JP5000914B2 - Video projection device - Google Patents

Description

  The present invention relates to a video projection apparatus using a semiconductor element as a light source.

The latest image projector illuminates an image display element called a micro display panel with an LED light source, which is a semiconductor element, via an illumination optical system, and projects an image created on the image display element onto a screen by a projection lens ( For example, see Patent Document 1).
Examples of the image display element include a transmissive and reflective liquid crystal panel, and a reflective DMD (digital micro mirror device) panel which is a MEMS (micro electro mechanical systems) device (see, for example, Patent Document 2).
Further, there is a system using a semiconductor laser or a semiconductor laser-pumped fixed laser and a wavelength converted light thereof as a projection light source. In this system, a screen is scanned using a beam scanning optical system to display an image (for example, patents). Reference 3). This scanning method includes a method of scanning a spot of light and a method of scanning a line of light.
JP 2001-42431 A JP 2006-65192 A Japanese Patent Laid-Open No. 2003-279943

By the way, in an illumination optical system using an LED as a projection light source, the light use efficiency is generally low due to the restriction of Etendue (product of light collection area and solid angle) of the image display element, and further, the light emission efficiency of the high output LED is low. The problem is that the overall electrical efficiency is low.
On the other hand, in an optical system using a laser as a light source, the laser and the scanning optical system are expensive, and there is a problem that interference of light called speckle must be suppressed. Laser light also has a problem from the viewpoint of safety for eyes.

  An object of the present invention is to provide a video projection apparatus that has a simple configuration, a long life, and high reliability by improving light utilization efficiency, reducing costs, and eliminating light interference.

In order to solve the above problems, the invention according to claim 1 is equipped with a surface emitting semiconductor laser (VCSEL ) two- dimensional array that serves both as a projection light source and an image display element as an optical engine ,
The surface-emitting semiconductor laser two-dimensional array is formed by an optical sampling imaging system comprising a beam splitter, an imaging lens, and a two-dimensional array imaging device inserted on the optical axis of the laser light from the surface-emitting semiconductor laser two-dimensional array. Video projection that measures the emission intensity distribution and feeds back to the surface emitting semiconductor laser drive circuit a two-dimensional signal for correcting the output variation between the single element surface emitting semiconductor lasers of the surface emitting semiconductor laser two-dimensional array. Features the device.

  A second aspect of the present invention is the video projection apparatus according to the first aspect, wherein the VCSEL two-dimensional array includes a wavelength converter.

  A third aspect of the present invention is the video projection apparatus according to the first or second aspect, wherein the laser light output of each element VCSEL of the VCSEL two-dimensional array is intensity-modulated based on a video signal. .

  A fourth aspect of the present invention is the image projection apparatus according to any one of the first to third aspects, wherein the VCSEL that emits one of the three primary colors of light or a two-dimensional array of wavelength converters thereof is used. A full-color image is projected by synthesizing the laser light of three primary colors.

  A fifth aspect of the present invention is the image projection apparatus according to the first aspect of the present invention, wherein the surface emitting semiconductor laser or its wavelength converter emits three primary colors of light into a two-dimensional array single plate. It includes a two-dimensional array of light emitting semiconductor lasers.

According to the present invention, a surface emitting semiconductor laser (VCSEL ) two- dimensional array that serves both as a projection light source and an image display element is mounted as an optical engine, so that the role of the projection light source and the image display element in a conventional image projector is represented by VCSE. Since the L2D array is also used as a single element, the optical engine has a simple configuration with only a projection optical system, and no illumination optical system or scan optical system is required. Loss can be suppressed.
Further, the surface emitting semiconductor laser (VCSEL) as a light source is suitable for mass production because its manufacturing process is almost the same as that of an LSI such as a semiconductor memory, and has a feature that it has a longer life and higher reliability than a normal semiconductor laser. In addition, since it is originally a laser beam, its luminance is higher than that of the emitted light from the light emitting diode (LED), and therefore the efficiency of light emission is high.
In addition, since each pixel VCSEL is independent in laser oscillation operation, there is no interference of light waves between the respective pixel VCSELs. Therefore, the pixel VCSEL is also suitable for an image display apparatus in which illumination light directly reaches the eye.
In addition, there are no mechanically movable parts compared to MEMS elements and scan systems, and since no light absorbing material is used like a polarizer of a liquid crystal panel, there is little optical deterioration of optical components, which is considerably higher than that of the prior art. High reliability and long life.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.
[First Embodiment]
FIG. 1 shows a configuration of a first embodiment to which the present invention is applied, in which a two-dimensional matrix array of surface emitting semiconductor lasers is used as a projection light source and an image display element.
That is, as shown in the figure, the image projection apparatus has three types (red, green, and blue) that oscillate at a wavelength corresponding to each primary color on the incident surface of each primary color of the color synthesis prism 2 in the projector optical engine 1. VCSEL two-dimensional array 3 in which single element VCSELs of a surface emitting semiconductor laser (VCSEL) are arranged in a matrix. Here, a wavelength converter may be combined with each element VCSEL as necessary.

