JP6108169B2 - Color mixing device and display device - Google Patents

Description

The present invention relates to a color mixing device and a display device.

Patent Document 1 discloses a display device that generates a display image by scanning laser light emitted from a laser light source on a screen using a scanning system.

In the above-described display device, for example, a red, green, and blue laser beam is synthesized, a color mixing device that emits the synthesized laser beam (synthetic laser beam), and a synthetic laser beam emitted from the color mixing device is scanned. And a scanning unit that generates a color image. The color mixing device performs white balance adjustment that expresses white by mixing red, green, and blue at a predetermined ratio. For example, the color mixing device expresses white by mixing colors so that the color mixture ratio of red, green, and blue light intensities is about 2.9: 2.4: 1. Specifically, the color mixing device performs white balance adjustment by controlling the current value of each laser light source so that the color mixing ratio of each laser beam becomes a predetermined ratio.

JP-A-7-270711

However, the laser light source described above has a current threshold value for starting laser oscillation. Near this current threshold (unstable oscillation region), laser oscillation becomes unstable. Therefore, in the unstable oscillation region, there is a problem that the color mixing device cannot emit light having a desired light intensity and cannot stably express white.

In view of the above-described problems, an object of the present invention is to provide a color mixing device and a display device that can stably express white even in a low luminance region.

The present invention employs the following means in order to solve the above problems. That is, the color mixing device according to the first aspect of the invention is a red light source that emits red light with a light intensity corresponding to the supplied first current and a green light that emits green light with a light intensity corresponding to the supplied second current. A light source, a blue light source that emits blue light with a light intensity according to the supplied third current, a light source control unit that controls these light sources, and the red light, the green light, and the blue light are combined. And a color mixing unit that emits light, and the color mixing unit includes a light intensity attenuating unit that transmits or reflects the blue light and attenuates the light to travel in an emission direction, and the blue light source emits the blue light. The light is emitted after being attenuated from other color lights.

In the color mixing device according to the first aspect of the present invention, the light intensity attenuating unit may receive the blue light and another color light and cause the blue light to attenuate more than the other color light and travel in the emission direction. Good.

In the color mixing device according to the first aspect of the present invention, the light source controller further includes a light intensity detector that detects the light intensity of the blue light that does not travel in the emission direction when the light intensity attenuator transmits or reflects. May control the blue light source in accordance with the light intensity of the blue light detected by the light intensity detector.

In the color mixing device according to the first aspect of the present invention, the light intensity attenuating unit is configured such that the light intensity of the blue light incident on the light intensity detection unit is equal to or greater than the light intensity of the blue light traveling in the emission direction. The transmittance or / and reflectivity may be adjusted.

Further, a display device according to a second aspect includes the color mixing device according to the first aspect, and a spatial light modulation unit (scanning unit) that generates an image by scanning the light mixed by the color mixing unit. It is characterized by that.

According to the color mixing device and the display device of the present invention, white can be stably expressed even in a low luminance region.

It is a figure for demonstrating the mounting aspect of the HUD apparatus which concerns on embodiment of this invention. It is a schematic sectional drawing of the HUD apparatus of the said embodiment. It is a schematic sectional drawing of the laser beam emission part of the said embodiment. It is a figure of the light intensity-current characteristic of the laser light source of the said embodiment. It is a figure explaining the wavelength dependence of the light intensity attenuation part of the said embodiment. It is an electrical block diagram in the HUD apparatus of the said embodiment. It is a figure of the light intensity-current characteristic of the laser light source of the said embodiment, and is a figure explaining the effect | action of a light intensity attenuation part. It is a figure explaining the relationship of the spectral radiance ratio of the laser beam R and the laser beam G on the basis of the laser beam B in all the gradations and white display in case the light attenuation member is not provided. It is a figure explaining the relationship of the spectral radiance ratio of the laser beam R and the laser beam G on the basis of the laser beam B in all gradation and white display in the case of providing an optical attenuation member. It is a schematic sectional drawing of the laser beam emission part in the modification of this invention.

Hereinafter, an embodiment in which a display device of the present invention is applied to a head-up display device (HUD device) mounted on a vehicle will be described with reference to the drawings. Note that although an example in which the display device is applied to a HUD device has been described in this embodiment, the present invention is not limited to this.

