Projection display apparatus

A projection display apparatus of the disclosure includes: a light valve (21) that modulates illuminating light (L1) on the basis of image data to output the modulated light; an illuminating unit (1) including a light source, and a plurality of optical members for illumination that generate the illuminating light (L1) on the basis of light from the light source to guide the illuminating light (L1) to the light valve (21); a projection lens (24) that projects the modulated light from the light valve (21) on a projection surface (30A), and allows detection light to enter from a direction opposite to a travelling direction of the modulated light; and an imaging device (22) that is disposed at a location optically conjugated with the light valve (21), and allows the detection light to enter through the projection lens. One or more of the plurality of optical members for illumination have optical property of reducing a noise component that affects the detection light and arises inside the illuminating unit (1).

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Phase of International Patent Application No. PCT/JP2015/067611 filed on Jun. 18, 2015, which claims priority benefit of Japanese Patent Application No. JP 2014-153406 filed in the Japan Patent Office on Jul. 29, 2014. Each of the above-referenced applications is hereby incorporated herein by reference in its entirety.

TECHNICAL FIELD

The disclosure relates to a projection display apparatus having a function of detecting an object on a projection surface or in the vicinity thereof.

BACKGROUND ART

In recent years, in a smartphone, a tablet terminal, or any other similar mobile apparatus, the use of a touch panel has made it possible to perform page scrolling or zooming and shrinking of images being displayed on a screen through pointing operation in response to human intuition. Meanwhile, a display apparatus that displays images by projecting them on a screen has been known as a projector over the years.

CITATION LIST

Patent Literature

SUMMARY OF THE INVENTION

In recent years, also in the projector, it has been desired to perform the pointing operation of projected images in such a manner that the touch panel is manipulated manually in response to the human intuition like the tablet terminal, or any other similar mobile apparatus. In particular, a small-sized projector of a handheld type has recently emerged in the market, and accordingly, it has been desired to perform the pointing operation of images being projected in a size ranging from about 20 inches to about 30 inches on a projection area. However, no touch panel is built into a screen or a wall on which images are projected, and therefore, it is necessary to detect manual operation using other means. Alternatively, apart from such a method, there are some projectors that enable images to be manipulated by operating, for example, a remote controller. However, the small-sized projector itself is small in size, and it would not be stylish to operate the small-sized projector using, for example, the remote controller.

PTL 1 proposes an apparatus that enables the pointing operation of images with coverage of the projection area by combining a projector with a detector that detects manual operation (gesture). However, in the apparatus proposed in PTL 1, a projector unit and a detector unit are separately configured as independent units. This easily results in an increase in size of a whole system. Further, in addition to the increase in size, calibration operation involving accuracy is also necessary in terms of, for example, a configuration of relative positional coordinates of an area being projected and an area to be detected. The calibration accuracy is important because it has a direct influence on the accuracy of the pointing operation. The calibration is cumbersome because it is necessary to deal with every corner of a screen.

PTL 2 and PTL 3 propose apparatuses that add an imaging function to a projector. However, in the apparatus proposed in PTL 3, light flux from a light source such as an ultrahigh-pressure mercury lamp is made to enter a polarization converter element that adjusts such light flux to a specific polarization component. The resultant polarization component is guided to a light valve. In this kind of polarization converter element, however, a component that has not been converted into the specific polarization component may enter an imaging device instead of the light valve. Accordingly, imaging may be affected by illuminating light for projection. Alternatively, if a dedicated polarization converter element for imaging use is added to avoid such a disadvantage, a projection lens becomes larger in size. Therefore, such a method is not suitable for practical use. On the contrary, in the apparatus proposed in PTL 2, the illuminating light is turned off in the imaging. This prevents the imaging from being affected by the illuminating light, without adding the dedicated polarization converter element for imaging. However, because the illuminating light is turned off in the imaging, when the apparatus is used under, for example, dark external environment, it is difficult to assure sufficient brightness necessary for the imaging. Therefore, the apparatus has restrictions in use as an apparatus that is often used under dark environment like a projector.

It is therefore desirable to provide a projection display apparatus that makes it possible to improve accuracy of object detection.

A projection display apparatus according to an embodiment of the disclosure includes: a light valve that modulates illuminating light on a basis of image data to output the modulated light; an illuminating unit including a light source, and a plurality of optical members for illumination that generate the illuminating light on a basis of light from the light source to guide the illuminating light to the light valve; a projection lens that projects the modulated light from the light valve on a projection surface, and allows detection light to enter from a direction opposite to a travelling direction of the modulated light; and an imaging device that is disposed at a location optically conjugated with the light valve, and allows the detection light to enter through the projection lens. One or more of the plurality of optical members for illumination have optical property of reducing a noise component. The noise component affects the detection light and arises inside the illuminating unit.

In the projection display apparatus according to the embodiment of the disclosure, the noise component is reduced by the one or more of the plurality of optical members for illumination. The noise component affects the detection light and arises inside the illuminating unit.

According to the projection display apparatus of the embodiment of the disclosure, the noise component is reduced by the one or more of the plurality of optical members for illumination. The noise component affects the detection light and arises inside the illuminating unit. Hence, it is possible to improve the accuracy of the object detection.

It is to be noted that some effects described here are not necessarily limitative, and any of other effects described herein may be achieved.

MODES FOR CARRYING OUT THE INVENTION

In the following, some embodiments of the disclosure are described in detail with reference to the drawings. It is to be noted that description is given in the following order.

