The present disclosure relates to a light source device and an electronic apparatus.
As a light source for an AR (Augmented Reality) eyewear or a projector, a technique of multiplexing pieces of laser light of three colors, RGB, through an optical waveguide has been studied. Further, as a light source of an AR eyewear, considerations on VCSEL (surface-emitting laser) have been started as a low-power-consuming and eye-safe light source. Combination of these two techniques makes it possible to achieve a low-power-consuming and ultra-small RGB light source.
PTL 1: Japanese Unexamined Patent Application Publication No. 2007-25256 PTL 2: Japanese Unexamined Patent Application Publication No. 2006-208794
Incidentally, in order to control power of a light source, it is conceivable to monitor light-emitting power of the light source and control a driving current in accordance with a change in the light-emitting power. The light-emitting power is generally monitored by branching light outputted from the light source (see, for example, Patent Literatures 1 and 2). However, in such a case, output power for drawing is reduced. Accordingly, it is desirable to provide a light source device and an electronic apparatus that make it possible to monitor light-emitting power of a light source without reducing output power for drawing.
A light source device according to a first embodiment of the present disclosure includes a first light source section that outputs first laser light for drawing, and a second light source section that is provided adjacent to the first light source section and outputs second laser light for monitoring. The light source device further includes a light receiver that receives the second laser light, and a controller that performs light emission control on the first light source section on the basis of a detection signal from the light receiver.
An electronic apparatus according to a second embodiment of the present disclosure includes the light source device according to the first embodiment of the present disclosure.
In the light source device according to the first embodiment of the present disclosure and the electronic apparatus according to the second embodiment of the present disclosure, the second light source section that outputs the laser light for monitoring is provided adjacent to the first light source section that outputs the first laser light for drawing. This makes it possible to receive the second laser light by the light receiver, and to perform the light emission control on the first light source section on the basis of the detection signal from the light receiver.
A light source device according to a third embodiment of the present disclosure includes: first light source sections that respectively output pieces of first laser light for drawing having respective light emission wavelengths different from each other; and second light source sections that are each provided adjacent to corresponding one of the first light source sections, and respectively output pieces of second laser light for monitoring having respective wavelengths different from each other. The light source device further includes a light receiver that receives the pieces of second laser light, and a controller that performs light emission control on the first light source sections on the basis of a detection signal from the light receiver.
An electronic apparatus according to a fourth embodiment of the present disclosure includes the light source device according to the third embodiment of the present disclosure.
In the light source device according to the third embodiment of the present disclosure and the electronic apparatus according to the fourth embodiment of the present disclosure, the second light source sections that respectively output pieces of second laser light for monitoring having respective wavelengths different from each other are each provided adjacent to corresponding one of the first light source sections that respectively output pieces of first laser light for drawing. This makes it possible to receive the pieces of second laser light by the light receiver, and to perform the light emission control on the first light source section on the basis of the detection signal from the light receiver.
In the following, description is given in detail of embodiments of the present disclosure with reference to the drawings. The following description is merely a specific example of the present disclosure, and the present disclosure should not be limited to the following aspects. Moreover, the present disclosure is not limited to arrangements, dimensions, dimensional ratios, and the like of each component illustrated in the drawings. It is to be noted that the description is given in the following order.
An example in which light sources are provided separately for drawing and for monitoring and optical waveguides are provided separately for drawing and for monitoring (
Modification Example A: an example in which multiple light sources for drawing are provided for each color (
Modification Example B: an example in which optical waveguides for monitoring are combined (
Modification Example C: an example in which an optical fiber is used for an optical waveguide (
Modification Example D: an example in which a mirror is used for an optical waveguide (
An example in which a light source device is applied to eyeglasses (
A light source device 1 according to an embodiment of the present disclosure will be described.
The light source section 10 includes multiple light source sections 11Gd, 11Bd, and 11Rd for drawing and multiple light source sections 11Gm, 11Bm, and 11Rm for monitoring. The light source sections 11Gd, 11Bd, and 11Rd respectively output pieces of laser light Lgd, Lbd, and Lrd for drawing having respective light emission wavelengths different from each other. The light source sections 11Gm, 11Bm, and 11Rm respectively output pieces of laser light Lgm, Lbm, and Lrm for monitoring having respective light emission wavelength different from each other. The multiple light source sections 11Gm, 11Bm, and 11Rm for monitoring have light emission wavelengths equal to light emission wavelengths of the light source sections 11Gm, 11Bm, and 11Rm for drawing.