A display device according to an embodiment of the present invention is a head-up display (HUD) device 1 shown in FIG. As shown in the figure, the HUD device 1 is disposed on the dashboard of the vehicle 2 and emits display light L representing an image M (see FIG. 2) for notifying predetermined information toward the windshield 3. The display light L reflected by the windshield 3 is visually recognized by the observer 4 (mainly the driver of the vehicle 2) as a virtual image V of the image M formed in front of the windshield 3. In this way, the HUD device 1 causes the observer 4 to visually recognize an image.

As shown in FIG. 2, the HUD device 1 includes a laser beam emitting unit 10, a light intensity detecting unit 20, a MEMS (Micro Electro Mechanical System) mirror 30, a screen 40, a first reflecting unit 50, a second The reflection part 60, the housing | casing 70, and the illumination intensity detection part 80 are provided.

The laser beam emitting unit 10 mixes a plurality of colors and emits a synthetic laser beam C, which will be described later, toward the MEMS mirror 30. As shown in FIG. 3, the laser beam emitting unit 10 includes laser diodes (hereinafter referred to as LDs) 11, 12, and 13, a condensing optical system 14, a multiplexing unit 15, a light control unit 16, and a light intensity. And a detection unit 20. The laser beam emitting unit 10 corresponds to a specific example of “color mixing device” in the present invention.

The LD 11 emits red laser light R having a peak at a wavelength of about 640 nm. The LD 12 emits green laser light G having a peak at a wavelength of about 520 nm. The LD 13 emits blue laser light B having a peak at a wavelength of about 450 nm. The LDs 11, 12, and 13 are supplied with a drive signal (drive current) from an LD control unit 100 described later, and each emits light at a predetermined light intensity and timing. The LDs 11, 12, and 13 have current-light intensity characteristics (see FIG. 4). The current-light intensity characteristics of the LDs 11, 12, and 13 will be described in detail later. The LD 11 corresponds to a specific example of “red light source” in the present invention. The LD 12 corresponds to a specific example of “green light source” in the present invention. The LD 13 corresponds to a specific example of “blue light source” in the present invention.

The condensing optical system 14 condenses the laser beams R, G, and B emitted from the LDs 11, 12, and 13, reduces the spot diameter, and forms convergent light. Specifically, the condensing optical system 14 includes condensing optical systems 14a, 14b, and 14c each formed of a lens or the like. The condensing optical system 14a is located on the optical path of the laser light R emitted from the LD 11, the condensing optical system 14b is located on the optical path of the laser light G emitted from the LD 12, and the condensing optical system 14c is emitted from the LD 13. Located on the optical path of the laser beam B.

The multiplexing unit 15 combines the laser beams R, G, and B emitted from the LDs 11, 12, and 13 and passing through the condensing optical system 14, and outputs the combined laser beam C as one synthetic laser beam C. Is. Specifically, the multiplexing unit 15 includes a first multiplexing unit 151 that reflects light and a second multiplexing unit that includes a dichroic mirror that reflects light of a specific wavelength but transmits light of other wavelengths. The wave unit 152, the third combining unit 153, and the light intensity attenuation unit 154 are configured. The multiplexing unit 15 corresponds to a specific example of “color mixing means” in the present invention.

The first multiplexing unit 151 reflects the incident laser light R toward the second multiplexing unit 152. The first multiplexing unit 151 may be configured not only by reflection but also by a member with transmission, and may transmit the incident laser light R toward the second multiplexing unit 152. Good. The second combining unit 152 transmits the laser beam R from the first combining unit 151 as it is and reflects the incident laser beam G toward the third combining unit 153. As a result, the combined laser beam in which the laser beam R and the laser beam G are combined is emitted from the second combining unit 152 toward the third combining unit 153. The third multiplexing unit 153 transmits the combined laser beam from the second multiplexing unit 152 as it is and reflects the incident laser beam B toward the dimming unit 16. In this way, the combined laser beam C obtained by combining the laser beams R and G and the laser beam B travels from the third combining unit 153 toward the light intensity attenuation unit 154.

The light intensity attenuating unit 154 is a member that attenuates the light intensity of the laser light B. For example, the light intensity attenuating unit 154 transmits light in a long wavelength region relatively well and does not transmit (reflect) light in a short wavelength region so much. 5 includes a dichroic mirror provided with a dielectric multilayer film having wavelength-transmittance characteristics (high-pass characteristics) as shown in FIG. 5, a reflective band-pass filter, and the like. The light intensity attenuating unit 154 is disposed between the third combining unit 153 and the dimming unit 16 with the light incident surface inclined so that the combined laser beam C is incident with a predetermined incident angle. A part of the synthetic laser light C is transmitted in the direction of the light control unit 16, and a part of the synthetic laser light C is reflected in the direction of the light intensity detection unit 20 as reflected light D. The detailed operation of the light intensity attenuator 154 will be described later.

