JP2015064539A - Video display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a video display device that has good efficiency of the use of light to provide stable target luminance.SOLUTION: A video display device 101 includes a light source LD that emits coherent light Lc, a light source driving unit 14 that supplies power to the light source LD, light control means M15 for controlling the intensity of the coherent light Lc, and an image creating unit 11 that creates desired display images from the coherent light Lc; and allows an observer ST to observe a video VM of the display images, where the light control means M15 includes a detection unit 35 that detects the intensity of light, a voltage adjustment unit 55 that adjusts the output voltage of the light source driving unit 14 on the basis of a result of the detection by the detection unit 35, and a time adjustment unit 75 that adjusts the output time of the output voltage, and controls the output of the light source LD by the combination of the voltage adjustment unit 55 and time adjustment unit 75.

Description

  The present invention relates to an image display apparatus using coherent light.

  Conventionally, coherent light, mainly laser light, has been applied in a wide range of fields such as optical recording devices, measuring instruments, printers, medical equipment, and office equipment, taking advantage of features such as small size, high efficiency, and high directivity. In particular, recently, a so-called laser projector, which is an image display device that displays an image by irradiating a projection surface such as a screen or a wall with laser light, has been generally known. Further, as a video display device other than a laser projector, it has been applied to a three-dimensional display, a head mounted display (HMD), a head-up display (HUD), and the like.

  As an example of a video display device applied to the above-described head-up display (HUD), Patent Literature 1 proposes a head-up display device 900 as shown in FIG. 6A and 6B are diagrams for explaining the head-up display device 900 of Conventional Example 1. FIG. 6A is a configuration diagram showing the head-up display device 900, and FIG. 6B is a synthetic laser beam. It is a block diagram of the generator 910. FIG.

  A head-up display device 900 shown in FIG. 6A includes a synthetic laser light generation device 910, a MEMS scanner 920, a color sensor 930, a transmission screen 940, a reflection unit 950, a housing 960, a light sensor 970, and the like. , And a control unit 980 that performs electrical control of the head-up display device 900. Further, as shown in FIG. 6B, the synthetic laser light generator 910 includes a plurality of laser diodes (911r, 911g, 911b) and a collection corresponding to each of the plurality of laser diodes (911r, 911g, 911b). Dichroic mirrors corresponding to the optical optical system (912r, 912g, 912b), a liquid crystal panel (polarization control element) 913, a polarizing plate (polarization unit) 914, and a plurality of laser diodes (911r, 911g, 911b) 915r, 915g, 915b). The head-up display device 900 is a device that allows a driver to visually recognize a display image representing vehicle information generated from a plurality of laser diodes (911r, 911g, 911b).

  And when making a driver | operator visually recognize a display image, it was necessary to adjust the brightness | luminance of a display image so that a driver | operator might be easy to visually recognize. In the head-up display device 900 of the conventional example, as the adjustment example 1, the polarization angle of the liquid crystal panel 913 is adjusted via the polarization control unit of the control unit 980 based on the calculated luminance target value, and the transmittance of the polarizing plate 914 is changed. By controlling, the display luminance of the display image is adjusted. Alternatively, as an adjustment example 2, when the external illuminance measurement value is equal to or greater than a predetermined boundary external illuminance, a luminance target value that is a luminance of a suitable display image is calculated from the external illuminance measurement value output from the light sensor 970, and the calculation is performed. Based on the result, the display luminance of the display image is adjusted by controlling the laser light intensity of the plurality of laser diodes (911r, 911g, 911b) via the laser light control unit of the control unit 980. On the other hand, when the external illuminance measurement value is less than the predetermined boundary external illuminance, the polarization angle of the liquid crystal panel 913 is adjusted through the polarization control unit of the control unit 980 based on the calculated luminance target value, and the transmittance of the polarizing plate 914 is determined. By controlling this, the display brightness of the display image is adjusted.

JP 2013-15738 A

  However, in both the adjustment examples 1 and 2, the polarizing plate 914 is used, and the polarization angle is adjusted by the liquid crystal panel 913. Therefore, it is difficult to finely adjust the luminance, and the luminance target value is stably obtained. It was difficult to do. Furthermore, since the luminance is adjusted by transmitting light through the polarizing plate 914 and reducing the light, there is a problem that the light use efficiency is necessarily lowered.

