part, 23 Reference value storage part, 24 Light source drive part, 25 1st drive circuit, 26 2nd drive circuit, 31 1st light source, 32 2nd light source, 33 light mixing part, 34 light quantity detection part, 35 blue-green LED light source, 36 blue LED light source, 37 mixed fluorescent substance, 38 red laser Light source, 39 temperature detection unit, 40 calculation unit, 41 color detection unit, 42 first light source light amount calculation unit, 43 second light source light amount calculation unit, 51 first optical sheet, 52 second optical sheet, 53 light guide diffusion Plate, 54 light guide diffuser plate, 60 light reflection sheet, 70 correction unit, 71 wavelength shift detection unit, 72 correction calculation unit, 73 correction coefficient calculation unit 74 weighting unit.

Claims (4)

A spatial light modulation element that spatially modulates illumination light to generate a display image;
A first light source that emits light in a first wavelength region;
A second light source comprising a laser light source that emits light in a second wavelength range that is a wavelength range included in the first wavelength range; and
A light mixing section that mixes two kinds of light respectively emitted from the first light source and the second light source to generate the illumination light, and radiates the illumination light to the spatial light modulator;
A part of the illumination light is received, a light component in a wavelength region different from the second wavelength region is detected, a first light quantity detection value is output, and a light component in the second wavelength region is detected. A light amount detection unit for outputting a second light amount detection value;
A light source driving unit for individually driving the first light source and the second light source;
A light source control unit that controls the light source driving unit based on the first light amount detection value and the second light amount detection value to adjust the chromaticity of the illumination light;
A temperature detector for detecting a temperature in the vicinity of the second light source;
A correction unit that calculates a shift amount of the light emission wavelength of the second light source based on a temperature in the vicinity of the second light source, and corrects a light source light amount value of the second light source using the shift amount of the light emission wavelength; >
The light source control unit controls light emission intensity of the first light source using the first light quantity detection value, and uses the first light quantity detection value and the second light quantity detection value to perform the second. An image display device that controls light emission intensity of the second light source by controlling light emission intensity of the light source and using a light source light amount value of the second light source corrected by the correction unit. The light source control unit sets a value obtained by subtracting a value obtained by multiplying the first light quantity detection value by a predetermined coefficient from the second light quantity detection value as a light source light quantity value of the second light source. The image display device according to claim 1, wherein The first light source includes a semiconductor light emitting element that emits blue light;
A phosphor that absorbs part of the emitted light of the semiconductor light emitting element as excitation light and emits green and red light, and
The second light source, the image display apparatus according to claim 1 or 2, characterized in that it comprises a semiconductor light emitting element that emits red light. A spatial light modulation element that spatially modulates illumination light to generate a display image;
A first light source that emits light in a first wavelength region;
A second light source comprising a laser light source that emits light in a second wavelength range that is a wavelength range included in the first wavelength range; and
A light mixing section that mixes two kinds of light respectively emitted from the first light source and the second light source to generate the illumination light, and radiates the illumination light to the spatial light modulator;
A part of the illumination light is received, a light component in a wavelength region different from the second wavelength region is detected, a first light quantity detection value is output, and a light component in the second wavelength region is detected. A light amount detection unit for outputting a second light amount detection value;
A light source driving unit for individually driving the first light source and the second light source ;
A light source controller for adjusting the chromaticity of the illumination light by controlling the light source driving section based on the first light quantity detecting value before Symbol and said second light amount detection value,
A temperature detector for detecting a temperature in the vicinity of the second light source;
An image including a correction unit that calculates a shift amount of the emission wavelength of the second light source based on a temperature in the vicinity of the second light source and corrects a light source light amount value of the second light source using the shift amount of the emission wavelength. A light source control method for a display device, comprising:
Controlling the light emission intensity of the first light source using the first light quantity detection value;
And a step of controlling a light emission intensity of the second light source by using both the first light quantity detection value and the second light quantity detection value.

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