Touch projection system

A touch projection system includes a light source device, a micromirror device, and an image-capturing device. The micromirror device can provide three reflection directions. The micromirror device can selectively reflect projection light emitted by the light source device in one of the reflection directions to project the reflected projection light onto a screen to form an image. The micromirror device also can reflect image light from the screen in another one of the reflection directions. Further, the micromirror device can reflect the image light from the screen in the other one of the reflection directions, which has a larger deflection angle, to be received by the image-capturing device, for example for determining a touch operation performed on the screen. Thereby, the limitation of structural interference by other components to the image-capturing device is reduced, so that the touch projection system can be assembled in a compact configuration.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a projection system, and especially relates to a touch projection system.

2. Description of the Prior Art

Recently, touch applications develop rapidly. Some kinds of projectors are designed to cooperate with touch technology. Common touch technology at present is to form an infrared light curtain in front of a screen. A receiving module is added into a projector for receiving image light produced by the infrared light curtain, so that a touch operation of a user can be determined by analyzing an image of the user interrupting the infrared light curtain. In practice, the receiving module can be integrated with a projection lens of the projector. The image light enters the projector through the projection lens and is reflected by a micromirror device (e.g. a digital micromirror device, DMD) to an image-capturing device. In this case, the micromirror device performs the function of modulating (e.g. selectively reflecting) light produced by a light source device of the projector and projecting the modulated light onto the screen to form images, and also the function of reflecting the image light, which enters the projector, to be received by the image-capturing device. The micromirror of a common digital micromirror device usually offers two states. One is defined as ON state, at which the micromirror reflects light to be projected toward the screen by the projection lens. The other is defined as OFF state, at which the micromirror reflects light to deflect off the projection lens so that the light is prevented from being projected onto the screen. In general, the micromirror rotates relative to a single axis to offers the ON state and the OFF state based on the limit positions of positive rotation and negative rotation. Thereby, the components of the projector can be disposed with less structural interference and operate normally. Therefore, the micromirror device uses the OFF state to reflect the image light to the image-capturing device. However, the rotation angle of the micromirror is restricted so that it is hard to configure the components of the projector compactly leading to incapability of effectively reducing the volume of the projector.

SUMMARY OF THE INVENTION

An objective of the invention is to provide a touch projection system. Its micromirror device can offer more reflection directions so that its image-capturing device can be disposed conveniently and the components of the touch projection system also can be disposed compactly.

The touch projection system of the invention includes a screen, a light source device, an image-capturing device, and a micromirror device. The light source device is used for emitting projection light. The image-capturing device is used for receiving image light from the screen. The micromirror device is used for reflecting the projection light and the image light. The micromirror device includes a plurality of micromirrors arranged in an array. The micromirror is controllable to be selectively located at a first angled position, a second angled position, or a third angled position. The micromirror has a first normal direction, a second normal direction, and a third normal direction corresponding to the first angled position, the second angled position, and the third angled position respectively. Therein, when the micromirror is located at the first angled position, the projection light from the light source device is reflected by the micromirror and travels in a first reflection direction to be projected onto the screen. When the micromirror is located at the second angled position, the image light from the screen travels to the micromirror in a reverse direction reverse to the first reflection direction, is reflected by the micromirror, and travels in a second reflection direction. The second reflection direction and the first reflection direction are nonparallel. When the micromirror is located at the third angled position, the image light from the screen travels to the micromirror in the reverse direction, is reflected by the micromirror, and travels in a third reflection direction to be received by the image-capturing device. The third reflection direction is nonparallel to the first reflection direction and the second reflection direction.

Compared with the prior art, the micromirror device of the touch projection system of the invention offers more reflection directions to the image light from the screen, so that the disposition of the image-capturing device is more flexible. In practice, the image-capturing device usually is disposed to receive the reflected image light much deflecting off the projection direction (i.e. the first reflection direction) for the projection light. For example, an included angle between the third reflection direction and the first reflection direction is larger than an included angle between the second reflection direction and the first reflection direction, so that the image-capturing device can obtain a larger disposition space. In other words, the light source device, the image-capturing device, and the micromirror device can be disposed compactly. In practice, the light source device, the image-capturing device, and the micromirror device are usually integrated in a projector casing. In the case, the projector casing can be smaller than the conventional touch projector. In addition, in practice, the micromirror of the invention can perform the above angled positions by a rotation mechanism of single axis or multiple axes.