1. Example Embodiment of Projection Display Apparatus Having Detection Function (FIGS. 1 to 9)

1.2 Operation and Workings

1.2.1 Basic Operation

1.2.2 Workings of Polarizer

1.2.3 Regarding Reduction in Noise Component Arising inside Illuminating Unit

2. Modification Examples

2.7 Seventh Modification Example

2.8 Other Modification Examples

3. Other Example Embodiments

1. EXAMPLE EMBODIMENT OF PROJECTION DISPLAY APPARATUS HAVING DETECTION FUNCTION

FIG. 1illustrates an example of an overall configuration of a projection display apparatus (projector) according to an example embodiment of the disclosure. The projection display apparatus may have a function of performing object detection actively using near-infrared light, along with video image display.FIG. 2illustrates an example of a state where video image display and object detection are performed in the projection display apparatus.FIG. 3illustrates an example of a state where the projection display apparatus illustrated inFIG. 2is viewed from a lateral side direction.FIG. 4illustrates an example of light entering a light valve21and an imaging device22in the projection display apparatus illustrated inFIG. 1.FIG. 5schematically illustrates a concept of the video image display and the object detection performed by the projection display apparatus.

Referring toFIG. 1, the projection display apparatus may include an illuminating unit1, a light valve21, an imaging device22, a wire grid27that may serve as a polarization split element, a projection lens24, a polarizer25S that may serve as a polarizing member, an image processor26, and an illumination controller29.

The illuminating unit1may output illuminating light L1from a first direction Z1toward the wire grid27, as illustrated inFIG. 4. The illuminating unit1includes a light source, and a plurality of optical members for illumination that generate the illuminating light L1on the basis of light from the light source to guide the illuminating light L1to the light valve21. The light source may include a plurality of light sources that are disposed on different optical paths. The illuminating unit1may also include an optical path combination element that combines two or more of the optical paths on which respective two or more light sources of the plurality of light sources are disposed.

In a more specific example, the illuminating unit1may include a blue laser11B, a green laser11G, and a red laser11R, as the plurality of light sources that are disposed on the different optical paths. The illuminating unit1may also include, as the plurality of optical members for illumination, a first coupling lens12B, a second coupling lens12G, a third coupling lens12R, a driving optical element14, a mirror18, a first dichroic prism131, a second dichroic prism132, a first fly-eye lens151, a second fly-eye lens152, a first condenser lens161, a second condenser lens162, a third condenser lens163, and a fourth condenser lens164.

The blue laser11B is a laser light source that may emit blue light with a wavelength of about 450 nm, for example. The green laser11G is a laser light source that may emit green light with a wavelength of about 520 nm, for example. The red laser11R is a laser light source that may emit red light with a wavelength of about 640 nm, for example.

The illumination controller29may perform a light emission control of a first light source (for example, the blue laser11B), a second light source (for example, the green laser11G), and a third light source (for example, the red laser11R). For example, the illumination controller29may perform the light emission control of each of the first to third light sources in a field sequential method.

The second coupling lens12G may be a lens (coupling lens) that collimates the green light outputted from the green laser11G (into parallel light) to couple the resultant light to the first dichroic prism131. Similarly, the first coupling lens12B may be a lens (coupling lens) that collimates the blue light outputted from the blue laser11B to couple the resultant light to the first dichroic prism131. Further, the third coupling lens12R may be a lens (coupling lens) that collimates the red light outputted from the red laser11R to couple the resultant light to the second dichroic prism132. It is to be noted that in one preferable example, these coupling lenses12R,12G, and12B may collimate their respective entering laser light (into the parallel light).

Each of the first dichroic prism131and the second dichroic prism132may serve as the optical path combination element that combines the two or more of the optical paths on which the respective two or more light sources are disposed. The first dichroic prism131may be a prism that selectively transmits the blue light entering through the first coupling lens12B, while selectively reflecting the green light entering through the second coupling lens12G. The second dichroic prism132may be a prism that selectively transmits the blue light and the green light outputted from the first dichroic prism131, while selectively reflecting the red light entering through the third coupling lens12R. Thus, color synthesis (optical path combination) relative to the red light, the green light, and the blue light may be carried out.

The driving optical element14may be an optical element that reduces speckle noise and an interference pattern in the illuminating light L1, and be disposed on an optical path between the first condenser lens161and the second condenser lens162. The driving optical element14may vibrate minimally in a direction along an optical axis or in a vertical direction relative to the optical axis, for example, to vary a state of passing-through light flux, thereby allowing for reduction in the speckle noise and the interference pattern in the illuminating light L1.

Each of the first fly-eye lens151and the second fly-eye lens152may be an optical member (integrator) in which a plurality of lenses are arranged two-dimensionally on a substrate, and spatially divide entering light flux, depending on arrangement of the plurality of lenses, to output the resultant light flux. The first fly-eye lens151may be disposed on an optical path between the second dichroic prism132and the first condenser lens161. The second fly-eye lens152may be disposed on an optical path between the second condenser lens162and the third condenser lens163. Uniformization of distribution of an in-plane light quantity may be attained by the first fly-eye lens151and the second fly-eye lens152.

The mirror18may be an element that bends an optical path of the illuminating light L1. The mirror18may be disposed on an optical path between the first condenser lens161and the driving optical element14. The first condenser lens161may be a lens that collects the light outputted from the first fly-eye lens151to make the resultant light enter the driving optical element14through the mirror18. The second condenser lens162may be a lens that collects the light outputted from the driving optical element14to make the resultant light enter the second fly-eye lens152.

Each of the third condenser lens163and the fourth condenser lens164may be a lens that collects the light outputted from the second fly-eye lens152to output the resultant light, as the illuminating light L1, toward the wire grid27.

The wire grid27may be a metallic grid with minute meshes formed on a glass substrate, for example. As illustrated inFIG. 4, the wire grid27may allow the illuminating light L1to enter from the first direction Z1. The light valve21may be disposed in a second direction Z2. The polarizer25S and the imaging device22may be disposed in a third direction Z3. The projection lens24may be disposed in a fourth direction Z4.

