JP2024040664A - projector - Google Patents

Abstract

An object of the present invention is to provide a projector that can adjust the depth of focus of a displayed image and can project a displayed image with less blur even on a screen including a curved or inclined surface.
SOLUTION: A projector 1 that projects a display image V, which includes a laser light source 11 that emits a laser beam, a spatial phase modulator 13 that diffracts the laser beam to form a display image V, and a spatial phase modulator 13 The controller 15 includes a depth of focus adjustment means that adjusts the depth of focus of the display image V by changing the display image forming area 13a of the spatial phase modulator 13.
[Selection diagram] Figure 1

Description

The present disclosure relates to a projector.

2. Description of the Related Art A projector that projects a display image using a spatial light modulator (SLM) is known (for example, see Patent Document 1).

Special Publication No. 2009-536747

However, this type of projector has a problem in that when a display image is projected onto a screen that includes a curved surface or an inclined surface, a projection area is generated that is out of focus, and the display image is likely to be blurred.

Therefore, an object of the present disclosure is to provide a projector that can adjust the depth of focus of a displayed image and can project a displayed image with less blur even on a screen including a curved surface or an inclined surface.

In one aspect, a projector that projects a display image,
a laser light source that emits laser light;
a spatial phase modulator that diffracts the laser beam to form the display image;
A control unit that controls the spatial phase modulator,
A projector is provided in which the control unit includes a depth of focus adjustment means for adjusting a depth of focus of the display image by changing a display image forming area of the spatial phase modulator.

According to the present disclosure, it is possible to provide a projector that can adjust the depth of focus of a displayed image and can project a displayed image with less blur even on a screen that includes a curved surface or an inclined surface.

FIG. 2 is a schematic diagram showing the configuration of the projector of the present embodiment in a cross-sectional view from the side. (a) is a schematic diagram showing a state in which the display image forming area of the spatial phase modulator is wide, and (b) is a schematic diagram showing that the depth of focus is narrow (shallow) due to the wide display image forming area of the spatial phase modulator. FIG. (a) is a schematic diagram showing a state in which the display image forming area of the spatial phase modulator is narrowed, and (b) is a schematic diagram showing a state in which the display image forming area of the spatial phase modulator is narrowed, so that the depth of focus becomes wider (deeper). FIG. FIG. 3 is a diagram showing the influence of zero-order light that may occur on a displayed image. FIG. 3 is a diagram showing a dispersion pattern (one example) displayed in a mask area of a spatial phase modulator. 6 is a diagram showing the effect of the dispersion pattern of FIG. 5. FIG. It is a figure which shows the dispersion pattern (another example) displayed on the mask area of a spatial phase modulator. 8 is a diagram showing the effect of the dispersion pattern of FIG. 7. FIG. (a) is a diagram showing an example of the brightness level determined from the display image forming pattern, (b) is a diagram showing the dispersion pattern in FIG. 5 in terms of brightness level, and (c) is a diagram showing the dispersion pattern in FIG. 7 in terms of brightness level. This is a diagram. FIG. 6 is a diagram showing an example of calculation of a display image formation pattern. FIG. 7 is a diagram showing a display image when lens data is added to a mask area. FIG. 7 is an explanatory diagram when lens data is not added to a mask area. FIG. 7 is a diagram showing the effect when lens data is not added to a mask area. (a) is a diagram showing an example of the mask area, (b) is a diagram showing a first modification of the mask region, (c) is a diagram showing a second modification of the mask region, and (d) is a diagram of the mask region. A diagram showing a third modification example, and (e) a diagram showing a fourth modification example of the mask area. FIG. 3 is a diagram showing an example of application of the projector according to the present embodiment.

Hereinafter, each embodiment will be described in detail with reference to the accompanying drawings. Note that in the drawings, for ease of viewing, only some of the parts having the same attribute may be labeled with reference numerals.

FIG. 1 is a schematic diagram showing the configuration of a projector 1 according to the present embodiment in a cross-sectional view from the side.
As shown in FIG. 1, the projector 1 of this embodiment projects a display image V onto a screen (not shown) by emitting display light PL. For example, the projector 1 emits display light PL including interference fringes forming a computer-generated hologram (CGH).

The projector 1 includes a laser light source 11 , a collimating section 12 , a spatial phase modulator 13 , a case 14 , and a control section 15 .

