This application relates to and claims priority from Japanese Patent Application No. 2012-169789 filed on Jul. 31, 2012, the entire disclosure of which is incorporated herein by reference.
(1) Field of the Invention
The present invention relates to an optical scanning apparatus and an optical scanning image projection apparatus, and in particular, relates to a small optical scanning apparatus configured to scan using a light flux in a two-dimensional configuration, and to an optical scanning image projection apparatus using the same.
(2) Description of the Related Art
In recent years, various optical scanning image projection apparatuses have been proposed that include a function of projecting a two-dimensional image onto a projection screen surface by use of an afterimage effect by projecting a light flux that is emitted from a semiconductor laser light source onto a screen surface or the like and scanning the light flux in a two-dimensional configuration on the screen surface by deflection means such as a biaxial deflection mirror or the like.
A configuration in which a composite laser light source is provided with a plurality of semiconductor laser light sources in a single housing is effective to reduce the size in the above type of image projection apparatus of the optical scanning apparatus that is configured to scan a light flux in a two-dimensional configuration.
However, when the above type of composite laser light source is used as the light source of the optical scanning image projection apparatus, a plurality of light fluxes that are emitted from respective semiconductor laser light sources in the composite laser light source must become incident in a configuration of being synthesized into a single light flux onto the screen surface through predetermined deflection means such as a biaxial deflection mirror or the like.
An actual example of optical means for concentrating a plurality of light fluxes into a single light flux includes an example that uses an optical prism as disclosed in U.S. Pat. No. 7,883,214B2.
However, U.S. Pat. No. 7,883,214B2 is only configured to align the irradiation position of a plurality of light fluxes on a deflection mirror surface, and does not cause the plurality of light fluxes to adopt a parallel configuration. Therefore, the problem arises that the plurality of light fluxes are again separated before being reflected by the deflection mirror and becoming incident on the screen surface that is the display surface of the image, and as a result, correct image projection is not enabled.
The present invention is proposed in light of the above circumstances, and has the object of providing an optical scanning apparatus, and an optical scanning image projection apparatus using the same, that includes optical means configured to execute irradiation with a correctly aligned configuration and to also avoid separation of the plurality of light fluxes on the display surface by causing the plurality of light fluxes to become incident in a configuration in which both the irradiation position and the parallel characteristics in relation to the deflection mirror are made to substantially coincide.
The above object can be attained by the present invention as disclosed in the scope of the patent claims.
According to the present invention, an optical scanning apparatus, and an optical scanning image projection apparatus using the same, which apparatus is realized that enhances the light flux alignment configuration on the display surface that uses a composite laser light source.
These and other features, objects and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings wherein:
The embodiments of the present invention will be described below making reference to the figures. However, it goes without saying that the present invention is not limited to the configurations of the embodiments described below.
Reference numerals 1 and 2 denote semiconductor laser light sources having mutually different wavelengths. For example, reference numeral 1 is a light source that emits blue laser light having a wavelength in the 400 nm band, and reference numeral 2 is a light source that emits red laser light having a wavelength in the 600 nm band.
The light sources 1 and 2 are housed in one housing 51, and the emission point of the light source 1 is disposed at a position that is made to substantially coincide with the main optical axis of a light flux conversion lens 4 that is disposed in front of the light source 1. On the other hand, the emission point of the light source 2 is disposed at a position that is separated by a predetermined distance S in a substantially vertical direction relative to the main optical axis of the light flux conversion lens 4 relative to the emission point of the light source 1.
However, this configuration is merely an example of a combination of the wavelengths of laser light emitted from the light sources 1, 2 and a combination of the emission point positions, and of course, there is no limitation in relation to the present invention on the type or position of the light source. For example, a configuration in which the both light sources 1, 2 are disposed at a position that is separated by an equal distance from the main optical axis of the light flux conversion lens 4 also falls within the scope of the present invention.
Various emission laser light fluxes 102 and 202 emitted from the semiconductor laser light sources 1, 2 are converted to a substantially parallel light flux or a weakly convergent light flux 103 and 203 respectively through the common light flux conversion lens 4 that is disposed at a position that is separated by a predetermined distance L1 from the respective emission points of the light sources 1 and 2, and become incident on a light flux synthesis unit 52 that is the main component of the present invention.
The central optical axis 101 and 201 of the light fluxes 103 and 203 become incident on the light flux synthesis unit 52 in a configuration that is inclined respectively by a predetermined angle since the light emission points of the light source that emits the respective light fluxes are disposed by separation of a predetermined distance S in a substantially vertical direction relative to the main optical axis of the light flux conversion lens 4 in the housing 51 as described above.