The light source section 11Gd outputs, for example, the green laser light Lgd (for example, a waveband of higher than or equal to 500 nm and lower than or equal to 550 nm). The light source section 11Gm outputs, for example, the green laser light Lgm. The light source sections 11Gd and 11Gm include respective surface-emitting semiconductor light-emitting elements (VCSELs) provided on a common crystal growth substrate and having a common light emission wavelength. The light source sections 11Gd and 11Gm include, for example, a GaInN-based semiconductor material. The light source section 11Gm is provided adjacent to the light source section 11Gd, and includes the same material as and has the same layer structure as the light source section 11Gd. Accordingly, a similarity between a light emission characteristic of the light source section 11Gm and a light emission characteristic of the light source section 11Gd is high.
The light source section 11Bd outputs, for example, the blue laser light Lbd (for example, a waveband of higher than or equal to 430 nm and lower than or equal to 500 nm). The light source section 11Bm outputs, for example, the blue laser light Lbm. The light source sections 11Bd and 11Bm include respective surface-emitting semiconductor light-emitting elements (VCSELs) provided on a common crystal growth substrate and having a common light emission wavelength. The light source sections 11Bd and 11Bm include, for example, a GaInN-based semiconductor material. The light source section 11Bm is provided adjacent to the light source section 11Bd, and includes the same material as and has the same layer structure as the light source section 11Bd. Accordingly, a similarity between a light emission characteristic of the light source section 11Bm and a light emission characteristic of the light source section 11Bd is high.
The light source section 11Rd outputs, for example, the red laser light Lrd (for example, a waveband of higher than or equal to 610 nm and lower than or equal to 780 nm). The light source section 11Rm outputs, for example, the red laser light Lrm. The light source sections 11Rd and 11Rm include respective surface-emitting semiconductor light-emitting elements (VCSELs) provided on a common crystal growth substrate and having a common light emission wavelength. The light source sections 11Rd and 11Rm include, for example, a GaInN-based semiconductor material. The light source section 11Rm is provided adjacent to the light source section 11Rd, and includes the same material as and has the same layer structure as the light source section 11Rd. Accordingly, a similarity between a light emission characteristic of the light source section 11Rm and a light emission characteristic of the light source section 11Rd is high.
The optical waveguide 21 guides the pieces of laser light Lgd, Lbd, and Lbd for drawing from the light source sections 11Gd, 11Bd, and 11Rd to an outside. The optical waveguide 21 includes: optical waveguides 21g, 21b, and 21r respectively provided for the light source sections 11Gd, 11Bd, and 11Rd; and a multiplexer 21c that combines the optical waveguides 21g, 21b, and 21r. The optical waveguide 21g guides the laser light Lgd for drawing from the light source section 11Gd to the multiplexer 21c. The optical waveguide 21b guides the laser light Lbd for drawing from the light source section 11Bd to the multiplexer 21c. The optical waveguide 21r guides the laser light Lrd for drawing from the light source section 11Rd to the multiplexer 21c. The multiplexer 21c is, for example, an optical component that combines the optical waveguides 21g, 21b, and 21r. The multiplexer 21c, for example, multiplexes the pieces of laser light Lgd, Lbd, and Lrd respectively transmitted through the optical waveguides 21g, 21b, and 21r, and guides the multiplexed light to one optical waveguide.
The optical waveguide 22 is an optical waveguide separate from the optical waveguide 21. The optical waveguide 22 guides the pieces of laser light Lgm, Lbm, and Lbm for monitoring from the light source sections 11Gm, 11Bm, and 11Rm to the light receiver 30. The optical waveguide 22 includes optical waveguides 22g, 22b, and 22r respectively provided for the light source sections 11Gm, 11Bm, and 11Rm. The optical waveguide 22g guides the laser light Lgd for drawing from the light source section 11Gm to a light receiver 30g (to be described below). The optical waveguide 22b guides the laser light Lbd for drawing from the light source section 11Bm to a light receiver 30b (to be described below). The optical waveguide 22r guides the laser light Lrd for drawing from the light source section 11Rm to a light receiver 30r (to be described below).
