JP6805587B2 - Light source device, image display device and object device - Google Patents

Description

The present invention relates to a light source device, an image display device, and an object device.

Conventionally, there is known an apparatus that divides light from a light source into transmitted light and reflected light and controls the amount of emitted light of the light source based on the amount of reflected light (see, for example, Patent Document 1).

In a conventional device such as the device disclosed in Patent Document 1, in order to accurately control the amount of emitted light of the light source, the amount of reflected light is substantially linearly (substantially linear) with respect to the change in the amount of emitted light of the light source. ) It is desirable to change.

However, in the apparatus disclosed in Patent Document 1, there is room for improvement in changing the amount of reflected light substantially linearly with respect to the change in the amount of emitted light of the light source.

The present invention is arranged on a plurality of light sources including a first light source and a second light source, and light from the first light source and light from the second light source, respectively , and the light is arranged. It is arranged on the optical path of the light from the first light source and the light path of the light from the second light source shaped by each of the apertures, and the incident light is divided into transmitted light and reflected light. The aperture and the branching element are provided with a flat plate-shaped branching element that branches into, a light receiving element that receives at least a part of the reflected light, and an estimation means for estimating the wavelength of light from the plurality of light sources. , 2 × d × cos θ × tan [arcsin (sin θ ÷ n)]> 0.5 × D, the branching element reflects a part of the light from the first light source, and the second By transmitting a part of the light from the first light source, a part of the light from the first light source and a part of the light from the second light source are combined and emitted toward the light receiving element. A part of the light from the first light source and a part of the light from the second light source are transmitted by transmitting a part of the light from the first light source and reflecting a part of the light from the second light source. The plurality of light sources are semiconductor lasers that synthesize a part of the light of the above and emit it to the outside, and the plurality of light sources oscillate in the vertical multi-mode, and the estimation means is based on the amount of light received by the light receiving element . The light source device is characterized in that it estimates a wavelength obtained by weighted averaging the wavelength components of light from a light source and a wavelength obtained by weighted averaging the wavelength components of light from the second light source .
However, d: the thickness of the branching element n: the refractive index of the branching element θ: the angle of incidence of the incident light on which the first light is incident on the branching element D: the aperture of the aperture of the light from the first light source on the optical path . Opening diameter.

According to the present invention, the amount of reflected light can be changed substantially linearly with respect to the change in the amount of emitted light of the light source.

It is a figure which shows the schematic structure of the HUD apparatus of one Embodiment. It is a block diagram which shows the hardware composition of the control system of a HUD apparatus. It is a functional block diagram of the HUD apparatus. It is a figure for demonstrating the optical deflector of a HUD apparatus. It is a figure which shows an example of the scanning line locus at the time of two-dimensional scanning. It is a figure for demonstrating the light source apparatus of a HUD apparatus. A light (beam B ₂₎ which is reflected by the entrance surface of the optical path splitting element, is a diagram for explaining interference of the primary back reflection beam B ₄ -1 of the light reflected by the exit-side surface (beam B ₄₎ .. It is a graph which shows the received light amount change with respect to the drive current change, and is the graph which shows the example which the received light amount change is not substantially linear with respect to the drive current change. Is a diagram showing an example in which a light shielding member for shielding the primary back reflection beam B ₄ -1. Is a diagram showing an example in which the incident beam B ₂ and the primary back reflection beam B ₄ -1 to the light receiving element. It is a graph which shows the change of the received light amount with respect to the drive current change, and is the graph which shows the example which the received light amount change is substantially linear with respect to the drive current change. It is a graph which shows the reflectance change with respect to the wavelength change of the incident light of the branch element coated with antireflection. It is a figure for demonstrating an example in which p-polarized light is incident on a branch element. It is a graph which shows the incident angle dependence of the reflectance of the incident side surface of a branch element. It is a graph which shows the incident angle dependence of the reflectance of the ejection side surface of a branch element. It is a figure for demonstrating how to obtain a reference wavelength. It is a chromaticity diagram for demonstrating the procedure of setting the emission light amount of each semiconductor laser. It is a flowchart for demonstrating the color light generation process. It is a flowchart for demonstrating the emission light amount setting process. It is a figure for demonstrating the light source apparatus of the modification 1. It is a figure for demonstrating the light source apparatus of the modification 2. It is a figure for demonstrating the light source apparatus of the modification 3. It is a diagram for explaining interference of the beam B ₂ and the primary back reflection beam B ₄ -1.

Hereinafter, the HUD device 100 as the image display device of one embodiment will be described with reference to the drawings. In addition, "HUD" is an abbreviation for "head-up display".

FIG. 1 schematically shows the overall configuration of the HUD device 100 of the present embodiment.

<< Overall configuration of HUD device >>
By the way, the projection method of the head-up display is a "panel method" in which an intermediate image is formed by an imaging device such as a liquid crystal panel, a DMD panel (digital mirror device panel), and a vacuum fluorescent display (VFD), and is emitted from a laser light source. There is a "laser scanning method" in which an intermediate image is formed by scanning a laser beam with a two-dimensional scanning device. In particular, the latter laser scanning method, unlike the panel method in which an image is formed by partial shading of full-screen light emission, can assign light emission / non-light emission to each pixel, and thus generally forms a high-contrast image. be able to.

Therefore, the HUD device 100 employs a "laser scanning method". Of course, the "panel method" can also be used as the projection method.

As an example, the HUD device 100 is mounted on a moving body such as a vehicle, an aircraft, or a ship, and navigation information (for example, movement) necessary for maneuvering the moving body via the front windshield 50 (see FIG. 1) of the moving body. Information such as body speed, direction of travel, distance to destination, current location name, presence / absence and position of an object in front of the moving body, signs such as speed limit, traffic jam information, etc.) can be visually recognized. In this case, the front windshield 50 also functions as a transmission / reflection member that transmits a part of the incident light and reflects at least a part of the rest. In the following, an example in which the HUD device is mounted on an automobile provided with the front windshield 50 will be mainly described.

As shown in FIG. 1, the HUD device 100 includes an optical scanning means 10 including a light source unit 11, an optical deflector 15, and a scanning mirror 20 (for example, a concave mirror), a screen 30, and a concave mirror 40, and includes a front window. By irradiating the shield 50 with light (image light) that forms an image, the virtual image I can be visually recognized from the viewpoint position of the viewer A (here, the driver who is a occupant of the automobile). That is, the viewer A can visually recognize the image (intermediate image) formed (drawn) on the screen by the optical scanning means 10 as a virtual image I via the front windshield 50.

The HUD device 100 is arranged below the dashboard of the automobile as an example, and the distance from the viewpoint position of the viewer A to the front windshield 50 is about several tens of cm to at most 1 m.

Here, the concave mirror 40 is designed by using existing optical design simulation software so as to have a constant focusing power so that the imaging position of the virtual image I becomes a desired position.

In the HUD device 100, the focusing power of the concave mirror 40 is set so that the virtual image I is displayed at a position (depth position) of 1 m or more and 10 m or less (preferably 6 m or less) from the viewpoint position of the viewer A. There is.

Normally, the front windshield is not flat but slightly curved. Therefore, the image formation position of the virtual image I is determined by the curved surfaces of the concave mirror 40 and the front windshield 50.

The light source unit 11 synthesizes laser beams of three colors of R, G, and B modulated according to the image data. A part of the combined light in which the three colors of laser light are combined is guided to the reflecting surface of the light deflector 15. The optical deflector 15 is a MEMS scanner manufactured by a semiconductor manufacturing process or the like, and includes a single micromirror that can swing independently around two orthogonal axes. The optical deflector 15 may be a combination of two MEMS scanners including a minute mirror that can swing around one axis. Further, the scanner is not limited to the MEMS scanner, and for example, a galvano scanner or a polygon scanner may be used. Details of the light source unit 11 and the light deflector 15 will be described later.

The light corresponding to the image data from the light source unit 11 (a part of the synthetic light) is deflected by the light deflector 15, folded back while being suppressed by the scanning mirror 20, and irradiated to the screen 30. Therefore, the screen 30 is light-scanned to form an intermediate image on the screen 30. It is preferable that the concave mirror 40 is designed and arranged so as to correct an optical distortion element in which the horizontal line of the intermediate image becomes convex upward or downward due to the influence of the front windshield 50.

The light passing through the screen 30 is reflected by the concave mirror 40 toward the front windshield 50. A part of the luminous flux incident on the front windshield 50 passes through the front windshield 50, and at least a part of the remaining light flux is reflected toward the viewpoint position (eye point) of the viewer A. As a result, the viewer A can visually recognize the enlarged virtual image I of the intermediate image through the front windshield 50. That is, the virtual image I is enlarged and displayed through the front windshield 50 when viewed from the viewer.

Even if a combiner is arranged as a transmission reflection member on the viewpoint position side of the viewer A with respect to the front windshield 50 and the combiner is irradiated with the light from the concave mirror 40, the case where only the front windshield 50 is used is used. Similarly, a virtual image can be displayed.

<< Hardware configuration of the control system of the HUD device >>
FIG. 2 shows a block diagram showing the hardware configuration of the control system of the HUD device 100. As shown in FIG. 2, the control system of the HUD device 100 includes an FPGA 600, a CPU 602, a ROM 604, a RAM 606, an I / F 608, a bus line 610, an LD driver 6111, and a MEMS controller 615.