DETAILED DESCRIPTION

Please refer toFIG. 1, which is a schematic diagram illustrating a touch projection system1of a preferred embodiment according to the invention. The touch projection system1includes a processing and controlling module12, a light source device14, a micromirror device16, an image-capturing device18, a light curtain generating device20, a screen22, and a lens24. The processing and controlling module12is electrically connected to the light source device14, the micromirror device16, and the image-capturing device18individually. The processing and controlling module12controls the light source device14to emit projection light PL (represented by solid lines with arrows inFIG. 1), controls the micromirror device16to selectively reflect the projection light PL from the light source device14and reflect image light IL (represented by dashed lines with arrows inFIG. 1) from the screen22, and controls the image-capturing device18to receive the image light IL from the screen22. The light curtain generating device20generates a light curtain202in front of the screen22. The image light IL is produced by the light curtain202. In the embodiment, the processing and controlling module12, the light source device14, the micromirror device16, and the image-capturing device18are integrated into a projector casing10(represented by a dashed rectangle inFIG. 1); however, the invention is not limited thereto.

Please also refer toFIG. 2.FIG. 2is a schematic diagram illustrating the side view of the micromirror device16. The micromirror device16includes a base162, a plurality of micromirrors164, and a plurality of rotation mechanisms166correspondingly to the plurality of micromirrors164. The rotation mechanisms166are disposed on the base162. Each micromirror164is rotatably disposed on the base162through the corresponding rotation mechanism166. The micromirrors164are arranged in an array. The processing and controlling module12controls the operation of the rotation mechanisms166so that the micromirrors164can selectively reflect the projection light PL to pass through the lens24to be projected onto the screen22(i.e. the light traveling upward inFIG. 2) to form a projection image. Please refer toFIG. 3, which is a schematic diagram illustrating the operation of the micromirror164. The rotation mechanism166is connected to the corresponding micromirror164so that the rotation mechanism166can control the corresponding micromirror164to rotate relative to a rotation axis164a(represented by a cross mark inFIG. 3) to be selectively located at a first angled position P1(shown by solid lines inFIG. 3), a second angled position P2(indicated by dashed lines inFIG. 3), or a third angled position P3(indicated by dashed lines inFIG. 3). In other words, the micromirror164is controllable to be selectively located at the first angled position P1, the second angled position P2, or the third angled position P3. The micromirror164has a first normal direction N1, a second normal direction N2, and a third normal direction N3corresponding to the first angled position P1, the second angled position P2, and the third angled position P3. In the embodiment, the first normal direction N1, the second normal direction N2, and the third normal direction N3are coplanar. The rotation axis164ais perpendicular to the first normal direction N1and the second normal direction N2. It is added that, in the specification and figures, the rotation mechanism166is illustrated only by a single support that offers the corresponding micromirror164pivot or deflection relative to the base162, and the position of the rotation axis164ais indicated conceptually by the cross mark. In practice, the rotation mechanism166can be realized through an electromechanical integration design, for example based on a common DMD, of which the operation detail is easily obtained and understood by people in the field of the invention and will not be described in addition. However, the invention is not limited thereto.

Please refer toFIG. 1andFIG. 3. When the micromirror164is located at the first angled position P1, the projection light PL from the light source device14is reflected by the micromirror164and travels in a first reflection direction D1to be projected onto the screen22, as represented by a solid line with an arrow inFIG. 3. At the moment, the state at which the micromirror164is located at the first angled position P1can be defined as an ON state, that is, for projecting the projection light PL to form a projection image. At this state, the image light IL (not shown inFIG. 3) will pass through the lens24to enter the projector casing10in a reverse direction along the projection path of the projection light PL, so the image light IL will not travel toward the image-capturing device18(represented by a dashed rectangle inFIG. 3); the image-capturing device18cannot capture the touch image produced by the light curtain202. It is added that in general, because the light curtain202is usually formed by invisible light, e.g. infrared, the image light IL into the projector casing10will not affect the projection image formed by the projection light PL even though the image light IL travels in the reverse direction along the projection path of the projection light PL. But the invention is still not limited thereto. For example, a filter can be disposed between the light source device14and the micromirror device16so that the image light IL can be filtered out.

