JP5549545B2 - projector - Google Patents

Description

  The present invention relates to a projector that projects an image on a projection plate.

  There is known a projector that measures a distance to an external screen, moves a lens of a projection optical system, and projects a projected image on the external screen in a focused state (see, for example, Patent Document 1).

JP 2010-130225 A

  According to the projector described in Patent Document 1, it is necessary to secure a space for moving the lens of the projection optical system in order to bring the projection optical system into focus, and there is a problem that the projector cannot be reduced in size. there were.

  In the projector according to the present invention, a first microlens array in which a plurality of first microlenses are arranged, and a plurality of display pixels that output a projection pixel signal are arranged in correspondence with each of the plurality of first microlenses. A display device, an illumination device that illuminates the display element and emits a plurality of projection light beams from a plurality of display pixels, and projects a plurality of projection light beams from a plurality of display pixels that have passed through the first microlens array on a projection surface. An optical system for projecting the projected image and a generation means for generating a projection pixel signal so that the projected image is projected in a state corresponding to the projection distance from the optical system to the projection surface. The element and the optical system are in an optically conjugate relationship with respect to the first microlens array.

  According to the present invention, the projector can be reduced in size.

It is sectional drawing which showed the whole structure of the projector in the 1st Embodiment of this invention. It is a front view of an image sensor and a microlens array. It is the figure which showed the several display pixel corresponding to the micro lens seen from the scheduled image formation surface of a projector, and the micro lens. It is a figure for demonstrating projection of the projection image by the projector. It is a figure which shows the example of a pair of light receiving element area | region on the image pick-up element used for the focus position calculation using a pupil division type phase difference detection system. It is a figure which shows an example of the projection image for focus position calculation. It is a figure which shows an example of the area | region containing the several display pixel in which the display image for focus position calculation is displayed. It is a figure which shows the example of the phase difference of a pair of light reception signal. It is a figure which shows the correlation amount of a pair of received light signal in the minimum value vicinity. It is sectional drawing which showed the whole structure of the projector in the 2nd Embodiment of this invention.

--- First embodiment ---
A projector according to a first embodiment of the present invention will be described. FIG. 1 is a cross-sectional view showing an overall configuration of projector 100 according to the first embodiment of the present invention. In FIG. 1, a projector 100 includes an optical system 110 including a lens and a diaphragm, an optical element 120, a microlens array 130, an image sensor 140, a focal position calculation device 150, a projection pixel signal generation device 160, an illumination device 170, and a display element. 180 and a microlens array 190.

  The optical system 110 includes a photographing lens and a diaphragm. The optical element 120 reflects an incident light beam incident from the projection screen 200 via the optical system 110 toward the imaging element 140. The incident light beam reflected by the optical element 120 enters the image sensor 140 through the microlens array 130. In the microlens array 130, a plurality of microlenses are arranged two-dimensionally. FIG. 2 is a front view of the image sensor 140 and the microlens array 130. As shown in FIG. 2, a plurality of light receiving elements 14 are arranged in the imaging element 140. The plurality of light receiving elements 14 arranged in the image sensor 140 receive incident light beams incident on the image sensor 140 and photoelectrically convert them into light reception signals. The image sensor 140 outputs the received light signal to the focal position calculation device 150. The light receiving element 14 covered by each microlens 13 receives the incident light beam that has passed through the microlens 13 and photoelectrically converts it into a light reception signal.

  The focal position calculation device 150 calculates the focal position of the image on the projection surface of the projection screen 200 based on the light reception signal output from the image sensor 140. The focal position calculation device 150 delivers the calculated focal position data to the projection pixel signal generation device 160.

  The focal position of the image on the projection surface depends on the projection distance from the optical system 110 to the projection screen 200. The projection surface of the projection screen 200 is not necessarily a plane perpendicular to the optical axis 1100 of the optical system 110. FIG. 1 shows an example in which the projection surface of the projection screen 200 forms a curved surface. In addition, there may be a case where the projection surface of the projection screen 200 is not perpendicular to the optical axis 1100, or a case where the projection surface is uneven or uneven. That is, the projection distance may be different for each of a plurality of areas constituting the projection image. Therefore, the focal position calculation device 150 calculates the above-described focal position for each of a plurality of areas constituting the projection image. This can be realized, for example, by performing focal position calculation for each microlens 13 based on a pair of light reception signals of a pair of light receiving elements 14 covered by the microlens 13 shown in FIG.