The FPGA 600 is an LD control circuit that controls the LD described later via the LD driver 6111 based on the image data, the output of the photodetector 117 or the signal processing unit 120 described later, and the output of the scanning light detection unit 60. Includes an optical deflector control circuit that controls the optical deflector 15 via the 700 and the MEMS controller 615. The CPU 602 controls each function of the HUD device 100. The ROM 604 stores an image processing program executed by the CPU 602 to control each function of the HUD device. The RAM 606 is used as a work area for the CPU 602. The I / F 608 is an interface for communicating with an external controller or the like, and is connected to, for example, a CAN (Controller Area Network) of an automobile.

<< Functional block of HUD device >>
FIG. 3 shows a block diagram showing the functions of the HUD device 100. As shown in FIG. 3, the HUD device 100 includes a vehicle information input unit 800, an external information input unit 802, an image data generation unit 804, and an image drawing unit 806. Vehicle information (information such as speed, mileage, distance to an object, brightness of the outside world, etc.) is input to the vehicle information input unit 800 from CAN or the like. Information outside the vehicle (navigation information from GPS, etc.) is input to the external information input unit 802 from the external network. The image data generation unit 804 generates image data of an image to be drawn based on the information input from the vehicle information input unit 800 and the external information input unit 802, and sends the image data to the FPGA 600. The image drawing unit 806 includes a control unit 8060, and the control unit 8060 transmits a control signal for starting or ending image drawing to the FPGA 600.

<< Configuration of optical deflector >>
FIG. 4 shows the configuration of the light deflector 15. The optical deflector 15 is a MEMS scanner manufactured by a semiconductor process, and as shown in FIG. 4, includes a mirror 150 having a reflecting surface and a plurality of beams arranged in the X-axis direction, and two adjacent beams. Has a pair of meandering portions 152 connected so as to meander through the folded portions. The two adjacent beams of each meandering portion 152 are beam A (152a) and beam B (152b), and are supported by the frame member 154. A plurality of piezoelectric members 156 (for example, PZT) are individually provided on the plurality of beams. By applying different voltages to the piezoelectric members of the two adjacent beams of each meandering portion, the two adjacent beams of the meandering portion bend in different directions, which are accumulated, and the mirror 150 is rotated around the X axis (=). It will rotate at a large angle in the vertical direction). With such a configuration, optical scanning in the vertical direction centered on the X-axis becomes possible at a low voltage. On the other hand, in the horizontal direction centered on the Y-axis, optical scanning by resonance is performed using a torsion bar or the like connected to the mirror 150.

The light deflector 15 configured as described above scans the laser beam two-dimensionally (for example, raster scan) with respect to the image drawing area of the screen 30 (see FIG. 5), and at the scanning position of the laser beam. By controlling the light emission of the LD accordingly, it is possible to draw each pixel and display a virtual image. In FIG. 5, Ps is the scanning line pitch.

《Optical scanning, virtual image display》
From the HUD device 100, only a point image corresponding to the diameter of the laser beam is instantaneously projected, but since scanning is performed at a very high speed, a sufficient afterimage remains in the human eye in one frame image. By utilizing this afterimage phenomenon, the driver perceives that the image is projected on the "display area". In reality, the image reflected on the screen 30 is reflected by the concave mirror 40 and the front windshield 50 and perceived by the driver as a virtual image in the "display area". Since it is such a mechanism, if the image is not displayed, the light emission of the LD may be stopped. That is, it is possible to set the brightness of the portion other than the portion where the virtual image is displayed in the "display area" to substantially zero.

That is, the imaging position of the virtual image by the HUD device 100 is an arbitrary position within a predetermined "display area" where the virtual image can be imaged. This "display area" is determined by the specifications at the time of designing the HUD device.

In this way, by adopting the "laser scanning method", it is possible to take measures such as turning off the LD or reducing the amount of light because there is no need to display the portion other than the portion to be displayed.

On the other hand, in the "panel method" in which an intermediate image is expressed by an imaging device such as a liquid crystal panel or a DMD panel, it is necessary to illuminate the entire panel, so that the image signal is displayed in black in order to hide it. Even if it is, it is difficult to completely set it to 0 due to the characteristics of the liquid crystal panel and the DMD panel. Therefore, the black part may appear to be raised, but the laser scanning method makes it possible to eliminate the black part.

Here, as shown in FIG. 5, the scanning light detection unit 60 is provided in the peripheral region of the image drawing region (also referred to as “effective scanning region”) on the screen 30. The scanning light detection unit 60 is provided to detect the operation of the photodetector 15, and detects the scanning timing (scanning position of the beam) by irradiating the signal region with light, and the light accompanying the environment and changes over time. It is used to control changes in the characteristics of the deflector 15 to maintain a constant image quality. The scanning light detection unit 60 includes, for example, a photodiode, a phototransistor, and the like. The output signal of the scanning light detection unit 60 is sent to the FPGA 600.

《Light source device》
The light source unit 11 will be described in detail below. FIG. 6 schematically shows the configuration of the light source unit 11. In the following, the αβγ three-dimensional Cartesian coordinate system shown in FIG. 6 and the like will be described as appropriate.

As shown in FIG. 6 as an example, the light source unit 11 includes a plurality of (for example, three) semiconductor lasers (light sources) each having a single or a plurality of light emitting points. The three semiconductor lasers are referred to as semiconductor lasers 111R, 111G, and 111B, respectively.

In addition to the above three semiconductor lasers, the light source unit 11 includes a plurality of (for example, three) coupling lenses 112R, 112G, 112B, a plurality of (for example, three) apertures 113R, 113G, 113B, and a reflection mirror 118. It includes an optical path synthesis element 114, an optical path synthesis element 115, an optical path branching element 119, a condensing lens 116, a light receiving element 117a, and the like. Each component of the light source unit 11 is assembled to the housing 11a. In FIG. 6, the reflection mirror 118, the optical path synthesis element 114, the optical path synthesis element 115, and the optical path branching element 119 are separate bodies, but at least two of them may be integrally provided.

Each semiconductor laser is an end face emitting type semiconductor laser (LD: laser diode) having different oscillation wavelength bands. That is, the semiconductor laser 111R is a red semiconductor laser, the semiconductor laser 111G is a green semiconductor laser, and the semiconductor laser 111B is a blue semiconductor laser. Here, the ejection directions of the semiconductor lasers 111R, 111G, and 111B are all in the + α direction. Each semiconductor laser is mounted on a circuit board 200 provided with an LD driver 6111.

The luminous fluxes Lr, Lg, and Lb emitted from the LD111R, 111G, and 111B are coupled to the subsequent optical system by the corresponding coupling lenses 112R, 112G, 112B.

The coupled light flux is shaped by the corresponding apertures 113R, 113G, 113B. The opening shape of each aperture can be various shapes such as a circle, an ellipse, a rectangle, and a square depending on the divergence angle of the light flux.

The luminous flux Lb via the aperture 113B is reflected by the reflection mirror 118 in the −β direction and is incident on the optical path synthesizer 114 (for example, a dichroic prism or a dichroic mirror).

The luminous flux Lg via the aperture 113G is optical path-combined with the luminous flux Lb by the optical path synthesizing element 114. More specifically, the luminous flux Lb via the reflection mirror 118 is transmitted in the −β direction through the center of the optical path synthesizer 114, and the luminous flux Lg via the aperture 113G is reflected in the −β direction at the center of the optical path synthesizer 114.

Then, the combined luminous flux Lgb in which the luminous flux Lg and the luminous flux Lb are combined and the luminous flux Lr via the aperture 113R are optically path-synthesized by the optical path synthesizer 115 (for example, a dichroic prism or a dichroic mirror), and the combined luminous flux Lrgb is an optical path branching element. It is incident on 119.

The combined luminous flux Lrgb is branched into a transmitted luminous flux Lrgb1 and a reflected luminous flux Lrgb2 by an optical path branching element 119 (plate type beam splitter).

The transmitted luminous flux Lrgb1 is irradiated to the light deflector 15 via a light transmitting window member 5 attached to the periphery of the opening of the housing 11a so as to cover the opening, and an image is drawn (virtual image display) on the screen 30. Used for. A meniscus lens having a concave surface facing the optical deflector 15 may be installed on the optical path between the optical path branching element 119 and the optical deflector 15.

The reflected luminous flux Lrgb2 is guided to the photodetector 117 via the condenser lens 116. The photodetector 117 outputs a signal corresponding to the amount of light of the received reflected luminous flux Lrgb2 to the LD control circuit 700 via the signal processing unit 120 described later. The photodetector 117 includes a light receiving element 117a and a current-voltage converter 117b that converts the output current of the light receiving element 117a into a voltage signal (light receiving signal). As the light receiving element 117a, for example, a photodiode (PD) or a phototransistor can be used.

A signal processing unit 120 that time-averages the received signal is provided in the subsequent stage of the current-voltage converter 117b. The signal processing unit 120 integrates the received light signals input in a certain time zone T, averages the integrated values over time (divides by T), and outputs the integrated values to the LD control circuit 700. The signal processing unit 120 is not essential, and may directly output the received signal from the current-voltage converter 117b to the LD control circuit 700.