Please also refer toFIG. 4.FIG. 4is a schematic diagram illustrating the micromirror164at the second angled position P2. When the micromirror164is located at the second angled position P2, the image light IL from the screen22travels to the micromirror164in a reverse direction reverse to the first reflection direction D1, is reflected by the micromirror164, and travels in a second reflection direction D2, as represented by a dashed line with an arrow inFIG. 4. Therein, the second reflection direction D2and the first reflection direction D1are nonparallel (i.e. a non-zero included angle therebetween exists). After reflected by the micromirror164, the projection light PL from the light source device14travels deflecting off the first reflection direction D1, also deflecting off the second reflection direction D2. Therefore, the reflected projection light PL will not be projected onto the screen22, as represented by a solid line with an arrow inFIG. 4. At the moment, the state at which the micromirror164is located at the second angled position P2can be defined as an OFF state, that is, for preventing the reflected projection light PL from forming a projection image. In the embodiment, the image light IL reflected to travel in the second reflection direction D2is not toward the image-capturing device18(represented by a dashed rectangle inFIG. 4), so the image-capturing device18cannot capture the touch image produced by the light curtain202. Furthermore, the image-capturing device18is usually designed to be capable of only receiving the image light IL, e.g. infrared. In general, the projection light PL is visible light, so it will not be received by the image-capturing device18. However, in practice, for avoiding unnecessary interference, for example in a case that the image-capturing device18cannot receive infrared only or the projection light PL may contain little infrared, the second angled position P1can be designed such that the projection light PL will not travel to the image-capturing device18after reflected by the micromirror164.

Please also refer toFIG. 5.FIG. 5is a schematic diagram illustrating the micromirror164at the third angled position P3. When the micromirror164is located at the third angled position P3, the image light IL from the screen22travels to the micromirror164in the reverse direction (i.e. reverse to the first reflection direction D1), is reflected by the micromirror164, and travels in a third reflection direction D3to be received by the image-capturing device18(represented by a dashed rectangle inFIG. 5), as represented by a dashed line with an arrow inFIG. 5. Therein, the third reflection direction D3is nonparallel to the first reflection direction D1and the second reflection direction D2. At the moment, after reflected by the micromirror164, the projection light PL from the light source device14travels deflecting off the first reflection direction D1, also deflecting off the second reflection direction D2and the third reflection direction D3. Therefore, he reflected projection light PL will not be projected onto the screen22, as represented by a solid line with an arrow inFIG. 5. At the moment, the state at which the micromirror164is located at the third angled position P3can be defined as a CAMERA state; that is, the processing and controlling module12can control the image-capturing device18to receive the image light IL to form a touch image and analyze the touch image to determine a touch operation. Therein, the reflected projection light PL cannot form a projection image. Afterward, the processing and controlling module12can control the micromirror device16to project the projection light PL onto to the screen22to form a projection image in response to the touch operation (e.g. a user touches an object or points a cursor position). In the embodiment, an included angle A1between the third reflection direction D3and the first reflection direction D1is larger than an included angle A2between the second reflection direction D2and the first reflection direction D1(referring toFIG. 4). Therefore, the included angle A1allows disposing the image-capturing device18and other components (e.g. prism) in a compact configuration. In another aspect, the projector casing10can be provided with a smaller volume.