The light control unit 16 includes a polarization control element (not shown) such as a liquid crystal panel, and polarizing plates (not shown) disposed on both sides of the light control control element. The dimming unit 16 is configured to control the synthesized laser light C incident on the polarization control element under the control of the dimming control unit 300 described later (based on the dimming control data supplied from the dimming control unit 300). The polarization angle is adjusted, and the light intensity of the synthetic laser light C transmitted through the light control unit 16 is adjusted. The synthetic laser light C that has passed through the light intensity attenuating unit 154 is emitted toward the MEMS mirror 30. Note that an organic material and an insulating film are used for a portion constituting the alignment film of the liquid crystal panel. Organic materials have the property of deteriorating when irradiated with blue or laser light having a shorter wavelength than blue. Therefore, the light intensity attenuating unit 154 is installed between the LD 13 and the light control unit 16, so that the attenuated laser light B can be irradiated to the liquid crystal panel, and the color mixing accuracy is suppressed while suppressing the deterioration of the organic material. Can be raised.

The light intensity detection unit 20 includes a color sensor, a photodiode, and the like, receives the reflected light D reflected by the light intensity attenuation unit 154, and detects the light intensity of each color laser light C constituting the received reflected light D. . Specifically, the light intensity detector 20 outputs a detection signal (voltage) corresponding to the light intensity, and this detection signal is converted into a digital value by an A / D (Analog / Digital) converter (not shown). As light intensity information, it outputs to the main control part 400 mentioned later. The light intensity detection unit 20 only needs to be able to detect the light intensity of each color laser beam C. Therefore, for example, the laser beam R, the laser beam G, and the laser beam before synthesis are not the optical path of the synthesized laser beam C. It may be provided separately at a location where the light intensity of each B can be detected.

The MEMS mirror 30 receives the synthetic laser light C from the laser light emitting unit 10 and receives the light under the control of the scanning control unit 200 described later (based on the scanning control signal supplied from the scanning control unit 200). The synthesized laser beam C is scanned on the screen 40. As a result, the image M is displayed on the screen 40. MEMS mirror 3
0 corresponds to a specific example of “scanning unit” in the present invention.

The screen 40 receives the synthetic laser light C from the MEMS mirror 30 on the back surface and transmits it, thereby displaying the image M on the front surface side. The screen 40 is configured by, for example, a holographic diffuser, a microlens array, a diffusion plate, or the like.

The first reflecting unit 50 is made of a plane mirror or the like, receives display light L representing the image M displayed on the screen 40, and reflects the display light L toward the second reflecting unit 60 side.

The second reflection unit 60 is formed of a concave mirror or the like, and reflects the display light L from the first reflection unit 50 in the direction of the windshield 3. The display light L reflected by the second reflecting unit 60 reaches the windshield 3 via the light transmitting unit 71.

The housing 70 houses the laser beam emitting unit 10, the light intensity detecting unit 20, the MEMS mirror 30, the screen 40, the first reflecting unit 50, the second reflecting unit 60, and the like, and has a light shielding property. These members are formed. In addition, a translucent portion 71 made of a translucent resin such as acrylic is fitted in a part of the housing 70, and the translucent portion 71 winds the display light L from the second reflecting portion 60. The light is transmitted in the direction of the shield 3 and is formed in a curved shape so that external light from the outside of the HUD device 1 is not reflected in the direction of the observer 4.

The illuminance detection unit 80 is an illuminance sensor arranged inside the translucent unit 71, detects the illuminance around the observer 4 (vehicle 2), and transmits illuminance data related to the luminance adjustment of the image M to the main control unit 400 is output as an electrical signal. Note that the illuminance detection unit 80 is not provided in the translucent unit 71 of the HUD device 1, but only needs to be able to detect the illuminance around the vehicle 2, and is therefore disposed on the windshield 3 or dashboard (not shown) of the vehicle 2. May be. In addition, the illuminance detection unit 80 does not directly output the illuminance data to the main control unit 400 of the HUD device 1 but outputs the illuminance data to the HUD luminance signal after being converted by the ECU of the vehicle 2 to the main control unit 400. May be.