  The present invention solves the above-described problems, and an object of the present invention is to provide an image display device capable of obtaining a stable target luminance with high light use efficiency.

  In order to solve this problem, an image display device of the present invention includes a light source that emits coherent light, a light source driving unit that supplies power to the light source, a light control unit that controls the light intensity of the coherent light, An image generation unit that generates a desired display image from the coherent light, and allows an observer to observe the image of the display image, wherein the light control unit detects the light intensity. A voltage adjusting unit that adjusts an output voltage of the light source driving unit based on a detection result of the detection unit, and a time adjusting unit that adjusts an output time of the output voltage, and the voltage adjusting unit, The output of the light source is controlled in combination with the time adjustment unit.

  According to this, the video display device of the present invention can finely divide and adjust the output level, and can finely control the desired target light intensity (luminance). Furthermore, since the light intensity (luminance) is not adjusted using a polarizing plate as in the conventional example, the output coherent light is not wasted. As a result, the light use efficiency is good, and the light intensity (luminance) can be adjusted stably with respect to the target light intensity (luminance).

  The video display device of the present invention is characterized in that the output time is adjusted by the time adjustment unit when the detected value of the light intensity is equal to or less than a predetermined boundary value.

  According to this, when the detected value of the light intensity is equal to or less than a predetermined boundary value, that is, when the light source has a low output, the output of the light source is changed while keeping the voltage (current) constant. For this reason, this low output region has a small change in output with respect to a change in voltage (current) and is an unstable change region. Therefore, in this low output region, the voltage (current) value is kept constant. Thus, the output of the light source can be adjusted. Thus, the light intensity (luminance) can be adjusted stably with respect to the target light intensity (luminance).

  In the video display device of the present invention, the light control unit includes an external light detection unit that detects an illuminance of external light, and the voltage adjustment is performed based on an external illuminance measurement value measured by the external light detection unit. The output of the light source is controlled by using at least one of the unit and the time adjustment unit.

  According to this, it is possible to adjust the output of the light source in accordance with the difference in brightness of outside light, for example, day and night. Thereby, the brightness of the image visually recognized by the observer can be changed to suit the situation at that time, and an image that is easy for the observer to view can be provided.

  In the video display device of the present invention, the light control unit includes a current limiting unit that limits a current flowing through the light source, and the current limiting unit has a current value equal to or lower than a preset reference current value. Thus, the light source driving unit is controlled.

  According to this, it is possible to prevent an excessive current from flowing through the light source due to the deterioration of the light source or the deviation of the optical axis due to an impact. As a result, damage to the light source can be reduced and the life of the light source can be extended.

  The video display device according to the present invention includes a plurality of the light sources, and a plurality of the voltage adjusting units and the time adjusting units corresponding to the plurality of light sources. It is said.

  According to this, since a plurality of light sources are provided, it is possible to make a plurality of colors of the image visually recognized by the observer, and to enrich the expression of the image. Furthermore, since a plurality of voltage adjustment units and time adjustment units are provided corresponding to a plurality of light sources, even if the display image area is different in different colors, each voltage adjustment unit and time adjustment unit respectively The light intensity (brightness) of each displayed image can be kept constant by adjusting the output of the light source.

  In the video display device of the present invention, the image generation unit includes a holographic optical element that diffracts the coherent light to generate video light, and an optical member that guides the video light from the holographic optical element. The detection unit detects the light intensity of the image light, and the voltage adjustment unit and the time adjustment unit control the output of the light source based on a detection result of the detection unit. .

  According to this, it is possible to adjust the brightness of the display image at any time corresponding to the display image. As a result, the light intensity (luminance) can be accurately adjusted to the target light intensity (luminance), and the light utilization efficiency can be improved.

  The video display apparatus of the present invention can finely control the output level and finely control the desired target light intensity (luminance). Furthermore, since the light intensity (luminance) is not adjusted using a polarizing plate as in the conventional example, the output coherent light is not wasted. As a result, the light use efficiency is good, and the light intensity (luminance) can be adjusted stably with respect to the target light intensity (luminance).

