JP5375532B2 - Integrated light source, projector apparatus, and mobile device - Google Patents

Description

  The present invention relates to an integrated light source in which light sources are integrated, a projector apparatus having an optical system that projects laser light from the integrated light source onto a screen, and a mobile device equipped with the projector apparatus.

  In recent years, development of an ultra-compact projector that reproduces a two-dimensional image by driving a semiconductor laser and a MEMS (Micro Electro Mechanical Systems) -driven scanning mirror in synchronization is progressing. After collimating each laser beam emitted from a semiconductor laser having a wavelength corresponding to each color of RGB and aligning the optical axes using a synthesis means for synthesizing optical paths such as a dichroic mirror and a polarization reflection mirror, MEMS is used. The laser beam is scanned two-dimensionally by a mirror, and a two-dimensional image is reproduced by synchronizing with the intensity modulation of the semiconductor laser.

  By using a small semiconductor laser and a MEMS-driven scanning mirror, the integrated light source of a small projector has become considerably small. However, when such a small projector is mounted on a mobile device such as a mobile phone, further downsizing is required. A small projector mounted on a mobile phone is also required to be downsized without deteriorating image quality.

  As a measure for realizing further integration, it can be considered that the housing, the holder, and the combining means are further miniaturized and integrated.

  In addition to downsizing, it is desired to have a low power consumption and be able to project a bright image. For this reason, it is required to increase the light use efficiency for allowing the laser light from the semiconductor laser to reach the screen. . In order to improve the light utilization efficiency of the semiconductor laser, a configuration in which laser light is collimated is important, and Patent Document 1 discloses a configuration in which a single lens is used for collimation. FIG. 12A shows an example of an arrangement diagram of an integrated light source in which three semiconductor lasers are integrated using a configuration in which a single lens is collimated. The emitted lights of the semiconductor lasers k10 to k12 are condensed using the lenses e10 to e12, respectively, and the optical paths are combined using the dichroic prisms d10 to d12 to generate the laser beam b10. In such an integrated light source, an optical system shown in FIG. 12B can be adopted as a measure for improving the light utilization efficiency. FIG. 12B shows the lens power increased while maintaining the NA of the lens of the optical system in FIG. By taking such measures, it is possible to improve light utilization efficiency while downsizing the optical system.

JP-A-2005-157111

  If it is attempted to reduce the size of the integrated light source by reducing the size of the combining means, handling during manufacture becomes difficult, and an inclination error of the scanning mirror surface remains. This residual error causes an optical axis inclination between the laser beams of the respective colors. Due to the inclination of the optical axis, when the laser beam reaches the screen, the colors are separated and the image quality is deteriorated. Furthermore, if the synthesizing unit is made as small as the laser beam, the light beam is scattered at the edge of the synthesizing unit due to the remaining error, and the spot becomes larger on the screen due to the influence of diffraction, degrading the resolution of the image. End up.

  By collimating using a single lens with high power, the lens diameter is reduced while keeping the light utilization efficiency of the semiconductor laser high, and if integration is attempted, the magnification between the laser light source and the spot on the screen increases, and the spot The diameter increases and the resolution of the image deteriorates.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an integrated light source that achieves miniaturization and high light utilization efficiency without degrading the resolution of an image, a projector apparatus using the integrated light source, and a mobile device using the integrated light source. And

  The above object is achieved by the invention described below.

1. A first laser light source emitting a first laser light;
A second laser light source emitting a second laser light;
A third laser light source emitting a third laser light;
Each first lens provided corresponding to each of the first to third laser light sources and condensing each laser beam to a first condensing position;
Of the laser beam emitted from each of the first lenses, the first combining means for forming a first combined light by combining the said first laser beam and said second laser beam,
A second light disposed at a position downstream of the first combining means and combining the first combined light and the third laser light emitted from the first lens to form a second combined light. A synthesis method of
With
The first synthesizing unit and the second synthesizing unit are arranged such that the first condensing position is a position in the second synthesizing unit or an optical path downstream position emitted from the second synthesizing unit,
The integrated light source further comprising: a second lens for collimating the laser light diverging from the first condensing position.

2. 2. The integrated light source according to 1 above, wherein the first to third laser light sources are bare chip semiconductor laser light sources and are mounted inside a package.