In the above embodiment, the rotation mechanism166is realized by a rotation mechanism of single rotation axis for offering only one-dimensional rotation; however, the invention is not limited thereto. Please refer toFIG. 6, which is a schematic diagram illustrating a rotation mechanism366rotating the micromirror164in a micromirror device according to an embodiment. The micromirror device of this embodiment is similar to the micromirror device16of above embodiment, so other descriptions of the micromirror device of this embodiment can refer to the relational descriptions of micromirror device16and will not be described in addition. The difference between the micromirror device of this embodiment and the micromirror device16of above embodiment is mainly that the rotation mechanism366can offer two-dimensional rotation. In the embodiment, in logic, the rotation mechanism366includes a flexible support3662(or a mechanism capable of deflecting the micromirror164relative to the base162), four electrode pads3664disposed on the base162, and four electrostatic zones3666disposed on the surface of the micromirror164toward the base162. The four electrostatic zones3666correspond to the four electrode pads3664. The flexible support3662is capable of being applied with a force (or moment) to be bent or deflect the micromirror164relative to the base162. In the embodiment, by applying voltage to the electrode pad3664so that an attraction force or repulsion force is produced between the electrode pad3664and the corresponding electrostatic zone3666, the micromirror164can deflect relative to the base162. In logic, the interaction of the four electrode pads3664with the four corresponding electrostatic zones3666can move the micromirror164as the micromirror164rotates relative to two axes. Therefore, the micromirror164has at least four states (i.e. four angled positions) in principle.

Please refer toFIG. 1andFIGS. 6 to 9.FIGS. 7 to 9are schematic diagrams illustrating the micromirror164being located at a first angled position P1′, a second angled position P2′, and a third angled position P3′ respectively. The rotation mechanism366is connected to the corresponding micromirror164so that the rotation mechanism366can control the micromirror164to rotate relative to a first rotation axis164band a second rotation axis164c(shown by chain lines inFIGS. 6 to 9) to be selectively located at the first angled position P1′, the second angled position P2′, and the third angled position P3′. As shown byFIG. 7, the micromirror164is located at the first angled position P1′. The projection light PL from the light source device14is reflected by the micromirror164and travels in a first reflection direction D1′ to be projected onto the screen22, as represented by a solid lines with an arrow inFIG. 7. At the moment, the state at which the micromirror164is located at the first angled position P1′ can be defined as an ON state, that is, for projecting the projection light PL to form a projection image. At this state, the image light IL (not shown inFIG. 7) will enters the projector casing10in a reverse direction along the projection path of the projection light PL, so the image light IL will not travel toward the image-capturing device18so that the image-capturing device18cannot capture the touch image formed by the light curtain202. Therein, for a simple drawing, the image-capturing device18is not shown in the figure, which is also applied in the following and will not be mentioned in addition.

When the micromirror164is controlled by the corresponding rotation mechanism366so that the micromirror164rotates relative to the first rotation axis164band the second rotation axis164cindividually from the first angled position P1′ (as shown byFIG. 7) to the second angled position P2′ (as shown byFIG. 8), the image light IL from the screen22travels to micromirror164in a reverse direction reverse to the first reflection direction D1′, is reflected by the micromirror164, and travels in a second reflection direction D2′, as represented by a dashed line with an arrow inFIG. 8. Therein, the second reflection direction D2′ and the first reflection direction D1′ are nonparallel. After reflected by the micromirror164, the projection light PL from the light source device14travels deflecting off the first reflection direction D1′, also deflecting off the second reflection direction D2′. Therefore, the reflected projection light PL will not be projected onto the screen22, as represented by a solid line with an arrow inFIG. 8. At the moment, the state at which the micromirror164is located at the second angled position P2′ can be defined as an OFF state, that is, for preventing the reflected projection light PL from forming a projection image. In the embodiment, the image light IL reflected to travel in the second reflection direction D2′ is not toward the image-capturing device18(referring toFIG. 4for the traveling path thereof), so the image-capturing device18cannot capture the touch image produced by the light curtain202.