Next, the electrical configuration of the HUD device 1 will be described.

In addition to the above, the HUD device 1 includes an LD control unit 100, a scan control unit 200, a dimming control unit 300, an LD control unit 100, a scan control unit 200, and a dimming control unit, as shown in FIG. A main control unit 400 that controls 300. These control units are mounted on, for example, a printed circuit board (not shown) disposed in the housing 70. These control units are arranged outside the HUD device 1, and are connected to the HUD device 1 (LD11, 12, 13, dimming unit (polarization control element) 16, light intensity detection unit 20, MEMS mirror 30, and the like by wiring. ) And may be electrically connected.

The LD control unit 100 includes a driver IC (Integrated Circuit) that drives the LDs 11, 12, and 13, and the like, under the control of the main control unit 400 (based on gradation control data from the main control unit 400). Each of the LDs 11, 12, and 13 is subjected to gradation control by a PWM (Pulse Width Modulation) control method or a PAM (Pulse Amplitude Modulation) control method.

The scanning control unit 200 includes a driver IC or the like that drives the MEMS mirror 30, and drives the MEMS mirror 30 under the control of the main control unit 400 (based on the scanning control data from the main control unit 400). The image M is generated on the screen 40.

The dimming control unit 300 includes a driver IC that controls the polarization control element and the like, and is synthesized by the polarization control element under the control of the main control unit 400 (based on the dimming control data from the main control unit 400). The polarization angle of the laser light C is adjusted, and the transmittance of the synthetic laser light C in the light control unit 16 is controlled. The dimming control data is a signal indicating at least a high light output mode in which the transmittance of the dimming unit 16 is high and a low light output mode in which the transmittance is low. The main control unit 400 is an ECU ( The dimming control data corresponding to the signal input from the electronic control unit) is output to the dimming control unit 300.

The high output mode is a mode for increasing the luminance of the image M (increasing the luminance) when the environment in which the observer 4 visually recognizes the image M is bright such as in the daytime. Permeate C with little attenuation. The low output mode is a mode for lowering the brightness of the image M when the environment in which the viewer 4 views the image M is dark, such as at night (making the brightness low). The laser beam C is attenuated. In this low output mode, the LD control unit 100 only performs gradation control substantially equivalent to that in the high output mode, and does not reduce the drive current of the LDs 11, 12, and 13 (drives in the vicinity of the unstable oscillation region). Low brightness display of the image M can be realized.

The main control unit 400 includes a microcontroller, an FPGA (Field Programmable Gate Array), an ASIC (Application Specific Integrated Circuit), and the like, and includes a CPU (Central Processing Unit) 401 and a storage unit 402. The storage unit 402 stores programs and data necessary for the operation of the HUD device 1, and includes an EEPROM (Electrically Erasable Programmable Read-Only Memory), Flash, and the like.

The CPU 401 controls each unit by reading a program from the storage unit 402 and executing the program. The CPU 401 includes an LD indicating vehicle information and an activation signal from an external device (not shown) such as an ECU of the vehicle 2, illuminance data from the illuminance detection unit 80, HUD luminance signal, and values of currents flowing through the LDs 11, 12, and 13. Various information such as current data and light intensity information from the light intensity detection unit 20 is input. Based on these information, the CPU 401 drives the light control data for controlling the light control unit 16 and the LD control unit 100. Gradation control data and scan control data for driving the scan control unit 200 are generated and output, and comprehensive control of the HUD device 1 is performed. That is, the CPU 401 drives the LDs 11, 12, 13, the MEMS mirror 30, and the dimming unit 16 via the LD control unit 100, the scan control unit 200, and the dimming control unit 300 according to the input information, and the image M is generated. Thereby, the display light L representing the image M is emitted toward the windshield 3, and the observer 4 can visually recognize the image M as the virtual image V.

The HUD device 1 having the above configuration expresses white by mixing the laser light R, laser light G, and laser light B emitted from the LDs 11, 12, and 13 at a predetermined ratio. The predetermined ratio for expressing white is, for example, C = 2.9: 2.4: 1. For example, in the HUD device 1, white balance adjustment is performed by controlling the current values of the LDs 11, 12, and 13. The white balance adjustment method will be specifically described below.