As is clear from FIG. 6, the optical path lengths from each semiconductor laser to the optical path synthesizer 115 are different from each other. Specifically, the optical path length from the semiconductor laser 111B to the optical path synthesis element 115 is the longest, and the optical path length from the semiconductor laser 111R to the optical path synthesis element 115 is the shortest. This is because when white is composed of a virtual image, the RGB composition ratio is about 2.5: 1: 0.5, a large amount of red light is required, and conversely, the amount of blue light may be small. This is to suppress the decrease in light utilization efficiency due to the semiconductor laser.

The LD control circuit 700 generates a modulation signal (pulse signal) for each semiconductor laser based on the output of the photodetector 117 or the signal processing unit 120, and sends it to the LD driver 6111. The LD driver 6111 applies a drive current corresponding to the modulation signal of each semiconductor laser to the semiconductor laser.

Here, the spectral distribution of the emitted light of the semiconductor laser changes according to the ambient temperature around the semiconductor laser and the amount of emitted light of the semiconductor laser, and the reproducibility is poor. In particular, in the HUD device, since the dynamic range of light and darkness of the surrounding environment of the vehicle is large, the fluctuation of the self-temperature due to the fluctuation of the amount of emitted light required to cope with it becomes large, and the ambient temperature changes depending on the time and the position of the vehicle. Since it fluctuates, the oscillation wavelength fluctuates. That is, the oscillation wavelength of the semiconductor laser has "self-temperature dependence" and "atmospheric temperature dependence".

Hereinafter, a device including a light source unit 11, a photodetector 117, a signal processing unit 120, an LD control circuit 700, and an LD driver 6111 will be referred to as a “light source device 300”.

By the way, in order to generate desired colored light and display a virtual image, the power balance of the emitted light of each semiconductor laser is appropriately adjusted based on the wavelength of the light (emitted light) emitted from three semiconductor lasers having different oscillation wavelengths. Must be set.

This power balance is determined based on the wavelength of the emission light of each semiconductor laser, but in order to set the desired power balance, it is necessary to monitor the amount of light emitted from the semiconductor laser.

However, since the semiconductor laser used in the HUD device is required to have a high output, it is difficult to divert the back light monitor method generally used for the low output semiconductor laser as it is.

Therefore, in the present embodiment, as shown in FIG. 6, the light from the three semiconductor lasers 111R, 111G, and 111B is combined, the combined light is branched into the transmitted light and the reflected light by the optical path branching element 119, and the reflected light is divided. A method of guiding light to the light receiving element 117a is adopted.

Here, when a plate-type beam splitter as shown in FIGS. 6 and 7, that is, a flat plate-shaped transmission / reflection member is used as the optical path branching element 119, it is necessary to pay close attention to the transmission / reflection member. It is the interference of light reflected on the incident side surface (hereinafter also referred to as “incident side surface”) and the emission side surface (hereinafter also referred to as “injection side surface”). The "transmitted reflection member" means a member that transmits a part of the incident light and reflects at least a part (other part) of the remaining part as described above. Here, the material of the transmission / reflection member is optical glass or optical resin.

This light interference will be described with reference to FIG.
In FIG. 7, the incident beam B ₀ to the optical path branching element 119 is branched into a transmitted beam B ₁ and a reflected beam B ₂ at the incident side surface 119a of the optical path branching element 119. The reflected beam B ₂ is incident on the light receiving element 117a via the condenser lens 116.

On the other hand, a part (beam B ₃ ) of the transmitted beam B ₁ passes through the injection side surface 119b of the optical path branching element 119 and heads for the light deflector 15, but another part (beam B ₄ ) is on the injection side surface 119b. Be reflected. Some of the beam _{B 4} (1 primary back reflection beam _B 4 -1) is transmitted through the entrance-side surface 119a, interferes with beam _{B 2.} Although another part of the beam B ₄ is reflected again by the incidence side surface 119a, 2-order back reflection beam, tertiary backside reflected beam, ..., since the gradually lost rapidly energy, essentially of the beam B ₂ in order to consider the Do interference, it is sufficient to consider only the interference between the primary rear reflection beam B ₄ -1 of the beam B _4.

When such interference occurs, as shown in FIG. 8, the light-receiving amount P _moni of the light receiving element 117a is linearity in accordance with the current value I _LD to be injected into the semiconductor laser _(the current value of the driving current) It becomes a undulating curve (function) without being maintained. In this case, the amount of light of the beam (emission light) emitted from the semiconductor laser cannot be set to an appropriate amount, and as a result, a virtual image of a desired color cannot be generated.

Here, LD control circuit 700 monitors the received light amount _{P moni} of the light receiving element 117a, the light amount _{P LD} beam (emitted light) emitted from the semiconductor laser to determine the _{I LD} so that the desired amount of light That is, the amount of emitted light of the semiconductor laser is determined. _The correspondence relationship between _{P moni} and _{P LD,} since previously _known, by monitoring the _{P moni,} it is possible to uniquely determine _{I LD} to a desired _{P LD.}

In the two beams B ₃ and B ₂ branched by the optical path branching element 119, if the amount of light of the beam B ₃ is P ₃ and the amount of light of the beam B ₂ is P ₂ , the setting is set to P ₃ >> P ₂ . Is preferable. This is because it is necessary to dynamically change the brightness of the virtual image of the HUD device 100 according to the brightness outside the vehicle (depending on the season and day and night), and it is also necessary to give gradation to the image to generate various colored lights. Is.

However, assuming that the reflectance of the incident side surface 119a of the optical path branching element 119 is R _in = 1% and the reflectance of the ejection side surface 119b is R _out = 1%.
P ₃ = P ₀ x (1-R _in ) x (1-R _out ) = 0.98 P ₀
P ₂ = P ₀ x R _in = 0.01P ₀
(However, the amount of light of the incident beam B ₀ to the optical path branching element 119 is P ₀ , and the absorption inside the optical path branching element 119 is ignored.).

As described above, although 98% of the light amount of the incident beam B ₀ is used to generate a virtual image by the HUD device 100, assuming that the light amount of the beam B ₄ reflected by the injection side surface 119b is P ₄ .
P ₄ = P ₀ × (1-R _in ) ² × R _out = 0.01P ₀
The amount of light is almost the same as that of P ₂ . The amount of the primary back reflection beam _B 4 -1 beams _{B 4} nor much different _{P 2.}

Therefore, the beam _{B 2,} 1-order back reflection beam _B 4 -1 of the beam _{B 4} are cause interference, resulting in the result shown in FIG.

When estimating the amount of light _{P LD} from the received light amount _{P moni,} there must be in the what relationship _{P moni} and _{I LD} has similarity transformation of the relationship between _{P LD} and _{I LD.} In other words, it is shown in Figure 8 can _not be estimated _{P LD} from _{P moni.}

Therefore, after diligent studies, the inventors have found that the amplitude of the swell shown in FIG. 8 can be reduced and the interference component can be ignored by appropriately setting the thickness d of the optical path branching element 119.

That is, almost by the thickness d, the primary back reflection beam B ₄ -1 of the beam B ₂ and the beam B ₄ reflected by the entrance surface 119a of the optical path splitting element 119 can be sufficiently spaced originally interference ( It is possible to prevent it from occurring (to the extent that it can be ignored in actual use).

In this case, the received light amount P _moni of the light receiving element 117a can be maintained substantially linearity in accordance with the current value I _LD to be injected into the semiconductor laser (see FIG. 11), the beam emitted from the semiconductor laser The amount of light (emission light) can be set to an appropriate amount, and as a result, a virtual image of a desired color can be generated.

Specifically, when the beam diameter of the incident light on the optical path branching element 119 is D,
2 × d × cos θ × tan [arcsin (sin θ ÷ n)] ≧ 0.5 × D… (1)
(However, n is the refractive index of the optical path branching element, θ is the angle of incidence of the incident light on the optical path branching element)
By setting the thickness d so as to satisfy the above conditions, the interference component can be almost ignored. The "beam diameter" can be defined as, for example, the width at the intensity when the peak intensity value drops to 1 / e ² (13.5%).

More specifically, for example, when the intensity distribution of the beam B ₀ is a Gaussian distribution, the intensity distribution of the beam B ₂ and the primary back reflection beam B ₄ -1 as shown in Figure 23 is also a Gaussian distribution. In Figure 23, the beam B ₂ and the primary back reflection beam B ₄ -1, a portion (portion of the skirt) overlap, but the interference is occurring at this overlapped portion, at a very low intensity compared to the peak intensity some _reason, does not affect the I _{LD -P moni} characteristics.

If the cross section of the emitted light of the semiconductor laser has an axisymmetric shape (a beautiful ellipse), the beam diameter can be easily obtained by replacing it with, for example, a circle having the same area, but in reality, the cross-sectional shape of the emitted light Is slightly broken and it may be difficult to determine the beam diameter.

Therefore, instead of the "beam diameter of the incident light on the optical path branching element 119", the "opening diameter of the aperture" may be set to D in the above equation (1). In this case, the thickness d can be set to an appropriate value regardless of the cross-sectional shape of the emitted light of the semiconductor laser.

