CN110365956A - a projection device - Google Patents

Abstract

The invention discloses a projection device. The device includes an illumination light source, a reflection prism, a DMD module and a rotatable reflection mirror, the illumination light source, the reflection prism and the rotatable reflection mirror are arranged in sequence, and the light emitted from the illumination light source passes through the reflection prism and the rotatable reflection mirror. After the DMD module is coupled, it is incident on the rotatable mirror and is reflected by the rotatable mirror, and the rotatable mirror is configured to rotate around the first axis when the DMD module is turned on The reciprocating rotation and the delay setting time period reciprocating rotation around the second axis, so that a single pixel expands in directions perpendicular to the first axis and perpendicular to the second axis.

Description

a projection device

technical field

The present invention relates to the field of optical technology, and more particularly, to a projection device.

Background technique

DLP projection display equipment usually includes an illumination light source, a TIR prism, a DMD module and a projection lens. The illumination light source is used for outgoing light. The TIR prism receives the light beam from the illumination light source, refracted and then exits to the DMD module. The DMD module is used to reflect the light beam from the TIR prism back to the TIR prism. After the TIR prism converts the light path of the light beam, the light beam is incident on the projection lens. The beam is enlarged by the projection lens and then projected as an image.

However, the pixels of existing DLP projection display devices depend on the size of the micro-mirrors of the DMD module. In general, the dimensions of the micromirrors are fixed. The pixels of the DLP projection display device cannot be improved, resulting in poor projection imaging effect, which cannot meet people's requirements for a high-definition look and feel of projected images.

Therefore, it is necessary to provide a new technical solution to solve the above-mentioned technical problems.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a new technical solution for a projection device.

According to a first aspect of the present invention, a projection device is provided. The device includes an illumination light source, a reflecting prism, a DMD module and a rotatable reflecting mirror, the illumination light source, the reflecting prism and the rotatable reflecting mirror are arranged in sequence, and the light emitted from the illumination light source passes through the reflecting prism and the rotatable reflecting mirror. After the DMD module is coupled, it is incident on the rotatable mirror and is reflected by the rotatable mirror, and the rotatable mirror is configured to rotate around the first axis when the DMD module is turned on The reciprocating rotation and the delay setting time period reciprocating rotation around the second axis, so that a single pixel expands in directions perpendicular to the first axis and perpendicular to the second axis.

Optionally, the first axis and the second axis are perpendicular.

Optionally, the period in which the rotatable mirror rotates around the first axis is the duration of the opening of the DMD module, and the period in which the rotatable mirror rotates around the first axis is the same as the period in which the rotatable mirror rotates around the second axis. The rotation cycles are the same, and the delay time of the rotation of the rotatable mirror around the second axis relative to the rotation around the first axis is a quarter of its own cycle.

Optionally, the distance at which a single pixel is extended in directions perpendicular to the first axis and perpendicular to the second axis is half a pixel.

Optionally, the rotatable mirror is a MEMS reflective galvanometer.

Optionally, further comprising a projection lens located downstream of the rotatable mirror, wherein the extension of a single pixel in at least one of the directions perpendicular to the first axis and perpendicular to the second axis The distance is calculated as Δy,

Δy=L×2θ

Wherein, L is the distance between the rotatable mirror and the projection lens; θ is the radian of the rotatable mirror's rotation relative to the initial position.

Optionally, the illumination light source is a laser light source or an LED light source.

Optionally, the total duration of the reciprocating rotation of the rotatable mirror around the first axis and the second axis is less than or equal to the duration of the human eye delay effect.

Optionally, the starting moment of the reciprocating rotation of the rotatable mirror around the first axis is the same as the opening moment of the DMD module.

Optionally, a single pixel is 5.4 μm.

Optionally, the reflecting prism is a TIR prism or an ITIR prism.

According to an embodiment of the present disclosure, one pixel is expanded into a plurality of pixels by utilizing the time-delay effect of the human eye, thereby achieving the effect of expanding the pixel resolution, thereby effectively improving the resolution of the projected image.

Other features and advantages of the present invention will become apparent from the following detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings.

Description of drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention.

FIG. 1 is a schematic structural diagram of a projection apparatus according to an embodiment of the present disclosure.

FIG. 2 is a schematic structural diagram of another projection apparatus according to an embodiment of the present disclosure.

FIG. 3 is a schematic diagram of shifting a pixel after being reflected by a galvanometer mirror according to an embodiment of the present disclosure.

4 is a schematic diagram of a pixel and a galvanometer rotating around two axes according to an embodiment of the present disclosure.

5 is a flowchart of pixel expansion according to one embodiment of the present disclosure.

