JP7446432B2 - light source device - Google Patents

Description

The present disclosure relates to a light source device, and particularly to a light source device with improved light utilization efficiency.

In solid-state light sources used in projection display devices and the like, increasing output and improving coupling efficiency are issues. For example, Patent Document 1 discloses a light source including a plurality of light emitting points, a collimating lens that collimates the emitted light from the light source, and a collimating lens that has a different inclination angle with respect to the main surface and that has a plurality of collimating lenses for each of the plurality of emitted lights. A light source unit is disclosed that includes an optical element having an entrance surface. In particular, Patent Document 1 discloses a configuration in which an optical element has a plurality of mirrors each having an incident surface, as shown in FIG. 16 etc., in order to realize miniaturization of the light source unit.

International Publication No. 2014/115194

In a configuration using a mirror as in Patent Document 1, if the light intensity distribution of the parallelized light rays emitted from the collimating lens becomes uneven with respect to the optical axis, the light utilization efficiency on the optical axis will decrease. However, in Patent Document 1, no consideration is given to the reduction in light utilization efficiency on the optical axis due to the apparent inclination of the light source.

The present disclosure has been made in order to solve the above problems, and aims to provide a light source device that improves the efficiency of using light on the optical axis.

A light source device according to the present disclosure is a light source device that irradiates light to an irradiation target in a Z-axis direction in an XYZ coordinate system including an a first light source and a second light source that are arranged such that the divergence angle in the Y-axis direction is smaller than the divergence angle in the X-axis direction in the XYZ coordinate system; a collimating lens that collimates the emitted light flux; a first optical surface of a plane that is disposed between the light source group and the collimating lens in the Z-axis direction and deflects the light emitted by the first light source; A second optical surface of a plane that deflects the light emitted by a second light source is configured to have a concave shape toward the irradiation target in the Z-axis direction, and deflects the light flux emitted from the light source group to a light deflecting element that causes the light to be incident on the optical lens, the first light source is arranged to face the first optical surface in the Z-axis direction, and the second light source is arranged to face the first optical surface in the Z-axis direction. The two optical surfaces are arranged to face each other.

According to the light source device of the present disclosure, it is possible to provide a light source device with high light utilization efficiency on the optical axis.

1 is a diagram showing a schematic configuration of a light source device of Embodiment 1. FIG. 1 is a diagram showing a schematic configuration of a light source device of Embodiment 1. FIG. 3 is a diagram showing light distribution characteristics of a light source of the light source device of Embodiment 1. FIG. FIG. 3 is a diagram showing an example of ray tracing of the light source device according to the first embodiment. FIG. 3 is a diagram illustrating the operation of the light deflection element of the light source device of Embodiment 1. FIG. 12 is a diagram showing a schematic configuration when the light deflection element of the light source device of Embodiment 2 is replaced with a mirror. 7 is a diagram showing ray tracing results of the light source device of Embodiment 2. FIG. FIG. 2 is a diagram illustrating the inclination angle of a light beam emitted from a light source with respect to an optical axis. 7 is a diagram showing the results of reverse ray tracing of the light source device of Embodiment 2. FIG. FIG. 7 is a diagram showing the results of back ray tracing of the collimating lens of the light source device of Embodiment 2; 7 is a diagram showing the illuminance distribution of the light source device of Embodiment 2. FIG. 7 is a diagram showing the illuminance distribution of the light source device of Embodiment 2. FIG. FIG. 7 is a diagram showing the results of back ray tracing of the mirror of the light source device according to the second embodiment. 3 is a diagram showing the illuminance distribution of the light source device of Embodiment 1. FIG. 7 is a diagram showing the illuminance distribution of the light source device of Embodiment 2. FIG. FIG. 3 is a diagram showing an illuminance distribution of a comparative example of the light source devices of Embodiments 1 and 2; 3 is a diagram showing the illuminance distribution of the light source device of Embodiment 1. FIG. 7 is a diagram showing the illuminance distribution of the light source device of Embodiment 2. FIG. 7 is a diagram showing the illuminance distribution of the light source device of Embodiment 2. FIG. FIG. 7 is a diagram showing a schematic configuration of a light source device according to a third embodiment. FIG. 7 is a diagram illustrating the operation of the light deflection element of the light source device of Embodiment 3. 7 is a diagram showing the results of reverse ray tracing of the light source device of Embodiment 3. FIG. FIG. 7 is a diagram showing the results of back ray tracing of the collimating lens of the light source device of Embodiment 3; 7 is a diagram showing an illuminance distribution of a light source device according to a third embodiment. FIG. FIG. 3 is a diagram for explaining the positional relationship between the light source group and the collimating lens of the light source device according to the first embodiment. FIG. 7 is a diagram for explaining the positional relationship between the light source group and the collimating lens of the light source device of Embodiment 3; FIG. 3 is a diagram showing the results of back ray tracing in the X-axis direction of the light source device according to the first embodiment. 7 is a diagram showing the results of back ray tracing in the X-axis direction of the light source device of Embodiment 3. FIG. 7 is a diagram showing an illuminance distribution of a light source device according to a third embodiment. FIG. 7 is a diagram showing an illuminance distribution of a light source device according to a third embodiment. FIG. 7 is a diagram showing an illuminance distribution of a light source device according to a fourth embodiment. FIG. 7 is a diagram showing an illuminance distribution of a light source device according to a fourth embodiment. FIG. FIG. 3 is a diagram showing the illuminance distribution when an anamorphic aspherical surface is applied to the collimating lens of the light source device of Embodiment 1; FIG. 7 is a diagram showing the illuminance distribution when a toroidal surface is applied to the collimating lens of the light source device of Embodiment 1; FIG. 7 is a diagram showing a schematic configuration of a light source device according to a fifth embodiment.

<Embodiment 1>
A schematic configuration of light source device 100 according to Embodiment 1 will be described using FIGS. 1 and 2. FIG. FIG. 1 shows a view of the YZ plane observed from the −X-axis direction, and FIG. 2 shows a view of the ZX plane observed from the +Y-axis direction. As shown in FIGS. 1 and 2, the light source device 100 includes a light source group 1, a light deflection element 2, and a collimating lens 3, and the light deflection element 2 is arranged between the light source group 1 and the collimating lens 3. ing. The light deflection element 2 is provided with optical surfaces 21 and 22 for light deflection on the light exit side, and the optical surfaces 21 and 22 are both inclined toward an optical axis C1 passing through the center of the collimating lens 3. ing. The light source group 1 includes a light source 1a and a light source 1b arranged in the Y-axis direction as shown in FIG.

<Coordinate settings>
In this embodiment, for ease of explanation, XYZ coordinates are used in the figures shown below, and light travels in the +Z-axis direction. Further, clockwise rotation about the X-axis center is +RX, clockwise rotation about the Y-axis center is +RY, and clockwise rotation about the Z-axis center is +RZ.

<Light source 1a, light source 1b>
The light source 1a and the light source 1b are solid light sources having different divergence angles in the X-axis direction and Y-axis direction, and are, for example, laser diodes. Here, the XY plane of the light source 1a and the light source 1b is the light emitting surface, the side in the Y-axis direction is longer than the side in the X-axis direction, and the divergence angle in the Y-axis direction (angle in the ±RX direction) is the divergence in the X-axis direction. It shall be smaller than the angle (angle in ±RY direction). For example, the length of the light sources 1a and 1b in the Y-axis direction is 70 μm, and the length in the X-axis direction is 1 μm. Hereinafter, the Y-axis direction with a small divergence angle will also be referred to as the first direction, and the X-axis direction will also be referred to as the second direction.

<Light distribution characteristics of light source 1a and light source 1b>
FIG. 3 shows the light distribution characteristics of the light emitted from the light sources 1a and 1b. In FIG. 3, the vertical axis shows the relative light intensity (arbitrary unit), and the horizontal axis shows the light divergence angle (°). A characteristic 301 indicated by a solid line indicates a light distribution characteristic of light diverging in the X-axis direction (±RY direction), and a characteristic 302 indicated by a dashed dotted line indicates a light distribution characteristic of light diverging in the Y-axis direction (±RX direction). Showing optical properties. As described above, the divergence angle in the Y-axis direction is smaller than the divergence angle in the X-axis direction.

Note that the broken line 303 indicates the position where the relative light intensity is 1/e ² , that is, the position where the relative light intensity is approximately 0.135. Generally, the specification of the divergence angle of a laser diode is often expressed as an angle at a position where the relative light intensity is 1/e ² , which serves as a measure of the spread of light. Here, the angle at the position where the characteristic 301 is 1/e ² is about ±37°, and the angle at the position where the characteristic 302 is 1/e ² is about ±5°. Hereinafter, when we refer to the range of divergence angles of the light sources 1a and 1b, we mean the angular ranges based on the position where the relative light intensity is 1/ ^e2 .