The "aperture opening diameter" is the diameter when the aperture shape of the aperture is circular, and the opening area when the aperture shape of the aperture is a shape other than a circle such as an ellipse, a rectangle, or a square. Is the diameter of a circle with the same area as.

Further, instead of the beam diameter of the incident light on the optical path branching element 119, the effective beam diameter of the incident light on the optical path branching element 119 may be D. Also in this case, the thickness d can be set to an appropriate value regardless of the cross-sectional shape of the emitted light of the semiconductor laser.

Here, the "effective beam diameter" is a predetermined percentage (for example, a predetermined% of 10% to 90%, preferably a predetermined% of 20% to 80%, more preferably 30%) with respect to the peak intensity of the measured beam. The area equal to the area of the portion having an intensity of ~ 70% (predetermined%) or more is replaced with the area of a circle, and is defined by the diameter at that time. The "effective beam diameter" may be set by the "aperture aperture diameter".

When, for example, a surface emitting laser (VCSEL) is used instead of the semiconductor laser, the cross-sectional shape of the emitted light is circular, so that the “beam diameter of the incident light on the optical path branching element 119” is set to single mode. In the case, it is defined as the width at the intensity when it drops to 1 / e ² (13.5%) from the peak intensity value, and in the case of multi-mode, it is defined as the intensity when it drops from the peak intensity value to 1 / e. It can be defined as a width or a half-price width (width at 50% of the peak intensity value). The "beam diameter" may be set by the "aperture aperture diameter". Of course, when a surface emitting laser is used, the "effective beam diameter of the incident light on the optical path branching element 119" and the "aperture aperture diameter" may be set to D.

The thickness d can be sufficiently thicker than the minimum value which the equation (1) is satisfied, and protrude from the light receiving element 117a beams B ₂ and the primary back reflection beam B ₄ -1 are due to environmental fluctuation or vibration without something _like, I _{LD -P moni} characteristic is as shown in Figure 11.

Further, if the thickness d be sufficiently larger than the minimum value which the equation (1) is satisfied, the distance of the beam B ₂ and the beam B ₄ of the primary back reflection beam B ₄ -1 increases since, it is possible to adopt a method of shielding the primary back reflection beam B ₄ -1 in the light shielding member 105 as shown in FIG. The light-shielding member 105 is preferably made of a material that absorbs light. The light-shielding member 105 may be a member that reflects light in a direction that does not affect the light intensity monitor or virtual image generation. In this case, a member having light absorption may be arranged in the direction of reflection of light from the light-shielding member 105.

In this case, the above equation (1) is satisfied, and if there is no possible beam _{B 2} is such as to extend to the outside of the light receiving element 117a by environmental changes or _vibration, I _{LD -P moni} characteristic it is as shown in Figure 11.

However, when a plurality of beams having different wavelengths are branched by the optical path branching element 119 as in the present embodiment, the optical path of each beam is different, so that the thickness d of the optical path branching element 119 may not be so thick.

In such a case where the thickness d above (1) can not be sufficiently thicker than the minimum satisfied, the distance of the beam B ₂ and the primary back reflection beam B ₄ -1 modest can not, may be adopted to be incident beam B ₂ and the primary back reflection beam B ₄ -1 to the light-receiving element 117a as shown in FIG. 10.

In this case, the above equation (1) is satisfied, and the beam _{B 2} and the primary back reflection beam _B 4 -1 is, unless something like protrude from the light receiving element 117a by environmental changes or _vibration, I _{LD -P moni} The characteristics are as shown in FIG.

Further, if the thickness d of the optical path branching element 119 can be set so as to satisfy the above equation (1), both sides (incident side surface 119a and ejection side surface 119b) of the optical path branching element 119 should not be coated with an antireflection film. ) Can be.

The non-coating has the advantage of reducing costs, but it is no longer necessary to consider the spectral characteristics of the antireflection film, and it is possible to reduce the fluctuation of reflectance / transmittance due to the wavelength fluctuation of the beam emitted from the semiconductor laser. ..

Spectral characteristics of the antireflection film is preferably smoothly varying depending on the wavelength ideally, actually has a very small noise component (see Fig. 12), which is the I _LD -P _moni characteristics It may be expressed as a swell component. For reducing the fine noise component of the spectral characteristics of the antireflection film is technically very difficult, if it is possible to the optical path branching element 119 into non-coated, obtaining a I _LD -P _moni characteristics in a more preferred form Can be done.

Here, in FIG. 13, the optical path branching element 119 is made of a material having a refractive index of n = 1.5. A p-polarized light incident beam B ₀ is incident on the optical path branching element 119 at an incident angle θ (= 45 °). The optical path branching element 119 is uncoated on both sides, and the incident angle dependence of the reflectance of the incident side surface 119a is as shown in FIG. Therefore, the reflectance R _in = 0.85% on the incident side surface 119a at the incident angle θ = 45 °.

Further, in FIG. 13, the incident angle φ of the beam B ₁ with respect to the injection side surface 119b is φ = sin ^-1 (sin 45 ° / 1.5) = 28.13 °, and the reflectance of the injection side surface 119b depends on the incident angle. The sex is as shown in FIG. Therefore, the reflectance R _out = 0.85% on the injection side surface 119b at the incident angle φ = 28.13 °.
At this time,
P ₁ = P ₀ x (1-R _in ) x (1-R _out ) = 0.98 P ₀
P ₂ = P ₀ x R _in = 0.01P ₀
Therefore, it is possible to create an ideal situation for the HUD device 100, which is P ₁ >> P ₂ .

Further, the thickness d of the optical path branching element 119 at this time is set to d = 2 mm because the beam spot size ω of each of the beam B ₂ and the beam B ₄ was 2 mm. At this time, 2 × d × cos θ × tan [arcsin (sin θ ÷ n)] = 1.51 mm, which satisfies the above equation (1), and it can be seen that interference can be prevented.

In the above example, the incident beam B ₀ for the optical path branching element 119 is linearly polarized with p-polarized light, but s-polarized light can also be used. However, when the incident beam B ₀ of s-polarized light is incident on the optical path branching element 119 at an incident angle θ (= 45 °), the reflectance R _in = 9.2% on the incident side surface 119a and the reflectance on the emission side surface 119b. R _out = 9.2%.
At this time,
P ₁ = P ₀ x (1-R _in ) x (1-R _out ) = 0.82 P ₀
P ₂ = P ₀ x R _in = 0.1P ₀
Therefore, P ₁ is reduced and P ₂ is increased as compared with the case of p-polarized light, and an ideal situation for the HUD device 100 cannot be created.

In fact, as can be seen from FIG. 15, the reflectance of s-polarized light never falls below 4%, and in principle it is not possible to create the same situation as p-polarized light. Even if R _in = 5%, the layout of the optical path branching element 119 is significantly deteriorated in the vicinity of the incident angle θ = 25 °.

From such a situation, it can be understood that the polarization of the incident beam with respect to the optical path branching element 119 is preferably p-polarized light.

Specifically, when the semiconductor laser is arranged so that the polarization direction (direction parallel to the active layer) is parallel to the αβ plane, for example, the arrangement of the optical path branching element 119 as shown in FIG. 6 (optical path branching). By arranging the element 119 perpendicular to the αβ plane), the incident beam B _{0 with} respect to the optical path branching element 119 becomes p-polarized.

On the other hand, when the semiconductor laser is arranged so that the polarization direction (direction parallel to the active layer) is perpendicular to the αβ plane, for example, the arrangement of the optical path branching element 207 (optical path branching element 207) as shown in FIG. 20 (Arranged at an angle with respect to the αβ plane), the incident beam B _{0 with} respect to the optical path branching element 207 becomes p-polarized.

Returning to FIG. 6, the LD control circuit 700 includes a wavelength estimation unit 700a, a power balance determination unit 700b, and a modulation signal generation unit 700c.

The wavelength estimation unit 700a estimates the wavelength of the emission light of each semiconductor laser based on the output signal of the photodetector 117 (the signal corresponding to the amount of received light) and the output signal of the temperature sensor 130.

Specifically, the wavelength estimation unit 700a _monitors the light reception light amount P _moni (output signal of the photodetector 117) in the light receiving element 117a, and the light utilization efficiency η from the semiconductor laser to the light receiving element 117a with _respect to the P _{moni. Is} calculated and converted into the amount of emitted light P of the current semiconductor laser (P = P _moni ÷ η).

As the oscillation method of the semiconductor laser, various pulse oscillations can be considered depending on what kind of information is generated as a virtual image of the HUD device. If the emitted light amount P is defined as "time averaged time average light amount", the wavelength The inventors have found that the estimation can be performed accurately.

Here, the wavelength estimated by the wavelength estimation unit 700a (wavelength to be estimated) will be described.

For example, in a semiconductor laser having a spectrum distribution of vertical multimode oscillation in the oscillation wavelength band, unlike a semiconductor laser that oscillates in vertical single mode, what is the wavelength of the emitted light of this semiconductor laser (estimation target). It is very difficult to determine (wavelength).