The light receiver 30 receives the pieces of laser light Lgm, Lbm, and Lbm for monitoring. The light receiver 30 includes the light receiver 30g that receives the laser light Lgm for monitoring, the light receiver 30b that receives the laser light Lbm for monitoring, and the light receiver 30r that receives the laser light Lrm for monitoring. The light receivers 30g, 30b, and 30r each include, for example, a photodiode that photoelectrically converts light in the visible region.
The storage 50 stores correction data to be used for control of light-emitting power of the light source sections 11Gd, 11Bd, and 11Rd. The storage 50 includes, for example, a nonvolatile memory such as a flash memory. The correction data may include, for example, I-L characteristic data (see
The controller 40 performs light emission control on the light source sections 11Gd, 11Bd, and 11Rd on the basis of a detection signal from the light receiver 30. The controller 40 also performs light emission control on the light source sections 11Gm, 11Bm, and 11Rm. For example, as illustrated in (A) and (B) of
The controller 40 measures an I-L characteristic of each of the light source sections 11Gm, 11Bm, and 11Rm when performing the first light emission control. Specifically, as illustrated in (A) and (B) of
In
The controller 40 may measure I-L-T characteristic data of each of the light source sections 11Gm, 11Bm, and 11Rm when performing the first light emission control. In this case, first, the controller 40 measures active-layer temperature T of each of the light source sections 11Gm, 11Bm, and 11Rm on the basis of the detection signal obtained from the light receiver 30 when performing the first light emission control. The controller 40 measures the active-layer temperature T of each of the light source sections 11Gm, 11Bm, and 11Rm using, for example, the following equation.
T=F(I, P)
I: electric current I flowing in each of the light source sections 11Gm, 11Bm, and 11Rm (a value set by the controller 40)
P: light-emitting power P of each of the light source sections 11Gm, 11Bm, and 11Rm obtained on the basis of the detection signal obtained from the light receiver 30
F(I, P): a mathematical function using the electric current I (a value set by the controller 40) and the light-emitting power P as parameters
Thereafter, the controller 40 derives the I-L-T characteristic data of each of the light source sections 11Gm, 11Bm, and 11Rm on the basis of: the obtained active-layer temperature T; and the detection signal obtained from the light receiver 30 by applying the measurement drive signal to the light source sections 11Gm, 11Bm, and 11Rm. That is, the controller 40 derives the I-L-T characteristic data of each of the light source sections 11Gm, 11Bm, and 11Rm on the basis of: the detection signal obtained from the light receiver 30 by the first light emission control; and the detection signal obtained from the light receiver 30 by applying the measurement drive signal to the light source sections 11Gm, 11Bm, and 11Rm.
In
Next, effects of the light source device 1 according to the present embodiment will be described.
As a light source for an AR eyewear or a projector, a technique of multiplexing pieces of laser light of three colors, RGB, through an optical waveguide has recently been studied. Further, as a light source of an AR eyewear, considerations on VCSEL have been started as a low-power-consuming and eye-safe light source. Combination of these two techniques makes it possible to achieve a low-power-consuming and ultra-small RGB light source.
Incidentally, in order to control power of a light source, it is conceivable to monitor light-emitting power of the light source and control a driving current in accordance with a change in the light-emitting power. The light-emitting power is generally monitored by branching light outputted from the light source.
For example, in the invention disclosed in PTL 1, array optical waveguides coupled to light-emitting elements each include a main waveguide and a branch waveguide in each waveguide, and the branch waveguides combine together to configure a coupled waveguide. Light outputted from the coupled waveguide is received by one light receiving element. Further, for example, the invention disclosed in PTL 2 provides a light-emitting element, and an optical waveguide that guides the light outputted from the light-emitting element. A notch is provided in a portion of the optical waveguide, and light leaked from the notch is monitored by the light receiving element.
However, in each of the inventions disclosed in PTLs 1 and 2, multiple light-emitting elements output light simultaneously during image drawing, and it is not possible to control light-emitting power for each light-emitting element. Further, some of the light outputted from the light-emitting element is branched to the light receiving element, and thus the light-emitting power of the light used for image drawing is lowered. Further, in a case where light emission for light emission control is performed separately from light emission for drawing, a user can visually recognize the light emission for the light emission control.
