JP2016128871A - Light source device and projection type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light source device capable of stable output control, with a simple configuration.SOLUTION: A light source device 1 includes a light output part 10 which includes a solid light source 11 and emits light emitted from the solid light source 11 to the outside, a first optical fiber 21 which includes an incident end on which a part of the light emitted from the light output part 10 is made incident, a light detection element 22 which is optically coupled to the emission end of the first optical fiber 21 and detects a part of the light made incident on the first optical fiber 21, and a control part 30 which controls the output of the solid light source 11 on the basis of the detection result of the light detection element 22.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a light source device and a projection display device.

In recent years, in a projection display device (projector) using a liquid crystal display (LCD) or a digital micromirror device (DMD) as a display element, a light source device using a solid light source such as a semiconductor laser or a light emitting diode (LED) is used. ing.
Since the amount of light of a solid light source changes depending on the usage environment, aging, etc., in a light source device using a solid light source, feedback control using an optical sensor is performed for the purpose of stabilizing brightness and whiteness. . That is, the amount of light emitted from the solid light source (light source device) is measured using an optical sensor, and the output of the light source device is controlled based on the measurement result so that the amount of emitted light becomes a predetermined value.
In such feedback control, in many cases, in order to measure the amount of light from the light source device, unnecessary light (so-called unnecessary light) that is not used for image display of the projector among light emitted from the light source device is used. A method of detecting by an optical sensor is used. For example, Patent Document 1 describes a method of detecting unnecessary light reflected or transmitted by a dichroic mirror disposed on the incident side of a display element. Patent Document 2 describes a method of detecting unnecessary light reflected when a DMD micromirror is in an OFF state.

JP 2014-167610 A JP 2007-316660 A

In the above-described detection method, the optical sensor needs to be arranged at a position where unnecessary light in the projector can be received, so that the degree of freedom of arrangement of the optical sensor becomes low and the component configuration becomes complicated. Further, in the detection method described in Patent Document 2, processing for output control is complicated, and it is difficult to perform stable output control in terms of light detection sensitivity.
Therefore, an object of the present invention is to provide a light source device capable of stable output control with a simple configuration. Another object of the present invention is to provide a projection display device using the light source device.

In order to achieve the above-described object, a light source device of the present invention has a solid light source, a light output unit that emits light emitted from the solid light source to the outside, and a part of the light emitted from the light output unit A first optical fiber having an incident end on which light is incident, a light detecting element optically coupled to an output end of the first optical fiber, and detecting a part of the light incident on the first optical fiber; And a control unit that controls the output of the solid-state light source based on the detection result of the detection element.
According to another aspect of the invention, there is provided a projection display apparatus, the light source apparatus described above, a display element that modulates light emitted from the light source apparatus in accordance with an image signal, and projection optics that projects the light emitted from the display element. Part.

  As described above, according to the present invention, it is possible to provide a light source device capable of stable output control with a simple configuration and a projection display device including the same.

It is a schematic block diagram of the light source device by one Embodiment of this invention. It is the schematic front view which looked at the optical fiber bundle of this embodiment from the emission direction of light. It is the schematic which shows one structural example of the projection type display apparatus provided with the light source device by this embodiment.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a light source device according to an embodiment of the present invention. Hereinafter, the light source device of the present embodiment will be described by taking a case where a semiconductor laser is used as a solid light source as an example. However, the present invention is not limited to this, and other solid light sources such as a light emitting diode (LED) are used. It can also be used.

The light source device 1 according to the present embodiment includes a light output unit 10, a light detection unit 20, and a control unit 30.
The light output unit 10 includes a semiconductor laser unit 11 having a plurality of semiconductor lasers, a drive circuit 12 for driving the semiconductor laser unit 11, a plurality of optical fibers 13 for light irradiation, and a cooling unit for cooling the semiconductor laser unit 11. 14.
The plurality of light irradiation optical fibers (second optical fibers) 13 are optically coupled to the plurality of semiconductor lasers of the semiconductor laser unit 11, respectively. Therefore, in the plurality of optical fibers 13 for light irradiation, laser light from each semiconductor laser is incident from one end (incident end), propagates inside, and is emitted to the outside from the other end (exit end). It is like that. The plurality of light irradiation optical fibers 13 are bundled together at least on the emission end side to form an optical fiber bundle 15. The cooling unit 14 includes heat radiating means such as a heat sink and a fan, and has a function of releasing the heat of the semiconductor laser unit 11 to keep the temperature of the semiconductor laser unit 11 constant.