  The projection pixel signal generation device 160 performs a plurality of displays on the display element 180 based on the focus position calculated by the focus position calculation device 150 and the light reception signal output from the image sensor 140 by photographing the subject in advance. A projection pixel signal output from the pixel 18 is generated. The light reception signal and the projection pixel signal output from the image sensor 140 after photographing the subject in advance correspond to the image data used for image composition disclosed in Japanese Patent Laid-Open No. 2007-4471, and are specified according to the projection distance. The position of the image plane is determined. That is, the position of the designated image plane is the above-described focal position. A projection pixel signal output from the display pixel 18 on the display element 180 corresponding to the virtual pixel on the designated image plane at the focal position is generated.

  FIG. 2 is a front view of the display element 180 and the microlens array 190. A plurality of display pixels 18 are arranged on the display element 180, and the plurality of display pixels 18 output a projection pixel signal generated by the projection pixel signal generation device 160. The illumination device 170 disposed on the back surface of the display element 180 illuminates the plurality of display pixels 18 that output the projection pixel signal, whereby a projection light beam is emitted from each of the plurality of display pixels 18. The projected light beam from the display pixel 18 covered by each microlens 19 passes through the microlens 19. The projected light beam thus emitted passes through the microlens array 190 and the optical element 120 and is projected onto the projection screen 200 by the optical system 110. The projected light beam is projected onto the projection screen 200, whereby a projected image is projected.

  The imaging element 140 and the display element 180 are arranged at equivalent positions with respect to each of the projection screen 200, the optical system 110, and the optical element 120. For each of the projection screen 200, the optical system 110, and the optical element 120, the microlens array 130 and the microlens array 190 are disposed at equivalent positions. The optical system 110 and the image sensor 140 are substantially conjugate with respect to the microlens array 130. The optical system 110 and the display element 180 are substantially conjugate with respect to the microlens array 190.

  FIG. 3 is a diagram for explaining projection image projection by the projector 100 according to the present embodiment. In the projection of the projected image by the projector 100, as described above, the plurality of display pixels 18 that output projection pixel signals corresponding to image data used for image composition disclosed in Japanese Patent Application Laid-Open No. 2007-4471 are illuminated. As a result, a projected light beam is emitted. Of the projected light beam emitted, a projected image is formed on the above-described designated image plane 210. The outer edge of the partial light beam that has passed through the virtual pixel 2 on the designated image plane 210 defined at the focal position h in the optical axis direction of the optical system 110 with the top surface of the microlens array 190 as the origin is expressed by rays 51 and 52. 3 and FIG. 3A shows a light beam center line 50 of the partial light beam. The partial light flux that has passed through the virtual pixel 2 corresponds to the constituent pixel 1 included in the projection image projected on the projection surface of the projection screen 200. Similarly, the partial light flux that has passed through the virtual pixel 2 a corresponds to the constituent pixel 1 a included in the projection image projected on the projection plane of the projection screen 200, and the partial light flux that has passed through the virtual pixel 2 b This corresponds to the constituent pixel 1b included in the projection image projected on the projection plane.

As shown in FIG. 3B, the partial light flux passing through the virtual pixel 2 on the designated image plane 210 defined by the focal position h is emitted from the display pixel 18a on the display element 180 and is microlens 19a. , A light beam 71 emitted from the display pixel 18b on the display element 180 and passing through the micro lens 19b, and a light beam 72 emitted from the display pixel 18c on the display element 180 and passing through the micro lens 19c. including. That is, the image in the virtual pixel 2 is obtained by synthesizing the projection pixel signals output from the plurality of display pixels 18 that emit the partial light fluxes that pass through the virtual pixel 2 including the display pixels 18a, 18b, and 18c. In the arrangement of the micro lens array 190, the output I _{k, l} (h) of the virtual pixel at the focal position h in the optical axis direction of the k, l-th micro lens 19 is a horizontal function f (i) indicating the neighborhood to be referred to. , J) and the function g (i, j) in the vertical direction are expressed by Expression (1).

FIG. 4 shows hatching of a plurality of display pixels 18 that emit a partial light flux that passes through the virtual pixel 2, including display pixels 18 a, 18 b, and 18 c that output a projection pixel signal for obtaining an image in the virtual pixel 2. FIG. The smaller the focal position h at which the designated image plane 210 is defined, the more the display pixels 18 that emit partial light beams that pass through the virtual pixel 2 are covered with the microlens 19a. Therefore, the focal position h of the designated image plane 210 corresponding to the plurality of display pixels 18 shown in FIG. 4A is the focal point of the designated image plane 210 corresponding to the plurality of display pixels 18 shown in FIG. It is smaller than the position h. Since the display pixel outputs P _{i, j} of the plurality of display pixels 18 are used to output a plurality of virtual pixels, they are expressed by Expression (2).