In contrast, the present embodiment provides the multiple light source sections 11Gm, 11Bm, and 11Rm for monitoring each provided adjacent to corresponding one of the multiple light source sections 11Gd, 11Bd, and 11Rd for drawing. Thus, it is possible to receive the multiple pieces of laser light Lgm, Lbm, and Lrm for monitoring by the light receiver 30, and to perform the light emission control on the multiple light source sections 11Gd, 11Bd, and 11Rd for drawing on the basis of the detection signal from the light receiver 30. As a result, it is possible to monitor the light-emitting power of each of the light source sections 11Gd, 11Bd, and 11Rd without reducing the output power for drawing.
Further, in the present embodiment, the light source section 11Gd for drawing and the light source section 11Gm for monitoring include the respective semiconductor light-emitting elements provided on the common semiconductor substrate. Further, the light source section 11Bd for drawing and the light source section 11Bm for monitoring include the respective semiconductor light-emitting elements provided on the common semiconductor substrate. The light source section 11Rd for drawing and the light source section 11Rm for monitoring include the respective semiconductor light-emitting elements provided on the common semiconductor substrate. This increases the similarity between the light emission characteristic of the light source section 11Gm for monitoring and the light emission characteristic of the light source section 11Gd for drawing. Further, this increases the similarity between the light emission characteristic of the light source section 11Bm for monitoring and the light emission characteristic of the light source section 11Bd for drawing. Further, this increases a similarity between a light emission characteristic of each of the multiple pieces of laser light Lgm, Lbm, and Lrm for monitoring and the light emission characteristic of the light source section 11Rd for drawing. As a result, it is possible to store a relative error between the light emission characteristic of the light source section 11Gm for monitoring and the light emission characteristic of each of the multiple light source sections 11Gd, 11Bd, and 11Rd for drawing in the storage 50 in advance as the correction data, and to use the relative error for the light emission control.
Further, in the present embodiment, the light-emitting power of each of the multiple light source sections 11Gd, 11Bd, and 11Rd for drawing is controlled on the basis of the detection signal obtained from the light receiver 30 when the first light emission control is performed. Here, when the first light emission control is performed, the active-layer temperature of each of the light source sections 11Gm, 11Bm, and 11Rm is approximately equal to the active-layer temperature of each of the light source sections 11Gd, 11Bd, and 11Rd. Further, the light-emitting power of each of the pieces of laser light Lgm, Lbm, and Lrm outputted from the light source sections 11Gm, 11Bm, and 11Rm is approximately equal to the light-emitting power of each of the pieces of laser light Lgd, Lbd, and Lrd outputted from the light source sections 11Gd, 11Bd, and 11Rd. It is therefore possible to accurately control the light-emitting power of each of the multiple light source sections 11Gd, 11Bd, and 11Rd for drawing on the basis of the detection signal obtained by the light receiver 30 receiving the multiple pieces of laser light Lgm, Lbm, and Lrm for monitoring.
Further, in the present embodiment, the light-emitting power of each of the multiple light source sections 11Gm, 11Bm, and 11Rm for monitoring is controlled on the basis of: the detection signal (a second detection signal) obtained from the light receiver 30 when the drive signal that is different from the drive signal to be applied to the multiple light source sections 11Gd, 11Bd, and 11Rd for drawing is applied to the multiple light source sections 11Gm, 11Bm, and 11Rm for monitoring; and the detection signal obtained by the first light emission control. Here, it is possible to derive the active-layer temperature T of each of the multiple light source sections 11Gm, 11Bm, and 11Rm for monitoring from the second detection signal, and also to control the light-emitting power of each of the multiple light source sections 11Gm, 11Bm, and 11Rm for monitoring on the basis of the I-L characteristic data corresponding to the derived active-layer temperature T. As a result, it is possible to control with high accuracy the light-emitting power of each of the multiple light source sections 11Gd, 11Bd, and 11Rd for drawing.
Next, modification examples of the light source device 1 according to the above-described embodiment will be described.