The wire grid27may serve as the polarization split element that splits entering light into a first polarization component (for example, a P polarization component) and a second polarization component (for example, an S polarization component) to output the components in different directions from each other. The wire grid27may selectively reflect the specific first polarization component, and selectively transmit the specific second polarization component. For example, as illustrated inFIG. 4, the wire grid27may output (reflect) most of a P polarization component Lp1toward the second direction Z2, and output (transmit) most of an S polarization component Ls1toward the third direction Z3. The P polarization component Lp1may be included in the illuminating light L1entering from the first direction Z1. Further, as illustrated inFIG. 4, the wire grid27may output (reflect) most of a P polarization component Lp3toward the third direction Z3. The P polarization component Lp3may be included in detection light L2entering from a direction opposite to the fourth direction Z4.

The light valve21may be a reflective liquid crystal device such as an LCOS (Liquid Crystal On Silicon) device. For example, as illustrated inFIG. 4, the light valve21modulates, on the basis of image data, the first polarization component (for example, the P polarization component Lp1) entering from the second direction Z2through the wire grid27. The first polarization component may be included in the illuminating light L1. Further, the light valve21outputs the modulated light toward the fourth direction Z4through the wire grid27. As illustrated inFIG. 4, the light valve21may output, for example, the S polarization component Ls2, as the modulated light, a polarization state of which is rotated from a polarization state at time of entering. It is to be noted that in the light valve21, it is possible to perform black display by returning the entering P polarization component Lp1back to the wire grid27in a polarization state as it is.

The projection lens24projects the modulated light from the light valve21on a projection surface30A of a screen30. The modulated light may enter the projection lens24from the fourth direction Z4through the wire grid27. Further, as illustrated inFIG. 4, the projection lens24allows the detection light L2to enter from a direction opposite to a travelling direction of the modulated light. The projection lens24may be a projection optical system for image projection, and also function as an imaging optical system for object detection.

The imaging device22may include a solid-state imaging device such as a CMOS (Complementary Metal-Oxide Semiconductor) device and a CCD (Charge-Coupled Device). The imaging device22is disposed at a location that is optically conjugated with the light valve21. In one more specific example, when the light valve21is the reflective liquid crystal device, arrangement may be made in such a manner that a display surface (liquid crystal surface) for creating images and an imaging surface of the imaging device22are located at optically conjugated positions. As illustrated inFIG. 4, the imaging device22allows the detection light L2to enter from the third direction Z3through the projection lens24and the wire grid27.

The polarizer25S may serve as the polarization member that is one of optical members that reduces the second polarization component included in the illuminating light L1. The polarizer25S may be disposed between the imaging device22and the wire grid27. The polarizer25S may remove the second polarization component (for example, the S polarization component) included in entering light. As illustrated inFIG. 4, the polarizer25S may remove at least the S polarization component Ls1included in the illuminating light L1entering through the wire grid27, as the second polarization component.

The image processor26may detect, on the basis of a result of imaging by the imaging device22, a position P1of a feature point of a pointing object (physical object)71by making the position P1correspond to coordinates of a projection image V2projected on the projection surface30A, as illustrated inFIGS. 2, 3, and 5. Examples of the pointing object71may include a human finger or a pointer. As an example of the feature point, a position of a human finger tip is illustrated in each ofFIGS. 2, 3, and 5. However, the position is not limited thereto, and a center of gravity of the human finger, a center of gravity of a human hand, or any other position may be selectable as appropriate.

Each ofFIGS. 2 and 3illustrates a configuration assuming a case where the projection display apparatus is a short focus type. As illustrated inFIGS. 2 and 3, the projection display apparatus may include a near-infrared light projecting unit40under a main body100. The projection surface30A may be, for example, a flat floor surface. The near-infrared light projecting unit40may serve as a light source unit for detection that emits near-infrared light for detection41as invisible light for detection at a predetermined height h from the projection surface30A. The near-infrared light projecting unit40may emit the near-infrared light for detection41, to provide coverage of at least a projection area31on the projection surface30A with the near-infrared light for detection41from the predetermined height h. The imaging device22may allow near-infrared scattered light La, as the detection light, to enter through the projection lens24and the wire grid27. The near-infrared scattered light La may be diffused by the pointing object71. It is to be noted that the near-infrared light projecting unit40may irradiate the projection surface30A with the near-infrared light for detection41having a thickness in a direction of the height h, as the invisible light for detection. In this case, the near-infrared light for detection41and the projection surface30A may not be completely spaced apart at the predetermined height h. For example, a state may be permitted where part of light (light at the height h of 0 (h=0)) in a direction of the thickness (the direction of the height h) of the near-infrared light for detection41touches (overlaps) the projection surface30A.

In the projection display apparatus, the projection lens24may be an ultrashort focus lens with a throw ratio of about 0.38 or less. Here, the throw ratio is expressed as L/H, where L is a distance from the projection lens24to the projection surface30A, and H is a width of the projection area, as illustrated inFIGS. 2 and 3.

1.2 Operation and Workings

In the projection display apparatus, as illustrated inFIGS. 1 and 5, image information V1formed on the light valve21may be projected on the projection surface30A of the screen30by the projection lens24to perform enlarged display of such an image as a projection image V2. Further, in the projection display apparatus, a position of an object on the projection surface30A, for example, the position P1of the feature point of the pointing object (physical object)71may be detected with use of the imaging device22. Examples of the pointing object71may include the human finger and the pointer. The imaging device22may carry out imaging of an imaging area32. The imaging area32may be substantially a same area as the projection area31on the projection surface30A.

In the projection display apparatus, laser light sources may be used in the illuminating unit1. This makes it possible to adjust the polarization component of the illuminating light L1to be dominant. In one specific example, the first polarization component may be adjusted to 99% or more, and more preferably, to 99.5% or more. Here, as the dominant first polarization component, either the S polarization component Ls1or the P polarization component Lp1may be selectable depending on characteristics of a polarization converter device.