  Next, focus position calculation in projector 100 of the present embodiment will be described. As described above, the focus position can be calculated by performing the focus detection calculation of the optical system 110 by a known pupil division type phase difference detection method. FIGS. 5A and 5B are diagrams illustrating an example of a pair of light receiving element regions P1 and P2 on the imaging element 140 used for focal position calculation using the pupil division type phase difference detection method. The pair of light receiving element regions P1 and P2 are defined for each microlens 13, and are shown with different types of hatching in FIG. Each of the pair of light receiving element regions P1 and P2 includes a plurality of light receiving elements 14, but may include one light receiving element 14. The distance g between the centers of gravity of the pair of light receiving element regions P1 and P2 is defined by the distance between the center of gravity G1 and G2 of each of the pair of light receiving element regions P1 and P2.

  By displaying the display image for calculating the focal position on the plurality of light receiving elements 18 of the display device 180, for example, black stripes 515 and white stripes 516 are arranged at uneven intervals on the projection screen 200 as shown in FIG. The projected focal position calculation image 510 is projected. As shown in FIG. 7, the display image for calculating the focal position is preferably displayed for each microlens 19 on a plurality of display pixels 18 included in a hatched region 610 at the center of the microlens 19. In this case, since the plurality of display pixels 18 included in the hatched region 610 are located only near the optical axis of the microlens 19, the F value of the microlens 19 is set to the display image for calculating the focal position. A corresponding depth of field is given.

The phase difference between the pair of light receiving element regions P1 and P2 on the image sensor 140 that has received the incident light beam from the focus position calculation projection image 510 shown in FIG. 6, and the distance g between the centers of gravity of the pair of light receiving element regions P1 and P2. The focal position h is calculated based on Specifically, the focal position h, the phase difference k ₀ of the pair of light receiving element regions P1 and _P2, the distance between the centers of gravity g, using the focal length f _m of the microlens 13, represented by the formula (3).

In the case of the detection columns n of the A column and the B column, which are a pair of light receiving signal columns defined by the pair of light receiving element regions P1 and P2 defined for each microlens 13, the A column indicates the light reception signal a _i = a _j , A _{j + 1} ,..., A _{j + n} , and the B column includes received light signals b _i = b _j , b _{j + 1 ,.} FIG. 8 shows changes in the received light signal intensity of the pair of received light signals a _i and b _i when i = j to j + n. FIG. 8 shows an example of the phase difference k ₀ between the pair of light reception signals a _i and b _i . The correlation amount C (k) when the A column is shifted by the shift amount k is defined by equation (4).

The phase difference k ₀ can be obtained using the correlation amount C (k) in the vicinity of the minimum value C (x) in the equation (4). FIG. 9 shows the minimum value C (x) in equation (4) and the correlation amounts C (x−1) and C (k + 1) in the vicinity thereof. By the interpolation calculation, the phase difference k ₀ is expressed by Expression (5).

The focal position h is calculated by substituting the phase difference k ₀ obtained by Expression (5) into Expression (3). By repeating such calculation over the entire area of the microlens array 130 while changing the value of the variable j, a depth map including the focal position h for each microlens 13 can be obtained. The spherical aberration and chromatic aberration of the optical system 110 can be corrected by using this depth map and a known correction technique. As described above, the projection pixel signal generation device 160 uses the data on the focal position h obtained in this way and the light reception signal output from the image sensor 140 by photographing the subject in advance. A projection pixel signal displayed by the plurality of display pixels 18 is generated.

The projector 100 according to the first embodiment has the following operational effects.
(1) When projecting a projection image on the projection screen 200, it is not necessary to move the lens of the optical system 110 in order to bring the optical system 110 into focus. Since it is not necessary to secure a space for moving the lens and a space for providing the lens driving unit, the projector 100 can be reduced in size.

(2) The focal position calculation based on the pair of light reception signals of the pair of light receiving elements 14 covered by the microlens 13 is performed for each microlens 13, and a projection pixel signal is generated based on the calculated focal position. When the projection surface of the projection screen 200 forms a curved surface, when the projection surface of the projection screen 200 is not perpendicular to the optical axis 1100, the projection surface is in focus even when there are irregularities or steps. Projected images can be projected.