In the above-described embodiment, for example, as illustrated in
In the embodiment and the modification example thereof described above, for example, as illustrated in
Here, for example, as illustrated in
In the embodiment and the modification examples thereof described above, for example, as illustrated in
In the embodiment and the modification examples thereof described above, for example, as illustrated in
Next, an application example of the light source device 1 according to the embodiment and the modification examples thereof described above will be described.
The image projectors 110R and 110L each includes a light source device 1(R) that outputs R (red) light, a light source device 1(G) that outputs G (green) light, a light source device 1(B) that outputs B (blue) light, and an optical waveguide 2 that multiplexes the R light, the G light, and the B light. The image projector 110R further includes a mirror 3 that reflects white light generated by the multiplexing performed by the optical waveguide 2, and a scan mirror 4 that scans biaxially a surface of the combiner 120R via a lens 5 using the white light reflected by the mirror 3. The image projector 110L further includes a mirror 3 that reflects white light generated by the multiplexing performed by the optical waveguide 2, and a scan mirror 4 that scans biaxially a surface of the combiner 120L via a lens 5 using the white light reflected by the mirror 3.
The combiner 120R diffracts light drawn on the surface of the combiner 120R by the image projector 110R and projects the light onto a retina of a right eye 1000R. The imaging section 130R performs imaging to thereby acquire image data including the right eye 1000R, and detects a position of the right eye 1000R on the basis of the acquired image data. The imaging section 130R outputs the detected position of the right eye 1000R to the image projector 110R. The image projector 110R controls the scanning of the scan mirror 4 in such a manner that the light is projected at the position of the right eye 1000R obtained from the imaging section 130R.
The combiner 120L diffracts light drawn on the surface of the combiner 120L by the image projector 110L and projects the light onto a retina of a left eye 1000L. The imaging section 130L performs imaging to thereby acquire image data including the left eye 1000L, and detects a position of the left eye 1000L on the basis of the acquired image data. The imaging section 130L outputs the detected position of the left eye 1000L to the image projector 110L. The image projector 110L controls the scanning of the scan mirror 4 in such a manner that the light is projected at the position of the left eye 1000L obtained from the imaging section 130L.
In the present application example, the light source device 1 according to the embodiment and the modification examples thereof described above is used as a light source of each of the image projectors 110R and 110L. It is therefore possible to perform light combining and light-output monitoring with an easily-achievable configuration by the image projectors 110R and 110L.
Although the disclosure is described hereinabove with reference to the example embodiment and modification examples, these embodiments are not to be construed as limiting the scope of the disclosure and may be modified in a wide variety of ways. It should be appreciated that the effects described herein are mere examples. Effects of the example embodiment and modification examples of the disclosure are not limited to those described herein. The disclosure may further include any effects other than those described herein. Further, the present disclosure may also have the following configurations.
In the light source device according to the first embodiment of the present disclosure and the electronic apparatus according to the second embodiment of the present disclosure, the second light source section that outputs the laser light for monitoring is provided adjacent to the first light source section that outputs the first laser light for drawing. This makes it possible to receive the second laser light by the light receiver, and to perform the light emission control on the first light source section on the basis of the detection signal from the light receiver. As a result, it is possible to monitor the light-emitting power of the light source without reducing the output power for drawing.
In the light source device according to the third embodiment of the present disclosure and the electronic apparatus according to the fourth embodiment of the present disclosure, the second light source sections that respectively output pieces of second laser light for monitoring having respective wavelengths different from each other are each provided adjacent to corresponding one of the first light source sections that respectively output pieces of first laser light for drawing. This makes it possible to receive the pieces of second laser light by the light receiver, and to perform the light emission control on the first light source section on the basis of the detection signal from the light receiver. As a result, it is possible to monitor the light-emitting power of the light source without reducing the output power for drawing. It is to be noted that the effects of the present disclosure are not necessarily limited to the effects described herein, and may be any effects described herein.
This application claims the benefit of Japanese Priority Patent Application JP2021-119675 filed with the Japan Patent Office on Jul. 20, 2021, the entire contents of which are incorporated herein by reference.
It should be understood by those skilled in the art that various modifications, combinations, sub-combinations, and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof.
Number | Date | Country | Kind |
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2021-119675 | Jul 2021 | JP | national |
Filing Document | Filing Date | Country | Kind |
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PCT/JP2022/011867 | 3/16/2022 | WO |