It is a block diagram explaining the video display apparatus of 1st Embodiment of this invention. It is a block diagram explaining the control system concerning the video display apparatus of 1st Embodiment of this invention. It is a block diagram explaining the video display apparatus of 2nd Embodiment of this invention. It is a block diagram explaining the control system concerning the video display apparatus of 2nd Embodiment of this invention. It is a block diagram explaining the control system concerning the video display apparatus of the modification 1 of 1st Embodiment of this invention. 6A and 6B are diagrams illustrating a head-up display device 900 according to a conventional example 1. FIG. 6A is a configuration diagram illustrating the head-up display device 900, and FIG. 6B is a diagram illustrating a synthetic laser light generation device 910. It is a block diagram.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is a configuration diagram illustrating a video display apparatus 101 according to the first embodiment of the present invention. FIG. 2 is a block diagram illustrating a control system related to the video display apparatus 101 according to the first embodiment of the present invention.

  As shown in FIG. 1, the video display device 101 according to the first embodiment of the present invention is mounted on a vehicle and used as a head-up display (HUD).

  Further, as shown in FIG. 1, the video display apparatus 101 according to the first embodiment of the present invention includes a light source LD that emits coherent light Lc, a light source driving unit 14 that supplies power to the light source LD, and the coherent light Lc. An image generation unit 11 that generates a desired display image and a light control unit M15 that controls the light intensity of the coherent light Lc are configured. Then, the light control means M15 adjusts the output of the light source LD so that the observer ST can observe (view) the image VM of the adjusted image light Lf through the windshield FG.

  As shown in FIGS. 1 and 2, the light source LD of the video display device 101 is provided with two color light sources LD (RLD, GLD) in the first embodiment of the present invention. It has been. Although not shown in detail, in order to emit red and green light, two types of semiconductor laser elements are used. Thereby, since the semiconductor laser element is used, the coherent light Lc having high coherence (coherent) can be emitted from the light source LD. In addition, since a plurality of light sources LD are provided (two in the first embodiment of the present invention), the video VM visually recognized by the observer ST can have a plurality of colors, and the expression of the video VM is rich. Can be.

  As the semiconductor laser element, for example, an element that emits light with a wavelength of 642 nm is preferably used in the case of red, and an element that emits light with a wavelength of 515 nm is preferably used in the case of green. . In the first embodiment of the present invention, the semiconductor laser element is preferably used in order to obtain the coherent light Lc having high coherence (coherent). However, the present invention is not limited to this. For example, coherent light can also be produced by passing monochromatic light such as sodium lamp light through a pinhole, and such a light source may be used.

  The light source drive unit 14 of the video display device 101 is a drive circuit in which an operational amplifier is incorporated, and is connected to each light source LD (RLD, GLD), and each light source LD (RLD, RLD, GLD).

  The image generation unit 11 of the video display device 101 includes a holographic optical element 41 that diffracts the coherent light Lc into the video light Lf, and an optical member OP that guides the video light Lf from the holographic optical element 41. Is done.

  The holographic optical element 41 has a function of diffracting the coherent light Lc from the light source LD into the image light Lf. Specifically, in the first embodiment of the present invention, phase modulation LCOS (Liquid crystal on silicon) is used, and the “hologram pattern” written in the phase modulation LCOS is irradiated with coherent light Lc. As a result, diffracted light is generated and emitted as image light Lf, which is coherent light, through the Fourier lens FL1 shown in FIG. The “hologram pattern” records the intensity and phase of light.

  Further, as shown in FIG. 1, an LCOS driver 51 is connected to the holographic optical element 41. The LCOS driver 51 converts the “hologram pattern” created by the central processing unit 71 into a phase modulation type LCOS. In addition, it has a function of writing at any time.

  The optical member OP is mainly composed of an optical component that guides the image light Lf from the holographic optical element 41. In the first embodiment of the present invention, as shown in FIG. 22), an optical lens 32 that collects or collimates the light, a slitter 52 that defines the display range of the display screen, and a diffuser 13 that diffuses the video light Lf that is coherent light. In addition, the optical member OP also includes an optical lens 42 that collects or collimates the coherent light Lc from the light source LD.

