JP6349743B2 - Light source device and image projection device using the light source device - Google Patents

Description

  The present invention relates to a light source device and an improvement of an image projection device using the light source device.

  2. Description of the Related Art Today, an image projection apparatus (projector) that projects an image on a screen using image data of a personal computer, video image data, image data stored in a memory card, or the like is known.

  This image projection device (projector) projects light emitted from a light source device onto a screen using a micromirror display element as a digital micromirror device, a liquid crystal plate, and the like to form an image on the screen.

  Conventionally, the light source device of this image projection apparatus has mainly used a high-intensity discharge lamp as a light source. However, in recent years, a light source device using a combination of a solid-state light emitting element that generates excitation light as a light source and a phosphor that absorbs excitation light and converts it into fluorescence having a predetermined wavelength band has been developed.

As the solid-state light emitting element, a semiconductor element such as a light emitting diode (LED), a laser diode (LD), or an organic EL is used.
A light source device using this type of solid state light emitting device has advantages such as improved color reproducibility, light emitting efficiency, light utilization efficiency, etc., and longer life compared to a discharge lamp. .

  In addition, the light source device using this kind of solid-state light-emitting element has the advantage that the optical system can be easily designed, color composition is simplified, the projection lens has a low NA (numerical aperture), etc. There is also.

  However, when a laser light source is used for the light source device of the image projection apparatus, the laser light is coherent light with a uniform wavefront and has a high straightness. For this reason, it is desirable that the laser light is not directly incident on the human eye.

  In addition, it is desirable to prevent a laser beam having a large energy intensity from hitting human skin. For this reason, products with laser light sources are classified according to international standards (IEC60825) and Japanese domestic standards (JIS C6802: 2005), and manufacturers and users comply with each class. There are guidelines to be taken. This contributes to improving the safety of laser products.

  If the light source device of the image projection device is equipped with a laser light source, the energy density of the laser light is reduced so that high-power laser light is not emitted directly to the outside in order to improve safety against laser light. A diffusing member is provided in the traveling light path of the laser light.

However, if the diffusing function of the diffusing member deviates from the traveling optical path of the laser light and the diffusing function is lowered, the safety against the laser light is lowered. For example, the diffusion function deteriorates due to the fall of the image projection apparatus or some external factor, so that the diffusing member deviates from the traveling light path, or is damaged, deformed, or destroyed by laser light irradiation.
Therefore, it is desirable to adopt a configuration that detects a decrease in the function of the diffusing member. Moreover, when it is set as the structure which detects the function fall of a diffusion member, it is desirable to set it as the structure which can be detected, without losing the illumination light rate by a laser beam as much as possible.

  The light source device of the image projection apparatus includes a laser light source and light beam conversion means corresponding to a diffusing member for expanding or diffusing the laser light, and the laser light is converted by the light beam conversion means to produce high-power laser light. Is not directly emitted to the outside, and the function deterioration of the light beam conversion means is detected by a sensor provided outside the effective screen range of the screen (see Patent Document 1). According to this configuration, it is possible to indirectly detect a decrease in the function of the light beam conversion means by the sensor provided on the laser beam emission side of the light beam conversion means.

  In the light source device in which the diffusion member for diffusing the laser beam is provided in the traveling light path of the laser beam in order to contribute to the improvement of the safety against the laser beam, the present invention diffuses without losing the illumination light rate by the laser beam as much as possible. It is an object of the present invention to provide a light source device that can directly detect a decrease in function of a member.

The light source device according to the present invention includes a laser light source that emits laser light, an incident surface that is provided in a traveling light path of the laser light, and the laser light incident on the incident surface is diffused and emitted. A diffusing member having an exit surface and an ineffective in the diffusing member when passing through the diffusing member provided at a position that does not interfere with the traveling light path of the laser light emitted from the exit surface and used as an effective light beam And a light receiving member for receiving the laser beam,
By detecting the invalid laser beam by the light receiving member, it is determined that the function of the diffusing member is degraded.