On an assumption that the first polarization component is the P polarization component, and the second polarization component is the S polarization component, the wire grid27may reflect most of the P polarization component, and transmit most of the S polarization component. Therefore, for example, 99.5% of the illuminating light L1may be assigned to the P polarization component Lp1as the dominant polarization component, and remaining 0.5% may be assigned to the S polarization component Ls1. For example, as illustrated inFIG. 4, the wire grid27may reflect most of the dominant P polarization component Lp1to output the reflection to the light valve21. The P polarization component Lp1entering the light valve21may be modulated (rotated) by the light valve21to become the modulated light of the S polarization components Ls2, and thereafter, enter the projection lens24through the wire grid27. As illustrated inFIG. 5, the S polarization component Ls2as the modulated light may be projected as the projection image V2on the projection surface30A of the screen30through the projection lens24.

In the projection display apparatus, the imaging device22is disposed at a location that is optically conjugated with the light valve21. Further, the projection lens24may be the projection optical system for image projection, and also function as the imaging optical system for object detection. This allows the imaging device22to perform the imaging of the imaging area32that is the same area as the projection area31, as illustrated inFIG. 5. The light valve21and the imaging device22are located at conjugated positions, which makes it possible to monitor the position P1of the feature point of the pointing object71such as the human finger or the pointer on the projection surface30A by overlaying the position P1on the projection image V2through the projection lens24. Further, for example, the image processor26may perform image processing of a shape of the pointing object71to detect coordinates of the position P1of the feature point of the pointing object71, thereby allowing for pointing operation of the projection image V2. At this time, any coordinate position in the projection area31may correspond to a coordinate position in the imaging area32on a one-to-one basis. Therefore, coordinates of a detected position P2on the side of the imaging device22may correspond to the coordinates of the position P1of the feature point of the pointing object71. It is to be noted that the number of the pointing objects71may be two or more. For example, coordinates of finger tips of both hands may be detectable. The use of the position of the feature point of the pointing object71detected in such a manner makes it possible to perform the operation in an intuitive manner as if a touch panel were built into the projection image V2of the projector.

In the projection display apparatus, as illustrated inFIGS. 2 and 3, a membrane-like near-infrared light barrier may be provided over the projection area31at a predetermined height h, to provide the coverage of the projection area31in an area direction and of two or three millimeters in a height direction. The height h may be within a range of, for example, several millimeters to dozens of millimeters from the projection surface30A. As a result, because the projection surface30A is generally flat, if there is no shielding object or no pointing object71such as the finger and a pointing rod, a membrane of emitted near-infrared light may travel straight ahead without being shielded on the way. Therefore, no image of such a membrane is formed on the imaging device22that is monitoring the projection surface30A. In such a state, if the finger or any other object is moved closer to a position at a distance of several millimeters from the projection surface30A provided with the near-infrared light barrier, or operation of, for example, touching the projection surface30A is performed, light of the barrier is shielded by the finger to be diffused at that point. The light hitting the finger to be diffused travels toward every direction, and part of the light returns to an aperture of the projection lens24. Such return light passes through the projection lens24, and is reflected by the wire grid27to reach the imaging device22. At this time, since the light valve21and the imaging device22that create images are disposed at conjugated positions, a bright spot diffusion point arising as a dot on the projection surface30A forms an image on the imaging device22, and forms the image at a position corresponding to the projected image in a one-to-one relationship. This allows for position detection. Further, in a case of the ultrashort focus type, projection light passes in the vicinity of the projection surface30A, and a part of an operator's body is unlikely to shield the projection light. This leads to an advantage of enhanced visibility of a screen during operation.

Next, description is provided on workings of the polarizer25S with reference toFIG. 4. The detection light L2entering the wire grid27may include an S polarization component Ls3and the P polarization component Lp3as polarization components. The wire grid27may reflect most of the P polarization component Lp3in the third direction Z3. Assuming that the polarizer25S removes the S polarization component, almost all of the reflected P polarization component Lp3may reach the imaging device22. Further, out of the illuminating light L1entering the wire grid27, the S polarization component Ls1may be outputted toward the third direction Z3. The S polarization component Ls1becomes a noise component that may affect the detection light L2. If the S polarization component Ls1enters the imaging device22, an S/N ratio during detection may be reduced, leading to degradation of detection accuracy. Disposing the polarizer25S to remove the S polarization component Ls1makes it possible to increase the S/N ratio and to improve the detection accuracy.

As described above, it is, ideally, possible to make only the detection light L2enter the imaging device22in such a manner that the P polarization component Lp1of the illuminating light L1may be reflected by the wire grid27in a direction different from the imaging device22, and the S polarization component Ls1may be removed by the polarizer25S. However, there is possibility that an unwanted noise component included in the illuminating light L1may enter the imaging device22, depending on an entering angle of light that enters the wire grid27or optical performance of the wire grid27and the polarizer25S. Accordingly, as illustrated inFIG. 6to be described below, a configuration may be desirable in which the noise component that may affect the detection light may be reduced inside the illuminating unit1.

[1.2.3 Regarding Reduction of Noise Component Arising Inside Illuminating Unit]

In the projection display apparatus, the projection lens24may be communalized by disposing the light valve21for image display and the imaging device22for object detection at optically conjugated positions. Thus, the whole optical system is reduced in size. Further, the infrared light for detection may be sent from a different optical system from the light source for image display. This allows for high-accuracy object detection that reduces a load of image processing. However, in an event of generation of light serving as the noise component that may degrade the detection accuracy on the light source side for image display, there is likelihood that the noise component may enter the imaging device22to cause a failure in object detection or significant degradation in the detection accuracy. In this case, for example, it may be considered to dispose a dedicated part such as a filter that cuts the light serving as the noise component on an optical path between the imaging device22and the illuminating unit1. But addition of the dedicated part such as the filter causes an additional count of parts or an increase in size of the optical system, and does not provide any fundamental solution to the characteristics in the illuminating unit1.