  The slitter 52 passes most of the irradiation range of the video light Lf, and the range corresponding to the video light Lf that has passed through is the display range of the video VM (see FIG. 1) visually recognized by the observer ST, that is, It becomes a display image.

  As shown in FIG. 1, the diffuser 13 is disposed on the rear side of the optical path of the slitter 52 and diffuses the transmitted video light Lf. The diffuser 13 is connected to a drive unit 13d that drives the diffuser 13, and rotates the diffuser 13. Thereby, the directivity of the image light Lf which is coherent light is reduced. Thereby, the speckle pattern resulting from coherent light can be reduced, and the quality of the video VM visually recognized by the observer ST can be improved. The speckle pattern referred to here means that when light having high coherence is scattered on the irradiated object, the scattered light scattered at each part on the irradiated object interferes with each other. This refers to the fine interference fringes that occur. In the first embodiment of the present invention, the diffuser 13 is rotated. However, the present invention is not limited to this. For example, the diffuser 13 may be vibrated and moved.

  The plane mirrors (12, 22), the optical lens 32, and the optical lens 42 use commonly used optical components and do not have special specifications. In addition, in order to prevent the bad influence of daylight as an optical member OP, various filters may be used and arranged in the middle of the optical path, or a curved mirror may be used instead of the flat mirrors (12, 22). . Further, the present invention is not limited to the combination of the optical members OP shown in FIG.

  As shown in FIG. 1, the light control means M15 of the video display device 101 includes a detection unit 35 that detects light intensity, and a voltage adjustment unit that adjusts the output voltage of the light source driving unit 14 based on the detection result of the detection unit 35. 55, a time adjustment unit 75 that adjusts the output time of the output voltage of the light source driving unit 14, and a control unit 95 that controls the voltage adjustment unit 55 and the time adjustment unit 75.

  The detection unit 35 detects the light intensity of the image light Lf, which is coherent light, and is arranged in the vicinity of the slitter 52 as shown in FIG. 1, corresponding to the two light sources RLD and GLD 2. The detection part 35R and the detection part 35G are provided. The light intensity is detected separately for each of the red (Red) and green (Green) colors with respect to the video light Lf irradiated to each of the detection units 35. As the detection unit 35, a photodiode (PD) is suitably used.

  The voltage adjustment unit 55 includes a control circuit having a D / A converter (Digital to Analog Converter), and adjusts the output voltage of the light source driving unit 14 based on the detection result of the detection unit 35 (35R, 35G). . In addition, as shown in FIG. 1, the voltage adjusting unit 55 includes two light sources LD (RLD, GLD) corresponding to two light sources LD (RLD, GLD). The voltage adjustment unit 55R and the voltage adjustment unit 55G are connected to the detection unit 35R and the detection unit 35G via the control unit 95, respectively. Thereby, even if it is the area of a different display image with a different color, the output of each light source LD can be adjusted by each voltage adjustment part 55 (55R, 55G).

  The time adjustment unit 75 includes a control circuit having a PWM (Pulse Width Modulation) circuit, and adjusts the output time of the light source LD based on the detection result of the detection unit 35 (35R, 35G). Further, as shown in FIG. 1, the time adjusting unit 75 corresponds to the two light sources LD (RLD, GLD), and the time adjusting unit 75R and the time adjusting unit 75G have two light sources LD (RLD, GLD). The time adjustment unit 75R and the time adjustment unit 75G are connected to the detection unit 35R and the detection unit 35G via the control unit 95, respectively. Thereby, even if it is the area of a different display image with a different color, the output of each light source LD can be adjusted by each time adjustment part 75 (75R, 75G).

  The control unit 95 uses an integrated circuit (IC) and mainly controls the voltage adjustment unit 55 and the time adjustment unit 75 to adjust the output of the light source LD. In addition to the function of adjusting the output of the light source LD based on the detection result of the detection unit 35, the control unit 95 also adjusts the output change of the light source LD accompanying the temperature change caused by the heat generation of the light source LD. have.

  As shown in FIG. 2, the video display apparatus 101 configured as described above is configured by combining a voltage adjustment unit 55 (55R, 55G) and a time adjustment unit 75 (75R, 75G), and a light source LD (RLD, GLD). ) Is controlled to keep the brightness of the displayed video VM constant.