<Distance between light source 1a and light source 1b>
The light source 1a and the light source 1b emit red light with a center wavelength of 638 nm, for example. When increasing the output power by arranging multiple light sources adjacent to each other, compared to a light source that emits blue light with a center wavelength of, for example, 450 nm and a light source that emits green light with a center wavelength of, for example, 525 nm, red light A light source that emits light is highly sensitive to temperature, and as the temperature increases, luminous efficiency decreases and wavelength shift occurs. Therefore, in consideration of cooling, it is preferable that the arrangement interval between the light sources 1a and the light sources 1b, that is, the interval in the arrangement direction, in this embodiment, the interval in the Y-axis direction is wide. However, in general, as the arrangement interval between the light sources 1a and 1b increases, the light utilization efficiency on the optical axis C1 decreases, so in order to improve the light utilization efficiency, the light sources 1a and 1b must be Preferably located nearby.

<Relationship between the distance between the light source 1a and the light source 1b and light utilization efficiency>
When the optical deflection element 2 is not arranged, that is, when only the light source group 1 and the collimating lens 3 are used, the light emitted from the light source 1a and the light emitted from the light source 1b are refracted by the collimating lens 3, and then rotate along the optical axis C1. gradually moving away from the border. Therefore, when a condenser lens is arranged after the collimating lens 3 and the light emitted from the plurality of light source devices 100 is condensed onto the optical axis C1, the light condensed onto the optical axis C1 of the condenser lens is becomes less efficient.

FIG. 4 is a diagram showing an example of ray tracing. FIG. 4 shows an optical system composed only of the light source group 1 and the collimating lens 3, and also shows an enlarged view of the area "A" including the light source group 1 and the collimating lens 3.

As shown in FIG. 4, a light ray 401 emitted from the center of the light source 1a is shown by a solid line, and a light ray 402 emitted from the center of the light source 1b is shown by a chain line. Note that the spread of each light beam in the Y-axis direction was set to ±5° as explained using FIG. The light rays 401 and 402 emitted from the collimating lens 3 gradually move away from the optical axis C1 in the arrangement direction of the light sources, more specifically, the light ray 401 advances in the −Y-axis direction and the light ray 402 advances in the +Y-axis direction. It can be confirmed that As a result, in the arrangement direction of the light sources, the light from the light source group 1 moves away from the optical axis C1, and the light utilization efficiency on the optical axis C1 decreases. Here, assuming that the array interval from the optical axis C1 to the emission position of each light source is the image height, the shorter the focal length of the collimating lens 3, the higher the image height at the arrival plane, that is, at any position in the Z-axis direction. , the light beam reaches a position away from the optical axis C1. On the other hand, the light rays emitted on the optical axis C1 reach the vicinity of the optical axis C1 on the arrival surface as well. Here, the term "near" means that the light ray has a width in the ±Y-axis direction due to the influence of the divergence angle of the light source, so light rays parallel to the optical axis C1 also reach the arrival surface, so the width in the ±Y-axis direction is In consideration of the fact that

<Light deflection element>
FIG. 5 is a conceptual diagram for explaining the action of the optical deflection element 2, and the features of the optical deflection element 2 will be explained using FIG. By arranging the light deflection element 2 between the light source 1a and the collimating lens 3 (FIG. 1), the light ray 501cc emitted from the center of the light source 1a is deflected by +Y with respect to the optical axis C1 due to the deflection action of the light deflection element 2. It becomes possible to make the light incident on the collimating lens 3 at an angle α1 in the axial direction. The light ray that has traveled in the +Z-axis direction at the angle α1 is emitted as a light ray parallel to the optical axis C1 by the collimating lens 3, thereby suppressing a decrease in light utilization efficiency on the optical axis C1. The same effect is applied to the light source 1b by making the optical axis C1 line symmetrical. That is, by arranging the optical deflection element 2, the light rays parallel to the optical axis C1 emitted from the central portions of the light sources 1a and 1b are deflected in the +Y-axis direction and the -Y-axis direction after being refracted. It is possible to cause a light source placed apart from C1 in the ±Y axis direction to behave as if it were placed on the optical axis C1 or at a position displaced in parallel to the optical axis C1 direction.

For example, as shown in FIG. 5, the length y1a in the Y-axis direction of the light source 1a is 70 μm, the length y1b in the Y-axis direction of the light source 1b is 70 μm, and the length y1a in the Y-axis direction of the light source 1a and the optical axis C1 is The distance y1ac between the ends of the light source 1a in the −Y-axis direction and the ends of the light source 1b in the +Y-axis direction is 140 μm, and the distance y1d between the center of the light source 1a and the center of the light source 1b is 210 μm. . Furthermore, the distance D1 between the light emitting surfaces of the light sources 1a and 1b and the light incident surface of the light deflection element 2 is 350 μm, and the thickness T1 of the minimum portion of the light deflection element 2 is 280 μm. In addition, the intersection point between the light beam parallel to the optical axis C1 of the light emitted from the central part of the light source 1a and the light incident surface of the optical deflection element 2 is defined as P50, and the optical axis C1 of the light emitted from the central part of the light source 1a is defined as P50. When the intersection of the parallel light ray and the exit surface side of the optical deflection element 2 is P51, the distance D2 between P50 and P51 is approximately 315 μm.

Here, the material of the optical deflection element 2 is, for example, BSC7 manufactured by HOYA Corporation, and the refractive index at a wavelength of 638 nm is about 1.515.

<Behavior of light rays>
As shown in FIG. 5, the light ray 501cu shows the locus of the light ray emitted from the center of the light source 1a at an angle α2=-5°, and the light ray 501cc shows the trajectory of the light ray emitted from the center of the light source 1a at an angle of 0°, i.e. , shows the locus of a light ray parallel to the optical axis C1, and a light ray 501cd shows the locus of a light ray emitted from the center of the light source 1a at an angle α5=+5°.

The light beam 501cc exits from the center of the light source 1a and enters the optical deflection element 2 at an angle of 0°. After reaching the exit surface of the light deflection element 2, it is refracted and travels in the +Z-axis direction at an angle α1. The angle α1 is calculated using the following formula (1) using Snell's law. Note that the angle is calculated as an absolute value.

1.515×sin(|α8|)=sin(|α1|+|α8|)...(1)
Here, if the inclination angle α8 of the exit surface of the light deflection element 2 in the Y-axis direction (+RX direction) with respect to the XY plane is +18.81°, the angle α1 is calculated by the following equation (2). Note that angles are calculated using absolute values.

1.515×sin(18.81°)=sin(|α1|+18.81°)...(2)
From the above equation (2), |α1|=10.43°, and considering the emission direction, α1=−10.43°. Note that since the refractive index and angle are calculated as approximate values by rounding, errors occur in the calculated angle.

The light ray 501cu exits from the center of the light source 1a and enters the optical deflection element 2 at an angle α2=-5°. The incident light is refracted and travels to the exit surface of the optical deflection element 2 at an angle α3. At the exit surface of the light deflection element 2, after being refracted, the light travels in the +Z-axis direction at an angle α4.

The angle α3 is calculated using the following formula (3). Note that angles are calculated using absolute values.

sin(|α2|)=1.515×sin(|α3|)...(3)
According to the above formula (3), |α3|=3.3°, and considering the emission direction, α3=−3.3°.

The angle α4 is calculated using the following formula (4). Note that angles are calculated using absolute values.

1.515×sin(|α8|+|α3|)=sin(|α8|+|α4|)...(4)
Substituting the known angle into equation (4) results in equation (5) below.

1.515×sin(22.11°)=sin(18.81°+｜α4｜)...(5)
From formula (5), |α4|=15.96°, and considering the emission direction, α4=−15.96°.

The light ray 501cd exits from the center of the light source 1a and enters the optical deflection element 2 at an angle α5=+5°. The incident light is refracted and travels to the exit surface of the optical deflection element 2 at an angle α6. At the exit surface of the light deflection element 2, after being refracted, the light travels in the +Z-axis direction at an angle α7.

The angle α6 is calculated using the following formula (6). Note that angles are calculated using absolute values.

sin(|α5|)=1.515×sin(|α6|)...(6)
From formula (6), |α6|=3.3°, and considering the emission direction, α6=+3.3°.

The angle α7 is calculated using the following formula (7). Note that angles are calculated using absolute values.

1.515×sin(|α8|-|α6|)=sin(|α8|+|α7|)...(7)
Substituting the known angle into Equation (7) results in Equation (8) below.

1.515×sin(15.51°)=sin(18.81°+｜α7｜)...(8)
From equation (8), |α7|=5.09°, and considering the emission direction, α7=−5.09°.

A light ray 501dd shows a trajectory of a light ray that is emitted from the end of the light source 1a in the −Y-axis direction and is inclined at an angle α5=+5 degrees with respect to the optical axis C1. In consideration of light utilization efficiency, it is preferable that the light ray 501dd passes in the +Y-axis direction from the intersection P52 between the optical axis C1 and the output surface of the optical deflection element 2.

The light ray 501dd exits the end of the light source 1a in the −Y-axis direction at an angle α5=+5°, reaches the light incident surface of the optical deflection element 2, and after being refracted, it irradiates in the +Z-axis direction at an angle α6=+3.3°. proceed. It is further refracted by the exit surface of the optical deflection element 2 and travels in the +Z-axis direction at an angle α7=-5.09°. It is preferable from the viewpoint of light utilization efficiency that the intersection point P53 of the light beam 501dd and the exit surface side of the light deflection element 2 is located in the +Y-axis direction from the point P52. Note that the light ray 501cd and the light ray 501dd are in a parallel relationship. Note that the light from the light source 1b has a line-symmetrical relationship with the light from the light source 1a with respect to the optical axis C1.