Accordingly, in one preferable example, one or more of the plurality of optical members for illumination inside the illuminating unit1may have optical property of reducing the noise component that arises inside the illuminating unit1. As an example, description is provided on an example case where in the illuminating unit1, the red laser11R emits weak infrared light LIRwith a wavelength of, for example, about 800 nm as the noise component in addition to red light LRwith a wavelength of, for example, about 640 nm. In this case, for example, the second dichroic prism132may have wavelength property of transmitting light of a blue (B) band, a green band (G), and an infrared (IR) band, and reflecting light of a red (R) band, as illustrated inFIG. 7. It is to be noted that inFIG. 7, a horizontal scale denotes a wavelength, and a vertical scale denotes reflectance. As a result, as illustrated inFIG. 6, the second dichroic prism132may transmit the blue and green light guided by the first dichroic prism131, and reflect the red light LRguided by the third coupling lens12R. At the same time, the second dichroic prism132may transmit the infrared light LIRguided by the third coupling lens12R. The red light LRemitted by the red laser11R may be reflected by the second dichroic prism132, and guided as the illuminating light L1toward the light valve21, the projection lens24, and the projection surface30A to form an image. Meanwhile, the infrared light LIRmay pass through the second dichroic prism132, and be guided toward a direction deviated from the optical path of the illuminating light L1. This keeps the infrared light LIRfrom being guided to the imaging device22, which allows for reduction in the noise component that may affect the detection light L2.

If the infrared light LIRserving as the noise component is not reduced, a large quantity of the noise component that may affect a detection signal may enter the imaging device22, as illustrated inFIG. 8. On the contrary, when the noise component is reduced by the second dichroic prism132, the noise component that may affect the detection signal is reduced as illustrated inFIG. 9. This allows for characteristics equivalent to those obtained by inserting an infrared light cutoff filter in an illuminating optical system, thereby improving the detection accuracy. It is to be noted that in each ofFIGS. 8 and 9, a horizontal scale denotes a wavelength, and a vertical scale denotes a quantity of entering light.

It is to be noted that an absorber200may be provided, as illustrated inFIG. 6, on an optical path of the infrared light LIRthat has passed through the second dichroic prism132. The absorber200may absorb the infrared light LIR. In another alternative example, an inner wall of a housing that accommodates the illuminating unit1may be processed so as to absorb the infrared light LIR. This makes it possible to prevent the infrared light LIRfrom, for example, being reflected by the inner wall of the housing and returning to the optical path of the illuminating light L1.

As described, in this embodiment, the second dichroic prism132may serve as one of the optical members for illumination, and reduce the noise component that affects the detection light and arises inside the illuminating unit1. Hence, it is possible to reduce the noise component that is unwanted during the object detection, thereby allowing for improved accuracy of the object detection. Further, it is possible to provide a small-sized and inexpensive configuration by communalizing the effect of reducing the noise component with the combination of the optical paths inside the illuminating unit1. This make it possible to provide a small-sized, high-definition, and interactive laser projector that is installable on a small and lightweight electronic apparatus.

It is to be noted that effects described herein are merely exemplified and not limitative, and effects of the disclosure may be other effects or may further include other effects. The same is true for any other example embodiments and modification examples to be described below.

2. MODIFICATION EXAMPLES

2.1 First Modification Example

Each ofFIGS. 1 and 4illustrates a configuration example with use of the wire grid27as the polarization split element. In an alternative configuration, however, a polarizing beam splitter23may be used instead of the wire grid27, as in a first modification example illustrated inFIG. 10. Further, in the first modification example, a polarizer25that removes the P polarization component may be provided instead of the polarizer25S that removes the S polarization component.

The polarizing beam splitter23may adopt a configuration of lamination of prisms each of which is coated with a multi-layer film, or may be a beam splitter similar to prisms that sandwich an element having polarizing property.

The wire grid27in the configuration illustrated inFIG. 4may reflect the P polarization component that serves as the first polarization component, and transmit the S polarization component that serves as the second polarization component. However, the polarizing beam splitter23may have characteristics reverse to such characteristics.

The polarizing beam splitter23may have four optical surfaces. Here, description is given, with two surfaces facing in a horizontal direction inFIG. 10being defined as a first optical surface and a third optical surface, and two surfaces facing in a vertical direction being defined as a second optical surface and a fourth optical surface. As illustrated inFIG. 10, the illuminating light L1may enter the first optical surface of the polarizing beam splitter23from the first direction Z1. The light valve21may be disposed in the second direction Z2relative to the second optical surface of the polarizing beam splitter23. The polarizer25and the imaging device22may be disposed in the third direction Z3relative to the third optical surface of the polarizing beam splitter23. The projection lens24may be disposed in the fourth direction Z4relative to the fourth optical surface of the polarizing beam splitter23.

The polarizing beam splitter23may be the polarization split element that splits entering light into the first polarization component (for example, the S polarization component) and the second polarization component (for example, the P polarization component) to output such components in different directions from each other. The polarizing beam splitter23may selectively reflect the specific first polarization component, and selectively transmit the specific second polarization component. For example, as illustrated inFIG. 10, the polarizing beam splitter23may output (reflect), toward the second direction Z2, almost all of the S polarization component Ls1included in the illuminating light L1entering from the first direction Z1, and output (transmit), toward the third direction Z3, almost all of the P polarization component Lp1. Further, as illustrated inFIG. 10, the polarizing beam splitter23may output (reflect), toward the third direction Z3, almost all of the S polarization component Ls3included in the detection light L2entering from a direction opposite to the fourth direction Z4.

On an assumption that the first polarization component is the S polarization component, and the second polarization component is the P polarization component, the polarizing beam splitter23may reflect most of the S polarization component, and transmit most of the P polarization component. Therefore, for example, 99.5% of the illuminating light L1may be assigned to the S polarization component Ls1as the dominant polarization component, and remaining 0.5% may be assigned to the P polarization component Lp1. As illustrated inFIG. 10, the polarizing beam splitter23may reflect almost all of the dominant S polarization component Ls1to output the reflection to the light valve21. The S polarization component Ls1entering the light valve21may be modulated (rotated) by the light valve21to become the modulated light of the P polarization component Lp2, and thereafter, enter the projection lens24through the polarizing beam splitter23. As illustrated inFIG. 5, the P polarization component Lp2as the modulated light may be projected as the projection image V2on the projection surface30A of the screen30through the projection lens24.