First, the current-light intensity characteristics of the LDs 11, 12, and 13 constituting the HUD device 1 will be described. The LDs 11, 12, and 13 have current-light intensity characteristics as shown in FIG. FIG. 4 is a diagram for explaining the current-light intensity characteristics in consideration of the light intensity mixing ratio in the white balance adjustment of the RGB laser light source. As shown in the figure, the LDs 11, 12, and 13 have current thresholds It (Itr, Itg, Itb) for starting laser oscillation, respectively. The current value range near the current threshold It becomes an unstable oscillation region in which laser oscillation becomes unstable, and considering the margin, a lower limit that is a lower limit current value for driving the LDs 11, 12, and 13 so as not to become an unstable oscillation region. The drive current value is It + α. Here, α is about several mA.

In the unstable oscillation region, the light intensity becomes unstable, and the display image flickers or white balance is lost. This is because the laser beams R, G, and B emitted from the LDs 11, 12, and 13 are combined to perform color expression, but the light intensity in the unstable oscillation region is approximately the same in each of the LDs 11, 12, and 13. is there.

Further, the LDs 11, 12, and 13 have an upper limit drive current value Ih (Ihr, Ihg, Ihb1 (Ihb2)) that is the maximum light intensity in consideration of the light intensity mixing ratio in white balance adjustment. 4 and 7, the current value that gives the maximum light intensity taking into account the light intensity color mixture ratio in white balance adjustment when the light intensity attenuating unit 154 is not provided is described as (Ihb1), and FIG. Describes the current value that is the maximum light intensity in consideration of the light intensity color mixture ratio in white balance adjustment when the light intensity attenuating unit 154 is provided as (Ihb2).

By the way, the display device performs gradation expression by LD APC (Auto Power Control). Accordingly, a region where stable display and white balance adjustment are possible (hereinafter referred to as a stable region) is Ih− (It + α) from the upper limit drive current value Ih to the lower limit drive current value (It + α). Therefore, it is desirable that all gradation expression and white balance adjustment over all gradations are performed within the region of Ih− (It + α).

When the light intensity attenuation unit 154 is not provided, the stable region of the LD 13 is Ihb1- (Itb + α). That is, the LD 13 emits the laser beam B with a light intensity corresponding to the third current having a value of Ihb1− (Itb + α). Similarly, the LD 11 emits a laser beam R with a light intensity corresponding to the first current having a value of Ihr− (Itr + α). Further, the LD 12 emits the laser light G with a light intensity corresponding to the second current having a value of Ihg− (Itg + α).

The range width of the stable region of the LD 13 is narrower than the range width of the stable region of the LDs 11 and 12. In addition, there is a limit due to the resolution of the LD applied current in the first drive unit. Therefore, when gradation representation is performed in a low luminance region, that is, a low gradation region, the current value input to the LD 13 is less than Itb + α. That is, an unstable oscillation region is used. When the LD 13 is used in the unstable oscillation region, the light intensity of the laser beam B is extremely reduced, so that a predetermined ratio expressing white, for example, C = 2.9: 2.4: 1 is obtained. It will collapse.

FIG. 8 shows measured values and ideal ratios of spectral radiance ratios when the LD 13 in all gradations / white display is used as a reference when the light intensity attenuation unit 154 is not provided. As shown in the figure, the R ratio approximates the R ideal ratio in the high gradation region and the medium gradation region (21 to 64/64), but deviates from the R ideal ratio in the low gradation region (1 to 20/64). And become a high value. Similarly, the G ratio approximates to the G ideal ratio in the high gradation region and the medium gradation region (21 to 64/64), but deviates from the G ideal ratio in the low gradation region (1 to 20/64). High value. In particular, in the 1st to 8th gradations, the drive current I of the LD 13 is less than the current threshold It, and the measured values of the R ratio and the G ratio are larger than the ideal ratio by a factor of 10 or more. For this reason, white balance adjustment cannot be performed stably, and the display screen is greatly deviated from the standard white, which is so-called white balance collapse.

Next, a case where the light intensity attenuation unit 154 is provided will be described. By providing the light intensity attenuating unit 154, a drive current I that is equal to or greater than a predetermined value (lower limit current value Itb + α) can be input even in a low gradation region, so that a region where gradation expression can be stably performed is Ihb1- (Itb + α ) To Ihb2- (Itb + α) (see FIG. 7). As a result, a stable region where white balance adjustment can be stably performed is also expanded.