  ADVANTAGE OF THE INVENTION According to this invention, there exists an effect that the functional fall of a diffusion member can be detected directly, without impairing the illumination efficiency by a laser beam as much as possible, and it can contribute to the improvement of the safety | security with respect to a laser beam.

FIG. 1 is a main part configuration diagram of a light source device according to Embodiment 1 of the present invention. 2A and 2B are explanatory views showing an example of the configuration of the light receiving member of the light source device according to the first embodiment of the present invention. FIG. 2A is a view showing a condensing lens as a capturing member, and FIG. It is a figure which shows the scattering member as a member. FIG. 3 is an explanatory diagram showing an example of a decrease in the diffusing function of the diffusing member of the light source device according to the first embodiment of the present invention, and shows a state where the diffusing member deviates from the traveling light path. FIG. 4 is a configuration diagram of a main part of the light source device according to the second embodiment of the present invention, and shows a state in which a diffusion member is disposed obliquely in the traveling light path of the laser light. FIG. 5 is a configuration diagram of a main part of a light source device according to a third embodiment of the present invention, in which a parallel flat plate is used as a diffusion member and the light guide function of the parallel flat plate is used to lower the diffusion function of the diffusion member. It is explanatory drawing which shows the structure which detects this. FIG. 6 is a main part configuration diagram of a light source device according to Embodiment 4 of the present invention, and is an explanatory view showing an example of a light source device for forming a color image. FIG. 7 is a plan view of the optical path switching board shown in FIG. FIG. 8 is a plan view of the phosphor shown in FIG. FIG. 9 is a diagram showing a schematic configuration of an image projection apparatus incorporating the light source device shown in FIG. FIG. 10 is a flowchart for explaining the operation of the image projection apparatus shown in FIG.

Example 1
FIG. 1 to FIG. 3 are principal part optical views showing a first embodiment of a light source device according to the present invention. In FIG. 1, reference numerals 1a, 1b and 1c are laser light sources, reference numerals 2a to 2c are coupling lenses for condensing the laser light P emitted from the laser light sources 1a, 1b and 1c, and reference numeral 2 is the coupling lens. Reference numeral 3 denotes a converging lens for converging the laser light P collected by 2a to 2c, and a collimating lens 3 for converting the laser light P converged by the converging lens 2 into a parallel light beam.

  In the traveling light path of the laser light P emitted from the laser light sources 1a, 1b, and 1c, a diffusion member 4 that relaxes the energy density of the laser light P by diffusing the laser light P is provided.

The diffusing member 4 has an incident surface 4a on which the laser beam P is incident and an exit surface 4b on which the laser beam P incident on the incident surface 4a is emitted.
When the diffusing member 4 is disposed in the traveling optical path of the laser light P, the laser light P diffuses when the laser light P is emitted from the emission surface 4b due to interface reflection caused by the difference in refractive index between the diffusing member 4 and the air. Is done.

  The exit surface 4b is preferably a diffusion surface in which minute irregularities 4b 'are formed to provide a diffusion function. The diffusion member 4 is made of a highly transparent glass material or plastic material. A diffusion surface such as etching or mechanical polishing may be applied to these materials to form a diffusion surface on the injection surface 4b, or by forming minute irregularities 4b ′ on the injection surface 4b by molding. May be formed.

The incident surface 4a is preferably a flat surface that has not been subjected to diffusion treatment. As shown in FIG. 1, the laser light P incident on the diffusing member 4 through the incident surface 4a is reflected and scattered by the incident surface 4a and the exit surface 4b to become an invalid light beam. Further, it is diffused when exiting from the exit surface 4b of the diffusing member 4, its main light beam is diffused as an effective light beam and guided to the traveling light path of the laser light, and the remaining light beam is diffused as an invalid light beam. Is done.
Here, the main light beam is a light beam necessary for use as illumination light, and an invalid light beam is a laser beam (back scattered light) that returns to the incident side without passing through the diffusion member 4, and passes through the diffusion member 4. The luminous flux that cannot be used as illumination light among the laser light P that has been transmitted, that is, laser light that has passed through the diffusing member 4 and greatly scattered forward.