However, when considering the generation of the color of a virtual image in the HUD device, the wavelength to be estimated is the wavelength obtained by weighted averaging the wavelength components having an intensity of -20 dB or more of the peak intensity in the vertical multimode (hereinafter, "weighted average"). When defined as "wavelength"), the inventors have found that the correlation between power balance and color generation based on this wavelength is very high.

Wavelength components with an intensity smaller than -20 dB can be almost ignored as an error in color generation, and if it is a weighted average wavelength, the color coordinates of a semiconductor laser like the dominant wavelength used in LEDs and the like. It is easy to measure because it is not necessary to obtain.

On the other hand, in a semiconductor laser that oscillates in a vertical single mode, the wavelength of a single spectrum itself is the wavelength to be estimated.

Here, since the wavelength of the emission light of the semiconductor laser depends on the ambient temperature as described above, it is preferable to install the temperature sensor 130 at a position where the ambient temperature of the semiconductor laser can be acquired. Of course, the package temperature in which the semiconductor laser is housed may be monitored, but in that case, a process of extracting the ambient temperature from the information is required, and there is a concern that the wavelength estimation accuracy may be lowered.

Further, in order to speed up the pulse oscillation of the semiconductor laser, it is preferable that the wiring length between the LD driver 6111 and the semiconductor laser is short. In this case, the heat generated by driving the LD driver 6111 causes the ground layer of the circuit board 200 to be generated. It propagates and promotes the temperature rise of the semiconductor laser. That is, since the package temperature in which the semiconductor laser is housed is the temperature at which the three temperature components of the ambient temperature, the semiconductor laser temperature, and the LD driver 6111 temperature are combined, it is extremely difficult to extract the ambient temperature from this temperature. It is difficult to.

Therefore, in the present embodiment, as an example, the temperature sensor 130 is installed in the vicinity of the aperture 113B in the housing 11a, which is some distance away from each semiconductor laser. Of course, it may be provided at other positions such as near other apertures, near the reflection mirror, near the optical path synthesizer, near the condensing lens, etc., but in any case, it is suitable for measuring the ambient temperature around the semiconductor laser. It is desirable to install it within a distance range.

The temperature sensor 130 may be any temperature sensor capable of measuring the temperature of the atmosphere around the semiconductor laser, and examples thereof include a thermocouple, a thermistor, a resistance temperature detector, and a radiation thermometer.

The inventors have focused on the fact that the temperature dependence of the wavelength of the emitted light is linear regardless of the type of the semiconductor laser, and by utilizing this property, the wavelength of the emitted light of the semiconductor laser can be estimated accurately. I found.

Therefore, in the present embodiment, the ambient temperature around the semiconductor laser is monitored by using the temperature sensor 130, and the amount of emitted light of the semiconductor laser is monitored by using the photodetector 117, thereby indicating "atmospheric temperature dependence". The wavelength of the emitted light of each semiconductor laser is estimated from both sides of "self-temperature dependence".

Specifically, the wavelength estimation unit 700a monitors the measured temperature of the temperature sensor 130 in addition to monitoring the amount of light received by the light receiving element 117a, and estimates the current wavelength of the emitted light of the semiconductor laser.

At this time, the current wavelength λ of the emission light of the semiconductor laser is
λ ⁽⁰⁾ : Reference wavelength α: Atmospheric temperature coefficient T _a : Current atmospheric temperature _Ta ⁽⁰⁾ : Atmospheric temperature at the time of reference wavelength measurement β: Light intensity coefficient P: Current emission light intensity P ⁽⁰⁾ : Reference wavelength measurement The amount of emitted light at an hour is expressed by the following equation (2).
λ = λ ⁽⁰⁾ + α × (T _a −T _a ⁽⁰⁾ ) + β × (PP ⁽⁰⁾ )… (2)

The reference wavelength λ ⁽⁰⁾ is preferably the weighted average wavelength. In this case, the current wavelength λ is also substantially the weighted average wavelength.

By using the above equation (2), the current wavelength λ can be estimated accurately regardless of the current atmospheric temperature and the current amount of emitted light.

The reference wavelength λ ⁽⁰⁾ is “a certain condition” at an arbitrary ambient temperature _Ta ⁽⁰⁾ and an arbitrary light intensity P ⁽⁰⁾ if the pulse condition oscillated from the semiconductor laser is always fixed. However, the information generated as a virtual image of the HUD device 100 is various, and it is necessary to change the brightness of the virtual image of the HUD device 100 according to the brightness outside the vehicle. It is generally unlikely that it is fixed under one condition.

In this case, the reference wavelength λ ⁽⁰⁾ is preferably defined as a virtual wavelength at P ⁽⁰⁾ = 0 [W]. This is because there is no situation common to all pulse conditions other than P ⁽⁰⁾ = 0 [W].

Naturally, the wavelength cannot be actually measured under the condition of P ⁽⁰⁾ = 0 [W], but as shown in FIG. 16, P ₁ , P ₂ , ..., P ₅ , P ₆ and the amount of emitted light of the semiconductor laser are emitted. The virtual wavelength at P ⁽⁰⁾ = 0 [W] can be obtained by linearly interpolating from the corresponding wavelengths λ ₁ , λ ₂ , ..., λ ₅ and λ _{6 by} changing. The wavelength is λ ⁽⁰⁾ . At this time, since the ambient temperature can be regarded as substantially constant for an extremely short time, the measurement error of the reference wavelength hardly occurs.

In FIG. 16, the emission light amount of the semiconductor laser is changed in 6 steps and the wavelength is measured in each step. However, the wavelength is not limited to this, and the point is that the emission light amount of the semiconductor laser is changed in at least 2 steps. The wavelength may be measured at each stage. Since most LDs have very good linearity, for example, the intersection (intercept) between the straight line and the vertical axis passing through the two plots obtained by measuring the wavelength in two steps (low emission light amount and high emission light amount) is used as a reference. You can also find the wavelength.

Further, even among semiconductor lasers having the same oscillation wavelength band (same color), there are individual differences in the oscillation wavelength in the range of about ± 5 nm, so it is preferable to measure the reference wavelength for each semiconductor laser.

On the other hand, the temperature coefficient α and the light intensity coefficient β are determined to be constant values for each color because there is almost no individual difference for each semiconductor laser. Of course, in order to improve the wavelength estimation accuracy, the temperature coefficient α and the light amount coefficient β may be measured in advance for each individual, and the measured values may be written in the firmware of the wavelength estimation unit 700a.

The process of obtaining the reference wavelength shown in FIG. 16 is performed for each semiconductor laser using a wavelength measuring device (for example, a spectrum analyzer or the like). The acquired reference wavelength, the atmospheric temperature at the time of measuring the reference wavelength, and the amount of emitted light at the time of measuring the reference wavelength are substituted into the above equation (2). Specifically, the acquired reference wavelength, the atmospheric temperature at the time of measuring the reference wavelength, and the numerical values of the amount of emitted light are written in the firmware of the wavelength estimation unit 700a.

Wavelength estimator 700a includes a semiconductor laser 111R, 111G, emitted at different timings from 111B received light amount _{P moni} of light received at different timings by the light receiving element 117a _{^(red), P moni ^(green), P moni} ^(blue) And calculate the amount of light emitted by the current semiconductor laser P ^(red) , P ^(green) , P ^(blue) from the monitor information (P ^(red) = P _moni ^(red) ÷ η ^(red) , P ^(Green) = P _moni ^(green) ÷ η ^(green) , P ^(blue) = P _moni ^(blue) ÷ η ^(blue) ).

Then, the wavelength estimator 700a from the information of the current ambient temperature T _a of the temperature sensor 130, a current wavelength λ of light being emitted from the semiconductor laser, is calculated by the equation (2), the calculated The result is sent to the power balance determination unit 700b.

The power balance determination unit 700b is based on the color of each pixel of the image data and the current wavelengths of the three semiconductor lasers, so that each semiconductor has a suitable (appropriate) power balance for generating light of that color. The amount of light emitted by the laser is set, and the set value is sent to the modulation signal generation unit 700c.

Specifically, for example, in the chromaticity diagram shown in FIG. 17, when the current wavelengths of the three semiconductor lasers 111R, 111G, and 111B are set to 650 nm, 515 nm, and 445 nm, respectively, two of the three semiconductor lasers 111R, 111G, and 111B are used. The amount of light emitted by one semiconductor laser is appropriately determined to generate a color P, and the amount of light emitted by the remaining one semiconductor laser is set to an appropriate value according to the color P so as to be a desired color (target color). In FIG. 17, all colors in a triangle having three points of 650 nm, 515 nm, and 445 nm as vertices can be generated. The horseshoe-shaped edge of FIG. 17 is called the "spectral locus" and is a line in which wavelength and color correspond.

The modulation signal generation unit 700c generates a modulation signal for each semiconductor laser based on the emission light amount and image data of each semiconductor laser set by the power balance determination unit 700b, and generates a modulation signal for each semiconductor laser as an output signal from the scanning light detection unit 60. It is output to the LD driver 6111 at a predetermined timing based on the above.

As a result, the power balance of the emitted light is optimized from the three semiconductor lasers to generate synthetic light of a desired color, and the image drawing area is scanned by the synthetic light to display a virtual image of the desired color.

That is, it is possible to display a high-quality color virtual image that faithfully reproduces the color information of each pixel of the image data.