3. 3. The integrated light source according to 1 or 2, wherein the first to third laser light sources are three laser light sources each having a wavelength corresponding to red, blue, and green.

  4). 4. At least one flat plate that transmits light from a light source and is configured to be rotatable between at least one of the first lens and the second lens. The integrated light source described.

  5. 5. The integrated light source according to any one of 1 to 4, wherein the integrated light source has a predetermined diameter and has an opening arranged at the first condensing position.

  6). 6. The integrated light source according to any one of 1 to 5, wherein the integrated light source is sealed in a package.

7). 6. The integrated light source according to any one of 1 to 5, wherein the first to third laser light sources are arranged with an emission opening directed in the same direction.

  8). A projector apparatus using the integrated light source according to any one of 1 to 7 above.

  9. 9. A mobile device using the projector device according to 8.

  It is possible to provide an integrated light source, a projector using the integrated light source, and a mobile device using the integrated light source that can be downsized and achieve high light utilization efficiency without degrading the resolution of the image.

FIG. 3 is a layout diagram of an optical system of an integrated light source LN according to the present embodiment. It is a schematic diagram explaining the position of the 2nd condensing position f when the dichroic prism d inclines. It is an arrangement plan of an optical system at the time of setting the 1st condensing position f1 in the air. FIG. 3 is a layout diagram showing a configuration in which laser light from a semiconductor laser bare chip k1 is transmitted through a dichroic prism d1 and laser light from semiconductor laser bare chips k1 and k2 is reflected. 5 is a layout diagram showing a configuration in which a wavelength conversion type laser light source SL is employed instead of the semiconductor laser bare chip k1 in the optical system of FIG. It is a layout view of an optical system provided with parallel plates s1 to s3. FIG. 7A is a schematic diagram in which laser light is shifted using a parallel plate s. FIG. 7B is a schematic diagram for shifting the laser beam using the wedge w. FIG. 8A is a schematic view of the dichroic prism d4 viewed from the z direction in the drawing on the side surface side, and FIG. 8B is a schematic view of the dichroic prism d4 viewed from the x direction in the drawing on the top surface side. FIG. FIG. 9A is a schematic top view of the package, and FIG. 9B is a schematic perspective view. It is a schematic diagram which shows a mode that the projector apparatus LU carrying the integrated light source LN concerning this embodiment projects an image | video on the screen SC. It is a block diagram of portable terminal CU which is an example of a digital device with an image input function. It is an example of a layout diagram of an integrated light source LN in which three semiconductor lasers are integrated using a configuration in which a single lens is collimated.

  Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to the embodiments described below. In addition, the structure which attached | subjected the same code | symbol in each figure shows that it is the same structure, The description is abbreviate | omitted.

  FIG. 1 shows the arrangement of the optical system of the integrated light source LN according to this embodiment. In one package P, a plurality of laser light sources, for example, semiconductor laser light sources each having a wavelength corresponding to green (G), blue (B), and red (R), are formed as bare chips. Has been implemented.

  When each light source side is upstream, the first lenses L1 to L3 are arranged in order from the upstream side, cube-type dichroic prisms d1 to d3 that are optical path combining means, and the second lens e1. Here, a plate-like dichroic mirror may be used instead of the dichroic prism.

  The light emitted from the semiconductor laser bare chips k1 to k1 is condensed at a common condensing position f1 (first condensing position) using the first lenses L1 to L3, respectively, and the optical axis is used using the dichroic prisms d1 to d3. Are combined, the optical paths are combined, and the laser beam b1 is generated and collimated. The collimated laser light is projected onto the screen to form an image. In order to form an image, it is preferable that the laser beam is condensed. Accordingly, the collimate in the present embodiment includes a light that is focused on each point between infinity and the screen, and will be described hereinafter as a light that is focused on the second light focusing position f2.

  According to the optical system shown in FIG. 1, the laser light is condensed toward each dichroic prism d using the first lenses L1 to L3, so that the optical system shown in FIGS. 12A and 12B is compared. Thus, the light diameter of the laser light passing through each dichroic prism d can be reduced. Therefore, since a smaller dichroic prism d can be employed as compared with the conventional case, a miniaturized integrated light source LN can be realized.