  The laser beam P ″ that has become ineffective in the diffusing member 4 when passing through the diffusing member 4 is placed at a position that does not interfere with the traveling optical path of the laser beam P ′ that is emitted from the emission surface 4 b and used as an effective light beam. A light receiving member 5 for receiving light is provided.

  In the first embodiment, the diffusing member 4 is provided perpendicular to the traveling optical path of the laser beam P, and the light receiving member 5 emits the invalid laser beam P ″ reflected by the emitting surface 4b of the diffusing member 4 to the emitting surface side. Further, the light is received on the incident surface side.

  However, the light receiving member 5 capable of receiving the invalid laser light P ″ emitted from the emission surface 4b is disposed at a position that does not interfere with the traveling optical path of the laser light P ′ used as an effective light beam, as indicated by a broken line. It is good also as a structure to install.

  The light receiving member 5, for example, captures an invalid laser beam P ″ as shown in FIG. 2A and converts the laser beam P ″ captured by the capture device 5 a into an electrical signal. It is desirable to have a configuration having the sensor 5b. FIG. 2 (a) shows a condensing lens as the capturing element 5a, but a scattering member may be used as the capturing element 5a as shown in FIG. 2 (b).

  When the diffusing member 4 is present in the traveling light path of the laser beam P, the invalid laser beam P ″ from the exit surface 4b can be detected as shown in FIG. 1. On the other hand, as shown in FIG. When the diffusing member 4 deviates from the traveling optical path of P and the diffusing function is lowered by the diffusing member 4, the detection amount by the light receiving member 5 is reduced, which is shown by the two-dot chain line in FIG. Means that the diffusing member 4 does not exist at that position.

  Therefore, a decrease in the diffusion function of the diffusing member 4 can be determined by comparing the detection amount of the invalid laser beam P ″ with a predetermined threshold value and detecting whether or not the detection amount is equal to or less than the threshold value.

(Example 2)
In the second embodiment, as shown in FIG. 4, the diffusing member 4 is disposed obliquely with respect to the traveling light path of the laser light P. Here, the light receiving member 5 is configured to receive the laser beam P ″ that is invalid after being regularly reflected on the incident surface 4a on the incident side with respect to the incident surface 4a.

  That is, the light receiving member 5 is disposed at a position where it can receive the invalid laser beam P ″ reflected in the direction opposite to the side on which the laser beam P is incident with respect to the normal N standing on the incident surface 4a. In addition, the configuration may be such that invalid laser light P ″ reflected by the exit surface 4b can be received simultaneously.

  The incident surface 4a is provided with an antireflection coating that prevents reflection of light in the wavelength band of the laser beam P. However, even if the antireflection coating is applied, 100% of the amount of light cannot be transmitted. Some are always reflected.

  When there is no antireflection coating, usually about 4% of the laser light P incident on the incident surface 4a is reflected as invalid laser light P ″. At this time, a laser used as an effective light beam When it is considered that the power of the light P ′ is sufficient in design, it is desirable not to form an antireflection coating on the incident surface 4 a from the viewpoint of giving priority to the detection sensitivity of the light receiving member 5.

This is because the manufacturing cost of the diffusing member 4 can be reduced by the amount that the antireflection coating is not formed on the incident surface 4a.
Further, when the antireflection coating is provided on the incident surface 4a, the reflectance varies, and it is necessary to adjust the arrangement position of the light receiving member 5 in consideration of the reflectance variation of the antireflection coating. On the other hand, since the variation in the reflectance on the incident surface 4a when the antireflection coating is not provided is very small, the invalid laser beam P "is not necessary without adjusting the arrangement position of the light receiving member 5 more than necessary. Can be detected.
According to the second embodiment, the configuration is such that the ineffective laser beam P ″ regularly reflected by the incident surface 4a is detected. Therefore, compared to the first embodiment in which the ineffective laser beam P ″ that is diffused light is detected, Detection sensitivity is improved.