FIG. 2 is an enlarged view of a part of the VCSEL two-dimensional array 3. The arrangement pitch between unit (single element) VCSELs 4 is 15 microns, 1920 columns horizontally, and 1080 rows vertically. The overall size of the light emitting part is about 3 cm × 1.5 cm.
The VCSEL two-dimensional array 3 serves as both a light source and a video display element in a conventional projector apparatus.

Further, the incident surface of the projection lens 5 is arranged at a position away from the surface of the VCSEL two-dimensional array 3 by a back focus distance on the emission surface side of the color synthesis prism 2.
The projection lens 5 projects the VCSEL two-dimensional array 3 surface on the screen 6.

Here, the VCSEL two-dimensional array 3 is driven by a laser driver (not shown), and the laser driver is controlled by a video engine (not shown).
That is, each single element VCSEL4 in the VCSEL two-dimensional array 3 surface for each primary color (red, green, blue) operates as a pixel corresponding to each primary color image, and a signal change that specifies the brightness of the corresponding pixel The amount of laser oscillation changes according to the above. That is, the laser light output of each element VCSEL4 of the VCSEL two-dimensional array 3 is intensity-modulated based on the video signal.

The above is the basic configuration. Actually, in order to correct the variation in the amount of light between each single element VCSEL 4, as shown in the figure, an optical sampling imaging comprising a beam splitter 7, an imaging lens 8, and a two-dimensional array imaging device 9. The system is inserted on the optical axis 10.
Thereby, the projector optical engine 1 has a calibration function for calibrating the non-uniformity of the amount of radiated light of each single element VCSEL 4.
That is, the two-dimensional signal for measuring the emission intensity distribution on the surface of the VCSEL two-dimensional array 3 and correcting the output variation between the single element VCSELs 4 is fed back to a VCSEL driving circuit (not shown). This feedback can simultaneously correct the temporal change of the light output of each single element VCSEL4.

  With the configuration as described above, it is possible to guarantee an image that is uniform and excellent in color balance over a long period of time.

[Second Embodiment]
Next, FIG. 3 shows a configuration of a second embodiment to which the present invention is applied. The first embodiment described above uses a two-dimensional matrix array of surface emitting semiconductor lasers as a projection light source and an image display element. This is the same as the embodiment.
Unlike the first embodiment, there is only one VCSEL two-dimensional array panel 13 used in the optical engine 1 of this embodiment, but as shown in an enlarged view in FIG. 4, the VCSEL two-dimensional array panel 13 in this panel 13 is used. Is composed of three types of single-color VCSEL two-dimensional arrays 14 that respectively emit three primary colors of red (R), green (G), and blue (B).
According to the present embodiment, compared with the first embodiment, the pixel size is increased, but since a color synthesis system is not required, the configuration of the optical engine 1 is simplified and the cost merit is large. is there.

In the above embodiment, the rear projection type image projector is used. However, the present invention is not limited to this, and a front projection type image projector may be used.
In addition to the embodiment, it is a matter of course that the specific arrangement and detailed structure of the optical components can be changed as appropriate.

1 shows a configuration of a first embodiment to which the present invention is applied, and is a schematic configuration diagram of a video projection apparatus. It is an enlarged view of the arrow A part of FIG. FIG. 2 is a schematic configuration diagram of a video projection apparatus, showing a configuration of a second embodiment to which the present invention is applied. It is an enlarged view of the arrow A part of FIG.

Explanation of symbols

1 Optical engine 2 Color synthesis prism 3 VCSEL two-dimensional array (for red, green, and blue)
4 Single element VCSEL
5 Projection lens 6 Screen 7 Beam splitter 8 Imaging lens 9 Two-dimensional array imaging device 10 Optical axis 13 Single plate type three primary color VCSEL two-dimensional array panel 14 Single-color VCSEL two-dimensional array

Claims (5)

The surface-emitting type semiconductor lasers 2-dimensional array also serves as a projection light source and the image display device equipped with an optical engine,
The surface-emitting semiconductor laser two-dimensional array is formed by an optical sampling imaging system comprising a beam splitter, an imaging lens, and a two-dimensional array imaging device inserted on the optical axis of the laser light from the surface-emitting semiconductor laser two-dimensional array. Measuring the emission intensity distribution and feeding back to the surface emitting semiconductor laser driving circuit a two-dimensional signal for correcting the output variation between the single element surface emitting semiconductor lasers of the two-dimensional surface emitting semiconductor laser. A featured video projection device.   The image projection apparatus according to claim 1, wherein the two-dimensional surface emitting semiconductor laser two-dimensional array includes a wavelength converter.   3. The video projection apparatus according to claim 1, wherein the laser light output of each element of the two-dimensional surface emitting semiconductor laser two-dimensional array is intensity-modulated based on the video signal.   4. A full-color image is projected by synthesizing laser light from the surface-emitting type semiconductor laser that emits one of the three primary colors of light or a laser beam from the two-dimensional array of wavelength converters thereof into three primary colors. The video projection device according to any one of the above.   2. The image projection apparatus according to claim 1, wherein the two-dimensional surface emitting semiconductor laser two-dimensional array that emits three primary colors of light is included in a single plate of the surface emitting semiconductor laser two-dimensional array.

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