The laser light source 11 includes, for example, a laser diode that emits green laser light. In this embodiment, as an example, a single laser light source 11 (one color) is provided, but a plurality of laser light sources 11 may be provided. For example, three light sources for RGB may be utilized.

The collimator 12 converts the light from the laser light source 11 into parallel light, and emits the parallel light toward the spatial phase modulator 13 . The collimator 12 may cause the light from the laser light source 11 to enter the spatial phase modulator 13 in substantially the form of a plane wave.

The spatial phase modulator 13 is a reflective modulator (spatial light modulator) that displays interference fringes based on CGH. The spatial phase modulator 13 operates under the control of the control section 15. As the spatial phase modulator 13, for example, an LCOS-SLM (Liquid Crystal on Silicon-Spatial Light Modulator) is used.

Case 14 houses laser light source 11, collimator 12, and spatial phase modulator 13. The case 14 has an exit port 14a, and the display light PL is emitted from inside the case 14 toward the screen via the exit port 14a. Note that the emission port 14a may be covered with a transparent dustproof cover.

The control unit 15 is a control computer including a CPU, ROM, RAM, etc., and controls the spatial phase modulator 13 based on input or stored display image data to display the display image V on the screen. The control unit 15 includes a depth of focus adjustment means, a zero-order light dispersion means, a display image formation pattern calculation means, and the like as functional configurations realized through cooperation between hardware and software. Hereinafter, these functional configurations will be sequentially explained with reference to FIGS. 2 to 13.

2(a) is a schematic diagram showing a state in which the display image forming area 13a of the spatial phase modulator 13 is wide, and FIG. 2(b) is a schematic diagram showing a state in which the display image forming area 13a of the spatial phase modulator 13 is wide. , is a diagram showing that the depth of focus is narrowed (shallow).
The control unit 15 calculates a display image forming pattern VP of the spatial phase modulator 13 from input or stored display image data, and controls the spatial phase modulator 13 based on the calculated display image forming pattern VP. As shown in FIG. 2(a), in the normal display image forming pattern VP (a pattern in which the entire display area of the spatial phase modulator 13 is used as the display image forming area 13a), the depth of focus is narrow and If it is misaligned, the displayed image V is likely to become blurred. For example, as shown in FIG. 2B, assume that the screens are 300 mm, 400 mm, 500 mm, 600 mm, 700 mm, 800 mm, 900 mm, and 1000 mm in distance from the projector 1 (spatial phase modulator 13). When a display image V having a focal length of 600 mm is projected onto these screens, the display image V without blur will be displayed on the screen installed at a distance of 600 mm. On the other hand, with a screen installed at a distance of 500 mm or a screen installed at a distance of 700 mm, the displayed image V will be blurred. Further, in a screen installed at a distance of 400 mm or less or a screen installed at a distance of 800 mm or more, the blur may become severe and it may be difficult to recognize the displayed image V. Therefore, when the depth of focus is narrow, when the display image V is projected onto a screen including a curved surface or an inclined surface, an out-of-focus projection area may occur, and the display image V may become blurred.

3(a) is a schematic diagram showing a state in which the display image forming area 13a of the spatial phase modulator 13 is narrowed, and FIG. 3(b) is a schematic diagram showing a state in which the display image forming area 13a of the spatial phase modulator 13 is narrowed. This is a diagram showing that the depth of focus is widened (deepened) by this.
The depth of focus adjustment means adjusts the depth of focus of the display image V by changing the display image forming area 13a of the spatial phase modulator 13. For example, as shown in FIG. 3A, of the entire display area of the spatial phase modulator 13, the display image forming area 13a is narrowed down to only the center part, and the outer peripheral side thereof is a mask area 13b where no display image V is formed. By doing so, the depth of focus is widened. According to such depth of focus adjustment, by widening the depth of focus, it is possible to project a display image V with less blur even on a screen including a curved surface or an inclined surface. For example, as shown in FIG. 3B, assume that the screens are 300 mm, 400 mm, 500 mm, 600 mm, 700 mm, 800 mm, 900 mm, and 1000 mm in distance from the projector 1 (spatial phase modulator 13). When a display image V with a focal length of 600 mm and a wide depth of focus is projected onto these screens, a blur-free display image V is displayed not only on the screen installed at a distance of 600 mm but also on all screens. becomes possible. This principle is similar to how increasing the aperture value of a camera increases the depth of focus and widens the range of distances that are in focus.