  Specifically, for example, the voltage adjustment unit 55 uses 10-bit A / D conversion to adjust the voltage to 1024 stages, and the time adjustment unit 75 changes the duty cycle of the pulse width, The voltage output time is adjusted to 200 levels. Thereby, the video display apparatus 101 can finely divide and adjust the output level of the light source LD, and can finely control the desired target light intensity (luminance). Further, since the image display apparatus 101 does not adjust the light intensity (brightness) using the polarizing plate 914 unlike the conventional example, the output coherent light Lc is not wasted and the light use efficiency is good. .

  In particular, in the first embodiment of the present invention, the video display device 101 has a detection value of light intensity equal to or less than a predetermined boundary value, for example, 10% (this is a boundary value) or less with respect to the maximum light intensity. The time adjustment unit 75 adjusts the output time. This light source LD has a low output, and the region below 10% (this is the boundary value) has a small change in output with respect to a change in voltage (current) and is an unstable change region. In the region, it is possible to adjust the output of the light source LD with a constant voltage (current) value. Thus, the light intensity (luminance) can be adjusted stably with respect to the target light intensity (luminance).

  The effects of the video display device 101 according to the first embodiment of the present invention configured as described above will be described below.

  The video display device 101 according to the first embodiment of the present invention includes a voltage adjustment unit 55 (55R, 55G) that adjusts the output voltage of the light source driving unit 14 and a time adjustment unit 75 (75R, 75G) that adjusts the output time of the output voltage. ) To control the output of the light source LD, so that the output level can be finely divided and adjusted. For this reason, it is possible to finely control the desired target light intensity (luminance). Further, since the light intensity (luminance) is not adjusted using the polarizing plate 914 as in the conventional example, the output coherent light Lc is not wasted. As a result, the light use efficiency is good, and the light intensity (luminance) can be adjusted stably with respect to the target light intensity (luminance).

  Further, when the detected value of the light intensity is equal to or less than the predetermined boundary value, the output time is adjusted by the time adjustment unit 75. That is, when the light source LD is low in output, the output of the light source LD is kept constant with the voltage (current) kept constant. Is changing. For this reason, this low output region has a small change in output with respect to a change in voltage (current) and is an unstable change region. Therefore, in this low output region, the voltage (current) value is kept constant. Thus, the output of the light source LD can be adjusted. Thus, the light intensity (luminance) can be adjusted stably with respect to the target light intensity (luminance).

  In addition, since a plurality of light sources LD are provided, a plurality of colors of the video VM visually recognized by the observer ST can be provided, and the expression of the video VM can be enriched. In addition, since a plurality of voltage adjustment units 55 and time adjustment units 75 are provided corresponding to a plurality of light sources LD, the voltage adjustment unit 55 and the time are different even for different display image areas with different colors. The adjustment unit 75 can adjust the output of each light source LD, and can keep the light intensity (luminance) of each displayed video VM constant.

  In addition, the light intensity of the image light Lf from the holographic optical element 41 is detected by the detection unit 35 (35R, 35G), and the voltage adjustment unit 55 and the time adjustment unit 75 are based on the detection result of the detection unit 35. Since the output of the LD is controlled, it is possible to adjust the luminance of the display image at any time corresponding to the display image. As a result, the light intensity (luminance) can be accurately adjusted to the target light intensity (luminance), and the light utilization efficiency can be improved.

[Second Embodiment]
FIG. 3 is a configuration diagram illustrating the video display apparatus 102 according to the second embodiment of the present invention. FIG. 4 is a block diagram illustrating a control system related to the video display apparatus 102 according to the second embodiment of the present invention. Also, the video display device 102 of the second embodiment is different from the first embodiment in that the light control means M25 has an external light detection unit 27 and a current limiting unit 28. In addition, about the same structure as 1st Embodiment, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

  As shown in FIG. 3, the video display device 102 according to the second embodiment of the present invention is mounted on a vehicle, as in the first embodiment of the present invention, and is used as a head-up display (HUD, Head-Up Display). used.