  In addition, since the first condensing position f1 and the second condensing position f2 are in a conjugate relation via the second lens e1, the first condensing position f1 and the second condensing position f2 are caused by the inclination of the reflecting surface due to the adjustment error remaining of the dichroic prism d that is the combining means. Spot deviation on the screen can be reduced, and an image with good color reproduction can be provided.

  More specifically, as shown in FIG. FIG. 2 is a schematic diagram for explaining the position of the second condensing position f when the dichroic prism d is tilted. As shown in FIG. 2, even if the dichroic prism d drawn with a solid line arranged at the ideal position is inclined to the position of the dotted line and the traveling direction of the laser beam b1 is inclined, it passes through the second lens e1. The inclined traveling direction is pulled back, and the deviation between the position of the second light condensing position f2, which is the position of the laser beam b1 on the screen, and the target position is reduced.

  Table 1 shows the relationship between the distance from the light source to the screen and the beam diameter (beam waist). Assume that laser light travels in the z direction. B in the table indicates the distance from the light emitting point. w_x represents the diameter in the x direction, and w_y represents the diameter in the y direction. The propagation of the Gaussian beam was calculated assuming that the emission end face of the semiconductor laser bare chip assumed to have a wavelength of 640 nm has emission points of beam waists of 1 μm and 1.5 μm in the orthogonal axis direction (however, the thickness of the lens is considered) Not) The focal length of the first lens L is 1.45 mm, and the distance from the first lens L to the condensing position is 8 mm. The focal length of the second lens is 13 mm, and the focal point is 510 mm away from the second lens. The beam diameter can be reduced to about 720 μm before and after the focusing position of the first lens L.

  In the optical system according to the embodiment shown in FIG. 1, the first light collection position f <b> 1 is present in the dichroic prism d. Depending on the design of the optical system, it is possible to set the first condensing position f1 in the air instead of in the dichroic prism d. FIG. 3 shows an example of an optical system when the first light collection position f1 is set in the air. In FIG. 3, the opening a is arranged at the first light collecting position. In addition, the mirror M1 is used for the function of bending the traveling direction of the laser light from the semiconductor laser bare chip k3 by 90 degrees and combining it with the dichroic prisms d1 and d2.

  By providing the opening a and positioning and adjusting the laser light of the semiconductor laser bare chips k1 to k3 to the position of the opening a, the laser light of the semiconductor laser bare chips k1 to k3 can be accurately positioned at the first condensing position. . Further, the laser light of the semiconductor laser bare chips k1 to k3 may include noise light such as satellite light, or the laser light from the semiconductor laser bare chips k1 to k3 may generate unintended light such as ghost light. However, by disposing the opening a at the first condensing position f1, it is possible to shield such unnecessary light and prevent deterioration of image quality.

  FIG. 4 shows a configuration in which the laser light from the semiconductor laser bare chip k1 is transmitted through the dichroic prism d1, and the laser light from the semiconductor laser bare chips k1 and k2 is reflected. By allowing the laser beam from the semiconductor laser bare chip k1 to pass through the dichroic prism d1, the influence of the arrangement of the dichroic prism d1 on the performance of the optical system can be reduced.

  Further, the traveling direction of the laser light from the semiconductor laser bare chips k2 and k3 incident on the dichroic prism d1 can be appropriately adjusted by adjusting the rotation of the dichroic prism d1.

  FIG. 5 shows a configuration in which a wavelength conversion type laser light source SL is employed instead of the semiconductor laser bare chip k1 in the optical system of FIG. The wavelength conversion laser light source SL is a laser light source equipped with a wavelength conversion element that converts the wavelength of laser light into a wavelength such as a length of an integer. As a typical wavelength conversion laser light source SL, there is a wavelength conversion laser light source equipped with a second harmonic generation element that is a wavelength conversion element that converts the length of the fundamental wavelength in half (for example, Japanese Patent Laid-Open No. 5-27288). See the official gazette). In FIG. 5, instead of the semiconductor laser bare chip k1, the semiconductor laser bare chip k4, the lens e5 for condensing the laser light from the semiconductor laser bare chip k4, and the collected laser light are incident and wavelength-converted to the second harmonic. A second harmonic generation element SHG is included. The laser beam wavelength of the semiconductor laser bare chip k4 is green light having a wavelength of about 1060 nm and the second harmonic wavelength of about 530 nm.