In this way, the light deflection element 2 is arranged on the + side (in the light distribution direction) with respect to the light from the light source 1a, which is a light source arranged on the + side of the optical axis C1 in the arrangement direction of the light sources. In this embodiment, the function of deflecting the light from the light source 1b to the - side of the light distribution direction (-Y axis direction) and the light source disposed on the - side of the optical axis C1. It has the function of deflecting and emitting light in the direction). Thereby, the apparent positions of the light sources 1a and 1b in the Y-axis direction can be moved in the optical axis C1 direction. As a result, the apparent length of the entire light source in the Y-axis direction can be shortened.

<Apparent position of light source 1a>
From the light ray 501cu, the light ray 501cc, and the light ray 501cd, the angle with respect to the optical axis C1 when the light ray emitted from the center of the light source 1a travels to the collimating lens 3 was calculated. In other words, regarding the light rays 501cu, 501cc, and 501cd that proceed to the collimating lens 3, the behavior of the light rays in the -Z axis direction when assuming that the same light rays are emitted without placing the optical deflection element 2 is shown in the figure. 5, the light rays are represented by 502 cu, 502 cc, and 502 cd. That is, regarding the light rays 501cu, 501cc, and 501cd, the behavior of the light rays in the -Z-axis direction when the configuration in the -Z-axis direction is made into a black box is represented by the light rays 502cu, 502cc, and 502cd. It can be seen that through this process, the light rays behave in the same way as when the center of the light source 1a moves to the position P54 in FIG.

Here, the length y1p in the Y-axis direction of the position P54 is 21 μm, and the distance D3 in the Z-axis direction between the light source 1a and the position P54 is 214 μm. Note that since aberrations occur due to the influence of the optical deflection element 2, the position P54 is an approximate position.

That is, while the actual image height of the light source 1a with respect to the optical axis C1 is y1ac = 105 μm, by inserting the optical deflection element 2, the virtual image height, which is the apparent image height of the light source 1a with respect to the optical axis C1, is increased. It becomes possible to set y1p to 21 μm. In other words, it is possible to reduce the image height after exiting the collimating lens 3 to 1/5. In this way, by using the optical deflection element 2, it is possible to lower the apparent image height. This makes it possible to improve the light utilization efficiency near the optical axis C1.

Here, the angle α1 at which the light beam 501cc emitted from the center of the light source 1a exits the optical deflection element 2 is preferably as small as possible in consideration of reducing the diameter of the collimating lens 3 disposed at the subsequent stage. Since the collimating lens 3 is circular when observed from the XY plane, assuming that when the light ray moves in the Y-axis direction, the divergence angle of the light source 1a in the X-axis direction (±RY direction) is ±37°. This is because there is a high possibility that the amount of light incident on the collimating lens 3 will decrease.

Further, as described above, the apparent light source position P54 is moved by 214 μm in the +Z-axis direction from the actual light source position. Accordingly, it becomes necessary to shorten the focal length of the collimating lens 3 by 214 μm. Therefore, the light source image at the condensing position becomes slightly larger. For example, when a collimating lens with a focal length of 6.5 mm becomes a collimating lens with a focal length of 6.3 mm, and the image height is 21 μm, the image height 2000 mm away from the collimating lens 3 is It becomes 6.67 mm, which is slightly larger than 6.46 mm without 2. In other words, it becomes 1.03 times. However, the influence of such a magnification (1.03 times) can be said to be sufficiently small compared to the effect of lowering the image height, that is, the effect of increasing it to 1/5 times. The calculation formula is shown below.

In the case of a focal length of 6.5 mm, image height=21 μm×2000 mm/6.5 mm≈6.46 mm.

In the case of a focal length of 6.3 mm, image height=21 μm×2000 mm/6.3 mm≈6.67 mm.

<Other configuration examples>
For example, in the configuration shown in FIG. 5, the distance between the ends of adjacent light sources (interval y1c) is 140 μm, but the same effect can be obtained even if the distance y1c is 70 μm. In that case, the distance D1 can be set from 350 μm to 150 μm.

In this case, the position of the optical deflection element 2 is such that the light ray traveling in the +Z-axis direction at an angle α5 from the -Y-axis direction end of the light source 1a, that is, the light ray 501dd in FIG. 5, travels in the +Y-axis direction from P52. can be moved in the +Z-axis direction. Similarly, when the length y1a of the light source 1a in the Y-axis direction becomes longer, a light ray that travels in the +Z-axis direction at an angle α5 from the -Y-axis direction end of the light source 1a travels in the -Y-axis direction from P52. can move the position of the optical deflection element 2 in the -Z axis direction.

Note that it is possible to lengthen the distance D1 by changing the material of the optical deflection element 2 to a glass material or the like having a high refractive index. In that case, the angle α8 is changed. For example, when the optical deflection element 2 is made of FD60 manufactured by HOYA Corporation, the refractive index at a wavelength of 638 nm is 1.80. In this case, the angle α8 may be set so that the angle α1 is 10.43°, and specifically, the angle α8 can be set to 12.5°. Further, in consideration of the change in back focus length due to the difference in refractive index, the interval D1 can be set to 380 μm. Strictly speaking, if the optical deflection element 2 is moved in the +Z-axis direction or the angle α8 is changed, the positions of the apparent light source position P54 in the Y-axis direction and the Z-axis direction change, so in that case, the collimating lens 3 It becomes necessary to change the Z-axis direction position and focus of the image. Note that if the distance D1, the thickness T1 of the minimum part of the optical deflection element 2, and the angle α8 are set so that the apparent light source position P54 does not change in the Y-axis direction and the Z-axis direction, the Z of the collimating lens 3 Eliminates the need to change axial position and focus.

<Substitute with mirror>
Here, for example, the same function as the optical deflection element 2 can be realized using two mirrors. In this case, if α1=10.43°, the mirror is tilted by ±10.43/2≈5.22° with respect to the optical axis C1. More specifically, the light from the light source 1a placed on the +Y-axis side is tilted by −5.22°, and the light from the light source 1b placed on the −Y-axis side is tilted by +5.22°.

When the divergence angle of the light source 1a is ±5°, a part of the light emitted at −5° may reach the collimating lens 3 without reaching the mirror. This is because the light sources have a length in the Y-axis direction, which is the arrangement direction, so if the width of the mirror, that is, the length in the Z-axis direction, is not longer than the distance to the collimating lens 3, For example, if the light source 1a is placed on the +Y-axis side, the light emitted from the end in the +Y-axis direction may not reach the mirror.

<Embodiment 2: An example of using a mirror>
FIG. 6 shows a schematic configuration of a second embodiment in which the optical deflection element 2 is replaced by a mirror. For convenience, only the behavior of the light beam from the light source 1a is shown as in FIG. The length y1a of the light source 1a in the Y-axis direction is 70 μm, and the distance y1ac in the Y-axis direction between the center portion of the light source 1a and the optical axis C1 is 105 μm, which is the same as the example shown in FIG. The angle α2 and the angle α5 are also the same as in the example of FIG. Incidentally, the tilt angle α9 of the mirror M was set to −8°.

A light ray 503cc emitted from the center of the light source 1a in parallel to the optical axis C1 is reflected by the reflective surface of the mirror M, and then travels in the +Z-axis direction at an angle α11=−16° with respect to the optical axis C1. The light ray 503cu that is emitted from the center of the light source 1a at an angle α2=-5° is reflected from the mirror M and then moves toward the +Z axis at an angle α12=-11° (-(16°-5°)) with respect to the optical axis C1. proceed in the direction. The light ray 503cd that is emitted from the center of the light source 1a at an angle α5=+5° is reflected by the mirror M, and then moves in the +Z-axis direction at an angle α10=-21° (-(16°+5°)) with respect to the optical axis C1. proceed.

In addition, in FIG. 6, as for the behavior of the light ray in the -Z-axis direction, a light ray 504cc corresponding to the light ray 503cc parallel to the optical axis C1 is emitted from the light source 1a at an angle α2=-5° from the center of the light source 1a. A light ray corresponding to the light ray 503cu is shown as a light ray 504cu, and a light ray corresponding to the light ray 503cd emitted from the center of the light source 1a at an angle α5=+5° is shown as a light ray 504cd. As shown in FIG. 6, it can be confirmed that in this configuration, the behavior appears to be that the light rays are emitted from the light emitting point located at the position P55c. Also, if we pay attention to the light emitted from the end of the light source 1a in the +Y-axis direction, we can see that a ray 503uc is emitted parallel to the optical axis C1, a ray 503uu is emitted at an angle α2=-5°, and a ray 503uu is emitted at an angle α5=+5°. Regarding the light ray 503ud, if the respective light rays in the −Z-axis direction are represented by the light rays 504uc, 504uu, and 504ud, it can be confirmed that the light ray behaves as if it were emitted from a light emitting point located at the position P55u.