The color of the virtual image has been described above. Regarding the brightness of the virtual image, for example, the amount of emitted light after setting the three semiconductor lasers 111R, 111G, and 111B according to the output of the illuminance sensor that acquires the brightness around the automobile. It is possible to control the virtual image to a desired color and a desired brightness by uniformly increasing or decreasing the amount of each emitted light while keeping the ratio of. At this time, it is preferable to set the amount of emitted light of each semiconductor laser to be larger as the output of the illuminance sensor is larger.

The color light generation process (virtual image display process) using the light source device 300 of the present embodiment will be described below with reference to FIG. The flowchart of FIG. 18 is based on a processing algorithm executed by the LD control circuit 700. This color light generation process is started, for example, when the electric system of the automobile on which the HUD device 100 is mounted is turned on and the HUD device 100 is activated. When the HUD device 100 is activated, the optical deflector 15 starts operating.

In the first step S1, at least one semiconductor laser is turned on. Specifically, the modulation signal generation unit 700c generates a modulation signal of the semiconductor laser to be lit according to the color of each pixel of the image data, and the LD driver 6111 is at a predetermined timing based on the output signal of the scanning light detection unit 60. Output to. As a result, a drive current corresponding to the modulation signal of the semiconductor laser to be lit is applied to the semiconductor laser, and the drawing of the image according to the image data on the screen 30 and the display of the virtual image are started.

In the next step S2, it is determined whether or not the scan has been performed a predetermined number of times. Specifically, the number of reciprocating or one-way scanning in the main scanning direction is counted based on the output signal of the scanning light detection unit 60 and the horizontal scanning frequency of the optical deflector 15, and when the number of counts reaches a predetermined number. , The process proceeds to the next step S3. That is, it is in a waiting state until the number of scans reaches a predetermined number. The "predetermined number of times" may be one to at least one frame of reciprocating scanning when counting in units of reciprocating scanning, and one to at least one frame when counting in one-way scanning units. The number of one-way scans is sufficient.

In step S3, the "emission light amount setting process" is performed. The details of the emission light amount setting process will be described later.

In the next step S4, at least one semiconductor laser is turned on with the amount of emitted light after setting. Specifically, the semiconductor laser to be lit is lit with the amount of emitted light set in step S3. As a result, the power balance of the emission lights of the three semiconductor lasers becomes appropriate, and a virtual image of a desired color is displayed.

In the next step S5, it is determined whether or not the processing is completed. When the electric system of the automobile on which the HUD device 100 is mounted is ON, the determination here is denied and the process returns to step S2, and when it is OFF, the determination here is affirmed and the flow ends.

In step S2 of the color light generation process, it is determined whether or not the scanning has been performed a predetermined number of times. Instead, it may be determined whether or not a predetermined time has elapsed.

Hereinafter, the “emission light amount setting process” in step S3 of the color light generation process will be described with reference to FIG. The flowchart of FIG. 19 is based on a processing algorithm executed by the LD control circuit 700. This emission light amount setting process is continuous when the scanning light is not applied to the effective scanning area (image drawing area) (time period when the image is not drawn), for example, when the scanning light is applied to the peripheral area of the effective scanning area. It is carried out at the transition time between frames.

In the first step S12, the time average light amount for each semiconductor laser is acquired. Specifically, a signal from the signal processing unit 120 whose received signal is time-averaged is acquired.

In the next step S13, the ambient temperature is acquired. Specifically, the temperature measured by the temperature sensor 130 is acquired.

In the next step S14, the wavelength λ of the emission light of each semiconductor laser is estimated based on the acquired time average light amount (current emission light amount) and atmospheric temperature (current atmospheric temperature). Specifically, the wavelength λ is estimated using the above equation (2).

In the next step S15, the amount of emitted light of each semiconductor laser is set based on the estimated wavelength λ (see FIG. 17).

From the first viewpoint, the light source device 300 of the present embodiment described above has a light source, an aperture that is arranged on the optical path of light from the light source and shapes the light, and light that is shaped by the aperture. It is provided with a flat plate-shaped optical path branching element 119 (branching element) that is arranged on the road and branches the incident light into transmitted light and reflected light, and 2 × d × cos θ × tan [arcsin (sin θ ÷ n)]> 0. 5 × D holds.
However, d: the thickness of the optical path branching element n: the refractive index of the optical path branching element θ: the angle of incidence of the incident light on the optical path branching element D: the aperture diameter of the aperture.

Further, from the second viewpoint, the light source device 300 of the present embodiment is arranged on the light source and the optical path of the light from the light source, and is a flat plate-shaped optical path branching element that branches the incident light into transmitted light and reflected light. With 119 (branching element), 2 × d × cos θ × tan [arcsin (sin θ ÷ n)]> 0.5 × D is established.
However, d: the thickness of the optical path branching element n: the refractive index of the optical path branching element θ: the incident angle of the incident light with respect to the optical path branching element D: the effective beam diameter of the incident light.

Further, from the third viewpoint, the light source device 300 of the present embodiment is arranged on the light source and the optical path of the light from the light source, and is a flat plate-shaped optical path branching element that branches the incident light into transmitted light and reflected light. With 119 (branching element), 2 × d × cos θ × tan [arcsin (sin θ ÷ n)]> 0.5 × D is established.
However, d: the thickness of the optical path branching element n: the refractive index of the optical path branching element θ: the incident angle of the incident light with respect to the optical path branching element D: the beam diameter of the incident light.

According to the light source device 300 of the present embodiment, it is possible to suppress the interference between the light reflected by the incident side surface 119a of the optical path branching element 119 and the light reflected by the emission side surface 119b.

In this case, the amount of reflected light can be changed substantially linearly (substantially linearly) with respect to the change in the amount of emitted light of the light source (change in the current value of the drive current).

As a result, it is possible to accurately control the amount of light emitted from the light source.

Further, the light source device 300 from the second and third viewpoints is arranged on an optical path of light between the light source and the optical path branching element 119, and further includes an aperture for shaping the light, depending on the aperture diameter of the aperture. D may be set.

In this case, D can be easily set regardless of the cross-sectional shape of the emitted light of the light source.

Further, it is preferable that the light source device 300 further includes a light receiving element 117a that receives at least a part of the reflected light.

In this case, the amount of light received by the light receiving element 117a can be monitored, and the amount of light emitted from the light source can be controlled with high accuracy.

Further, it is preferable that the optical path branching element 119 does not have an antireflection film on either the incident side or the ejection side.

In this case, as compared with the case where the antireflection film is provided on the incident side or the emission side, it is possible to suppress the appearance of noise on the spectral characteristics, and as a result, the light amount change of the reflected light with respect to the emission light amount change (drive current change) of the light source. It is possible to suppress the collapse of the linearity of.

Further, the light source is a polarized light source, and it is preferable that the light source and the optical path branching element 119 are arranged so that the incident light on the optical path branching element 119 is p-polarized with respect to the optical path branching element 119.

In this case, the amount of transmitted light >> the amount of reflected light can be set, and for example, the amount of light used for virtual image generation can be sufficiently secured.

Further, the light source device 300 may further include a light-shielding member 105 that shields the reflected light that is reflected by the emission side surface 119b of the optical path branching element 119 and is emitted from the incident side surface 119a toward the light receiving element 117a. ..

In this case, the light reflected by the incident side surface 119a of the optical path branching element 119 can be reliably guided to the light receiving element 117a, and the linearity of the reflected light amount according to the emitted light amount of the light source can be improved.

Further, the size of the light receiving surface of the light receiving element 117a is set to a size capable of receiving the light reflected by the incident side surface 119a of the optical path branching element 119 and the light reflected by the emission side surface 119b among the reflected light. You may.

In this case, the light reflected by the incident side surface 119a of the optical path branching element 119 and the light reflected by the emission side surface 119b can be reliably guided to the light receiving element 117a, and the amount of reflected light is linear according to the amount of emitted light of the light source. The sex can be improved.

Further, there are a plurality of light sources, and the plurality of light sources have different emission wavelengths, are arranged on the optical path of light between the plurality of light sources and the optical path branching element 119, and synthesize light from the plurality of light sources. It may include a synthetic means having 114, 115.

In this case, the desired synthetic light can be generated.

Further, the plurality of light sources include a light source that emits red light, a light source that emits green light, and a light source that emits blue light.

In this case, desired color light (monochromatic light or multicolor light) can be generated.

Further, it is preferable to further include a wavelength estimation unit 700a (estimating means) that estimates the wavelength of light from the light source based on the amount of light received by the light receiving element 117a.

In this case, it is possible to obtain information (wavelength of light from a light source) for stably generating desired colored light while suppressing the increase in size of the device (for example, without providing a large device such as a wavelength measuring device). Can be done.

Further, the light source device 300 further includes a temperature sensor 130 for measuring the ambient temperature around the light source, and the wavelength estimation unit 700a estimates the wavelength of light from the light source based on the amount of received light and the temperature measured by the temperature sensor 130. It is preferable to do so.

In this case, the wavelength of the light from the light source can be estimated stably and accurately.

Further, it is preferable that the light source device 300 further includes a power balance determining unit 700b (emission light amount setting means) for setting the emission light amount of the light source based on the wavelength of the light from the light source estimated by the wavelength estimation unit 700a.