FIG. 6 is a schematic diagram of timing matching between a DMD module and a galvo mirror according to an embodiment of the present disclosure.

Description of reference numbers:

1: illumination light source; 2: TIR prism; 2a: ITIR prism; 3: DMD module; 4: galvanometer; 5: projection lens; 6: projected image.

Detailed ways

Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the invention unless specifically stated otherwise.

The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such techniques, methods, and apparatus should be considered part of the specification.

In all examples shown and discussed herein, any specific values should be construed as illustrative only and not limiting. Accordingly, other instances of the exemplary embodiment may have different values.

It should be noted that like numerals and letters refer to like items in the following figures, so once an item is defined in one figure, it does not require further discussion in subsequent figures.

According to one embodiment of the present disclosure, a projection apparatus is provided. As shown in FIGS. 1-2 , the device includes an illumination light source 1 , a reflecting prism, a DMD (Digital Micro Mirror) module 3 , a rotatable reflecting mirror and a projection lens 5 .

The reflection prism is a TIR prism 2 (total internal reflection prism) or an ITIR prism 2a (total internal reflection prism). As shown in FIG. 1 , the ITIR prism 2 a totally reflects the light that is formed by the illumination light source 1 incident on the DMD module 3 to the reflective galvanometer 4 . As shown in FIG. 2 , the TIR prism 2 totally reflects the light incident from the illumination light source 1 , and then the light passes through the DMD module 3 for imaging. The imaged light is transmitted through the TIR prism 2 and then irradiated onto the reflective galvanometer 4 .

The following description will take the ITIR prism as an example. The illumination light source 1, the ITIR prism 2a and the rotatable mirror are arranged in this order. For example, the illumination light source 1 may be, but not limited to, a laser light source or an LED light source. The light emitted by the illumination light source 1 is RGB light. The light emitted by the illumination light source 1 is coupled with the DMD module 3 via the ITIR prism 2a. Incident to the rotatable mirror and reflected by the rotatable mirror. The light is reflected and incident on the projection lens 5 . After being enlarged by the projection lens 5, the light forms a projected image 6 on the projection surface.

For example, during coupling, the ITIR prism 2 a receives the illuminating beam emitted by the illuminating light source 1 , and performs optical path conversion on the illuminating beam, so that the illuminating beam is incident on the DMD module 3 . After the illumination beam is reflected by the DMD module 3, it is incident on the ITIR prism 2a again. The ITIR prism 2a receives the projection light beam output by the DMD module 3 according to the illumination light beam, converts the light path of the projection light beam, and then emits it to the rotatable mirror.

The DMD module 3 includes a plurality of rotatable micro-mirrors. The size of the micro-mirror determines the pixels of the projection module. Each micromirror is capable of reflecting light. The DMD module 3 includes two states: open and closed. When turned on, the DMD module 3 reflects the illumination beam from the ITIR prism 2a. In the closed state, the DMD module 3 rotates so that the illumination beam is not reflected. The opening and closing states of the plurality of micro-mirrors are the same or different.

The rotatable mirror includes a mirror body and a driving device. The driving device is used for driving the mirror body to rotate around the first axis and the second axis. For example, the mirror body is a flat mirror. The projection beam hits the mirror body and is reflected by the mirror body.

Of course, in other examples, the mirror body is a convex mirror or a concave mirror. This can also play the role of offsetting the pixels.

As shown in FIG. 4 , the rotatable mirror is configured to reciprocate around the first axis when the DMD module 3 is turned on, and reciprocate around the second axis for a set delay time, so that a single pixel is perpendicular to the The first axis and the direction perpendicular to the second axis are expanded. For example, reciprocating rotation means that the rotatable mirror rotates unilaterally by a set angle relative to the first axis or the second axis, and then returns to the original position relative to the respective axis.

For example, as shown in Figure 4, the first axis is the x-axis. The second axis is the y-axis. The rotatable mirror is a galvanometer mirror 4 . Galvo mirror 4 includes a MEMS device and a mirror. MEMS devices are actuating devices. The reflector is the mirror body. For example, the mirrors are rectangular, circular, elliptical, and the like. The MEMS device drives the mirror to rotate around the x-axis and the y-axis. Of course, the material of the mirror body is not limited to glass, but can also be metal or the like.

Take an elliptical mirror as an example. The x-axis and the y-axis are located on the short and long axes of the mirror, respectively. This makes the rotation of the mirror around the x-axis and the y-axis more balanced. The mirrors have a more balanced effect on the expansion of the projected beam.

As shown in Fig. 3-5, the galvanometer 4 rotates around the x-axis first. The pixels on the projected image 6 are offset perpendicular to the x-axis. At this time, due to the delay effect of the human eye, one pixel is expanded into two pixels. The distance between the two pixels should be such that the human eye can distinguish the two pixels.