  In the integrated light source LN shown in FIGS. 3 to 5, the semiconductor laser bare chips are arranged so that the laser light emission openings are in the same direction, that is, the emission directions are the same direction. By emitting light in the same direction, the arrangement of optical components can be prevented from generating an extra space and can be further integrated. By using such a miniaturized integrated light source LN, it is possible to provide a micro projector and a mobile device including the micro projector.

  Next, assembly adjustment of the integrated light source LN will be described. In order to reproduce an image without color misregistration on the screen using the integrated light source LN as a light source for the projector, when the laser light from the semiconductor laser bare chip k of the integrated light source LN of this embodiment reaches the screen. It is important that the amount of positional deviation caused by the inclination of the optical axis of the laser beam coincides with the amount of positional deviation caused by the shift of the optical axis.

  Regarding the shift of the optical axis, the inclination of each optical axis can be adjusted by shifting the first lens L. However, it is difficult to adjust the shift direction of the optical axis by shifting the semiconductor laser bare chip k because the semiconductor laser bare chip k is small. Further, by shifting the dichroic prism d, shift adjustment in one axis direction is possible, but it is difficult to shift the optical axis in two axis directions. Therefore, a parallel plate is provided between the second lens L and at least one first lens L to shift the optical axis. FIG. 6 is a layout diagram of an optical system provided with parallel plates s1 to s3. The parallel plate s1 is disposed between the dichroic prism d1 and the aperture a, the parallel plate s2 is disposed between the dichroic prisms d1 and d2, and the parallel plate s3 is disposed between the dichroic prism d2 and the first lens L3.

  By rotating the parallel plate s in the yz plane, the optical axis can be shifted in the y direction. Fig.7 (a) is a schematic diagram which shifts a laser beam using a parallel plate. More specifically, as shown in FIG. 7A, the laser beam b1 has an optical axis shifted by a shift amount r because the refraction angle on the parallel plate s side is smaller than the refraction angle on the air side. The shift amount r depends on the refractive index and thickness of the parallel plate.

  Note that the parallel plate s can be shifted in the x direction by rotating 90 degrees around the z axis and rotating in the xz plane.

  Table 2 shows the calculation result of the shift amount of the optical axis when a parallel plate having a refractive index of 1.5 and a thickness of 0.5 mm is inclined by 45 degrees. Table 2 shows the calculation result of the shift amount of the optical axis in the case of two different incident angles. The shift amount of the optical axis can be changed by the incident angle, that is, the inclination of the parallel plate with respect to the optical axis.

  As described above, the angle with respect to the optical axis of the parallel plate arranged for each optical axis between the second lens L and at least one first lens L is set to a predetermined value, and thus transmitted through the dichroic prism d. Laser light shift adjustment can be performed.

  By combining with the optical axis tilt adjustment by the first lens L, it is possible to provide a projector that can reproduce an image with little color shift regardless of the screen position.

  Further, the adjustment of the focus direction can be similarly easily adjusted by using one flat plate or two in some cases. That is, focus adjustment is performed by changing the optical path length between the first lens L and the second lens e1. Specifically, the air conversion length (optical path length) can be changed by rotating the parallel plate and adjusting the transmission thickness. However, this object may not be achieved with a single parallel plate. That is, if the inclination for the target optical path length is taken, the shift of the optical axis may become large. In such a case, the focus adjustment can be performed by rotating the optical axis shift directions in directions that cancel each of the two parallel flat plates.

  It is also possible to use parallel air intervals instead of parallel plates. FIG. 7B is a schematic diagram for shifting the laser beam using the wedge. Specifically, as shown in FIG. 7B, two wedges w are arranged facing each other, and laser light is incident with the optical axis perpendicular to the incident surface. Then, the wedge w is shifted in the direction perpendicular to the optical axis to adjust the air interval, that is, the region where the optical axis is inclined, thereby shifting the optical axis. Further, by shifting the wedge w in the direction of the arrow ar without changing the air interval, the thickness that passes through the wedge w changes, and the distance between the first lens L and the second lens e1 changes. That is, focus adjustment is possible.