FIG. 9 shows an actual measurement value and an ideal ratio of the spectral radiance ratio when the light intensity attenuating unit 154 is provided and using the LD 13 in all gradations and white display as a reference. Even when compared with the measurement results shown in FIG. 8, it can be seen that the deviation from the ideal R / G ratio for white balance adjustment is dramatically improved. The maximum deviation from the ideal ratio can be suppressed to 2.25 times, and the white balance adjustment accuracy is improved by about 5 times compared with the case where the light intensity attenuation unit 154 is not provided (see FIG. 8).

As described above, according to the HUD device 1 according to the present embodiment, the light intensity attenuating unit 154 is provided between the multiplexing unit 15 and the dimming unit 16 so that the light is emitted from the LD 13 having a short wavelength (about 450 nm). The light intensity of the laser beam B can be attenuated. Therefore, the LD 13 can be used with a higher current value (Ihb2) than when the light intensity attenuation unit 154 is not provided. Therefore, when the LD 13 is used in the low gradation region, the LD 13 can be used in a current value region higher than the unstable region. In this way, since the LD 13 is used in the current value region that avoids the unstable region, the light intensity of the LD 13 can be stabilized. As a result, the HUD device 1 can stably express white.

In addition, since most of the laser beam B out of the combined laser beam C incident on the light intensity attenuating unit 154 is reflected as reflected light D to the light intensity detecting unit 20 side, the light intensity detecting unit 20 is a laser having a high light intensity. The light B can be detected, and the light intensity detection accuracy of the laser light B is improved. As a result, the LD control unit 100 can accurately adjust the drive current (third current) I of the LD 13 based on the light intensity of the laser light B detected by the light intensity detection unit 20, so that white balance adjustment is possible. Accuracy can be improved.

In addition, since the light control unit 16 that adjusts the light intensity of the laser light R, laser light G, and laser light B incident on the MEMS mirror 30 is provided, the drive current of the LD 11, LD 12, and LD 13 can be reduced (not bad). A low-luminance display of the image M can be realized (without driving near the stable oscillation region). Further, since the laser light B incident on the light control unit 16 is attenuated by the light intensity attenuation unit 154, the light control unit 16 adjusts the light intensity of the laser light B in the same manner as the laser light R and the laser light G. There is no need to perform special light intensity adjustment (large attenuation) of only the laser beam B, and white can be realized by easy control of the light control unit 16.

In addition, the LD control unit 100 is configured to output the LDs 11 and 12 in the low output mode in which the transmittance of the synthetic laser light C of the dimming unit 16 is reduced and in the high output mode in which the transmittance of the synthetic laser light C is higher than that in the low output mode. 13 are controlled in the same manner, and the image M is stable at high luminance (high output mode) and low luminance (low output mode) without complicating the gradation control by the LD control unit 100. Gradation control can be performed.

Further, when the liquid crystal panel is irradiated with the synthetic laser light C that is a mixture of the laser light R, the laser light G, and the laser light B, the deterioration of the liquid crystal panel is suppressed by attenuating the light intensity of the laser light B. be able to. This is because the organic material constituting the alignment film and the insulating film of the liquid crystal panel deteriorates when irradiated with the laser beam B. Since the degree of deterioration of the organic material is proportional to the light intensity of the laser beam B, the load on the organic material of the liquid crystal panel can be reduced by attenuating the light intensity of the laser beam B incident on the liquid crystal panel in advance. it can.

Further, by using the light intensity attenuating unit 154 having a transmittance distribution inversely proportional to the luminance distribution of each of the laser beams R, G, and B, the light intensity distribution in the irradiation surface of the laser beam can be made uniform. Thereby, when irradiating a liquid crystal panel with each laser beam R, G, B, deterioration of the liquid crystal panel can be suppressed. This is because, as a characteristic of laser light, it is known that the light intensity is stronger at the center of the irradiation range, and the light intensity decreases toward the periphery of the irradiation range. Therefore, the deterioration of the organic material or the like occurs from the center of the laser beam where the light intensity distribution of the laser beam is particularly high, and gradually spreads to the periphery. As a result, when the liquid crystal panel (polarization control element) is irradiated with the laser beam B, the organic material is deteriorated and damaged. This is because it is difficult to realize a long-life dimming function.