The light detection unit 20 includes a light detection optical fiber 21 and a light sensor 22 optically coupled to the optical fiber 21.
The light detection optical fiber (first optical fiber) 21 is reflected by an optical component (for example, a lens or a mirror) arranged outside of the light emitted from the emission end of the light irradiation optical fiber 13 to the outside. Alternatively, it has a function of receiving scattered light and transmitting it to the optical sensor 22. Accordingly, the optical detection optical fiber 21 has an end portion (incident end) that is not optically coupled to the optical sensor 22, and a part of the laser light emitted from the emission ends of the plurality of light irradiation optical fibers 13. It is arranged at the incident position. More specifically, the optical fiber 21 for light detection is bundled together with the plurality of optical fibers 13 for light irradiation in the optical fiber bundle 15, and the incident end of the optical fiber 21 for light detection is a plurality of light irradiation fibers. It is disposed adjacent to the exit end of the optical fiber 13. The light sensor (light detection element) 22 has a function of detecting light incident on the light detection optical fiber 21, specifically, converts light received through the light detection optical fiber 21 into an electrical signal and controls it. The function of outputting to the unit 30 is provided. The optical sensor 22 is thermally connected to the cooling unit 14 of the light output unit 10.

  The control unit 30 outputs a control signal for controlling the drive circuit 12 based on the detection result of the optical sensor 22 and adjusts the output of the semiconductor laser unit 11. Specifically, the control unit 30 calculates the amount of laser light of the semiconductor laser unit 11 from the output of the optical sensor 22, and controls the output of the semiconductor laser unit 11 so that the calculated value becomes a predetermined value. It has become.

Here, with reference to FIG. 2, the arrangement | positioning structure of the some optical fiber for light irradiation and the optical fiber for light detection in an optical fiber bundle is demonstrated. FIG. 2 is a schematic front view of the optical fiber bundle of the present embodiment as viewed from the light emitting direction.
As shown in FIG. 2, the plurality of light irradiation optical fibers 13 are arranged so as to surround the periphery of the light detection optical fiber 21 when viewed from the light emission direction (optical axis direction). Specifically, the plurality of light irradiation optical fibers 13 are arranged radially with the light detection optical fiber 21 as the center. More specifically, the plurality of light irradiating optical fibers 13 are arranged rotationally symmetrically about the light detecting optical fiber 21. Thus, since the optical fiber 21 for light detection is arrange | positioned near the center of the optical fiber bundle 15, the change of the light quantity of the laser beam from a semiconductor laser is more accurate than the case where it arrange | positions near the periphery. Detection can be performed well, and as a result, the accuracy of light detection can be improved.

Here, with reference to FIG. 1 again, the operation of the light source device of the present embodiment will be described.
Based on the control signal output from the control unit 30, the drive circuit 12 drives the semiconductor laser unit 11, and laser light is emitted from the semiconductor laser unit 11. Laser light emitted from the semiconductor laser unit 11 enters the incident end of the light irradiation optical fiber 13, propagates through the inside, and is emitted from the emission end. At this time, a part of the laser light emitted from the light irradiation optical fiber 13 is reflected or scattered by an optical component (for example, a lens or a mirror) disposed on the emission side of the light source device 1, and the reflection or scattering. The incident light enters the incident end of the optical fiber 21 for light detection. The light that has entered the optical fiber 21 for light detection propagates through the optical fiber 21 for light detection and is received by the optical sensor 22. The optical sensor 22 outputs an electrical signal corresponding to the amount of received light and transmits it to the control unit 30. The control unit 30 that has received the electrical signal from the optical sensor 22 calculates the amount of laser light from the semiconductor laser unit 11 based on the electrical signal. Then, the control unit 30 generates a control signal for causing the semiconductor laser unit 11 to emit a desired amount of laser light based on the calculated value, and outputs the control signal to the drive circuit 12. The drive circuit 12 is controlled by the control signal output from the control unit 30, the output of the semiconductor laser unit 11 is adjusted, and a predetermined amount of laser light is emitted from the semiconductor laser unit 11.