When the micromirror164is controlled by the corresponding rotation mechanism366so that the micromirror164rotates relative to the first rotation axis164bfrom the first angled position P1′ (as shown byFIG. 7) to the third angled position P3′ (as shown byFIG. 9), the image light IL from the screen22travels to micromirror164in the reverse direction reverse to the first reflection direction D1′, is reflected by the micromirror164, and travels in a third reflection direction D3′ to be received by the image-capturing device18, as represented by a dashed line with an arrow inFIG. 9. Therein, the third reflection direction D3′ and the first reflection direction D1′ are nonparallel. Furthermore, for a simple drawing, the image-capturing device18is not shown inFIG. 9; the logic of receiving the image light IL is the same as shown byFIG. 5. After reflected by the micromirror164, the projection light PL from the light source device14travels deflecting off the first reflection direction D1′, also deflecting off the third reflection direction D3′. Therefore, the reflected projection light PL will not be projected onto the screen22, as represented by a solid line with an arrow inFIG. 9. At the moment, the state at which the micromirror164is located at the third angled position P3′ can be defined as a CAMERA state; that is, the processing and controlling module12can control the image-capturing device18to receive the image light IL to form a touch image and analyze the touch image to determine a touch operation. Therein, the reflected projection light PL cannot form a projection image. Afterward, the processing and controlling module12can control the micromirror device16to project the projection light PL onto to the screen22to form a projection image in response to the touch operation (e.g. a user touches an object or points a cursor position).

It is added that in the embodiment, the micromirror164uses the two rotation axes164band164cto change its current state. Therefore, as a whole, the four angled positions (including the above angled positions P1′, P2′ and P3′) of the micromirror164are switched to one another in stereo. In other words, the normal directions N1′, N2′ and N3′ of the micromirror164corresponding to the angled positions P1′, P2′ and P3′ respectively are noncoplanar; the reflection directions D1′, D2′ and D3′ are also noncoplanar. Therefore, in principle, except for the ON state, any state at which the micromirror164is located can be defined as an OFF state, and the CAMERA state can be assigned to one of the rest states. The image-capturing device18is disposed according to the assignment of the CAMERA state. For example, the state at which the micromirror164is located inFIG. 7is still defined as the first angled position (i.e. the ON state). However, the state at which the micromirror164is located inFIG. 9is defined as the second angled position (i.e. the OFF state); the state at which the micromirror164is located inFIG. 8is defined as the third angled position (i.e. the CAMERA state). In other words, the micromirror164can be controlled by the corresponding rotation mechanism366so that the micromirror164rotates relative to the first rotation axis164bfrom the first angled position (as shown byFIG. 7) to the second angled position (as shown byFIG. 9); the micromirror164can be controlled by the corresponding rotation mechanism366so that the micromirror164rotates relative to the first rotation axis164band the second rotation axis164cfrom the first angled position (as shown byFIG. 7) to the third angled position (as shown byFIG. 8).

Furthermore, the four angled positions (including the above angled positions P1′, P2′ and P3′) of the micromirror164are switched to one another in stereo, which is conducive to flexibly, further compactly disposing the components inside the projector casing10of the touch projection system1. In addition, in the embodiment, a rotation angle (e.g. the included angle between the normal directions N1′ and N2′) of the micromirror164rotating relative to the rotation axes164band164cis substantially equal to the double of a square root of a rotation angle (e.g. the included angle between the normal directions N1′ and N3′) of the micromirror164rotating relative to the rotation axis164bor164c. In other words, even though the rotation angle offered alone by the rotation axis164bor164cis substantially equal to that offered by the micromirror of a conventional DMD, the micromirror164still can obtain a larger variation of rotation angle by rotating relative to both of the rotation axes164band164c. Such design is conducive to flexibly disposing the components in the projector casing10and also facilitates the disposition of the components.

As discussed above, the micromirror device of the touch projection system of the invention offers more reflection directions to the image light from the screen, so that the image-capturing device can obtain a larger disposition space and can be disposed more flexibly. In other words, the light source device, the image-capturing device, and the micromirror device can be compactly disposed, so that the volume of the projector casing is smaller than conventional touch projectors. In addition, the micromirror device of touch projection system of the invention can control the rotation of the micromirror by use of multiple rotation axes so as to diversify the angled positions for the micromirror. The switching of the micromirror from one to another of the angled positions shows a three-dimensional switching, which is conducive to the flexibility of the disposition of the components.