Similarly, looking at the light emitted from the end of the light source 1a in the −Y-axis direction, a light ray 503dc is emitted parallel to the optical axis C1, a light ray 503du is emitted at an angle α2=−5°, and an angle α5=+5°. When the light rays 503dd emitted in the −Z-axis direction are represented by the light rays 504dc, 504du, and 504dd, it can be confirmed that the light rays behave as if they are emitted from the light emitting point at the position P55d.

As a result, the light source 1a apparently behaves as if its light emitting surface is inclined at an angle α13=−16° with respect to the XY plane. Therefore, when the collimating lens 3 is arranged in the latter stage to make the light beam parallel to the optical axis C1, the width of the light beam will be different in the -Y-axis direction and the +Y-axis direction due to the influence of the tilt of the light emitting surface. , image blur occurs due to the tilt of the light emitting surface. However, by adjusting the collimating lens 3, the influence of image blur can be reduced.

By the way, when improving the light collection efficiency of the light source 1a using the mirror M, the light collection effect is highest when the following formula (9) is satisfied. The following is a conditional expression when the position P55c is on the optical axis C1.

y1ac/D4=sin(2×|α9|)...(9)
For example, when the distance y1ac is 105 μm and the inclination angle α9 of the mirror M is −8°, the distance D4 between the center of the light source 1a and the reflective surface of the mirror M is approximately 381 μm. Note that an error of, for example, 381 μm±10% (38 μm) is allowed for the mounting distance D4.

As shown in FIG. 6, when the tilt angle α9 of the mirror M is small, the light source 1a is tilted outward from the +Y-axis end of the light source 1a, that is, from the end in the direction away from the optical axis C1, that is, in the direction away from the optical axis C1. The light ray 503uu emitted at the angle α2 is difficult to reach the mirror M. When mirror M is used in this way, the effect of lowering the apparent image height and the effect of improving the light utilization efficiency near the optical axis C1 can be obtained, but the angular accuracy of mirror M is required, and the following There are such concerns. That is, it is necessary to increase the angle α11, which corresponds to the angle α1 in FIG. 5, and therefore there is a concern that the diameter of the collimating lens 3 in the subsequent stage may be increased or the efficiency of reaching the collimating lens 3 may be reduced.

However, if it is permissible to increase the diameter of the collimating lens 3, the use of a mirror M as a substitute for the optical deflection element 2 is not excluded. By using the mirror M, the traveling direction of the light can be changed from the +Z-axis direction to the ±X-axis direction, etc. Therefore, by adjusting the inclination of the mirror M or the distance from the light sources 1a and 1b to the collimating lens, in addition to suppressing the decrease in light utilization efficiency on the optical axis, the degree of freedom in component placement is improved. can.

However, when changing the traveling direction of light, such as in the ±X-axis directions, the mirror surface is tilted in two axes, so the tendency of the emitted light rays changes depending on the rotation center of the mirror. Unlike in FIG. 6, after reflection by the mirror, the light beam does not maintain its spread before reflection and travels in the X-axis direction.

<Collimating lens applied to Embodiment 1 and Embodiment 2>
In the first embodiment, the collimating lens 3 converts the light emitted from the optical deflection element 2 into light parallel to the optical axis C1. The collimating lens 3 is formed, for example, into an aspherical shape. The aspherical shape can be a toroidal shape having different shapes in the X-axis direction and the Y-axis direction. Further, the light incident surface can be formed into a convex shape or a concave shape.

In the second embodiment, the collimating lens 3 converts the light reflected by the mirror M into parallel light to the optical axis C1. The collimating lens 3 is formed, for example, into an aspherical shape. The aspherical shape can be a toroidal shape having different shapes in the X-axis direction and the Y-axis direction. Further, the light incident surface can be formed into a convex shape or a concave shape.

Furthermore, it is preferable that the light rays emitted from the central portion of the light source 1a and the central portion of the light source 1b be parallel to the optical axis C1. Thereby, at the arrival position of the light rays, the light rays emitted from the central part of the light source 1a and the central part of the light source 1b reach the vicinity of the optical axis C1, and it is possible to make the reached light source image the smallest.

<Results of ray tracing of the optical deflection element of Embodiment 1>
FIG. 7 is a diagram showing the ray tracing results of the light rays emitted from the light source 1a in the first embodiment. FIG. 7 shows an enlarged view of region "B" including the light source group 1 and light deflection element 2, and an enlarged view of region "C" of the exit surface of the collimating lens 3. Note that the positional relationship between the light source 1a and the optical deflection element 2 is similar to that shown in FIG. Further, a collimating lens 3 is arranged on the +Z-axis direction side of the optical deflection element 2. The focal length of the collimating lens is approximately 6.5 mm.

As shown in the enlarged view of region "B" in FIG. 7, light rays with a spread of ±5° are emitted from the light source 1a in the +Z-axis direction. It shows the ray tracing results of a ray 601u emitted from the end of the light source 1a in the +Y-axis direction, a ray 601c emitted from the center of the light source 1a, and a ray 601d emitted from the end of the light source 1a in the -Y-axis direction.

As shown in the enlarged view of region "C" in FIG. 7, the light rays 601u, 601c, and 601d exiting the collimating lens 3 are generally parallel to the optical axis C1.

<Confirmation of effects of Embodiment 1 and Embodiment 2>
FIG. 8 is a diagram illustrating the inclination angle of the light beam actually emitted from the light source 1a with respect to the optical axis C1. Note that the collimating lens 3 is a virtual thin lens 703, and the focal length F7 is 6.5 mm. It is assumed that the light source 1a is moved so that the center of the light source 1a is located on the optical axis C1. FIG. 8 shows the behavior of a light ray 701u emitted from the end of the light source 1a in the +Y-axis direction and a light ray 701d emitted from the end of the light source 1a in the -Y-axis direction. The angle βu and the angle −βd of the light ray 701u and the light ray 701d emitted from the thin lens 703 with respect to the optical axis C1 are expressed by the following equation (10).

βu=-βd=atan((y1a/2)/F7)
= atan (35μm/6500μm)
≒0.31°...(10)
From the results of angle βu and angle βd, the angle of the light ray emitted from the center of the light source 1a is 0°, the light ray 701u emitted from the end of the light source 1a in the +Y-axis direction, and the light ray 701d emitted from the end of the light source 1a in the -Y-axis direction, When emitting light from the collimating lens 3 at an angle of 0.31°, it can be assumed that the light source 1a is emitting from the optical axis C1.

In order to verify the above assumption, FIG. 9 shows the results of reverse ray tracing using the configuration shown in FIG. FIG. 9 shows an enlarged view of a region "D" including the light source group 1 and the light deflection element 2, and an enlarged view of a region "E" of the exit surface of the collimating lens 3. Here, the above assumption is confirmed by performing reverse ray tracing of the light beam traveling from the +Z-axis direction to the -Z-axis direction of the collimating lens 3 and confirming the imaging position.

FIG. 9 shows the back ray tracing results of the light ray 801u, the light ray 801c, and the light ray 801d in the first embodiment, and the light ray 801d has an angle of −0.31° with respect to the optical axis C1 and is 3, the light ray 801c enters the collimating lens 3 parallel to the optical axis C1, and the light ray 801u enters the collimating lens 3 at an angle of +0.31° to the optical axis C1. It is incident.

When checking the light rays on the light source 1a, the light ray 801u is focused (imaged) on the +Y-axis direction end of the light source 1a, the light ray 801c is focused (imaged) on the center of the light source 1a, and the light ray 801d It can be confirmed that the light is focused (imaged) on the end of the light source 1a in the −Y-axis direction. That is, it can be confirmed that by inserting the optical deflection element 2, the light beam behaves in the same way as when the light source 1a is on the optical axis C1. In this way, by using the optical deflection element 2, the effect of improving the light utilization efficiency near the optical axis C1 can be obtained.

In the above example, the light ray 801c is focused on the center of the light source 1a in the Y-axis direction, but the collimating lens 3 and light deflection when parallel light is incident from the +Z-axis direction side of the collimating lens 3 The condensing position of the parallel light by the optical system including the element 2 does not have to be precisely located on the light emitting surface of each of the light sources 1a and 1b. In other words, the center of each of the light source 1a and the light source 1b means, in the case of the light source 1a, within the range of ±y1a/3 from the center in the Y-axis direction, and within ±30 μm from the light-emitting surface of the light source 1a in the Z-axis direction. Preferably, it may include ±10 μm or less.

Here, as shown in FIG. 5, the position P54 in the Y-axis direction is the image height position of the light source 1a, but in FIG. doing. This is because the shape of the collimating lens 3 is set so that when light rays parallel to the optical axis C1 are incident on the collimating lens 3 from the +Z-axis direction, the light rays are concentrated at the position P54. Although the focal position of the collimating lens 3 is in the −Z-axis direction from the position P54, it is possible to cause the beam to behave as if the center of the light source 1a is located on the optical axis C1.