  Further, as shown in FIG. 3, the video display apparatus 102 according to the second embodiment of the present invention includes a light source LD that emits coherent light Lc, a light source driving unit 24 that supplies power to the light source LD, and coherent light Lc. An image generation unit 11 that generates a desired display image and a light control means M25 that controls the light intensity of the coherent light Lc are configured. Then, the light control means M25 adjusts the output of the light source LD so that the observer ST can observe (view) the image VM of the adjusted image light Lf through the windshield FG.

  As shown in FIGS. 3 and 4, the light source LD of the video display device 102 is provided with two color light sources LD (RLD, BLD) in the second embodiment of the present invention. It has been. Although not shown in detail, in order to emit red and blue light, two types of semiconductor laser elements are used. As the semiconductor laser element, for example, an element that emits light with a wavelength of 642 nm is preferably used in the case of red, and an element that emits light with a wavelength of 445 nm is preferably used in the case of blue. .

  The light source drive unit 24 of the video display device 102 is a drive circuit in which an operational amplifier is incorporated, and is connected to each light source LD (RLD, BLD), and each light source LD (RLD, BLD).

  Similarly to the first embodiment of the present invention, the image generation unit 11 of the video display device 102 diffracts the coherent light Lc into the video light Lf and the video light Lf from the holographic optical element 41. And an optical member OP that guides the light.

  The optical member OP is mainly composed of an optical component that guides the image light Lf from the holographic optical element 41. In the second embodiment of the present invention, as shown in FIG. 3, a planar mirror (12 22), an optical lens 32 for condensing or collimating light, a slitter 52 for defining the display range of the display screen, and a diffuser 13 for diffusing the video light Lf. In addition, the optical member OP also includes an optical lens 42 that collects or collimates the coherent light Lc from the light source LD.

  As shown in FIG. 3, the light control means M25 of the video display device 102 includes a detection unit 35 that detects light intensity, and a voltage adjustment unit that adjusts the output voltage of the light source driving unit 24 based on the detection result of the detection unit 35. 55, a time adjusting unit 75 that adjusts the output time of the output voltage of the light source driving unit 24, an external light detecting unit 27 that detects the illuminance of the external light DL, and a current limiting unit 28 that limits the current flowing through the light source LD. And a control unit 95 that controls the voltage adjustment unit 55 and the time adjustment unit 75.

  The detection unit 35 detects the light intensity of the video light Lf, and is arranged in the vicinity of the slitter 52 as shown in FIG. 3, and corresponds to the two light sources RLD and the light source BLD. 35R and a detection unit 35B are provided. The light intensity is detected separately for each color of red (Red) and blue (Blue) with respect to the video light Lf irradiated to each detection unit 35. As the detection unit 35, a photodiode (PD) is suitably used.

  The voltage adjustment unit 55 includes a control circuit having a D / A converter (Digital to Analog Converter), and adjusts the output voltage of the light source drive unit 24 based on the detection result of the detection unit 35 (35R, 35B). . Further, as shown in FIG. 3, the voltage adjustment unit 55 includes two light source LDs (RLD, BLD) corresponding to the two light sources LD (RLD, BLD). The voltage adjustment unit 55R and the voltage adjustment unit 55B are connected to the detection unit 35R and the detection unit 35B via the control unit 95, respectively. Thereby, even if it is the area of a different display image with a different color, the output of each light source LD (RLD, BLD) can be adjusted by each voltage adjustment part 55 (55R, 55B).

  The time adjustment unit 75 includes a control circuit having a PWM (Pulse Width Modulation) circuit, and adjusts the output time of the light source LD based on the detection result of the detection unit 35 (35R, 35B). As shown in FIG. 3, the time adjustment unit 75 includes two light sources LD (RLD, BLD) corresponding to the two light sources LD (RLD, BLD). The time adjustment unit 75R and the time adjustment unit 75B are connected to the detection unit 35R and the detection unit 35B via the control unit 95, respectively. Thereby, even if it is the area of a different display image with a different color, the output of each light source LD can be adjusted by each time adjustment part 75 (75R, 75B).