Meanwhile, the detection light L2entering the polarizing beam splitter23may include the S polarization component Ls3and the P polarization component Lp3as the polarization components. The polarizing beam splitter23may reflect almost all of the S polarization component Ls3in the third direction Z3. Assuming that the polarizer25removes the P polarization component, almost all of the S polarization component Ls3may reach the imaging device22. Further, out of the illuminating light L1entering the polarizing beam splitter23, the P polarization component Lp1may be outputted toward the third direction Z3. The P polarization component Lp1may become the noise component that may affect the detection light L2. If the P polarization component Lp1enters the imaging device22, the S/N ratio during detection may be reduced, leading to the degradation of the detection accuracy. Disposing the polarizer25to remove the P polarization component Lp1makes it possible to increase the S/N ratio and improve the detection accuracy.

As described above, it is, ideally, possible to make only the detection light L2enter the imaging device22in such a manner that the S polarization component Ls1of the illuminating light L1may be reflected by the polarizing beam splitter23in a direction different from the imaging device22, and the P polarization component Lp1may be removed by the polarizer25. However, there is possibility that the unwanted noise component included in the illuminating light L1may enter the imaging device22, depending on an entering angle of light that enters the polarizing beam splitter23or optical performance of the polarizing beam splitter23and the polarizer25. Accordingly, as illustrated inFIG. 6, the configuration may be desirable in which the noise component that may affect the detection light may be reduced inside the illuminating unit1.

2.2 Second Modification Example

FIG. 11illustrates a second example where the noise component is reduced, as an illuminating unit1A according to a second modification example.FIG. 11illustrates an example case where the green laser11G emits the weak infrared light LIRwith the wavelength of, for example, about 800 nm in addition to green light LGwith a wavelength of, for example, about 520 nm. In this case, for example, the second dichroic prism132may have wavelength property of transmitting blue light LBand the green light LG, reflecting the red light LR, and reflecting the infrared light LIR, as illustrated inFIG. 11. As a result, the infrared light LIRmay be guided toward the direction deviated from the optical path of the illuminating light L1. This keeps the infrared light LIRfrom being guided to the imaging device22, which allows for the reduction in the noise component that may affect the detection light L2.

It is to be noted that the absorber200may be provided, as illustrated inFIG. 11, on the optical path of the infrared light LIRthat is guided toward the direction deviated from the optical path of the illuminating light L1. The absorber200may absorb the infrared light LIR. In another alternative example, the inner wall of the housing that accommodates the illuminating unit1may be processed so as to absorb the infrared light LIR. This makes it possible to prevent the infrared light LIRfrom, for example, being reflected by the inner wall of the housing and returning to the optical path of the illuminating light L1. This may also apply to other modification examples to be described below.

2.3 Third Modification Example

FIG. 12illustrates a third example where the noise component is reduced, as an illuminating unit1B according to a third modification example. As with the example inFIG. 11,FIG. 12illustrates an example case where the green laser11G emits the weak infrared light LIRwith the wavelength of, for example, about 800 nm in addition to the green light LGwith the wavelength of, for example, about 520 nm. In this case, for example, the first dichroic prism131may have wavelength property of transmitting the blue light LB, reflecting the green light LG, and transmitting the infrared light LIR, as illustrated inFIG. 12. As a result, the infrared light LIRmay be guided toward the direction deviated from the optical path of the illuminating light L1. This keeps the infrared light LIRfrom being guided to the imaging device22, which allows for the reduction in the noise component that may affect the detection light L2.

2.4 Fourth Modification Example

FIG. 13illustrates a fourth example where the noise component is reduced, as an illuminating unit1C according to a fourth modification example.FIG. 13illustrates an example case where the blue laser11B emits the weak infrared light LIRwith the wavelength of, for example, about 800 nm in addition to the blue light LBwith the wavelength of, for example, about 450 nm. In this case, for example, the first dichroic prism131may have wavelength property of transmitting the blue light LB, reflecting the green light LG, and reflecting the infrared light LIR, as illustrated inFIG. 13. As a result, the infrared light LIRmay be guided toward the direction deviated from the optical path of the illuminating light L1. This keeps the infrared light LIRfrom being guided to the imaging device22, which allows for the reduction in the noise component that may affect the detection light L2.

As an alternative configuration, although not illustrated, for example, the second dichroic prism132may have property of transmitting the blue light LB, transmitting the green light LG, reflecting the red light LR, and reflecting the infrared light LIR.

2.5 Fifth Modification Example

FIG. 14illustrates a fifth example where the noise component is reduced, as an illuminating unit1D according to a fifth modification example. As illustrated inFIG. 14, the mirror18that bends the optical path may have property of reflecting the blue light LB, the green light LG, and the red light LR, and transmitting the infrared light LIR. As a result, even if any of the light sources of the blue laser11B, the green laser11G, and the red laser11R emits the infrared light LIR, it is possible to reduce the noise component that may affect the detection light L2.

Allowing the mirror18to have the property of reducing the infrared light LIRalso makes it possible to deal with a case where an optical member other than the light sources emits the infrared light LIR. For example, even if the infrared light LIRis generated because a multi-layer film of the second dichroic prism132excites the red light, the infrared light LIRmay be guided by the mirror18toward the direction deviated from the optical path of the illuminating light L1. This allows for the reduction in the noise component that may affect the detection light L2.

2.6 Sixth Modification Example

FIG. 15illustrates a configuration example of an illuminating unit1E according to a sixth modification example. As illustrated inFIG. 15, in one alternative configuration, the illuminating unit1E may include a single light source11and a coupling lens12instead of the blue laser11B, the green laser11G, and the red laser11R. In this case, the first dichroic prism131and the second dichroic prism132may be omitted.