In this case, the desired colored light can be stably generated.

Further, the light source is preferably a semiconductor laser. That is, the present invention is particularly effective when coherent light (light that can interfere) such as laser light is used.

Further, a HUD device 100 (image) including a light source device 300, a light deflector 15 (image forming element) that forms an image by light from the light source device 300, and a screen 30 that is irradiated with the light that forms the image. According to the display device), it is possible to form an image having good color reproducibility.

Further, since the HUD device 100 further includes a concave mirror 40 (light projection unit) that projects light through the screen 30 toward the front windshield 50 (transmissive reflection member), it displays a virtual image with good color reproducibility. It is possible.

Further, according to the mobile device including the HUD device 100 and the mobile body on which the HUD device 100 is mounted, it is possible to provide the driver of the mobile body with information based on a virtual image having good color reproducibility.

[Modification 1]
FIG. 20 shows a perspective view of the light source device 300A of the first modification.

Also in this modification 1, a semiconductor laser having three wavelengths is used to generate colored light and display a virtual image. In FIG. 20, reference numerals 201 (a), 201 (b), and 201 (c) indicate semiconductor lasers having 653 nm (red), 515 nm (green), and 453 nm (blue), respectively. Reference numerals 202 (a), 202 (b), and 202 (c) indicate coupling lenses, respectively. Reference numerals 203 (a), 203 (b), and 203 (c) indicate apertures, respectively. Reference numeral 204 indicates a mirror that bends the optical path of the blue beam emitted from the blue semiconductor laser 201 (c). Reference numeral 205 indicates a two-wavelength synthesizer that transmits a blue beam and reflects a green beam emitted from the green semiconductor laser 201 (b). Reference numeral 206 indicates a three-wavelength synthesis element that transmits the blue beam and the green beam emitted from the two-wavelength synthesis element 205 and reflects the red beam emitted from the red semiconductor laser 201 (a). Reference numeral 207 indicates an optical path branching element that reflects a part of the red beam, the green beam, and the blue beam emitted from the three-wavelength synthesis element 206 and transmits another part. Reference numeral 208 indicates a condenser lens. Reference numeral 209 indicates a light receiving element.

The wavelength of the beam emitted from each semiconductor laser is measured in a timely manner by a wavelength estimation unit (not shown), and based on that information, the power balance determination unit (not shown) produces the amount of light that becomes the desired color to be displayed on the HUD device. Is calculated, and the current value to be injected into each semiconductor laser based on the received light amount of the light receiving element 209 so that the calculated light amounts P _LD ^(red) , P _LD ^(green) , and P _LD ^(blue) are obtained. I _LD ^(red) , I _LD ^(green) , and I _LD ^(blue) are determined.

The linearly polarized light of the beam emitted from each semiconductor laser is preferably p-polarized light incident on the optical path branching element 207. On the other hand, it is preferable that the two-wavelength synthesizer 205 and the three-wavelength synthesizer 206 are s-polarized light incident. In this case, the number of film layers on the composite surface of the two-wavelength synthesizer 205 and the three-wavelength synthesizer 206 can be reduced, facilitating the design of the composite surface.

Therefore, in the first modification, each semiconductor laser is arranged so that the polarization direction (direction parallel to the active layer) is perpendicular to the αβ plane, and is incident on the mirror 204, the two-wavelength synthesis element 205, and the three-wavelength synthesis element 206. The optical paths of the beam and the composite beam are on the same plane parallel to the αβ plane, and the optical path of the beam reflected by the optical path branching element 207 is bent in the direction perpendicular to the αβ plane (+ γ direction) and passed through the condenser lens 208. The layout is such that the light is guided to the light receiving element 209.

The light source device 300A of the first modification described above can also obtain the same operations and effects as the light source device 300 of the above embodiment.

Even in the arrangement of the optical path branching element 119 as shown in FIG. 6, by arranging a 1/2 wavelength plate on the optical path between the optical path combining element 115 and the optical path branching element 119 and rotating the polarized light by 90 °, the above The same action and effect as in the first modification can be obtained.

[Modification 2]
FIG. 21 shows the light source device 300B of the second modification.
As shown in FIG. 21, the light source device 300B of the second modification has a configuration in which the optical path synthesis element 115 of the light source device 300 shown in FIG. 6 is replaced with an optical path branching element 119.

That is, in the light source device 300B of the second modification, the optical path branching element 119 also functions as an optical path synthesis element.

More specifically, a part of the combined luminous flux Lgb is transmitted in the −β direction through the center of the optical path branching element 119, and the rest is reflected in the + α direction at the center of the optical path branching element 119. A part of the luminous flux Lr via the aperture 113R is reflected in the −β direction at the center of the optical path branching element 119, and the rest is transmitted through the center of the optical path branching element 119 in the + α direction.

That is, from the optical path branching element 119, the combined luminous flux Lrgb1 in which a part of the combined luminous flux Lgb and a part of the luminous flux Lr are combined is emitted in the −β direction, and the balance of the combined luminous flux Lgb and the balance of the luminous flux Lr are combined. The luminous flux Lrgb2 is emitted in the + α direction.

The combined luminous flux Lrgb1 is applied to the light deflector 15 via a light transmitting window member 5 attached to the periphery of the opening of the housing 11a so as to cover the opening, and an image is drawn (virtual image display) on the screen 30. Used for. A meniscus lens having a concave surface facing the optical deflector 15 may be installed on the optical path between the optical path branching element 119 and the optical deflector 15.

The combined luminous flux Lrgb2 is guided to the photodetector 117 via the condenser lens 116. The photodetector 117 outputs a signal (light receiving signal) corresponding to the amount of light of the received combined luminous flux Lrgb2 to the wavelength estimation unit. The wavelength estimation unit estimates the wavelength of the emitted light of the semiconductor laser based on the received signal as in the above embodiment, and sends the estimation result to the power determination unit. The power determination unit sets the amount of light emitted from the semiconductor laser based on the wavelength estimated by the wavelength estimation unit, and sends the set value to the modulation signal generation unit. The modulation signal generation unit generates a modulation signal from the power determination unit based on the set value of the amount of emitted light, and outputs the modulation signal to the LD driver. The LD driver generates a drive current according to the modulation signal from the modulation signal generation unit and applies it to the semiconductor laser.

The light source device 300B of the second modification described above can also obtain the same operations and effects as the light source device 300 of the above embodiment.

[Modification 3]
FIG. 22 shows the light source device 300C of the third modification.
The light source device 300C of the third modification has a single semiconductor laser (light source) similar to the semiconductor laser of the above embodiment. Also in the third modification, the amount of emitted light from the light source can be set accurately by estimating the wavelength of the emitted light with high accuracy. Applications of the light source device having a single semiconductor laser include, for example, an image forming device for forming a two-color image, an image display device for displaying a two-color image, and the like.

In this case, the wavelength of the emitted light of the light source is estimated by the wavelength estimation unit, the amount of emitted light is calculated by the power setting unit based on the estimation result, and the modulation signal is generated by the modulation signal generation unit based on the calculation result. Therefore, the light source can be turned on with a desired amount of emitted light, and thus a desired color light can be generated.

In the above explanation, the wavelength of the emitted light is estimated from both the atmospheric temperature dependence and the self-temperature dependence of the wavelength of the emitted light of the semiconductor laser. For example, in an environment where the atmospheric temperature of the semiconductor laser can be regarded as substantially constant. As a modification 4, the wavelength of the emitted light may be estimated based only on the self-temperature dependence (only the amount of light received by the light receiving element 117a or the amount of averaged light). In this case, the temperature sensor may not be provided.

Here, "in an environment where the atmospheric temperature of the semiconductor laser can be regarded as substantially constant" means that the temperature inside the vehicle on which the HUD device 100 is mounted is kept substantially constant by air conditioning, or the light source of the present invention and the light source of the present invention. When a head mount display device, a prompter device, or a projector device as an image display device including a light source device including a wavelength estimation device is used indoors, it is assumed that the temperature in the room is kept substantially constant by air conditioning. To.

Specifically, the wavelength of the emitted light can be estimated using the following equation (3).
λ = λ ⁽⁰⁾ + β × (PP ⁽⁰⁾ )… (3)
However, λ: current wavelength λ ⁽⁰⁾ : reference wavelength β: light intensity coefficient P: current emission light intensity P ⁽⁰⁾ : emission light intensity at the time of reference wavelength measurement

In this case as well, the reference wavelength can be obtained in the same manner as in the above embodiment (see FIG. 16). In this case, in the semiconductor laser that oscillates in the vertical multimode, the wavelength to be estimated may be, for example, the weighted average wavelength or the wavelength at the peak intensity.

In the above embodiment and each modification, the wavelength of light from each semiconductor laser is estimated by using a wavelength estimation device including a light receiving element and a temperature sensor, but the present invention is not limited to this. For example, in FIGS. 6, 20, 21, and 22, a wavelength measuring device is provided in place of the wavelength estimation device at the subsequent stage of the light receiving element, and the measurement results of the wavelength measuring device when each semiconductor laser is turned on at different timings. The wavelength λ (preferably the weighted average wavelength) may be calculated from (spectrum distribution of light from the semiconductor laser), and the amount of emitted light of the plurality of semiconductor lasers may be controlled based on the wavelength λ. The wavelength measuring device can include, for example, a superheterodyne spectrum analyzer using an optical bandpass filter and a spectroscope including a prism and a diffraction grating.