<Characteristics of the collimating lens of Embodiment 1>
FIG. 10 is a diagram showing the results of reverse ray tracing when a ray parallel to the optical axis C1 is incident on the collimating lens 3 from the +Z-axis direction. In FIG. 10, an enlarged view of region "F" including light source group 1 is also shown. As shown in FIG. 10, it can be seen that the condensing point P80 of the collimating lens 3 is on the +Z-axis side of the light source 1a and on the +Y-axis side of the optical axis C1. It can also be seen that the focal position P80f of the collimating lens 3 is on the −Z-axis direction side from the condensing point P80. The reason why the focal position P80f is located on the +Z-axis side from the light source 1a is that the back focus of the collimating lens 3 becomes short due to the influence of the optical deflection element 2, which is an optical element. It is also considered that there is an influence of the angle α1 due to the deflection of the light beam. In the example of FIG. 10, the distance between the condensing point P80 and the focal point P80f in the Z-axis direction is about 140 μm.

In FIG. 10, the illuminance distributions on the condensing point P80 and on the focal point P80f when a parallel light beam is incident in the −Z-axis direction from the +Z-axis side of the collimating lens 3 are shown in FIGS. 11 and 12, respectively. In FIGS. 11 and 12, the horizontal axis represents the X axis (mm), the vertical axis represents the Y axis (mm), and the intensity of light is divided into five gradations. Note that the brightest white color represents 100% intensity.

As shown in FIG. 11, on the condensing point P80, there is a ring-shaped illuminance distribution with a hollow center, and it can be seen that the intensity is strong near an area with a radius of 20 μm. Further, as shown in FIG. 12, it can be seen that on the focal position P80f, a concentric illuminance distribution is formed and a small condensed spot is formed, which is the focal position.

In this way, by forming a ring-shaped region with strong light intensity on the +Z-axis direction side from the focal point position, even if the virtual light source position is located on the +Y-axis side, it is the same as when emitted from the optical axis C1. It becomes possible to make the rays behave as follows.

In the first embodiment, the optical surfaces 21 and 22 for light deflection are provided on the light output side of the light deflection element 2, but the optical surfaces 21 and 22 for light deflection may also be provided on the light incidence side. A similar effect can be obtained. Note that the effect of improving the light utilization efficiency on the optical axis C1 can be obtained even without forming a ring-shaped region with high light intensity. Further, also in the configuration using the mirror M of the second embodiment shown in FIG. 6, a ring-shaped illuminance distribution can be formed.

<Characteristics when using the mirror of Embodiment 2>
FIG. 13 shows the results of reverse ray tracing of the configuration using the mirror M of the second embodiment shown in FIG. FIG. 13 shows an enlarged view of a region "G" including the light source group 1 and the mirror M, and an enlarged view of a region "F" of the exit surface of the collimating lens 3.

FIG. 13 shows the results of reverse ray tracing when a light ray 1101u, a light ray 1101c, and a light ray 1101d are incident on the collimating lens 3 from the +Z-axis direction. Note that the light ray 1101u enters the collimating lens 3 at an angle of -0.31° with respect to the optical axis C1, the light ray 1101c enters the collimating lens 3 parallel to the optical axis C1, and the light ray 1101d , is incident on the collimating lens 3 at an angle of +0.31° with respect to the optical axis C1.

From FIG. 13, the light ray 1101u is focused (imaged) at the end of the light source 1a in the +Y-axis direction, the light ray 1101c is focused (imaged) at the center of the light source 1a, and the light ray 1101d is focused (imaged) at the end of the light source 1a. - It can be seen that the light is focused (imaged) at the end in the Y-axis direction.

It can also be seen that the light ray 1101u is focused in the −Z-axis direction compared to the focus position of the light ray 1101c. Furthermore, it can be seen that the light ray 1101d is focused in the +Z-axis direction compared to the focus position of the light ray 1101c. In other words, compared to the case where the optical deflection element 2 is used, the light condensing position in the Y-axis direction is shifted in the Z-axis direction, so that the light beam emitted from the light source 1a can reach any landing surface after exiting from the collimating lens 3. It can be seen that the beam width of is non-uniform in the Y-axis direction.

<Comparison between the optical deflection element and mirror of Embodiment 1 and Embodiment 2>
In FIG. 9, which is the result of performing reverse ray tracing using the configuration shown in FIG. 5 of the first embodiment, and FIG. 13, which is the result of performing reverse ray tracing using the configuration shown in FIG. FIGS. 14 to 16 show the illuminance distribution of the light emitted from the light source 1a on the evaluation plane (XY plane) at a distance of 2000 mm from . In addition, the divergence angle of the light source 1a is 1/e ² in the X-axis direction (RY direction) ± approximately 37°, and 1/e ² in the Y-axis direction (RX direction) is ± approximately 5°, as shown in Fig. 3. . In FIGS. 14 to 16, the horizontal axis represents the X axis (mm), the vertical axis represents the Y axis (mm), and the intensity of light is expressed divided into five gradations. Note that the brightest white color represents 100% intensity.

14 shows the illuminance distribution of light in the case of the first embodiment using the optical deflection element 2, and FIG. 15 shows the illuminance distribution of light in the case of the second embodiment using the mirror M. From FIG. 14, when the optical axis C1 is 0 mm in the Y-axis direction, the area where the light intensity is continuously 80% or more (80% with the maximum light intensity as 100%) is from -8.4 mm to +10.1 mm ( It can be seen that the light uniformly reaches a range of 18.5 mm). Furthermore, it can be seen that the region where the light intensity is 20% or more with the maximum light intensity as 100% is in the range of -10.3 mm to +12.3 mm (22.6 mm). From this, the ratio of the range in the Y-axis direction of the 80% or more uniform region to the 20% or more light intensity region is approximately 81.9% (18.5 mm/22.6 mm).

Furthermore, in the configuration shown in FIG. 8, if the focal length F7 is 6.5 mm and the distance from the virtual thin lens 703 (collimating lens 3) to the evaluation surface is 1993.5 mm, the image height of the light source 1a is as follows. It is expressed by formula (11).

(y1a/2)×(1993.5mm/6.5mm)=10.7mm...(11)
According to the illuminance distribution in FIG. 14, the illuminance range in the Y-axis direction is slightly below +10.7 mm on the + side from the region of light intensity of 20% or more, but is within -10.7 mm on the - side. Furthermore, the area with a light intensity of 80% or more is within ±10.7 mm, and considering the ratio of the range in the Y-axis direction of the area with a light intensity of 80% to the area with a light intensity of 20% or more, the optical axis C1 It is considered that almost the same results as in the case where the light source 1a is provided above are obtained.

On the other hand, from FIG. 15, it can be seen that the illuminance distribution in the Y-axis direction has a region of 80% or more light intensity in the range of -9.3 mm to -6.9 mm (2.4 mm). It can be seen that the region with high light intensity is located away from the optical axis C1. Furthermore, since the range of the region with the light intensity of 80% or more is narrow, it can be seen that the light with high light intensity is concentrated. Furthermore, it can be seen that the light intensity of 20% or more is in the range of -10.2 mm to +12.8 mm (22.8 mm). Since 40% or more of the light intensity is within the range of ±10.7 mm, it is considered that the range is approximately within ±10.7 mm. As a result, although the effect of improving light utilization efficiency near the optical axis C1 can be confirmed, the light intensity on the optical axis C1 is lower than the peak position, and it is thought that the apparent tilting of the light source 1a has an effect. Conceivable.

FIG. 16 is a diagram showing the illuminance distribution in the case of the configuration of FIG. 4 in which the optical deflection element 2 and the mirror M are not arranged as a comparative example. From FIG. 16, when the optical axis C1 is 0 mm in the Y-axis direction, the area of 20% or more light intensity is approximately uniform light in the range from -42.7 mm to -20.7 mm (22.0 mm). It turns out that it has arrived. In other words, it can be seen that the light ray does not reach the optical axis C1. From the above, it can be confirmed that the use of the optical deflection element 2 or the mirror M improves the light utilization efficiency on the optical axis C1. In other words, the effect of improving the light utilization efficiency on the optical axis C1 in the first and second embodiments can be seen.

Further, FIGS. 17 to 19 show the illuminance distribution of light on the evaluation surface at a distance of 2000 mm from the light sources 1a and 1b when both the light sources 1a and 1b are turned on. Note that the divergence angles of the light source 1a and the light source 1b are as follows: 1/e ² in the X-axis direction (RY direction) is ± approximately 37°, and 1/e ² in the Y-axis direction (RX direction) is ± The angle was approximately 5°. In FIGS. 17 to 19, the horizontal axis indicates the X axis (mm), the vertical axis indicates the Y axis (mm), and the intensity of light is expressed divided into five gradations. Note that the brightest white color represents 100% intensity.

17 shows the case of the first embodiment using the optical deflection element 2, FIG. 18 shows the case of the second embodiment using the mirror M, and FIG. 19 shows the case of the parallelizing lens 3 using the mirror M of the second embodiment. The illuminance distribution is shown when the focal point position is moved by 15 μm in the +Z-axis direction.

From FIG. 17, in the Y-axis direction, when the optical axis C1 is 0 mm, the area where the light intensity is 80% or more is uniformly illuminated in the range of -8.9 mm to +8.9 mm (17.8 mm). It can be seen that has been reached. Furthermore, it can be seen that the region where the light intensity is 20% or more is in the range of -11.5 mm to +11.6 mm (23.1 mm). From this, the ratio of the range in the Y-axis direction of the 80% or more uniform region to the 20% or more light intensity region is approximately 77.1% (17.8 mm/23.1 mm). In other words, it can be seen that within a range of approximately 77.1%, the light intensity is uniformly distributed without any peaks.