When the depth of focus is widened based on the above principle, the area of the spatial phase modulator 13 that can be used to form a display image is limited, so the resolution of the display image V may be reduced. Therefore, it is desirable to prepare a plurality of depth of focus adjustment patterns based on the relationship between the required resolution of the display image V and the depth of focus, and to be able to select a suitable depth of focus adjustment pattern from among them. For example, a pattern with a narrow depth of focus but a high resolution of the display image V and a pattern with a wide depth of focus but with a slightly lower resolution of the display image V are prepared, and either pattern can be selected.

FIG. 4 is a diagram showing the influence of zero-order light that may occur on the displayed image V.
Since the spatial phase modulator 13 of this embodiment is of a reflective type, even if a mask region 13b in which no display image V is formed is set, reflected light from the mask region 13b is generated. This reflected light becomes unnecessary light L0 and may deteriorate the quality of the displayed image V. For example, as shown in FIG. 4, zero-order light with strong brightness is generated at the center of the display image V, and this may become unnecessary light L0 and deteriorate the image quality of the display image V.

FIG. 5 is a diagram showing a dispersion pattern P1 (one example) displayed on the mask region 13b of the spatial phase modulator 13, and FIG. 6 is a diagram showing the effect of the dispersion pattern P1 of FIG. 5.
When narrowing the display image forming area 13a, the zero-order light dispersion means creates a dispersion pattern P1 that can disperse the zero-order light outside the display image forming area 13a in the mask area 13b on the outer peripheral side of the display image forming area 13a. Display. The dispersion pattern P1 shown in FIG. 5 is a lattice pattern in which two types of pattern elements P1a and P1b having different phases (brightness levels) are arranged in a lattice shape to generate a lattice-like phase difference (brightness level). According to such a dispersion pattern P1, as shown in FIG. 6, the unnecessary light L0 can be dispersed in four directions outside the display image forming area 13a, and deterioration in the image quality of the display image V can be avoided.

FIG. 7 is a diagram showing a dispersion pattern P2 (another example) displayed on the mask region 13b of the spatial phase modulator 13, and FIG. 8 is a diagram showing the effect of the dispersion pattern P2 of FIG. 7.
The dispersion pattern P2 shown in FIG. 7 is a horizontal stripe pattern in which two types of pattern elements P2a and P2b having different phases (brightness levels) are arranged in a horizontal stripe pattern to produce a horizontal stripe-like phase difference (brightness level). According to such a dispersion pattern P2, as shown in FIG. 8, the unnecessary light L0 can be dispersed in two directions outside the display image forming area 13a, and deterioration in the image quality of the display image V can be avoided. Note that the dispersion patterns P1 and P2 are not limited to the above-mentioned lattice pattern or horizontal striped pattern, but may be a vertical striped pattern or the like.

9(a) is a diagram showing an example of the brightness level determined from the display image forming pattern VP, FIG. 9(b) is a diagram showing the luminance level of the dispersion pattern P1 of FIG. c) is a diagram showing the dispersion pattern P2 of FIG. 7 in terms of brightness levels.
When displaying the phase-type CGH display image forming pattern VP in the spatial phase modulator 13, the phase difference provided is converted into a pixel brightness level and input to the spatial phase modulator 13. For example, when the brightness level of the spatial phase modulator 13 is 8 bits, the phase difference of the display image forming pattern VP is converted into a brightness level of 0 to 255 (see (a) in FIG. 9). Therefore, when displaying the dispersion pattern P1 shown in FIG. 5 in the mask area 13b of the spatial phase modulator 13, for example, the pattern element P1a with a luminance level of 0 and the pattern element P1b with a luminance level of 128 are arranged in a grid pattern. The arranged data is used (see (b) in FIG. 9). Further, when displaying the dispersion pattern P2 shown in FIG. 7 in the mask area 13b of the spatial phase modulator 13, for example, pattern element P2a with a luminance level of 0 and pattern element P2b with a luminance level of 128 are arranged in horizontal stripes. The arranged data is used (see (c) in FIG. 9).