Further, a plurality of wavelength estimation devices or wavelength measuring devices may be provided corresponding to a plurality of semiconductor lasers. For example, a wavelength estimation device that branches the light from each semiconductor laser with a branching element (for example, a cover glass that covers the opening (injection port) of a package that houses the semiconductor laser, a half mirror, a beam splitter, etc.). It may be incident on a wavelength measuring device.

When an end face emitting type semiconductor laser is used as the semiconductor laser, the light emitted from one end surface is used for image formation and virtual image display, and the light emitted from the other end surface is used as a corresponding wavelength estimation device or wavelength measuring device. May be incident on.

Further, both a light receiving element and a wavelength measuring device may be provided. That is, a part of the light from each semiconductor laser may be used for image formation and virtual image display, the other part may be guided to the wavelength measuring device, and the rest may be guided to the light receiving element. In this case, for example, the power balance of a plurality of semiconductor lasers is determined based on the measurement result of the wavelength measuring device, and the absolute value of the emitted light amount (output) of the plurality of semiconductor lasers is set based on the received light amount of the light receiving element. You may.

Further, in the above-described embodiment and each modification, the wavelength estimation unit does not have to be a component of the light source device. For example, the light source device may be composed of only the light source unit 11. In short, the light source device may be configured to include a light source (for example, a semiconductor laser) and an optical path branching element 119, and preferably further includes an aperture.

Further, although LD (end face emitting type semiconductor laser) is used as the semiconductor laser in the above-described embodiment and each modification, other semiconductor lasers such as a surface emitting type semiconductor laser (VCSEL) may be used. ..

Further, in the above embodiment and each modification, the light projecting portion is composed of the concave mirror 40, but the present invention is not limited to this, and may be composed of, for example, a convex mirror.

Further, in the above-described embodiment and each modification, the scanning mirror 20 is provided, but it may not be provided. That is, the light deflected by the light deflector 15 may be directly irradiated to the screen 30 or irradiated through a convex lens without folding back the optical path. Further, a plane mirror may be used as the scanning mirror 20.

Further, in the above-described embodiment and each modification, the image display device (HUD) has been described as being mounted on a moving body such as a vehicle, an aircraft, or a ship, but the point is that the image display device (HUD) may be mounted on an object. Just do it. In addition to moving objects, "objects" include objects that are permanently installed and objects that can be transported.

Further, the present invention is preferably applied to a HUD device as described in the above embodiment, but can be applied not only to a HUD device but also to, for example, a head-mounted display device, a prompter device, and a projector device. In this case as well, it is possible to generate desired colored light.

For example, when applied to a projector device, the projector device can be configured in the same manner as the HUD device 100. That is, the image light through the concave mirror 40 may be projected onto a projection curtain, a wall surface, or the like. The image light passing through the screen 30 may be projected onto a projection curtain, a wall surface, or the like without providing the concave mirror 40. Further, a free curved mirror may be used instead of the concave mirror 40.

Further, the light source device, the image display device, and the object device of the present invention are not limited to the specific configurations described in the above-described embodiment and each modification, and can be appropriately changed.

15 ... Light deflector (image forming element), 30 ... Screen, 40 ... Concave mirror (light source), 50 ... Front windshield (transmission reflection member), 100 ... HUD device (image display device), 105 ... Shading member , 113R, 113G, 113B ... Aperture, 114 ... Optical path synthesis element (part of synthesis means), 115 ... Optical path synthesis element (part of synthesis means) 117a ... Light source element, 119 ... Optical path branching element (branch element), 111R, 111G, 111B ... Semiconductor laser (light source), 300, 300A, 300B, 300C ... Light source device, 700a ... Wavelength estimation unit (estimation means, part of light source device), 700b ... Power balance determination unit (emission light amount setting means) , Part of the light source device)

Japanese Patent No. 5304380

Claims (14)

A plurality of light sources including a first light source and a second light source,
Is disposed on the light each light path from the light and the second light source from the first light source, and an aperture for shaping the light,
It is arranged on the optical path of the light from the first light source and on the optical path of the light from the second light source, which is shaped by each of the apertures, and has a flat plate shape that branches the incident light into transmitted light and reflected light. Branch element and
A light receiving element that receives at least a part of the reflected light and
An estimation means for estimating the wavelength of light from the plurality of light sources is provided.
The aperture and the branching element
Satisfying the relationship of 2 × d × cos θ × tan [arcsin (sin θ ÷ n)]> 0.5 × D,
The branch element is
A part of the light from the first light source and a part of the light from the second light source are transmitted by reflecting a part of the light from the first light source and transmitting a part of the light from the second light source. A part of the light is synthesized and emitted toward the light receiving element.
A part of the light from the first light source and a part of the light from the second light source are transmitted by transmitting a part of the light from the first light source and reflecting a part of the light from the second light source. A part of the light is synthesized and emitted to the outside,
The plurality of light sources are semiconductor lasers that oscillate in vertical multimode.
Said estimating means, on the basis of the amount of light received by the light receiving element, wherein the wavelength of wavelength components of the light from the first light source the weighted average, the wavelength of the wavelength components of the light-weighted average from the second light source light source device and estimates and.
However, d: the thickness of the branching element n: the refractive index of the branching element θ: the incident angle of the incident light on which the first light is incident on the branching element D: the aperture of the light path from the first light source . Opening diameter A plurality of light sources including a first light source and a second light source,
A flat plate-shaped branching element arranged on the optical path of light from the plurality of light sources and branching incident light into transmitted light and reflected light.
A light receiving element that receives at least a part of the reflected light and
An estimation means for estimating the wavelength of light from the plurality of light sources is provided.
The incident light incident on the branching element from the first light source and the branching element are
Satisfying the relationship of 2 × d × cos θ × tan [arcsin (sin θ ÷ n)]> 0.5 × D,
The branch element is
A part of the light from the first light source and a part of the light from the second light source are transmitted by reflecting a part of the light from the first light source and transmitting a part of the light from the second light source. A part of the light is synthesized and emitted toward the light receiving element.
A part of the light from the first light source and a part of the light from the second light source are transmitted by transmitting a part of the light from the first light source and reflecting a part of the light from the second light source. A part of the light is synthesized and emitted to the outside,
The plurality of light sources are semiconductor lasers that oscillate in vertical multimode.
Said estimating means, on the basis of the amount of light received by the light receiving element, wherein the wavelength of wavelength components of the light from the first light source the weighted average, the wavelength of the wavelength components of the light-weighted average from the second light source light source device and estimates and.
However, d: the thickness of the branch element n: the refractive index of the branch element θ: the angle of incidence of the incident light from the first light source on the branch element D: the intensity distribution of the incident light incident on the branch element from the first light source . , Diameter at which the intensity is 1 / e ^{2 of the} peak intensity Further provided with an aperture that is arranged on the optical path of light between the first light source and the branching element and shapes the light.
The light source device according to claim 2, wherein D is set according to the aperture diameter of the aperture. The light source device according to any one of claims 1 to 3, wherein the branching element does not have an antireflection film. The plurality of light sources are polarized light sources.
The invention according to any one of claims 1 to 4, wherein the plurality of light sources and the branching element are arranged so that the incident light from the plurality of light sources is p-polarized with respect to the branching element. The light source device described. Of the reflected light reflected by the branching element, the light from the first light source is reflected by the emitting side surface of the branching element and emitted from the incident side surface of the light from the first light source. The light source device according to any one of claims 1 to 5, further comprising a light-shielding member for light-shielding light. The size of the light receiving surface of the light receiving element is the surface on the incident side of the light from the first light source of the branching element among the reflected light reflected by the branching element from the light from the first light source. The light source device according to any one of claims 1 to 6, wherein the light source device is set to a size capable of receiving the reflected light and the light reflected by the surface on the emission side. Before SL plurality of light sources, different emission wavelengths from each other,
Any one of claims 1 to 7, further comprising a synthesizing means that is arranged on an optical path of light between the plurality of light sources and the branching element and synthesizes light from the plurality of light sources. The light source device according to. The light source device according to claim 8, wherein the plurality of light sources include a light source that emits red light, a light source that emits green light, and a light source that emits blue light. Further equipped with a temperature sensor for measuring the ambient temperature around the plurality of light sources,
The light source device according to any one of claims 1 to 9, wherein the estimation means estimates the wavelength based on the amount of received light and the temperature measured by the temperature sensor. The light source device according to any one of claims 1 to 10, further comprising a light emission amount setting means for setting the emission light amount of the plurality of light sources based on the wavelength estimated by the estimation means. .. The light source device according to any one of claims 1 to 11.
An image forming element that forms an image with light from the light source device,
An image display device including a screen on which the light forming the image is irradiated. The image display device according to claim 12, further comprising a light projecting unit that projects light through the screen toward a transmission / reflection member.
An object device including an object on which the image display device is mounted. The object device according to claim 13, wherein the object is a moving body.