--- Second Embodiment ---
A projector according to a second embodiment of the invention will be described. FIG. 10 is a sectional view showing an overall configuration of projector 1000 according to the second embodiment of the present invention. In FIG. 1, a projector 1000 includes an optical system 110 including a lens and a diaphragm, a focal position calculation device 150, a projection pixel signal generation device 160, an illumination device 170, a display element 180, and a microlens array 190.

The focal position calculation device 150 acquires the projection distance d from the optical system 110 to the projection surface of the projection screen 2000 from the external projection distance calculation device 910. The projection distance calculation device 910 may be a known distance measuring device. For example, a distance measuring device that does not generate a depth map, such as a so-called infrared active distance measuring device using an infrared light emitting device or a two-lens small phase difference distance measuring device may be used. In that case, only the projection distance d from the optical system 110 to one point on the projection surface of the projection screen 200 is acquired. Therefore, the projection surface of the projection screen 2000 is preferably a plane perpendicular to the optical axis 1100 of the optical system 110. At this time, the focal position h is expressed by Expression (6) using the focal length f0 and the projection distance d of the lens of the optical system 110. If aberration information of the lens of the optical system 110 is known in advance, the focal position h can be corrected by using a known correction technique.

  The projection pixel signal generation device 160 acquires, from the storage device 920, a light reception signal acquired as image data used for image synthesis by photographing a subject in advance in the imaging device disclosed in Japanese Patent Application Laid-Open No. 2007-4471. To do. The projection pixel signal generation device 160 generates a projection pixel signal based on the projection distance d acquired from the projection distance calculation device 910 and the received light signal acquired from the storage device 920.

  The mechanism for projecting the projection image on the projection screen 2000 based on the projection pixel signal is the same as in the first embodiment.

  The projector 1000 according to the second embodiment has the following operational effects. When projecting a projection image on the projection screen 2000, it is not necessary to move the lens of the optical system 110 in order to bring the optical system 110 into focus. Since it is not necessary to secure a space for moving the lens and a space for providing the lens driving unit, the projector 1000 can be miniaturized.

  The above-described embodiments and modifications may be combined. In addition, the present invention is not limited to the configurations in the above-described embodiments as long as the characteristic functions of the present invention are not impaired.

1 component pixel, 2 virtual pixel,
13, 19 micro lens, 14 light receiving element, 18 display pixel,
50 luminous flux centroid, 51, 52, 70, 71, 72 rays,
100, 1000 projector,
110 optical system, 120 optical element,
130, 190 Micro lens array, 140 Image sensor,
150 focal position calculation device, 160 projection pixel signal generation device,
170 illumination device, 180 display element, 200 projection screen,
210 designated image plane,
510 projection image for focal position calculation, 515 black stripes, 516 white stripes,
610 area

Claims (5)

A first microlens array in which a plurality of first microlenses are arranged;
A display element in which a plurality of display pixels that output a projection pixel signal are arranged corresponding to each of the plurality of first microlenses;
An illumination device that illuminates the display element and emits a plurality of projection light beams from the plurality of display pixels;
An optical system for projecting the plurality of projection light beams from the plurality of display pixels that have passed through the first microlens array onto a projection surface to project a projection image;
Generating means for generating the projection pixel signal so that the projection image is projected in a state corresponding to a projection distance from the optical system to the projection plane;
The projector, wherein the display element and the optical system are in an optically conjugate relationship with respect to the first microlens array. The projector according to claim 1, wherein
A projector further comprising a calculation means for calculating the projection distance. The projector according to claim 2,
A second microlens array in which a plurality of second microlenses are arranged;
An image sensor in which a plurality of light receiving elements that receive an incident light beam from the projection surface and output a light reception signal are arranged corresponding to each of the plurality of second microlenses;
An optical element that transmits the projected light beam and reflects the incident light beam toward the imaging device;
The optical system passes the incident light beam toward the optical element;
The image sensor and the optical system are in an optically conjugate relationship with respect to the second microlens array,
The calculation means calculates the projection distance by a pupil division type phase difference detection method using the received light signal,
The projector according to claim 1, wherein the generation unit generates the projection pixel signal using the light reception signal. The projector according to claim 3, wherein
The projector according to claim 1, wherein the calculation means calculates the projection distance for each partial region included in the projection image. The projector according to claim 3 or 4,
The display element and the imaging element are arranged at positions equivalent to each other with respect to the optical system,
The projector according to claim 1, wherein the first microlens array and the second microlens array are disposed at positions equivalent to each other with respect to the optical system.