From FIG. 18, there are two peak positions on the +Y-axis side and the -Y-axis side with respect to the reference position (optical axis C1 position), and compared to FIG. 15, the nonuniformity around the optical axis C1 is It can be seen that it has been reduced. In the Y-axis direction, there are two areas where the light intensity is 80% or more in the range of -9.4 mm to -5.5 mm (3.9 mm) and the range of +5.6 mm to +9.3 mm (3.7 mm). I understand. It can also be seen that the region where the light intensity is 20% or more is in the range of -12.0 mm to +12.0 mm (24.0 mm).

Further, in FIG. 19, it can be seen that the region where the light intensity is 80% or more is in the range of −2.7 mm to +2.7 mm (5.4 mm). Furthermore, it can be seen that the region where the light intensity is 20% or more is in the range of -10.8 mm to +10.7 mm (21.5 mm). From this, the ratio of the range in the Y-axis direction of the region where the light intensity is 80% or more to the region where the light intensity is 20% or more is about 25.1% (5.4 mm/21.5 mm). In other words, the area where the light intensity is 80% or more is concentrated in a range of about 25.1%, indicating that the light utilization efficiency on the optical axis C1 is high. In other words, it can be seen that the light intensity on the optical axis C1 is stronger, and it is possible to improve the light utilization efficiency in the optical axis C1 direction than in the case of FIG. 18. This improves the light utilization efficiency in the optical axis C1 direction by devising the design of the collimating lens 3 so that the back-traced light ray 1101u is focused near the end face in the +Y-axis direction of the light source 1a shown in FIG. This means that it is possible to improve Here, the fact that the back-traced light ray 1101u is focused near the end face in the +Y-axis direction of the light source 1a means that the light-converging position (focal position of the collimating lens 3) in FIG. 13 moves in the +Z-axis direction. It means.

Although FIG. 19 shows an example in which the focal position of the collimating lens 3 is moved by 15 μm in the +Z-axis direction using the mirror M, a configuration that achieves a light utilization efficiency on the optical axis C1 equivalent to or higher than that in FIG. The focal position of the conversion lens 3 may be moved by 15 μm±15 μm in the +Z-axis direction.

Further, when confirming the width in the Y-axis direction in a region where the light intensity is 80% or more, the width in FIG. 19 is 5.4 mm (±2.7 mm), and the width in FIG. 17 is 17.8 mm (±8.9 mm). Therefore, the light utilization efficiency on the optical axis C1 is higher in FIG. 19 using the mirror M which is a reflection type optical deflection element than in FIG. 17 using the transmission type optical deflection element 2. In addition, in FIG. 17, since there is no light loss due to the reflectance of the mirror M, the overall light use efficiency is high, and the light use efficiency on the evaluation surface is high.

From the above, by using the optical deflection element 2 suitably designed in Embodiment 1, the ratio of the range in the Y-axis direction of the region with high light intensity of 80% or more to the region of light intensity of 20% or more can be reduced to 75. % or more, and uniform light can be collected on the optical axis C1 while increasing the light utilization efficiency on the optical axis C1. For example, in light intensity uniform elements such as rod lenses and light pipes, the number of reflections within the element can be reduced, making it possible to shorten the size (length) of the optical system. Furthermore, by using the optical system including the suitably designed mirror M in the second embodiment, the ratio of the range in the Y-axis direction of the region with high light intensity of 80% or more to the region of light intensity of 20% or more can be reduced. It can be set to 30% or less, and the light utilization efficiency on the optical axis C1 can be further improved. As an example, when the aperture size of a light intensity uniform element, such as a rod lens or a light pipe, is small, it becomes possible to introduce light into the optical system with high light utilization efficiency.

Here, an example of an optical system including a suitably designed mirror M includes one in which the focal position of the collimating lens 3 is adjusted as described above. The focal position of the collimating lens 3 can be adjusted by moving the collimating lens 3 in the +Z-axis direction or by moving the light source group in the -Z-axis direction.

<Embodiment 3: Example of inverted arrangement of optical deflection elements>
FIG. 20 is a diagram showing a schematic configuration of a light source device 2101 according to the third embodiment. The light source device 100 of FIG. 1 is the same as the first embodiment except for the difference in the configuration of the optical deflection element 2 and the position of the collimating lens 3 in the Z-axis direction, so the description will be omitted as appropriate. The optical deflection element 212 of Embodiment 3 differs from the configuration in FIG. 1 in that it has optical deflection optical surfaces 2121 and 2122 on the −Z-axis direction side for deflecting incident light. The optical surfaces 2121 and 2122 are both inclined toward the optical axis C1 passing through the center of the collimating lens 3.

<Light deflection element 212 of Embodiment 3>
A conceptual diagram illustrating the action of the optical deflection element 212 is shown in FIG. The light source 1a, the light source 1b, the interval y1d, the interval y1ac, the interval y1c, the length y1a, and the length y1b are the same as those in FIG. 5, so their explanation will be omitted. The thickness T1 of the minimum portion of the optical deflection element 212 is 280 μm, which is the same as in FIG. Further, the distance D1a between the light source 1a and the recessed portion of the optical deflection element 212 is 520 μm. Here, the material of the optical deflection element 212 is, for example, BSC7 manufactured by HOYA Corporation, and the refractive index at a wavelength of 638 nm is about 1.515.

In addition, in the manufacturing method of the optical deflection element 2 (FIG. 1) and the optical deflection element 212, for example, the +Y-axis direction side may be produced by cutting and polishing, and the ZX plane including the optical axis C1 may be bonded as an adhesive interface. . In other words, one light deflection element 2 or light deflection element 212 may be formed by joining two trapezoidal square prism elements of the same shape. Note that the optical deflection element 2 or the optical deflection element 212 may be manufactured by molding without using bonding.

<Behavior of light rays in Embodiment 3>
The light ray 2101uu shows the locus of the light ray emitted from the end of the light source 1a in the +Y-axis direction at an angle α2=-5°, and the light ray 2101uc shows the trajectory of the light ray emitted from the end of the light source 1a in the +Y-axis direction at an angle of 0°, that is, the light The trajectory of the light ray parallel to the axis C1 is shown, and the light ray 2101ud shows the trajectory of the light ray emitted from the end of the light source 1a in the +Y-axis direction at an angle α5=+5°.

A light ray 2101cu indicates a trajectory of a ray emitted from the center of the light source 1a at an angle α2=-5°, and a ray 2101cc indicates a ray emitted from the center of the light source 1a at an angle of 0°, that is, a ray parallel to the optical axis C1. The light ray 2101cd shows the trajectory of the light ray emitted from the center of the light source 1a at an angle α5=+5°.

The light ray 2101du shows the locus of the light ray emitted from the end of the light source 1a in the -Y axis direction at an angle α2=-5°, and the light ray 2101dc shows the trajectory of the light ray emitted from the end of the light source 1a in the -Y axis direction at an angle of 0°, i.e. , shows the locus of a light ray parallel to the optical axis C1, and a light ray 2101dd shows the locus of a light ray emitted from the end of the light source 1a in the −Y-axis direction at an angle α5=+5°.

<Trajectories of ray 2101cu, ray 2101cc, and ray 2101cd>
In the trajectory of the light ray 2101uu and the light ray 2101du, the angle α2a at which the light ray 2101cu enters the optical deflection element 212 and advances, and the angle α2b at which the light ray exits the optical deflection element 212 and advances are equal, so that the light ray 2101cu is Only the locus will be explained. In addition, since the angle α1a at which the light ray 2101cc and the light ray 2101dc travel after entering the light deflection element 212 and the angle α1b at which the light ray 2101cc exits the light deflection element 212 and travels are equal, the trajectory of the light ray 2101cc is equal. I will only explain about. The light ray 2101ud and the light ray 2101dd have the same angle α5a at which the light ray 2101cd enters the optical deflection element 212 and travels, and the same angle α5b at which the light ray exits the optical deflection element 212 and travels. Only the locus will be explained.

<Behavior of ray 2101cu>
The light ray 2101cu is emitted from the center of the light source 1a at an angle α2=−5°, is refracted by the optical deflection element 212, and travels in the +Z-axis direction at α2a. The angle α2a is calculated using the following formula (12) using Snell's law. Note that angles are calculated using absolute values.

sin(|α8|-|α2|)=1.515×sin(|α8|-|α2a|)...(12)
For example, if α8 is +18.81°, α2a=−9.74°. Note that the occurrence of calculation errors is the same as in the first embodiment, and is also the same in the following calculations.

The light beam 2101cu that has traveled inside the optical deflection element 212 is refracted at the exit surface of the optical deflection element 212, and travels in the +Z-axis direction at an angle α2b. The angle α2b is calculated using the following formula (13). Note that angles are calculated using absolute values.

1.515×sin(|α2a|)=sin(|α2b|)...(13)
If α2a=-9.74°, then α2b=-14.85°.