For example, a single pixel is extended by a distance of half a pixel in the directions perpendicular to the first axis and perpendicular to the second axis. The distance of this extension is the offset. When the offset is half a pixel, the pixel is also half a pixel away from its neighbors. The human eye is able to distinguish a shifted pixel from the original pixel and another adjacent pixel without thinking it is coincident with other pixels.

Of course, the extended distance is not limited to half a pixel, and may be a distance slightly closer or farther from the original pixel, as long as the human eye can distinguish the shifted pixel from other pixels.

Then, after delaying the set time, turn it around the y-axis to one side. Pixels are offset perpendicular to the y-axis. At this time, due to the delay effect of the human eye, another pixel is extended. It should be noted that the pixel is offset by a distance of half a pixel, that is, one pixel is extended.

Next, the galvanometer mirror 4 returns to the original position around the x-axis. At this time, the rotation around the y-axis is still at a position deviated from the initial position, so it is extended by one pixel.

Finally, the galvanometer mirror 4 returns to the original position around the y-axis. Due to the time-lapse effect of the human eye, the human can see four pixels instead of one.

In the embodiment of the present disclosure, the rotatable mirror rotates around the first axis and the second axis, so as to rapidly scan the projection beam. The pixels are incident on the rotatable mirror. As the rotatable mirror rapidly scans around the first axis and the second axis and is reflected by the rotatable mirror, the projection beam moves rapidly in the direction perpendicular to the first axis and the direction perpendicular to the second axis. Using the time-delay effect of the human eye, one pixel is expanded into a plurality of pixels, thereby achieving the effect of expanding the pixel resolution, thereby effectively improving the resolution of the projected image 6 .

The total duration of the reciprocating rotation of the rotatable mirror around the first axis and the second axis is less than or equal to the duration of the human eye delay effect. In this way, within the delay effect time of the human eye, the human can see a plurality of pixels expanded from one pixel.

In other examples, the projection device can be expanded from one pixel to 2, 3, 5 or more pixels by setting the rotation of the rotatable mirror.

In one example, the first axis and the second axis are perpendicular. Compared with the case where the two axes are not vertical, when the rotatable mirror is rotated, the vertical arrangement of the two axes makes the distance between two adjacent pixels larger, and multiple pixels are easier to distinguish, while not overlapping.

In one example, as shown in FIG. 6 , the period during which the rotatable mirror rotates around the first axis is the opening time of the DMD module 3 . The period of rotation of the rotatable mirror about the first axis is the same as the period of rotation about the second axis.

Under normal circumstances, the DMD module 3 experiences a high level and a low level for one cycle. When at a high level, the DMD module 3 is in an open state; when at a low level, the DMD module 3 is in an off state. The duration of the open state and the closed state are equal.

Take the example of a rotatable mirror that rotates around a first axis (eg, the x-axis). When at a high level, the galvanometer 4 rotates about the x-axis by θ radians (eg, relative to the initial position); when at a low level, the galvanometer 4 rotates about the x-axis by -θ radians. In the initial position, the projection beam is perpendicular to the incident surface.

Preferably, the arc of reciprocating rotation of the rotatable mirror around the first axis is the same as the arc of reciprocating rotation around the second axis. That is, when at a high level, the galvanometer 4 rotates about the y-axis by θ radians (eg, relative to the initial position); when at a low level, the galvanometer 4 rotates about -θ radians with respect to the y-axis. In this way, the connection line of the four pixels is a square, which can ensure that the image spreads more evenly in the plane.

In this example, the period of rotation of the rotatable mirror about the first axis and the period of rotation about the second axis are half the period of the DMD module 3 . The starting moment of the reciprocating rotation of the rotatable mirror around the first axis is the same as the opening moment of the DMD module 3 . The rotation of the rotatable mirror about the second axis is delayed relative to the rotation about the first axis by a quarter of its period. This synchronizes the rotation and stop of the rotatable mirror with the opening and closing of the DMD module.

In this example, as shown in FIG. 3 , the galvanometer is rotated by θ radians, and the reflected light is rotated by 2θ radians. The extended distance of a single pixel in at least one of the directions perpendicular to the first axis and perpendicular to the second axis is counted as Δy. It can be concluded from Figure 3 that,

Δy=L×tan(2θ)

Since 2θ is a small radian, the above formula can be approximated as: Δy=L×2θ

Among them, θ is the arc of rotation of the rotatable mirror relative to the initial position; L is the distance between the rotatable mirror and the projection lens.

In one example, the size of one pixel of the DMD module 3 is 5.4 μm. The storage for half a pixel is 2.7 μm. That is, Δy=2.7 μm. In the usual case, L is known. θ can be calculated according to the above formula.