As described above, in the present embodiment, an optical fiber optically coupled to the optical sensor is used to receive a part of the light emitted from the light source device by the optical sensor. For this reason, the degree of freedom of the arrangement of the optical sensor can be increased. For example, when the light source device of the present embodiment is applied to the light source device of the projector, the optical sensor is arranged inside the projector on the emission side of the light source device. There is no need to do this. As a result, in this embodiment, it is possible to reduce the size of the projector. In addition, since complicated processing for output control is not required, stable output control can be realized.
By the way, the characteristics of the optical sensor change depending on the temperature. Therefore, in order to perform stable light detection, it is necessary to manage the temperature of the optical sensor or to correct the temperature of the sensor output. In some cases, this may lead to an increase in the number of parts and complexity of the control process. However, in the present embodiment, as described above, the optical sensor is arranged so as to be thermally connected to the cooling unit of the optical output unit (semiconductor laser unit) by increasing the degree of freedom of arrangement of the optical sensor. Is also possible. That is, the cooling unit that cools the semiconductor laser unit can also be used as a means for adjusting the temperature of the optical sensor. Therefore, it is not necessary to separately provide a temperature adjusting means for the optical sensor, and stable temperature management of the optical sensor is possible, so that further downsizing and cost reduction can be realized.
In the above-described embodiment, each optical fiber of the light source device has a circular cross section, but is not limited to this, and has a cross section of another geometric shape such as an ellipse or a rectangle. It may be.

  Next, a projection display device (projector) including the light source device of the present embodiment will be described. FIG. 3 is a schematic diagram illustrating a configuration example of a projector including the light source device of the present embodiment.

The projector 40 includes the light source devices 1R, 1G, and 1B of the present embodiment, the dichroic prisms 3 and 4, the image forming unit 5, and the projection optical unit 6.
The light source devices 1R, 1G, and 1B are configured to emit red light R, green light G, and blue light B, respectively. In other words, the light source device 1R includes a plurality of red semiconductor lasers and is configured to emit red light R, and the light source device 1G includes a plurality of green semiconductor lasers and configured to emit green light G. The light source device 1B includes a plurality of blue semiconductor lasers and is configured to emit blue light B.
The dichroic prisms 3 and 4 have a function of synthesizing three color lights (red light, green light, and blue light) emitted from the light source devices 1R, 1G, and 1B and outputting them as white light. That is, the dichroic prism 3 has a function of combining the blue light B and the green light G and outputting them as blue-green light C, and the dichroic prism 4 combines the blue-green light C and the red light R to produce a white color. It has a function to output as light. Specifically, the dichroic prism 3 is configured to transmit blue light B and reflect green light G, and the dichroic prism 4 is configured to transmit blue green light C and reflect red light R. Has been. The light emitted from the dichroic prisms 3 and 4 is not necessarily synthesized white light. For example, red light R, green light G, and blue light B are emitted in time division by time division control. You may come to be.

The image forming unit 5 includes a display element, an illumination optical unit that irradiates the display element with light emitted from the dichroic prism 4, and the like. The display element is composed of, for example, a liquid crystal display (LCD) or a digital micromirror device (DMD), and has a function of modulating incident light according to an image signal. The illumination optical unit may be configured to again separate light (white light) emitted from the dichroic prism 4 into red light, green light, and blue light. In that case, the separated red light, green light is separated. Display elements respectively corresponding to light and blue light are provided. On the other hand, as described above, when the dichroic prism 4 emits red light, green light, and blue light in a time division manner, it is not necessary to separate incident light again. Each color light can be modulated using two display elements.
The projection optical unit 6 includes a projection lens, and has a function of projecting light emitted from the image forming unit 5 onto a screen or the like and displaying it as an image. When white light is separated into red light, green light, and blue light by the image forming unit 5, after each color light is modulated by the display element of the image forming unit 5, the projection optical unit 6 They may be synthesized.