The light flux synthesis unit 52 in the present embodiment includes two reflective mirrors 5 and 6. The reflective mirror 5 is configured with a reflectance that enables selection of the wavelength. For example, the blue light flux in the wavelength 400 nm band of the light flux 103 (for example, only the central optical axis 101 is denoted for simplicity in
The reflective surface of the reflective mirror 5 is disposed in a configuration that is substantially inclined at 45 degrees relative to the central optical axis 101 of the incident light flux 103. In this manner, the thickness of the reflective mirrors 5 and 6 may be reduced in the optical axis direction of the light flux synthesis unit 52 because the respective positions in the optical axis direction are made to substantially coincide, and thereby the overall dimensions of the optical scanning apparatus can be reduced.
The light flux 203 propagates in a configuration that is inclined by a predetermined angle α relative to the light flux 103, becomes incident upon the light flux synthesis unit 52, and then becomes incident in the reflective mirror 6 that is disposed in an inner portion thereof. The reflective surface of the reflective mirror 6 is disposed to be substantially parallel to the reflective mirror 5, and further is inclined by a minute angle φ in relation to the reflective surface of the reflective mirror 5 so that the central optical axis 201 of the light flux 203 that is reflected on the reflective surface of the reflective mirror 6 becomes incident on the reflective surface at an angle of approximately 90 degrees relative to the central optical axis 101 of the light flux 103, that is to say, at an angle of approximately 45 degrees relative to the reflective surface of the reflective mirror 5.
The relative minute angle φ of the reflective mirror 6 and the reflective mirror 5 is half of the relative angle α between the light flux 203 and the light flux 103 that are incident on the light flux synthesis unit 52.
That is to say,
φ=α/2 (1)
The relative angle α between the light flux 203 and the light flux 103 is expressed as shown below by the distance L1 between the emission point of the light sources 1, 2 and the light flux conversion lens 4, and the relative interval S between the above semiconductor laser light sources 1 and 2.
α≈Tan−1[S/L1] (2)
When the light fluxes 103 and 203 are weakly convergent light fluxes or substantially parallel light fluxes, the distance L1 approximately coincides with the focal distance f of the light flux conversion lens 4.
L1≈f (3)
Using Equations (1) to (3) above, as a result, the relative minute angle φ can be expressed as written below in terms of f and S.
φ≈(1/2)×Tan−1[S/f] (4)
The provision of the reflective mirror 6 in a configuration that is inclined relative to the reflective mirror 5 by a relative minute angle φ to satisfy Equation (4) enables the light flux 203, which is reflected by the reflective surface of the reflective mirror 6 and reaches the reflective mirror 5 and then is further reflected by the wavelength selectable reflective surface, to describe a substantially parallel optical path at substantially the same position as the light flux 103 as shown in the figure, and to be emitted from the light flux synthesis unit 52 together with the light flux 103.
In
W=(L2/L1)×S≈(L2/f)×S (5)
The respective light fluxes that are emitted from the light flux synthesis unit 52 describe an optical path that is substantially the same as the respective light fluxes 104 and 204, and become incident on the two-dimensional optical scanning unit 7.
The two-dimensional optical scanning unit 7 includes for example a two-dimensional deflection mirror, and is provided with the function of performing high speed oscillating/rotating driving of the deflection mirror about a substantially vertically rotation axis to thereby execute a two-dimensional high speed scanning operation of the light flux that is reflected by the deflection mirror. After the light fluxes 104 and 204 that have become incident on the two-dimensional scanning unit 7 are reflected by the two-dimensional scanning unit 7, the light fluxes 104 and 204 become light fluxes 105 and 205, and become incident upon the display unit, and in particular, the projection screen (not illustrated) that is disposed at a forward predetermined position of the two-dimensional scanning unit 7 to thereby execute a two-dimensional scan of the display unit. The two-dimensional image is output onto the screen by modulating the light emission intensity of the semiconductor lasers 1 and 2, in synchrony with the two-dimensional scan, according to the image to be displayed.
Although an optical scanning image projection apparatus in which the display unit is integrated with the optical scanning apparatus, or an optical scanning image projection apparatus that includes an output unit for the light fluxes 105 and 205 by disposing the display unit on an outer portion of the optical scanning apparatus could be proposed, both configurations fall within the scope of the present invention.