Further, in the display device including the color mixing device having the above-described configuration, the LD 13 stably emits the laser light B, so that white balance can be adjusted and white can be stably expressed. As a result, display images other than white can be stably displayed. In particular, when a liquid crystal panel is used as the light control unit 16 and this liquid crystal panel is irradiated with laser light, the organic material constituting the liquid crystal panel is deteriorated by attenuating the light intensity of the laser beam B having the highest energy. Can be suppressed. As a result, the life of the liquid crystal panel can be extended.

[Modification] The present invention is not limited to the above embodiments and drawings. Changes (including deletion of constituent elements) can be added to the embodiments and the drawings as appropriate without departing from the scope of the present invention. Below, an example of a modification is described.

In the above embodiment, the light intensity attenuating unit 154 lowers the transmittance of laser light having a short wavelength, but is the second light intensity attenuating unit 154a that reduces the reflectance of laser light having a short wavelength. In such a case, the laser beam emitting unit 10 may cause the reflection direction of the laser beam B of the second light intensity attenuating unit 154a to coincide with the optical path of the synthetic laser beam C as shown in FIG. To place. Thereby, the light intensity of the laser beam B in the synthetic laser beam C can be reduced, and white balance adjustment can be performed stably.

For example, in the above embodiment, the laser light R, the laser light G, and the laser light B are combined on the optical path and mixed by the combining unit 15 on the optical path. However, the present invention is not limited to this. . For example, the colors may be mixed and mixed on the screen 40 that irradiates the laser light R, laser light G, and laser light B. In this case, the screen 40 functions as a color mixing unit.

Moreover, in the said embodiment, although the MEMS mirror 30 (scanning part) was used as a spatial light modulation element which produces | generates an image, it is not limited to this. The display device (HUD device 1) according to the present invention includes a spatial light modulator such as a TFT (Thin Film Transistor), LCOS (registered trademark: Liquid crystal on silicon), DMD (Digital Micromirror Device), etc., and an LD 11 that emits red light. The image may be displayed by the LD 12 that emits green light and the LD 13 that emits blue light.

DESCRIPTION OF SYMBOLS 1 HUD apparatus (display apparatus) 2 Vehicle 3 Windshield 4 Observer 10 Laser light emission part (color mixing apparatus) 11 LD (red light source) 12 LD (green light source) 13 LD (blue light source) 14 Condensing optical system 14a Condensing Optical system 14b Condensing optical system 14c Condensing optical system 15 Multiplexing unit (color mixing means) 15a Reflector 15b First multiplexing unit 15c Second multiplexing unit 16 Light intensity attenuating unit 17 Light control unit 20 Light intensity detecting unit 30 MEMS mirror (scanning unit) 40 screen 50 first reflecting unit 60 second reflecting unit 70 housing 710 translucent unit 100 LD control unit (light source control unit) 200 scanning control unit 300 dimming control unit 400 main control unit 401 CPU 402 Storage C Synthetic laser light L Display light M Image V Virtual image

Claims (6)

A red light source that emits red light with a light intensity corresponding to the supplied first current, a green light source that emits green light with a light intensity corresponding to the supplied second current, and a third current supplied A blue light source that emits blue light with a high light intensity, a light source control unit that controls these light sources, and a color mixing unit that emits light combining the red light, the green light, and the blue light, The color mixing unit includes a light intensity attenuating unit that transmits or reflects the blue light, attenuates the light, and travels in the emission direction, and emits the blue light emitted from the blue light source with attenuation from other color lights. A color mixing device characterized by that. 2. The light intensity attenuating unit receives the blue light and other color light, and attenuates the incident blue light from the other color light to travel in the emission direction. Color mixing device. The light intensity attenuator further includes a light intensity detector that detects the light intensity of the blue light that does not travel in the emission direction by being transmitted or reflected, and the light source controller is detected by the light intensity detector The color mixing apparatus according to claim 1, wherein the blue light source is controlled in accordance with a light intensity of the blue light. The light intensity attenuating unit is adjusted in transmittance or / and reflectance so that the light intensity of the blue light incident on the light intensity detector is equal to or higher than the light intensity of the blue light traveling in the emission direction. The color mixing device according to claim 3, wherein: 5. A display device comprising: the color mixing device according to claim 1; and a spatial light modulation unit that generates an image by spatially modulating light mixed by the color mixing unit. . A display device comprising: the color mixing device according to claim 1; and a scanning unit that generates an image by scanning light mixed by the color mixing unit.

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