  The external light detection unit 27 of the light control means M25 uses an illuminance sensor incorporating a photodiode (PD) and a current amplification circuit, and is disposed in the vicinity of the windshield FG as shown in FIG. The illuminance of outside light DL, here, mainly daylight (sunlight) is detected. Then, the light control means M25 controls the output of the light source LD using at least one of the voltage adjustment unit 55 and the time adjustment unit 75 based on the external illuminance measurement value measured by the external light detection unit 27. . Thereby, the output of the light source LD can be adjusted in accordance with the difference in brightness of the external light DL, for example, day and night, sunny and cloudy, inside or outside the tunnel, and the like. Thus, the brightness of the video VM visually recognized by the observer ST can be changed to match the situation at that time, and the video VM that is easy for the observer ST to view can be provided.

  3 is arranged between the diffuser 13 and the flat mirror 22 shown in FIG. 3, the light enters the video display device 102 from the windshield FG, is reflected by the flat mirror 22, and is reflected by the diffuser 13. It is possible to detect the illuminance of the external light DL that has reached. Thereby, the output of the light source LD can be finely adjusted with respect to the contrast change of the video VM due to the influence of the external light DL. Accordingly, it is possible to correct the contrast of the video VM visually recognized by the observer ST, and it is possible to provide the video VM that is easier for the observer ST to view. The video display apparatus 102 according to the second embodiment of the present invention includes a voltage adjusting unit 55 (55R, 55B) that adjusts the output voltage of the light source driving unit 24 and a time adjusting unit 75 (75R) that adjusts the output time of the output voltage. , 75B) to control the output of the light source LD, so that such delicate adjustment is facilitated.

  The current limiting unit 28 (28R, 28B) of the light control means M25 uses a comparator, and as shown in FIG. 3, the current limiting unit 28 (28R, 28B) respectively has a light source driving unit 24 that drives each light source LD (RLD, BLD). It is connected. And the light source drive part 24 is controlled so that it may become the electric current value below the preset reference electric current value, and the electric current which flows into light source LD is restrict | limited. Thereby, it is possible to prevent an excessive current from flowing through the light source LD due to the deterioration of the light source LD or the deviation of the optical axis due to an impact. As a result, damage to the light source LD can be reduced, and the life of the light source LD can be extended.

  As shown in FIG. 4, the video display device 102 configured as described above combines a voltage adjustment unit 55 (55R, 55B) and a time adjustment unit 75 (75R, 75B) to form a light source LD (RLD, BLD). ) Is controlled to keep the brightness of the displayed video VM constant.

  The effects of the video display device 102 according to the second embodiment of the present invention configured as described above will be described below.

  The video display device 102 according to the second embodiment of the present invention includes a voltage adjustment unit 55 (55R, 55B) that adjusts the output voltage of the light source driving unit 24 and a time adjustment unit 75 (75R, 75B) that adjusts the output time of the output voltage. ) To control the output of the light source LD, so that the output level can be finely divided and adjusted. For this reason, it is possible to finely control the desired target light intensity (luminance). Further, since the light intensity (luminance) is not adjusted using the polarizing plate 914 as in the conventional example, the output coherent light Lc is not wasted. As a result, the light use efficiency is good, and the light intensity (luminance) can be adjusted stably with respect to the target light intensity (luminance).

  Further, since the output of the light source LD is controlled using at least one of the voltage adjustment unit 55 and the time adjustment unit 75 based on the external illuminance measurement value measured by the external light detection unit 27, the brightness of the external light DL is controlled. For example, the output of the light source LD can be adjusted in response to, for example, day and night, sunny and cloudy, or inside and outside the tunnel. Thus, the brightness of the video VM visually recognized by the observer ST can be changed to match the situation at that time, and the video VM that is easy for the observer ST to view can be provided.

  In addition, since the light source driving unit 24 is controlled so that the current limiting unit 28 (28R, 28B) of the light control unit M25 has a current value equal to or less than a preset reference current value, the light source LD may be deteriorated or impacted. It is possible to prevent an excessive current from flowing through the light source LD due to a deviation of the optical axis. As a result, damage to the light source LD can be reduced, and the life of the light source LD can be extended.

  In addition, since a plurality of light sources LD are provided, a plurality of colors of the video VM visually recognized by the observer ST can be provided, and the expression of the video VM can be enriched. In addition, since a plurality of voltage adjustment units 55 and time adjustment units 75 are provided corresponding to a plurality of light sources LD, the voltage adjustment unit 55 and the time are different even for different display image areas with different colors. The adjustment unit 75 can adjust the output of each light source LD, and can keep the light intensity (luminance) of each displayed video VM constant.