(Example 3)
In the third embodiment, as shown in FIG. 5, the diffusing member 4 is composed of a parallel plane plate in which at least one of the entrance surface 4a and the exit surface 4b is a surface that provides a diffusing function. The plane parallel plate is provided perpendicular to the traveling light path of the laser beam P. Here, the emission surface 4b is a diffusion surface that provides a diffusion function in the same manner as in the first and second embodiments.

  The light receiving member 5 is disposed so as to face at least one end surface 4c excluding the entrance surface 4a and the exit surface 4b of the plane parallel plate. Of the laser light P incident on the plane parallel plate from the incident surface 4a, the main light beam is diffused as an effective light beam and guided to the traveling light path of the laser light P '. A part of the light flux is reflected at the exit surface 4b, propagates through the plane of parallel plane repeatedly by reflection at the interface between the entrance surface 4a and the exit surface 4b, and a part of the light is emitted from the end surface 4c.

  According to the first and second embodiments, there is a possibility that the laser beam P scattered by the holding member that holds the diffusing member 4, the housing of the light source device, and the like enters the light receiving member 5 as stray light. For this reason, there is a possibility that the detection accuracy of the invalid laser beam P ″ used to detect the decrease in the diffusion function of the diffusion member 4 may decrease.

  However, according to the third embodiment, since the plane-parallel plate functions as a light guide for the invalid laser beam P ″, the invalid laser beam P ″ used for detecting a decrease in the diffusion function of the diffusion member 4 is used. It can be detected reliably.

Example 4
In the fourth embodiment, as shown in FIG. 6, an optical path switching board 7 is provided in the traveling optical path of the laser light P between the laser light sources 1 a to 1 c and the diffusion member 4. This optical path switching board 7 uses the first optical path L1 provided with the diffusing member 4 and the laser light P emitted from the laser light sources 1a to 1c as the traveling optical path of the laser light P emitted from the laser light sources 1a to 1c. It plays a role of switching to the second optical path L2 provided with the phosphor 6 that is excited to generate fluorescence. Here, blue laser light is used as the laser light P.

  As shown in FIG. 7, the optical path switching board 7 has a reflection area 7a that reflects the laser light P and guides it to the second optical path L2, and a transmission area 7b that transmits the laser light P and guides it to the first optical path L1. . The optical path switching board 7 is rotationally driven by a drive motor 8.

  The phosphor 6 is constituted by a rotating wheel, and is driven to rotate in synchronization with the optical path switching board 7 by a drive motor 9. For example, in synchronization with one rotation of the optical path switching board 7, the phosphor 6 is rotated once.

  As shown in FIG. 8, the phosphor 6 is applied with a fluorescent material application region 6a that is excited by the laser light P to generate green fluorescence, and a fluorescent material application that is excited by the laser light P to generate red fluorescence. A region 6b and an unquestioned region 6c with or without a fluorescent material are provided.

  In the second optical path L2, the collimating lens 10 that condenses the laser spot light SP focused by the focusing lens 2 and reflected by the reflecting region 7a and converts it into a parallel light beam, and the red fluorescent light that transmits the laser light P and A dichroic mirror 11 that reflects green fluorescence; a laser beam P that converges and irradiates the phosphor 6 with the laser beam P; and is reflected by the phosphor 6; a red fluorescence that is generated by the irradiation of the laser beam P; A condensing lens 12 that condenses green fluorescence is provided.

  On the first optical path L1, the laser spot light SP (see FIG. 7) collected by the focusing lens 2 and transmitted through the transmission region 7b is collected between the optical path switching board 7 and the diffusing member 4 to collect parallel beams. A collimating lens 3 that converts the laser beam P into a parallel light beam by the collimating lens 3 and a reflecting mirror M1 that reflects the laser light P that is converted into a parallel light beam by the collimating lens 3 are provided.

  Here, the diffusing member 4 has the same function as in the first and second embodiments, and the diffusing member 4 is ineffective on the incident surface side of the diffusing member 4 by the diffusing member 4 as in the first and second embodiments. A light receiving member 5 for receiving the laser beam P ″ is provided.

  In the first optical path L1 and the second optical path L2, the optical path of the laser light P ′ that is transmitted as an effective light beam through the diffusing member 4 and the fluorescence (red fluorescence and green fluorescence) reflected by the dichroic mirror 11 is used. Are provided.