  Between the light source device 1R and the dichroic prism 4, a collimator lens 2R for collimating the laser light (red light R) emitted from the light irradiation optical fiber of the light source device 1R is disposed. Similarly, collimator lenses 2G and 2B are disposed between the light source devices 1G and 1B and the dichroic prism 4, respectively. In addition, when each light source device 1R, 1G, and 1B is comprised so that the collimated laser beam may be output, such a collimating lens does not need to be provided.

Hereinafter, an image projection operation by the projector 1 according to the present embodiment will be briefly described.
The blue light B emitted from the light source device 1B is collimated by the collimating lens 2B, enters the dichroic prism 3, and passes through it. On the other hand, the green light G emitted from the light source device 1G is collimated by the collimating lens 2G, enters the dichroic prism 3, and is reflected thereby. Thus, the blue light B and the green light G are combined by the dichroic prism 3 and become blue-green light C and enter the dichroic prism 4.
The red light R emitted from the light source device 1R is collimated by the collimating lens 2R, enters the dichroic prism 4, and is reflected thereby. On the other hand, the blue-green light C incident on the dichroic prism 4 passes through the dichroic prism 4. Thus, the blue-green light C and the red light R are combined by the dichroic prism 4 and become white light and enter the image forming unit 5.
At this time, in order to obtain white light having desired luminance and chromaticity, the light amounts of the red light R, the green light G, and the blue light B emitted from the light source devices 1R, 1G, and 1B are as described above. Based on the amount of light received by the optical sensor (for example, reflected light or scattered light by the collimating lenses 2R, 2G, and 2B and the dichroic prisms 3 and 4), the light amount is adjusted to a predetermined amount.
The white light incident on the image forming unit 5 is modulated by the display element of the image forming unit 5 according to the image signal. The modulated light enters the projection optical unit 6 and is projected onto a screen or the like by the projection lens of the projection optical unit 6 and displayed as an image.

  In the present embodiment described above, the projector is configured to have three light source devices that emit red light, green light, and blue light, respectively, but has one light source device that emits three color lights. It may be configured. That is, the projector is configured to include one light source device having three light output units that emit red light, green light, and blue light, three light detection units, and one control unit, respectively. May be.

  As described above, the light source device according to the present embodiment can be used not only as a light source device for a projector but also as a light source device for an image display device (display), for example.

1, 1R, 1G, 1B Light source device 2R, 2G, 2B Collimating lens 3, 4 Dichroic prism 5 Image forming unit 6 Projection optical unit 10 Light output unit 11 Semiconductor laser unit 12 Drive circuit 13 Optical fiber for light irradiation (second Optical fiber)
DESCRIPTION OF SYMBOLS 14 Cooling part 15 Optical fiber bundle 20 Optical detection part 21 Optical fiber for optical detection (1st optical fiber)
22 Light sensor (light detection element)
30 Control unit 40 Projector

Claims (8)

A light output unit that has a solid light source and emits light emitted from the solid light source to the outside;
A first optical fiber having an incident end on which a part of light emitted from the light output unit is incident;
A light detecting element optically coupled to an output end of the first optical fiber and detecting the part of the light incident on the first optical fiber;
A control unit for controlling the output of the solid-state light source based on the detection result of the light detection element;
A light source device.   The light output unit includes a second optical fiber that is optically coupled to the solid light source and emits light emitted from the solid light source to the outside, and the incident end of the first optical fiber includes: The light source device according to claim 1, wherein the light source device is disposed adjacent to an emission end of the second optical fiber.   The light source device according to claim 2, wherein the light output unit includes a plurality of the solid light sources and a plurality of the second optical fibers that are optically coupled to the plurality of solid light sources.   4. The light source device according to claim 3, wherein the plurality of second optical fibers are disposed so as to surround the first optical fiber as viewed from the light emitting direction. 5.   5. The light source device according to claim 4, wherein the plurality of second optical fibers are arranged radially around the first optical fiber as viewed from the light emitting direction.   The light source device according to claim 5, wherein the plurality of second optical fibers are arranged rotationally symmetrically with respect to the first optical fiber as viewed from the light emitting direction.   The light source according to claim 1, wherein the light output unit includes a cooling unit that cools the solid-state light source, and the light detection element is thermally connected to the cooling unit. apparatus.   8. The light source device according to claim 1, a display element that modulates light emitted from the light source device according to an image signal, and projection optics that projects light emitted from the display element. A projection display device.

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