  In addition, this invention is not limited to the said embodiment, For example, it can deform | transform and implement as follows, These embodiments also belong to the technical scope of this invention.

<Modification 1>
FIG. 5 is a block diagram illustrating a control system related to the video display apparatus C101 according to the first modification of the first embodiment of the present invention. In the first embodiment, two types of light sources LD (RLD, GLD) are used. However, three types of light sources LD (RLD, GLD, BLD) may be used. In that case, as shown in FIG. 5, it is preferable to provide a detection unit C35, a voltage adjustment unit C55, and a time adjustment unit C75 corresponding to the three types of light sources LD.

<Modification 2>
In the first modification, the light source LD is preferably configured so as to provide red (Red), green (Green), and blue (Blue) light sources LD (RLD, GLD, BLD). A configuration in which light sources of four colors added with (Yellow) may be provided, or a configuration in which light sources of four colors or more may be provided. Conversely, a configuration using a light source of one color may be used.

<Modification 3>
In the said 1st Embodiment, although it was set as the structure which does not use the external light detection part 27 used in the said 2nd Embodiment, when the illuminance meter is mounted in the vehicle, the external illuminance measurement value from the illuminance meter of Information can be input to the video display device 101. Thereby, by having the external light detection part 27, the function obtained with the video display apparatus 102 of the said 2nd Embodiment is realizable.

<Modification 4>
In the above embodiment, the diffuser 13 is suitably arranged on the rear side of the optical path of the slitter 52. However, the diffuser 13 only needs to be arranged in the optical path after the Fourier lens FL1.

<Modification 5>
In the embodiment described above, the present invention is applied to a head-up display (HUD, Head-Up Display) mounted on a vehicle, but is not limited to this. For example, a three-dimensional display or a head-mounted display (HMD, Head Mounted) Applicable to Display).

  The present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the scope of the object of the present invention.

DESCRIPTION OF SYMBOLS 11 Image generation part 41 Holographic optical element 14, 24 Light source drive part 35, 35B, 35G, 35R, C35 detection part 55, 55B, 55G, 55R, C55 Voltage adjustment part 75, 75B, 75G, 75R, C75 Time adjustment part 27 External light detection unit 28 Current limiting unit DL External light LD, RLD, GLD, BLD Light source Lc Coherent light Lf Image light M15, M25 Light control means OP Optical member ST Observer VM image 101, 102, C101 Image display device

Claims (6)

A light source that emits coherent light;
A light source driving unit for supplying power to the light source;
Light control means for controlling the light intensity of the coherent light;
An image generation unit that generates a desired display image from the coherent light,
A video display device that allows an observer to observe the video of the display image,
The light control means includes a detection unit that detects the light intensity;
A voltage adjusting unit that adjusts an output voltage of the light source driving unit based on a detection result of the detecting unit;
A time adjustment unit for adjusting the output time of the output voltage,
An image display device that controls the output of the light source by combining the voltage adjustment unit and the time adjustment unit.   The video display device according to claim 1, wherein when the detected value of the light intensity is equal to or less than a predetermined boundary value, the output time is adjusted by the time adjustment unit. The light control means includes an external light detection unit that detects the illuminance of external light,
3. The output of the light source is controlled using at least one of the voltage adjustment unit and the time adjustment unit based on an external illuminance measurement value measured by the external light detection unit. The video display device described in 1. The light control means includes a current limiting unit that limits a current flowing through the light source,
4. The video display according to claim 1, wherein the current limiting unit controls the light source driving unit so that a current value is equal to or less than a preset reference current value. 5. apparatus.   5. A plurality of the light sources are provided, and a plurality of the voltage adjusting units and a plurality of time adjusting units are provided corresponding to the plurality of light sources. The video display apparatus in any one. The image generation unit, a holographic optical element that diffracts the coherent light into video light,
An optical member for guiding the image light from the holographic optical element,
The detection unit detects the light intensity of the image light,
The video display device according to claim 1, wherein the voltage adjustment unit and the time adjustment unit control an output of the light source based on a detection result of the detection unit.