<Behavior of 2101cc light beam>
The light beam 2101cc is emitted from the center of the light source 1a at an angle of 0°, is refracted by the optical deflection element 212, and travels in the +Z-axis direction at α1a. α1a is calculated using the following formula (14). Note that angles are calculated using absolute values.

sin(|α8|)=1.515×sin(|α8|-|α1a|)...(14)
For example, if α8 is +18.81°, α1a=−6.52°.

The light beam 2101cc that has traveled inside the optical deflection element 212 is refracted at the exit surface of the optical deflection element 212, and travels in the +Z-axis direction at an angle α1b. The angle α1b is calculated using the following formula (15). Note that angles are calculated using absolute values.

1.515×sin(|α1a|)=sin(|α1b|)...(15)
If α1a=-6.52°, then α1b=-9.91°.

<Behavior of ray 2101cd>
The light ray 2101cd exits from the center of the light source 1a at an angle α5=+5°, is refracted by the optical deflection element 212, and travels in the +Z-axis direction at α5a. α5a is calculated using the following formula (16). Note that angles are calculated using absolute values.

sin(|α8|+|α5|)=1.515×sin(|α8|-|α2a|)...(16)
For example, if α8 is +18.81°, α5a=−3.36°.

The light beam 2101cd that has traveled inside the optical deflection element 212 is refracted at the exit surface of the optical deflection element 212, and travels in the +Z-axis direction at an angle α5b. The angle α5b is calculated using the following equation (17). Note that angles are calculated using absolute values.

1.515×sin(|α5a|)=sin(|α5b|)...(17)
If α5a=−3.36°, then α5b=−5.09°.

<Apparent position of light source 1a>
From the light ray 2101cu, the light ray 2101cc, and the light ray 2101cd, the angle with respect to the optical axis C1 at which the light ray emitted from the center of the light source 1a travels to the collimating lens 3 was calculated. Here, regarding the light rays 2101cu, 2101cc, and 2101cd that proceed to the collimating lens 3, the behavior of the light rays in the -Z axis direction when assuming that similar light rays are emitted without arranging the optical deflection element 212 is as follows. In FIG. 21, it is represented by a broken line. That is, regarding the light ray 2101cu, the light ray 2101cc, and the light ray 2101cd, the behavior of the light ray in the -Z-axis direction when the configuration in the -Z-axis direction is made into a black box is shown by a broken line. The same applies to the light rays 2101uu, 2101uc, and 2101ud emitted from the +Y-axis end of the light source 1a. The same applies to the light rays 2101du, 2101dc, and 2101dd emitted from the end of the light source 1a in the −Y-axis direction. As a result of this process, if the center of the light source 1a moves to the position P21c in FIG. 21, if the end of the light source 1a in the +Y-axis direction moves to the position P21u in FIG. It can be seen that the beam behaves in the same way as when the end moves to the position P21d in FIG. 21.

As described above, the optical deflection element 212 of the third embodiment is configured such that, as in FIG. The function of deflecting the light to the + side (+Y-axis direction) and emitting it, and the light from the light source placed on the - side of the optical axis C1, that is, the light source 1b, is It has the function of deflecting and emitting light in the direction (direction). Thereby, the apparent positions of the light sources 1a and 1b in the Y-axis direction can be moved in the optical axis C1 direction. As a result, the apparent length of the entire light source in the Y-axis direction can be shortened.

Further, as can be seen from FIG. 21, the apparent position of the light source 1a is inclined at an angle α21 with respect to the light source 1a. The angle α21 is, for example, 7°. However, the tilt is smaller than in the case of using the mirror shown in FIG. 6, and the influence of image blur is limited. From the back ray tracing results in FIG. 22, which will be described later, it is assumed that the influence of image blurring is small.

Here, the length y1pa of the position P21c in the Y-axis direction from the optical axis C1 is 17 μm, and the distance D3a in the Z-axis direction between the light source 1a and the position P21c is 97 μm, which is shorter than the distance D3 in FIG. I understand. Note that since aberrations occur due to the influence of the optical deflection element 212, the positions P21u, P21c, and P21d are approximate positions.

<Confirming the focus position in the Y-axis direction by back ray tracing>
FIG. 22 shows the back ray tracing results of the light source device 2101 of the third embodiment. FIG. 22 shows an enlarged view of the region "I" including the light source group 1 and the light deflection element 212, and an enlarged view of the region "J" of the exit surface of the collimating lens 3. Here, reverse ray tracing of the light beam traveling from the +Z-axis direction to the -Z-axis direction of the collimating lens 3 is performed to confirm the imaging position.

FIG. 22 shows the results of reverse ray tracing of a ray 2301u, a ray 2301c, and a ray 2301d, where the ray 2301d enters the collimating lens 3 at an angle of -0.31° with respect to the optical axis C1, The light ray 2301c is incident on the collimating lens 3 parallel to the optical axis C1, and the light ray 2301u is incident on the collimating lens 3 at an angle of +0.31° with respect to the optical axis C1.

When checking the light rays on the light source 1a, the light ray 2301u is focused (imaged) on the +Y-axis end of the light source 1a, the light ray 2301c is focused (imaged) on the center of the light source 1a, and the light ray 2301d It can be confirmed that the light is focused (imaged) on the end of the light source 1a in the −Y-axis direction. In other words, it can be confirmed that by inserting the optical deflection element 212, the light beam behaves in the same way as when the light source 1a is on the optical axis C1. In this way, by using the optical deflection element 212, the effect of improving the light utilization efficiency near the optical axis C1 can be obtained. Further, the apparent inclination α23 of the light source image confirmed in FIG. 21 is about 3°, and it is assumed that there is almost no influence on the illuminance distribution. It is assumed that this is because the tilt angle is reduced due to the aberration of the collimating lens 3.

<Relationship between the collimating lens 3 and the optical deflection element 212>
FIG. 23 is a diagram showing the results of reverse ray tracing when a ray parallel to the optical axis C1 is incident on the collimating lens 3 from the +Z-axis direction. In FIG. 23, an enlarged view of region "K" including light source group 1 is also shown. As shown in FIG. 23, it can be seen that the focal position P240f of the collimating lens 3 is on the −Z-axis direction side from the light source 1a. On the other hand, this embodiment also differs from the first embodiment in that the focal position P80f of the collimating lens 3 in FIG. 10 is located on the +Z-axis side from the light source 1a. As will be described later, this is because the shape of the collimating lens 3 is the same as in the first embodiment, but it is moved by 100 μm in the −Z-axis direction. Note that the distance D24 in the Z-axis direction between the light-emitting surface of the light source 1a and the focal point P240f in FIG. 23 is 33 μm, and the distance in the Z-axis direction between the light-emitting surface of the light source 1a in FIG. 10 and the focal point P80f is 67 μm. . In other words, the focal position is moved by 100 μm. The collimating lens 3 is moved by 100 μm in the −Z-axis direction in order to align the condensing position in the Y-axis direction in the reverse ray tracing shown in FIG. 22 near the light-emitting surface of the light source 1a.

<Illuminance distribution of Embodiment 3>
FIG. 24 shows the illuminance distribution of light on the evaluation plane (XY plane) at a distance of 2000 mm from the light sources 1a and 1b when both the light sources 1a and 1b are turned on using the optical deflection element 212. Note that the divergence angles of the light source 1a and the light source 1b are as follows: 1/e ² in the X-axis direction (RY direction) is ± approximately 37°, and 1/e ² in the Y-axis direction (RX direction) is ± The angle was approximately 5°. In FIG. 24, the horizontal axis indicates the X-axis (mm), the vertical axis indicates the Y-axis (mm), and the intensity of light is expressed divided into five gradations. Note that the brightest white color represents 100% intensity.

In the illuminance distribution in the X-axis direction, if the optical axis C1 is 0 mm, the area where the light intensity is 80% or more is separated from -7.2 mm to +7.2 mm (14.4 mm) around 0 mm. It turns out that it has arrived. Furthermore, it can be seen that the region where the light intensity is 20% or more is in the range of -11.5 mm to +11.4 mm (22.9 mm). It can be confirmed that the width in the X-axis direction is wider than the illuminance distribution of Embodiment 1 in FIG. 17.

In addition, in the illuminance distribution in the Y-axis direction, when the optical axis C1 is set to 0 mm, the continuous area where the light intensity is 80% or more is uniform in the range of -10.5 mm to +10.3 mm (20.8 mm). It can be seen that the light is reaching. Furthermore, it can be seen that the region where the light intensity is 20% or more is in the range of -11.9 mm to +12.0 mm (23.9 mm).

Compared to FIG. 17, the spread of the illuminance distribution in the Y-axis direction (area where the light intensity is 20% or more) is a little wider, but the effect of improving the light utilization efficiency on the optical axis C1 can be confirmed. Furthermore, it can be confirmed from FIG. 17 that the illuminance distribution spreads in the X-axis direction. This means that when a ray of light parallel to the optical axis C1 is incident from the +Z-axis direction to the -Z-axis direction, the light is focused on the light emitting surface of the light source 1a in the Y-axis direction, but the light emitted from the light source 1a is focused in the X-axis direction. This means that the light is not focused on the surface, that is, the light is focused in the -Z axis direction from the light emitting surface. In other words, this indicates that the light beams in the X-axis direction and the light beams in the Y-axis direction are focused at different positions. Therefore, by setting the inclined surface of the optical deflection element 212 in the −Z-axis direction, a new problem has arisen in that the condensing positions for the light beam in the X-axis direction and the light beam in the Y-axis direction are different enough to affect the illuminance distribution. it is conceivable that. However, for example, when using the light source device 2101 of Embodiment 3 and the screen size projected onto the screen is close to a square such as horizontal:vertical = 4:3, the horizontal side of the screen is aligned in the Y-axis direction of the light source device. By making the length of the screen correspond to the X-axis direction of the light source device, it becomes possible to guide light to the screen while suppressing a decrease in efficiency. The area where the light intensity in the X-axis direction is 20% or more is 22.9 mm, and the area where the light intensity in the Y-axis direction is 20% or more is 23.9 mm, so X:Y = 1:1.04, and horizontal: vertical = A ratio of 4:3 is relatively preferable.