  Furthermore, the number of parts can be reduced by adopting the configuration having the dichroic prism d4 shown in FIG. FIG. 8A is a schematic view of the dichroic prism d4 viewed from the z direction in the drawing on the side surface side, and FIG. 8B is a schematic view of the dichroic prism d4 viewed from the x direction in the drawing on the top surface side. FIG. With the configuration shown in FIG. 8, the optical axis can be shifted in any direction by shifting the dichroic prism d in the direction of the arrow or shifting the wedge. The focus direction is as described above.

  Next, adjustment of laser light that is performed using the opening a as an adjustment target will be described. As described above, the parallel plate s and the wedge w are used to shift the optical axis, the light intensity of the laser beam leaking from the opening a is measured, and the parallel plate s is set so that the light intensity of the laser beam is maximized. The position can be accurately adjusted by adjusting the wedge w.

  Specifically, adjustment is performed according to the following procedure. First, the semiconductor laser bare chip k is placed at a predetermined position. Next, the tilt of the optical axis of the laser light is adjusted by shifting the first lens in a plane perpendicular to the optical axis. The dichroic prism d is arranged, the light is directed to the provided aperture a, and the light intensity of the leaked light from the aperture a is measured using a light intensity measuring device (not shown), and the optical axis shift adjustment is performed as described above. Implement by method. Finally, a laser beam spot is detected at the second focusing position, and focus adjustment is performed. Here, the focus adjustment and the shift adjustment can be combined, for example, adjusted at the same time.

  Such adjustment completes the adjustment of the package as shown in FIG. FIG. 9 is a schematic view of the package, FIG. 9A is a schematic top view of the package, and FIG. 9B is a schematic perspective view. The package P is provided with a window LW for emitting laser light. The window LW is preferably made of a glass material that transmits laser light with high transmittance. The first lenses L1 to L3 are held by the lens frames c1 to c3, respectively. The size of the package is typically as small as 19 × 15 × 5 mm.

  The package P is sealed in an atmosphere such as nitrogen. By sealing, dust can be prevented from being mixed, and scattered light caused by dust can be suppressed to improve image quality.

  FIG. 10 is a schematic diagram showing a state in which the projector device LU equipped with the integrated light source LN according to the present embodiment projects an image on the screen SC. The projector device LU includes an integrated light source LN and a two-dimensional scanning mirror SR.

  In the projector device LU, a two-dimensional image can be displayed on the screen SC by performing a raster scan RS of the light rays emitted toward the screen SC. In this raster scanning RS, for example, from the start position Qa at the upper left end to the end position Qb at the lower right end, the laser beam is continuously scanned in the vertical direction while being reciprocated in the horizontal direction, and is equivalent to one screen (one time). The image display is complete.

  FIG. 11 is a block diagram of a mobile terminal CU that is an example of a digital device with an image input function. The projector device LU mounted on the portable terminal CU of FIG. 11 includes an integrated light source LN and a two-dimensional scanning mirror SR.

  The integrated light source LN generates a pulse signal that reproduces a two-dimensional image in synchronization with the two-dimensional scanning mirror SR. Accordingly, the projector device LU reproduces a two-dimensional image via the two-dimensional scanning mirror SR.

  Note that when such a projector device LU is mounted on a portable terminal CU with an image output function, the projector device LU is usually arranged inside the body of the portable terminal CU. However, when the mobile terminal CU performs the projector function, the projector device LU takes a form as necessary. For example, the unitized projector device LU may be detachable or rotatable with respect to the main body of the mobile terminal CU.

  By the way, the mobile terminal CU includes a signal processing unit 1, a control unit 2, a memory 3, and an operation unit 4 in addition to the projector device LU.

  The signal processing unit 1 performs, for example, image processing and image compression processing for correcting image distortion during projector reproduction, as necessary, on the image signal in the memory 3. Then, the processed signal is transmitted to the control unit 2.

  The control unit 2 is a microcomputer, and intensively performs processing necessary for image reproduction such as control of synchronization between the transmitted image signal and the two-dimensional scanning mirror SR. For example, the control unit 2 controls the projector device LU so as to perform at least one of still image reproduction and moving image reproduction stored in the memory 3.

  The operation unit 4 includes operation members such as operation buttons (for example, a reproduction button) and operation dials (for example, a mode dial that reproduces a projector image and communicates while viewing the same image as a communication partner). The transmitted information is transmitted to the control unit 2.