The optical path combining member 14 is composed of a dichroic mirror that transmits red fluorescent light and green fluorescent light and reflects laser light P ′ used as an effective light beam.
When the light source device according to the fourth embodiment is used in an image projection device, a color image can be projected onto a screen by combining red, blue, and green.

(Example 5)
FIG. 9 is an explanatory view showing an image projection apparatus having the light source device shown in FIG.
In the traveling optical path in which the laser light P ′ reflected by the optical path combining member 14 and used as an effective light beam and the fluorescence transmitted through the optical path combining member 14 travels, a condensing lens 15 that collects these light beams and an incident end face 16a. And a light tunnel 16 having an exit end face 16b.

  The laser beam P 'collected by the condenser lens 15 is incident on the incident end face 16a and is made uniform in light quantity distribution when propagating through the light tunnel 16, and is emitted from the exit end face 16b. The light tunnel 16 functions as a light quantity distribution uniforming member that makes the light quantity distribution of the laser light P ′ diffused by the diffusing member 4 uniform. Note that a fly-eye lens (not shown) may be used instead of the light tunnel 16.

  In front of the traveling direction of the light beam emitted from the exit end surface 16b, a collimator lens 17 that collects the light beam emitted from the exit end surface 16b and converts it into a parallel light beam, a relay lens 18, reflection mirrors M2, M3, and DMD An image forming element (image generating unit) 19 such as a (digital micromirror device) is provided.

This image projection apparatus has a control unit 20. Image data from the outside is input to the control unit 20 via the interface unit 21.
The control unit 20 controls on / off of the laser light sources 1 a to 1 c and the drive motors 8 and 9 based on the image data, and controls the image forming element 19.

  The image forming element 19 modulates the laser light P ′ diffused by the diffusing member 4 or the fluorescence from the phosphor 6 to form image forming light. The image forming light is projected onto a screen (not shown) through the projection lens system 22. As a result, a color image is formed on the screen.

  An electric signal as a detection amount is input from the light receiving member 5 to the control unit 20. The control unit 20 compares a predetermined threshold value with a detected amount, and determines whether or not the diffusion function of the diffusing member 4 is deteriorated depending on whether the detected amount is equal to or less than the threshold value.

  In the fifth embodiment, the diffusing member 4 is disposed between the reflecting mirror M1 and the optical path combining member 14. However, the present invention is not limited to this, and for example, between the optical path switching board 7 and the collimating lens 3. Further, it may be arranged between the collimating lens 3 and the reflecting mirror M1. On the other hand, it is desirable to provide the light tunnel 16 in the traveling light path of the laser light P ′ between the diffusing member 4 and the projection lens system 22 in order to make the light quantity distribution uniform.

(Example of diffusion function lowering control by the control unit 20)
Hereinafter, an example of the diffusion function lowering control by the control unit 20 will be described with reference to the flowchart shown in FIG.
If the diffusion member 4 deviates from the traveling optical path of the laser light P due to an impact caused by the fall of the image projection apparatus or the like, or if a crack or the like due to thermal degradation of the diffusion member 4 occurs, the diffusion function of the diffusion member 4 decreases. As a result, the voltage value V of the electric signal output from the light receiving member 5 decreases.

  The control unit 20 compares the voltage value V with the threshold value V0 (S.1), and when the voltage value V is equal to or higher than the threshold value V0, determines that the diffusion function of the diffusion member 4 is normal (NO), The image projection apparatus is continuously driven as usual (S.2).

  When the voltage value V is less than the threshold value V0, the control unit 20 determines that the diffusion function by the diffusion member 4 has decreased (abnormal YES), and outputs an abnormality determination signal (S.3). Next, for example, a shutter member SH (see FIG. 9) provided in the traveling light path of the laser light P is inserted into the traveling light path of the laser light P, and the image forming light (also referred to as projection light) is cut (S.4). . Alternatively, the control unit 20 controls the image forming element 19 so that a black image is formed by the image forming light (S.4 ').

