Phosphor wheel, light source device, and projector

Abstract

The present invention provides a phosphor wheel, light source device, and projector that can improve light utilization efficiency and reduce laser speckle. [Solution] A phosphor wheel 23 having phosphor regions 23r and 23g that convert the wavelength of blue laser light, and which rotates in response to the drive of a rotation mechanism, comprising a red phosphor region 23r that converts blue laser light to red laser light, a green phosphor region 23g that converts blue laser light to green laser light, and a transparent region 23b that transmits blue laser light, the transparent region 23b transmitting blue laser light through a microlens array.

Description

Technical Field

[0001] The present disclosure relates to a phosphor wheel, a light source device, and a projector.

Background Art

[0002] As shown in (a) of FIG. 7, a phosphor wheel 100 including a red phosphor region 101, a green phosphor region 102, and a transmission region 103 is known (see, for example, Patent Document 1). The red phosphor region 101 converts blue laser light LB into red laser light LR, the green phosphor region 102 converts blue laser light LB into green laser light LG, and the transmission region 103 transmits blue laser light LB. According to such a phosphor wheel 100, three primary color laser lights can be obtained in combination with a light source that emits blue laser light LB.

[0003] By the way, in such a phosphor wheel 100, as shown in (b) of FIG. 7, the fluorescence-excited red laser light LR and green laser light LG are emitted from the phosphor wheel 100 with a spread. On the other hand, the blue laser light LB transmitted through the transmission region 103 is emitted without spreading or in a different spreading manner from other laser lights, which may cause a decrease in display quality.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Therefore, the phosphor wheel of Patent Document 1 adjusts the spread of the transmitted blue laser light by providing a diffusion plate in the transmission region. However, using a diffusion plate may reduce the light utilization efficiency or generate laser speckles.

[0006] This disclosure aims to provide a phosphor wheel, light source device, and projector that can improve light utilization efficiency and reduce laser speckle. [Means for solving the problem]

[0007] In one respect, it offers the following solutions: A phosphor wheel having a phosphor region that converts the wavelength of blue laser light, and which rotates in response to the drive of a rotation mechanism, The aforementioned blue laser light is converted into red laser light by a red phosphor region, The aforementioned blue laser light is converted into green laser light by a green phosphor region, It has a transparent region that transmits the blue laser light, The aforementioned transmission region is characterized by transmitting the blue laser light through a microlens array. [Effects of the Invention]

[0008] According to this disclosure, it is possible to provide a phosphor wheel, a light source device, and a projector that can improve light utilization efficiency and reduce laser speckle. [Brief explanation of the drawing]

[0009] [Figure 1] This is a perspective view showing a schematic configuration of the projector. [Figure 2] (a) is a schematic front view showing the phosphor wheel according to this embodiment, and (b) is a schematic diagram showing the arrangement pattern of the microlens regions according to this embodiment. [Figure 3] This figure shows the change in diffusion distribution due to the rotation of the phosphor wheel according to this embodiment. [Figure 4] (a) is a schematic front view showing a modified phosphor wheel, and (b) is a schematic diagram showing the arrangement pattern of the microlens regions related to the modified example. [Figure 5] This figure shows the change in diffusion distribution due to the rotation of the phosphor wheel in the modified example. [Figure 6]This figure shows the relationship between the array pitch of the microlens region and the spot size of the blue laser light. [Figure 7] (a) is a schematic front view showing a conventional phosphor wheel, and (b) is a diagram showing the difference in the spread of laser light emitted from the phosphor wheel. [Modes for carrying out the invention]

[0010] The following describes the embodiments in detail with reference to the attached drawings.

[0011] [Projector] As shown in Figure 1, the projector 1 comprises a light source device 2, a collimator lens 3, a folding mirror 4, a prism 5, a scanning unit 6, a projection lens 7, and a control unit (not shown). Details of the light source device 2, which is the main part of this disclosure, will be described later.

[0012] The collimator lens 3 aligns the red laser beam LR, green laser beam LG, and blue laser beam LB emitted from the light source device 2, causing them to be incident on the folding mirror 4.

[0013] The folding mirror 4 reflects the red laser light LR, green laser light LG, and blue laser light LB incident from the light source device 2 via the collimator lens 3, and directs them into the prism 5.

[0014] The prism 5 reflects the laser beams LR, LG, and LB incident from the light source device 2 via the collimator lens 3 and folding mirror 4, directing them into the scanning unit 6, while simultaneously directing the red laser beam LR, green laser beam LG, and blue laser beam LB scanned by the scanning unit 6 into the projection lens 7.

[0015] The scanning unit 6 scans the incident red laser beam LR, green laser beam LG, and blue laser beam LB to form a color image. As the scanning unit 6, for example, a DMD (Digital Micromirror Device), LCOS (Liquid Crystal On Silicon), or the like is used.

[0016] The projection lens 7 projects the color image formed by the scanning unit 6 onto the screen S.

[0017] The control unit controls the light source device 2 and the scanning unit 6 to project a color image onto the screen S. Specifically, the control unit causes the red laser beam LR, green laser beam LG, and blue laser beam LB to be emitted from the light source device 2 in a time-sharing manner. The control unit has red-image data, green-image data, and blue-image data, and projects a color image by switching the image data of each color applied to the scanning unit 6 at the timing when the red laser beam LR, green laser beam LG, and blue laser beam LB are emitted.

[0018] [Light Source Device] Next, the light source device 2 will be described with reference to FIGS. 1 to 6.

[0019] As shown in FIG. 1, the light source device 2 includes a light source 21, a condenser lens 22, and a phosphor wheel 23.

[0020] The light source 21 emits a blue laser beam LB. For example, the light source 21 shown in FIG. 1 includes a plurality of LDs (laser diodes) that emit a blue laser beam LB, and the plurality of LDs are arranged in a matrix configuration.