For example, as illustrated inFIGS. 16 and 17, the light source11may have a configuration including a plurality of chips211A each of which emits different color light. For example, the light source11may include the three chips211A that emit the red light LR, the green light LG, and the blue light LB. In this case, as illustrated inFIG. 15, the mirror18may have property of reflecting the blue light LB, the green light LG, and the red light LR, and transmitting the infrared light LIR. As a result, even if the weak infrared light LIRis emitted from the light source11, it is possible to reduce the infrared light LIRserving as the noise component that may affect the detection light L2.

Further, the projection display apparatus may perform monochrome image display, for example. In this case, for example, as illustrated inFIGS. 18 to 20, the light source11may have a configuration including the single chip211A that emits single color light. Also in this case, the weak infrared light LIRemitted from the light source11may be guided by the mirror18toward the direction deviated from the optical path of the illuminating light L1, as illustrated inFIG. 15. It is to be noted that in one alternative configuration, all of the plurality of chips211A may emit the same color light, in the configurations illustrated inFIGS. 16 and 17.

Each of the configuration examples illustrated inFIGS. 16 and 17, orFIGS. 18 to 20represents a form of can type in which a solid-state light-emitting device211is housed in an internal space surrounded by a stem213and a cap214. The solid-state light-emitting device211may include the single or the plurality of edge-emitting type chips211A. It is to be noted thatFIG. 17illustrates a configuration of the light source11illustrated inFIG. 16as viewed from light-output-surface side.FIG. 19illustrates a configuration of the light source11illustrated inFIG. 18as viewed from the light-output-surface side.FIG. 20illustrates another configuration example of the light source11illustrated inFIG. 18.

The chip211A may include, for example, a light-emitting diode (LED), an organic EL light-emitting device (OLED), or a laser diode (LD).

The stem213may constitute a package of the light source11together with the cap214, and may include, for example, a support substrate213A, an outer frame substrate213B, and a plurality of connection terminals213C. The support substrate213A may support a sub-mount215. The outer frame substrate213B may be disposed on a back side of the support substrate213A.

The sub-mount215may be made of a material having conductivity and heat dissipation performance. Each of the support substrate213A and the outer frame substrate213B may have a configuration in which one or a plurality of insulating through-holes and one or a plurality of conductive through-holes are formed on a base member having the conductivity and the heat dissipation performance. The support substrate213A and the outer frame substrate213B may take disk shapes, and be stacked with their central axes (not illustrated) aligned with each other. A diameter of the outer frame substrate213B may be larger than a diameter of the support substrate213A. An outer edge of the outer frame substrate213B may be an annular flange that juts radially from the central axis of the outer frame substrate213B in a plane where the central axis of the outer frame substrate213B serves as a normal line. The flange may have a function of specifying a reference position in fitting the cap214into the support substrate213A in a manufacturing process.

The plurality of connection terminals213C may run through at least the support substrate213A. Terminals (hereinafter referred to as “terminals α” for descriptive purpose) excluding one or more terminals among the plurality of connection terminals213C may be electrically coupled, on a one-to-one basis, to electrodes (not illustrated) of the individual chips211A. For example, the terminals α may protrude long on side on which the outer frame substrate213B is disposed, and protrude short on side on which the support substrate213A is disposed. Further, terminals (hereinafter referred to as “terminals β” for descriptive purpose) excluding the above-described terminals α among the plurality of connection terminals213C may be electrically coupled to remaining electrodes (not illustrated) of all the chips211A. For example, the terminals β may protrude long on the side on which the outer frame substrate213B is disposed. End edges of the terminals β on the side on which the support substrate213A is disposed may be embedded in the support substrate213A. Out of each of the connection terminals213C, the part protruding long on the side on which the outer frame substrate213B is disposed may serve as a part to be fitted into, for example, a substrate. Moreover, out of each of the plurality of connection terminals213C, the part protruding short on the side on which the support substrate213A is disposed may serve as a part to be electrically coupled, on the one-to-one basis, to the individual chips211A through a wire216. Out of each of the plurality of connection terminals213C, the part embedded in the support substrate213A may serve as, for example, a part to be electrically coupled to all the chips211A through the support substrate213A and the sub-mount215. The terminals α may be supported by the insulating through-holes provided in the support substrate213A and the outer frame substrate213B, and insulated and isolated from the support substrate213A and the outer frame substrate213B by the through-holes. Further, the individual terminals α may be insulated and isolated from one another by the above-described insulating members. Moreover, the terminals β may be supported by the conductive through-holes provided in the support substrate213A and the outer frame substrate213B, and electrically coupled to the through-holes.

The cap214may seal the solid-state light-emitting device211. The cap214may include, for example, a tubular part214A provided with apertures on a top end and a bottom end. The bottom end of the tubular part214A may be, for example, in contact with a side surface of the support substrate213A. The solid-state light-emitting device211may be located in an internal space of the tubular part214A. The cap214may have a light transmission window214B that is disposed to block the aperture on top-end side of the tubular part214A. The light transmission window214B may be disposed at a position facing a light-output surface of the solid-state light-emitting device211, and have a function of transmitting light outputted from the solid-state light-emitting device211.

As described above, in a case where the chip211A includes a device of edge-emitting type, the solid-state light-emitting device211may emit light from a light-output region that includes a single or a plurality of dot-like emitting spots, or a single or a plurality of non-dot-like emitting spots. The solid-state light-emitting device211may include, for example, a single chip211A that emits light in a predetermined wavelength band. Alternatively, the solid-state light-emitting device211may include the plurality of chips211A that emit light in a same wavelength band. In another alternative, the solid-state light-emitting device211may include the plurality of chips211A that emit light in different wavelength bands. When the solid-state light-emitting device211includes the plurality of chips211A, the chips211A may be disposed in line in a horizontal direction, for example, as illustrated inFIGS. 16 and 17.