FIG. 10 is a diagram showing an example of calculating the display image forming pattern VP, and FIG. 11 is a diagram showing the display image V when the lens data D2 is added to the mask area 13b.
As shown in FIG. 10, the display image formation pattern calculation means calculates the display image formation pattern VP of the spatial phase modulator 13 by adding lens data D2 that determines the display position of the object to the object data D1 to be displayed. However, when the lens data D2 is added to the display image forming area 13a and the mask area 13b, as shown in FIG. There is a possibility that

FIG. 12 is an explanatory diagram when the lens data D2 is not added to the mask area 13b, and FIG. 13 is a diagram showing the effect when the lens data D2 is not added to the mask area 13b.
As shown in FIG. 12, when setting the mask area 13b to widen the depth of focus, the display image forming pattern calculation means does not add the lens data D2 to the mask area 13b and uses the dispersion patterns P1 and P2 as they are. In this way, as shown in FIG. 13, it becomes possible to widen the depth of focus and project a display image V in which no diffracted light L1 is generated.

Although each embodiment has been described in detail above, it is not limited to a specific embodiment, and various modifications and changes can be made within the scope of the claims. It is also possible to combine all or a plurality of the components of the embodiments described above.

For example, the shape of the mask region 13b is not limited to the shape in which the display image forming region 13a is rectangular as shown in FIG. 14(a), but also the shape as shown in FIGS. Good too. For example, according to the mask area 13b shown in FIG. 14(b), the display image forming area 13a can be made square. Further, according to the mask area 13b shown in FIG. 14(c), the display image forming area 13a can be made circular. Further, according to the mask area 13b shown in FIG. 14(d), the display image forming area 13a can be formed into an ellipse. In addition, in the mask area 13b shown in FIGS. 14(a) to 14(d), the display image forming area 13a is narrowed down in two directions (the vertical direction and the horizontal direction in FIG. 14), but in the mask area 13b shown in FIG. As shown, the narrowing down may be performed only in one direction (the horizontal direction in FIG. 14).

Further, the use of the projector 1 according to this embodiment can be arbitrarily selected. For example, as shown in FIG. 15, the projector 1 is installed on a ceiling 101 of a vehicle interior 100, and is suitable for use in projecting a display image V onto a steering wheel 102 or a meter panel 103. In this case, the steering wheel 102 and meter panel 103, which serve as screens, are inclined surfaces when viewed from the projector 1, and furthermore, since the steering wheel 102 includes a curved surface, in a normal projector, the projected display image V is blurred. Easy to occur. Further, since the steering wheel 102 and the meter panel 103 are located at different distances from the projector 1, it is difficult to project the display image V onto the steering wheel 102 and the meter panel 103 at the same time using a normal projector. On the other hand, since the projector 1 according to the present embodiment includes the depth of focus adjustment means described above, by widening the depth of focus, it becomes possible to project the display image V with less blur onto the steering wheel 102 and the meter panel 103. Moreover, if the depth of focus is further increased, it becomes possible to project the display image V onto the steering wheel 102 and the meter panel 103 at the same time.

1 Projector 11 Laser light source 13 Spatial phase modulator 13a Display image forming area 13b Mask area 15 Control units P1, P2 Dispersion pattern

Claims (4)

A projector that projects a display image,
a laser light source that emits laser light;
a spatial phase modulator that diffracts the laser beam to form the display image;
A control unit that controls the spatial phase modulator,
The projector, wherein the control unit includes a depth of focus adjustment unit that adjusts a depth of focus of the display image by changing a display image forming area of the spatial phase modulator. The spatial phase modulator is of a reflective type,
When the display image forming area is narrowed, the control unit controls the zero-order light to display a dispersion pattern in which the zero-order light can be dispersed outside the display image forming area in a mask area on the outer peripheral side of the display image forming area. The projector according to claim 1, comprising dispersion means. The projector according to claim 2, wherein the dispersion pattern is any one of a lattice pattern, a vertical stripe pattern, and a horizontal stripe pattern. The displayed image is a computer-generated hologram,
The control unit includes display image formation pattern calculation means for calculating a display image formation pattern of the spatial phase modulator by adding lens data that determines a display position of the object to object data to be displayed;
4. The projector according to claim 2, wherein the display image formation pattern calculation means does not add the lens data to the mask area.