The details of the modulation method for the emission intensity of the semiconductor laser 1 and 2 that is synchronized with the two-dimensional and the details of the structure of the two-dimensional scanning unit 7 scan have no direct relationship to the present invention, and therefore, details of description have been omitted.
However, although the reflective mirror 5 and the reflective mirror 6 in the light flux synthesis unit 52 according to the embodiment in
In the embodiment illustrated in
On the other hand, the prism surface 11 configures a normal reflective surface, and has the same function as the reflective mirror 6 in the embodiment illustrated in
In the same manner as the relationship between the reflective mirrors 5 and 6 in the embodiment illustrated in
Furthermore, prism surfaces, other than the prism surfaces 11 and 12, on which the light fluxes 103 or 203 are incident, are configured so that the respective light fluxes are transmitted with a transmittance of at least 90% for example.
However, the reflective mirror 5 or the prism surface 12 in the light flux synthesis unit 52 according to embodiment 1 as illustrated in
Furthermore, in addition to the example in which the light fluxes 103 and 203 have different wavelengths as in embodiment 1 and embodiment 2 illustrated in
In the first example and the second example as illustrated in
Furthermore, the semiconductor laser light sources for the three colors of red, green and blue may be housed in the same housing.
In
The example illustrated in
The reflective mirror 20 is disposed at a position at which the light flux 203 (only the central optical axis 201 is illustrated in the figure for simplicity) that is emitted from the light source 2 becomes incident onto the light flux synthesis unit 52 through the light flux conversion lens 4, and includes the function of guiding the light flux 203 that is reflected to thereby be incident upon the reflective mirrors 22 and 23 as illustrated in the figure.
The reflective mirror 21 is disposed at a position at which the light flux 303 (only the central optical axis 301 is illustrated in the figure for simplicity) that is emitted from the light source 3 becomes incident onto the light flux synthesis unit 52 through the light flux conversion lens 4, and includes the function of guiding the light flux 303 that is reflected to thereby be incident upon the reflective mirrors 22 and 23 as illustrated in the figure.
On the other hand, the reflective mirrors 22 and 23 are disposed at a position at which the light flux 103 (only the central optical axis 101 is illustrated in the figure for simplicity) that is emitted from the light source 1, disposed between the light sources 2 and 3, becomes incident onto the light flux synthesis unit 52 through the light flux conversion lens 4, and are installed so that the reflective surface of the respective reflective mirrors exhibits an angle of approximately ±45 degrees with respect to the central optical axis 101, and both reflective surfaces are in a crossing configuration.
The reflective surface of the reflective mirror 22 allows transmission of, for example, at least 90% of the light flux 103 that is directly incident on the reflective mirror 22 and the light flux 303 that is incident on the reflective surface of the reflective mirror 22 through the reflective mirror 21, and is provided with reflectance characteristics that reflect the light flux 203 that is incident on the reflective surface of the reflective mirror 22 through the reflective mirror 20 with a reflectance of at least 90% for example.
Conversely, the reflective surface of the reflective mirror 23 allows transmission of, for example, at least 90% of the light flux 103 that is directly incident on the reflective mirror 23 and the light flux 203 that is incident on the reflective surface of the reflective mirror 23 through the reflective mirror 20, and is provided with reflectance characteristics that reflect the light flux 303 that is incident on the reflective surface of the reflective mirror 23 through the reflective mirror 21 with a reflectance of at least 90% for example.
Although the reflective surfaces of the reflective mirror 20 and the reflective mirror 22 are substantially parallel and the reflective surfaces of the reflective mirror 21 and the reflective surface of the reflective mirror 23 are substantially parallel, a relative inclination expressed by the minute relative angle φ in Equation (4) is respectively provided.
Even when using a configuration in which the semiconductor laser light sources for the three colors of red, green and blue may be housed in the same housing by use of the light flux synthesis unit 52 that disposes the reflective mirrors 20 to 23, since the light fluxes that are emitted from the respective laser light sources are combined, are propagated on substantially the same light path, and can be guided to the display unit that is principally the projection screen through the two-dimensional optical scanning unit 7, the optical scanning apparatus and an image projection apparatus using the same can be downsized, and are extremely useful for improving the synthesis state of light flux on the screen.
While we have shown and described several embodiments in accordance with our invention, it should be understood that disclosed embodiments are susceptible of changes and modifications without departing from the scope of the invention. Therefore, we do not intend to be bound by the details shown and described herein but intend to cover all such changes and modifications that fall within the ambit of the appended claims.
Number | Date | Country | Kind |
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2012-169789 | Jul 2012 | JP | national |