When the solid-state light-emitting device211includes the single chip211A, a size (WV×WH) specified as the solid-state light-emitting device211may be equal to a size (WV1×WH1) of the single chip211A, for example, as illustrated inFIG. 19. However, for example, as illustrated inFIG. 20, when the solid-state light-emitting device211adopts a monolithic structure, the size may be as follows. That is, in the example illustrated inFIG. 20, the size (WV×WH) specified as the solid-state light-emitting device211may be WV1×2WH1or more. In contrast, when the solid-state light-emitting device211includes the plurality of chips211A, the size specified as the solid-state light-emitting device211may be equal to a size measured with all the chips211A lumped together, for example, as illustrated inFIG. 17. When the plurality of chips211A are disposed in line in the horizontal direction, the size (WV×WH) specified as the solid-state light-emitting device211may be WV1×3WH1or more in the example ofFIG. 17.

2.7 Seventh Modification Example

In the forgoing, the description is provided on examples where the infrared light LIRthat may serve as the noise component is reduced by reflection or transmission as the optical property of the optical members for illumination. However, one or two or more of the plurality of optical members for illumination may have property of absorbing the infrared light LIR. For example, one or two or more of the coupling lenses12B,12G, and12R, the condenser lenses161to164, the fly-eye lenses151and152, and the driving optical element14may have the property of transmitting the blue light LB, the green light LG, and the red light LR, and absorbing the infrared light LIR. Further, one or two or more of the mirror18, the first dichroic prism131, and the second dichroic prism132may have the property of absorbing the infrared light LIR.

Alternatively, all of the plurality of optical members for illumination may have the property of reducing the infrared light LIRby reflection, transmission, or absorption.

Even if an order of combining the optical paths of the blue laser11B, the green laser11G, and the red laser11R is changed, various example embodiments as described above allow for the reduction in the infrared light LIR.

2.8 Other Modification Examples

In the illuminating unit1in the configuration illustrated inFIG. 1, either the first fly-eye lens151or the second fly-eye lens152may be provided. When only the second fly-eye lens152is provided, the first condenser lens161and the second condenser lens162become unnecessary. When only the first fly-eye lens151is provided, the third condenser lens163and the fourth condenser lens164become unnecessary.

Further, when sufficiently optimal polarization characteristics are obtained, the polarizer25S used in the configuration illustrated inFIG. 1may be omitted.

Moreover, the technology may be also applicable to a projector of a digital mirror device method.

In addition, the infrared-band light is taken as an example of the detection light L2and the noise component thereof. However, ultraviolet-band light may exemplify the detection light L2and the noise component thereof.

3. OTHER EXAMPLE EMBODIMENTS

The technology according to the disclosure is not limited to the above-described example embodiments and modification examples, but various modifications may be made.

For example, the technology may be configured as follows.

A projection display apparatus, including:

a light valve that modulates illuminating light on a basis of image data to output the modulated light;

an illuminating unit including a light source, and a plurality of optical members for illumination that generate the illuminating light on a basis of light from the light source to guide the illuminating light to the light valve;

a projection lens that projects the modulated light from the light valve on a projection surface, and allows detection light to enter from a direction opposite to a travelling direction of the modulated light; and

an imaging device that is disposed at a location optically conjugated with the light valve, and allows the detection light to enter through the projection lens,

one or more of the plurality of optical members for illumination having optical property of reducing a noise component, the noise component affecting the detection light and arising inside the illuminating unit.

The projection display apparatus according to (1), wherein the one or more of the plurality of optical members for illumination have the optical property of reducing the noise component by absorption, reflection, or transmission.

The projection display apparatus according to (1) or (2), wherein

the light source includes a plurality of light sources that are disposed on different optical paths,

the plurality of optical members for illumination include an optical path combination element that combines two or more of the optical paths on which respective two or more light sources of the plurality of light sources are disposed, and

the optical path combination element has the optical property of reducing the noise component.

The projection display apparatus according to (3), wherein the optical path combination element has optical property of causing reflection or transmission of the noise component in a direction deviated from an optical path of the illuminating light.

The projection display apparatus according to any one of (1) to (4), wherein

the plurality of optical members for illumination include a mirror that bends an optical path of the illuminating light, and

the mirror has the optical property of reducing the noise component.

The projection display apparatus according to (5), wherein the mirror has optical property of transmitting the noise component in a direction deviated from the optical path of the illuminating light.

The projection display apparatus according to any one of (1) to (6), further including an absorber that is disposed in a direction deviated from an optical path of the illuminating light and absorbs the noise component, wherein

the one or more of the plurality of optical members for illumination have optical property of guiding the noise component in the direction deviated from the optical path of the illuminating light by reflection or transmission.

The projection display apparatus according to any one of (1) to (7), wherein the noise component includes light of an invisible light band.

The projection display apparatus according to any one of (1) to (8), wherein the noise component includes light of an infrared light band.

The projection display apparatus according to any one of (1) to (9), wherein the noise component includes light of a same wavelength band, as the detection light.

The projection display apparatus according to any one of (1) to (10), wherein the noise component is a component included in the light generated from the light source.

The projection display apparatus according to any one of (1) to (11), further including an image processor that detects, on a basis of a result of imaging by the imaging device, a position of a feature point of an object on the projection surface or in vicinity of the projection surface by making the position correspond to coordinates of a projection image projected on the projection surface.

The projection display apparatus according to any one of (1) to (12), further including a light source unit for detection that emits invisible light for detection at a predetermined height from the projection surface, wherein

the imaging device allows the invisible light diffused by hitting an object, as the detection light, to enter through the projection lens.

The projection display apparatus according to (13), wherein the light source unit for detection emits infrared light as the invisible light for detection.

The projection display apparatus according to any one of (1) to (14), further including a light source unit for detection that emits invisible light for detection, to provide coverage of at least a projection area on the projection surface with the invisible light for detection from a predetermined height, the projection area being an area projected by the projection lens, wherein

the imaging device allows the invisible light diffused by hitting an object in vicinity of the projection area, as the detection light, to enter through the projection lens.

This application claims the priority on the basis of Japanese Patent Application No. 2014-153406 filed on Jul. 29, 2014 in Japan Patent Office, the entire contents of which are incorporated in this application by reference.