As shown in Figure 5-6, the working process of the projection device is as follows:

S1. At the beginning, the DMD module 3 is at a high level, that is, the DMD module 3 is in an open state. The rotation of the galvanometer 4 around the x-axis is at a high level, that is, the galvanometer rotates around the x-axis by θ radians (relative to the initial position). At this time, due to the delay effect of the human eye, the pixels are shifted upward by half a pixel (ie, 2θ radians).

S2. After a quarter period of delay, the rotation of the galvanometer 4 around the y-axis starts and is at a high level, that is, the galvanometer continues to rotate θ around the y-axis on the basis of rotating around the x-axis by θ radians. radians (relative to the initial position). Since the x-axis is perpendicular to the y-axis, the projection device shifts half a pixel to the right on the basis of the expanded pixel.

S3. After a half cycle of rotating around x, the rotation of the galvanometer 4 around the y-axis and the DMD module 3 are still at a high level. The galvo mirror 4 remains rotated about the y-axis by θ radians (relative to the initial position). The rotation of the galvanometer 4 around the x-axis is at a low level, that is, the rotation radian is -θ, so that the galvanometer 4 reaches the initial position of the rotation around the x-axis. Based on the above, the pixel is shifted down by half a pixel.

S4. After three quarters of the cycle around x, the DMD module 3 is still at a high level. The rotation of the galvanometer 4 around the y-axis and the rotation around the x-axis are both low levels. The galvanometer mirror 4 is rotated around the y-axis by -θ radians, so that the galvanometer mirror 4 reaches the initial position rotated around the y-axis. Shifts the pixel to the left by half a pixel.

When the DMD module 3 is at a low level, the galvanometer mirror 4 does not rotate. Due to the time-lapse effect of the human eye, a human can see four pixels.

The pixel expansion shown in FIG. 5 is an expansion in a clockwise direction within the first quadrant. In other examples, when the rotation direction of the galvanometer mirror 4 changes, the expansion can also be performed in the second, third and fourth quadrants. The direction of expansion can also be counterclockwise.

Although some specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are provided for illustration only and not for the purpose of limiting the scope of the present invention. Those skilled in the art will appreciate that modifications may be made to the above embodiments without departing from the scope and spirit of the present invention. The scope of the invention is defined by the appended claims.

Claims (11)

1. A projection device, comprising an illumination light source, a reflection prism, a DMD module and a rotatable reflection mirror, the illumination light source, the reflection prism and the rotatable reflection mirror are arranged in sequence, and the illuminating light source emits After the light is coupled to the DMD module via the reflective prism, it is incident on the rotatable mirror and is reflected by the rotatable mirror, and the rotatable mirror is configured to be turned on when the DMD module is turned on In the lower part, it can reciprocate around the first axis and reciprocate around the second axis for a set delay time, so that a single pixel expands in directions perpendicular to the first axis and perpendicular to the second axis. 2. The projection device of claim 1, wherein the first axis and the second axis are perpendicular. 3 . The projection device according to claim 1 , wherein a period in which the rotatable mirror rotates around the first axis is an opening period of the DMD module, and the rotatable mirror rotates around the first axis. 4 . The period of rotation is the same as the period of rotation around the second axis, and the delay time of the rotation of the rotatable mirror around the second axis relative to the rotation around the first axis is a quarter of its own period. 4. The projection device of claim 1, wherein a distance by which a single pixel is expanded in directions perpendicular to the first axis and perpendicular to the second axis is half a pixel. 5. The projection device according to claim 1, wherein the rotatable mirror is a galvanometer mirror. 6. The projection apparatus of claim 5, further comprising a projection lens located downstream of the rotatable mirror, wherein a single pixel is positioned perpendicular to the first axis and perpendicular to the second axis The extended distance of at least one of the axial directions is calculated as Δy, Δy=L×2θ Wherein, L is the distance between the rotatable mirror and the projection lens; θ is the radian of the rotatable mirror's rotation relative to the initial position. 7. The projection device according to any one of claims 1-6, wherein the illumination light source is a laser light source or an LED light source. 8. The projection device according to any one of claims 1-6, wherein the total duration of the reciprocating rotation of the rotatable mirror around the first axis and the second axis is less than or equal to the human eye The duration of the delay effect. 9. The projection apparatus according to any one of claims 1-6, wherein the starting moment of the reciprocating rotation of the rotatable mirror around the first axis is the same as the opening moment of the DMD module. 10. The projection device of any of claims 1-6, wherein a single pixel is 5.4 [mu]m. 11. The projection device according to any one of claims 1-6, wherein the reflecting prism is a TIR prism or an ITIR prism.