In this embodiment, DMD is used for the image forming element 19, but when a liquid crystal panel is used, the liquid crystal panel may be controlled so that a black image is formed by the liquid crystal panel.
Alternatively, the controller 20 may directly stop driving (turning off) the laser light sources 1a to 1c in hardware or software (S.4 ").

  In this manner, the driving of the laser light sources 1a to 1c is stopped, the output of the laser light output from the laser light sources 1a to 1c is reduced, the traveling light path of the laser light P is blocked, or the image forming light Decreasing the amount of light can contribute to an improvement in safety.

  By appropriately combining the drive stop of the laser light sources 1a to 1c, the output interruption of the laser light P, and the reduction in the light amount of the image forming light, the image projection apparatus can be provided with a fail-safe function.

DESCRIPTION OF SYMBOLS 1a-1c ... Laser light source 4 ... Diffusion member 4a ... Incident surface 4b ... Ejection surface 5 ... Light-receiving member P, P ', P "... Laser beam

JP 2000-267621 A

Claims (11)

A laser light source for emitting laser light;
Possess an exit surface of laser light provided to the traveling path of the laser beam incident on the incident surface and the incident surface of the laser beam is incident and emits the diffused, the diffusion member disposed in a stationary state ,
A light receiving member that is provided at a position that does not interfere with the traveling light path of the laser light that is emitted from the emission surface and is used as an effective light beam, and that receives the laser light that has become invalid in the diffusion member when passing through the diffusion member And
The light source device, wherein the function of the diffusing member is judged to be lowered by detecting the invalid laser beam by the light receiving member.   The light source device according to claim 1, wherein the light receiving member receives the invalid laser light reflected at least on the incident side from the emission surface.   The light source device according to claim 1, wherein the diffusing member is disposed obliquely with respect to a traveling light path of the laser light, and the light receiving member receives the laser light reflected on the incident surface.   The light source device according to claim 1, wherein the emission surface is a surface that imparts a diffusion function to the laser light.   The diffusing member is composed of a parallel plane plate in which at least one of the incident surface and the exit surface is a surface that provides a diffusing function, and the light receiving member includes the entrance surface of the parallel plane plate and the exit surface. The light source device according to claim 1, wherein the light source device is disposed so as to face at least one end surface excluding the surface.   A traveling light path of the laser light emitted from the laser light source in the traveling light path between the laser light source and the diffusing member, a first optical path provided with the diffusing member, and a laser light emitted from the laser light source 6. The light source device according to claim 1, further comprising: an optical path switching board that switches to a second optical path provided with a phosphor that generates fluorescence when excited by light. .   The light receiving member includes a capturing element that captures the invalid laser light and a sensor that converts the laser light captured by the capturing element into an electric signal, and the capturing element is a condensing lens or a scattering member. The light source device according to claim 1, wherein the light source device is a light source device.   6. The light source device according to claim 1, an image generation unit that modulates laser light diffused by a diffusion member of the light source device to form image forming light, and the image generation unit A projection lens system for projecting the image forming light generated by the laser light source, and stopping the driving of the laser light source or detecting the laser light output from the laser light source when the detection amount by the light receiving member is a predetermined threshold value or less. An image projection apparatus comprising: a control unit that reduces output or blocks a traveling light path of laser light.   The light source device according to claim 6, an image generating unit that modulates the laser light diffused by the diffusion member of the light source device and the fluorescence generated from the phosphor of the light source device to form image forming light, and The projection lens system that projects the image forming light generated by the image generation unit and the driving of the laser light source is stopped or output from the laser light source when the detection amount by the light receiving member is equal to or less than a predetermined threshold value. An image projection apparatus comprising: a control unit that reduces the output of the laser beam or blocks the traveling optical path of the laser beam.   The image projector according to claim 8 or 9, wherein the control unit reduces the amount of the image forming light.   A light amount distribution uniformizing member is provided in the traveling light path of the laser light between the diffusing member and the projection lens system for uniformizing the light amount distribution of the laser light diffused by the diffusing member. The image projecting device according to claim 8.