  As described above, according to the present invention, a plurality of laser light sources, a first lens that is provided corresponding to each of the plurality of laser light sources, and condenses the laser light to the first condensing position, and each of the first lenses. Since it has a synthesizing unit that synthesizes the light emitted from one lens and a second lens that collimates the laser light that diverges from the first condensing position, it has high light utilization efficiency without degrading the resolution of the image. Thus, a miniaturized integrated light source can be realized.

  Further, according to the present invention, the plurality of laser light sources are bare chip-shaped semiconductor laser light sources, and since they are mounted inside the package, a plurality of small bare chip semiconductor lasers can be arranged close to each other in the package. The optical system can be made small and integrated.

  Further, according to the present invention, since the plurality of laser light sources are three laser light sources each having a wavelength corresponding to red, blue, and green, a color image can be reproduced by changing the light intensity ratio of the three primary colors. Yes. Furthermore, since the wavelength of the laser light source can be arbitrarily selected in the vicinity of the three primary colors, an image with good color reproducibility can be reproduced.

  In addition, according to the present invention, since there is at least one flat plate configured to transmit and rotate light from the light source between the second lens L and the at least one first lens L, the optical axis Can be shifted individually.

  Moreover, according to this invention, since it has a predetermined | prescribed diameter and has the opening arrange | positioned in the 1st condensing position, the unintended scattered light and inter-surface reflected light can be cut. In particular, since the light is condensed, the aperture size can be further reduced without lowering the light utilization efficiency, and scattered light and inter-surface reflected light can be efficiently cut. Furthermore, when adjusting an optical axis, it can be made into the object at the time of adjustment.

  In addition, according to the present invention, since the integrated light source is sealed, it is possible to prevent dust from being mixed, and to suppress scattered light due to dust and improve image quality.

  In addition, according to the present invention, since the plurality of semiconductor lasers are arranged with the emission openings directed in the same direction, the extra space can be reduced and the integration can be further increased.

  Further, according to the present invention, since the above-described integrated light source is used, an ultra-small projector device can be provided.

  Further, according to the present invention, since the projector device described above is used, an ultra-small mobile device can be provided.

L1, L2, L3 First lens e1 Second lens d Dichroic prism d1, d2, d3, d4 Dichroic prism b1 Laser light f1 First condensing position f2 Second condensing position k1, k2, k3, k4 Semiconductor laser Bare chip LN Integrated light source LU Projector unit CU Mobile terminal s1, s2, s3 Parallel plate M1 Mirror P Package SC Screen w Wedge

Claims (9)

A first laser light source emitting a first laser light;
A second laser light source emitting a second laser light;
A third laser light source emitting a third laser light;
Each first lens provided corresponding to each of the first to third laser light sources and condensing each laser beam to a first condensing position;
Of the laser beam emitted from each of the first lenses, the first combining means for forming a first combined light by combining the said first laser beam and said second laser beam,
A second light disposed at a position downstream of the first combining means and combining the first combined light and the third laser light emitted from the first lens to form a second combined light. A synthesis method of
With
The first synthesizing unit and the second synthesizing unit are arranged such that the first condensing position is a position in the second synthesizing unit or an optical path downstream position emitted from the second synthesizing unit,
The integrated light source further comprising: a second lens for collimating the laser light diverging from the first condensing position. 2. The integrated light source according to claim 1, wherein the first to third laser light sources are bare chip-shaped semiconductor laser light sources and are mounted inside a package. The integrated light source according to claim 1 or 2, wherein the first to third laser light sources are three laser light sources each having a wavelength corresponding to red, blue, and green.   4. The apparatus according to claim 1, further comprising at least one flat plate configured to transmit and rotate light from a light source between at least one of the first lens and the second lens. 5. An integrated light source as described in 1.   5. The integrated light source according to claim 1, wherein the integrated light source has a predetermined diameter and an opening disposed at the first light collection position.   6. The integrated light source according to claim 1, wherein the integrated light source is sealed in a package. The integrated light source according to any one of claims 1 to 5, wherein the first to third laser light sources are arranged with an emission opening directed in the same direction.   A projector apparatus using the integrated light source according to claim 1.   A mobile device using the projector device according to claim 8.

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