[0021] The condenser lens 22 condenses the blue laser beam LB emitted from the light source 21 and makes it incident on the phosphor wheel 23.

[0022] As shown in Figure 2, the phosphor wheel 23 has a red phosphor region 23r that converts blue laser light LB to red laser light LR, a green phosphor region 23g that converts blue laser light LB to green laser light LG, and a transparent region 23b that transmits blue laser light LB. The phosphors forming the red phosphor region 23r and the green phosphor region 23g are susceptible to heat and require cooling. Therefore, at least during use, the phosphor wheel 23 is rotated around its rotation axis O by a rotation mechanism (not shown).

[0023] The transmission region 23b transmits blue laser light LB through a microlens array. The microlens array has multiple (numerous) microlens regions ML, which are arranged in a sequence. Each microlens region ML is a convex lens, for example, having a shape such as a square or hexagon when viewed from the front. The convex lenses are formed so that the spreading of the blue laser light LB transmitted through the transmission region 23b matches the spreading of the red laser light LR and green laser light LG, which are fluorescence-excited by the red phosphor region 23r and the green phosphor region 23g.

[0024] Such a transparent region 23b allows for the adjustment of the spread of the blue laser light LB transmitted by the microlens array. Therefore, the spread of the blue laser light LB transmitted through the transparent region 23b can be matched to the spread of the red laser light LR and green laser light LG, which are fluorescence-excited in the red phosphor region 23r and green phosphor region 23g, respectively.

[0025] Furthermore, since the transmission region 23b spreads the blue laser light LB using a microlens array, the diffusion distribution of the blue laser light LB can be appropriately controlled based on the shape and arrangement of the microlens region ML, thereby improving the light utilization efficiency compared to using a diffuser plate. In addition, laser speckle can be reduced by using a microlens array. The effect of reducing laser speckle by a microlens array is well known and is shown, for example, in Japanese Patent Publication No. 2014-194472 and International Publication No. 2015 / 182619.

[0026] As shown in Figures 2(a), 2(b) and 2(b), the multiple microlens regions ML constituting the microlens array of the transmission region 23b are arranged along the circumference centered on the rotation axis O of the phosphor wheel 23. With this arrangement pattern of microlens regions ML, as shown in Figure 3, the diffusion distribution of blue laser light by the microlens regions ML remains stable even when the phosphor wheel 23 rotates, thus avoiding a decrease in light utilization efficiency due to fluctuations in the diffusion distribution.

[0027] Incidentally, as shown in Figures 4(a), (b) and 5, it is also possible to arrange the microlens regions ML in an orthogonal matrix arrangement instead of a circumferential arrangement. However, in this case, as shown in Figure 5, the diffusion distribution of the blue laser light by the microlens regions ML fluctuates (rotates) in accordance with the rotation of the phosphor wheel 23, which may reduce the light utilization efficiency.

[0028] The array pitch (lens size) of the microlens regions ML must be set according to the size (diameter) of the blue laser beam spot SP. As shown in Figure 6, if the array pitch of the microlens regions ML is too large relative to the size of the blue laser beam spot SP, the diffusion distribution will be biased depending on the relative position of the microlens regions ML and the spot SP. Conversely, if the array pitch of the microlens regions ML is too small relative to the size of the blue laser beam spot SP, the diffraction effect of the microlens array will be significant, and the diffusion distribution of the blue laser beam will become granular. For these reasons, it is desirable that the array pitch of the microlens regions ML be smaller than the size of the blue laser beam spot SP, and larger than half the size of the blue laser beam spot SP.

[0029] Although the embodiments have been described in detail above, the invention is not limited to any particular embodiment, and various modifications and changes are possible within the scope of the claims. Furthermore, it is possible to combine all or more of the components of the embodiments described above. [Explanation of symbols]

[0030] 1. Projector 2 Light source device 21 Light source 22 Focusing lenses 23 Phosphor Wheel 23r Red phosphor region 23g Green phosphor area 23b Transparent area 3. Collimator lens 4 Mirror 5 Prisms 6 Scanning Unit 7 Projection Lens ML Microlens Region

Claims

1. A phosphor wheel having a phosphor region that converts the wavelength of blue laser light, and which rotates in response to the drive of a rotation mechanism, The aforementioned blue laser light is converted into red laser light by a red phosphor region, The aforementioned blue laser light is converted into green laser light by a green phosphor region, It has a transparent region that transmits the blue laser light, The aforementioned transmission region is a phosphor wheel that transmits the blue laser light through a microlens array.

2. The aforementioned microlens array is configured by arranging a plurality of microlens regions, The phosphor wheel according to claim 1, wherein the plurality of microlens regions are arranged along a circumference centered on the rotation axis of the phosphor wheel.

3. A light source that emits blue laser light, A light source device comprising a phosphor wheel having a phosphor region for converting the wavelength of the blue laser light and rotating in accordance with the drive of a rotation mechanism, The aforementioned phosphor wheel is The aforementioned blue laser light is converted into red laser light by a red phosphor region, The aforementioned blue laser light is converted into green laser light by a green phosphor region, It has a transparent region that transmits the blue laser light, The aforementioned transmission region is a light source device that transmits the blue laser light through a microlens array.

4. The aforementioned microlens array is configured by arranging a plurality of microlens regions, The light source device according to claim 3, wherein the plurality of microlens regions are arranged along a circumference centered on the rotation axis of the phosphor wheel.

5. The light source device according to claim 4, wherein the array pitch of the plurality of microlens regions is smaller than the spot size of the blue laser light and larger than half the spot size of the blue laser light.

6. A projector comprising a light source device according to any one of claims 3 to 5.

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