Here, the projection device is generally composed of a light source device, an illumination optical system, and a projection optical system, and focuses the light of the light source device on a light intensity equalizing element that equalizes the intensity distribution of the light of the light source device. The light uniformized by the light intensity equalizing element is transferred to the display device by the illumination optical system, and the image formed by the display device is enlarged and projected onto the screen by the projection optical system.

Since the aspect ratios of the light intensity equalizing element and the display device are approximately equal, for example, the screen resolution is 4:3 when the screen resolution is XGA (eXtended Graphics Array), and 16:9 when the screen resolution is full HD (full high definition). This is the aspect ratio. Note that when the aspect ratio is 16:9, it is preferable that the spread of the illuminance distribution in the X-axis direction is narrower than the illuminance distribution in FIG. 24.

<Explanation of the difference in focusing position in the X-axis direction and Y-axis direction>
The positional relationship between the light source group 1 and the collimating lens 3 will be explained using FIGS. 25 and 26. FIG. 25 is a diagram similar to FIG. 7 shown in Embodiment 1, in which light rays extend in the +Z-axis direction from the +Y-axis end, the center, and the −Y-axis end of the light source 1a with a spread of ±5°. Shows the ray tracing results when progress is made. Further, FIG. 26 shows the ray tracing results when the rays travel in the +Z-axis direction with a spread of ±5° from the +Y-axis end, center, and −Y-axis end of the light source 1a of the third embodiment. .

When performing reverse ray tracing of a light beam in the X-axis direction, which will be described later, the height in the Y-axis direction at the time of exit from the collimating lens 3 is checked in order to determine the position in the Y-axis direction. From FIG. 25, the distance y26t1 between the height at which the ray emitted at -5° exits the collimating lens 3 and the optical axis C1 is 1.8 mm, and the height and optical axis at which the ray exited at +5° exits the collimating lens 3. The interval y26b1 of C1 is 0.5 mm. Also, from FIG. 26, the distance y26t2 between the height at which the ray emitted at -5° exits the collimating lens 3 and the optical axis C1 is 1.7 mm, and the height at which the ray emitted at +5° exits the collimating lens 3. The distance y26b2 between the optical axes C1 is 0.5 mm.

In addition, the distance D261 in the Z-axis direction between the light emitting surface of the light source 1a and the +Z-axis direction end of the collimating lens 3 in FIG. The distance D262 in the Z-axis direction between the ends is 8.04 mm, and the positions of the collimating lenses 3 differ by 100 μm.

<Reverse ray tracing in the X-axis direction of Embodiment 1>
FIG. 27 shows the results of back ray tracing in the X-axis direction of the first embodiment. In FIG. 27, as an enlarged view of region "L" including the light source 1a, a light ray is incident at a height of 0.5 mm in the +Y-axis direction from the optical axis C1 whose Y-axis direction position shown in FIG. 25 corresponds to the interval y26b1. FIG. 6 shows an enlarged view of a case where a light ray is incident at a height of 1.8 mm in the +Y-axis direction from the optical axis C1 whose position in the Y-axis direction corresponds to the interval y26t1. From FIG. 27, in the case of the interval y26b1, the range of the focusing position is Dz1m=41.9 μm on the −Z-axis direction side, Dz1p=47.3 μm on the +Z-axis direction side with respect to the light emitting surface of the light source 1a, In other words, it can be seen that the light is focused within the range of -41.9 μm to +47.3 μm. In addition, in the case of the interval y26t1, the range of the light focusing position is Dz2m=9.8 μm on the −Z-axis direction side and Dz2p=14.6 μm on the +Z-axis direction side with respect to the light emitting surface of the light source 1a, that is, − It can be seen that the light is focused within the range of 9.8 μm to +14.6 μm. It can be confirmed that the lower the Y-axis direction position, the wider the light collection range. Furthermore, when considered on average, it can be confirmed that the light condensing position is slightly shifted in the +Z-axis direction.

<Reverse ray tracing in the X-axis direction in Embodiment 3>
FIG. 28 shows the results of back ray tracing in the X-axis direction of the third embodiment. FIG. 28 is an enlarged view of the region "M" including the light source 1a, where a light ray is incident at a height of 0.5 mm in the +Y-axis direction from the optical axis C1 whose Y-axis direction position shown in FIG. 26 corresponds to the interval y26b2. FIG. 6 shows an enlarged view of a case in which a light ray is incident at a height of 1.7 mm in the +Y-axis direction from the optical axis C1 whose position in the Y-axis direction corresponds to the interval y26t2. From FIG. 28, in the case of the interval y26b2, the range of the condensing position is Dz3m=142 μm and Dz3p=52.8 μm, that is, −142 μm to −52. It can be seen that the light is focused within a range of 8 μm. In addition, in the case of the interval y26t2, the range of the light focusing position is Dz4m=111.9μm and Dz4p=85.7μm, that is, −111.9μm to − in the −Z-axis direction with respect to the light emitting surface of the light source 1a. It can be seen that the light is focused within a range of 85.7 μm. It can be confirmed that the lower the Y-axis direction position, the wider the light collection range. Further, it can be seen that, on average, the light condensing position is moved by 50 μm or more, about 98 μm, in the −Z-axis direction with respect to the light emitting surface of the light source 1a. - Since the condensing position has moved by approximately 98 μm in the Z-axis direction, the light rays emitted from the center of the light source 1a while spreading in the X-axis direction have a different angle after exiting the collimating lens 3 than in the first embodiment. In other words, the fact that the light is emitted with low parallelism is considered to be the reason why the illuminance distribution spreads in the X-axis direction as shown in FIG.

<Illuminance distribution when moving the collimating lens 3 and the optical deflection element 212>
29 and 30 show the illuminance distribution of light on the evaluation surface at a distance of 2000 mm from the light source 1a and the light source 1b when both the light source 1a and the light source 1b of the third embodiment are turned on. FIG. 29 shows the illuminance distribution when the collimating lens 3 and the optical deflection element 212 of the third embodiment are moved by 150 μm in the +Z-axis direction. FIG. 30 shows the illuminance distribution when the collimating lens 3 and the optical deflection element 212 of the third embodiment are moved by 100 μm in the +Z-axis direction. Note that the divergence angles of the light source 1a and the light source 1b are as follows: 1/e ² in the X-axis direction (RY direction) is ± approximately 37°, and 1/e ² in the Y-axis direction (RX direction) is ± The angle was approximately 5°. In FIGS. 29 and 30, the horizontal axis indicates the X axis (mm), the vertical axis indicates the Y axis (mm), and the intensity of light is expressed divided into five gradations. Note that the brightest white color represents 100% intensity.

Here, in the illuminance distribution in the X-axis direction of Embodiment 1 shown in FIG. 17, when the optical axis C1 is set to 0 mm, the area where the light intensity is 80% or more continuously ranges from -0.6 mm to +0. It can be seen that the light reaches uniformly within a range of 6 mm (1.2 mm). Furthermore, it can be seen that the region where the light intensity is 20% or more is in the range of −1.8 mm to +1.8 mm (3.6 mm).

On the other hand, in the illuminance distribution in the X-axis direction in FIG. 30, when the optical axis C1 is set to 0 mm, the continuous region where the light intensity is 80% or more is in the range of -0.8 mm to +0.8 mm (1.6 mm). It can be seen that the light reaches the image evenly. Furthermore, it can be seen that the region where the light intensity is 20% or more is in the range of -1.9 mm to +1.9 mm (3.8 mm). It can be confirmed that the width in the X-axis direction is slightly wider than the illuminance distribution in FIG. 17 . In addition, in the illuminance distribution in the Y-axis direction in FIG. 30, if the optical axis C1 is 0 mm, the continuous region where the light intensity is 80% or more is in the range of -10.0 mm to +10.0 mm (20.0 mm). It can be seen that the light reaches the image evenly. Furthermore, it can be seen that the region where the light intensity is 20% or more is in the range of -12.3 mm to +12.4 mm (24.7 mm). From this, it can be confirmed that the width in the Y-axis direction is slightly wider than the illuminance distribution in FIG. 17.

As can be seen from the illuminance distribution in the X-axis direction in FIG. 30, by moving the collimating lens 3 and the optical deflection element 212 by 100 μm in the +Z-axis direction, the focal position in the X-axis direction is approximately set on the light emitting surface of the light source 1a. Therefore, the spread of the illuminance distribution in the X-axis direction is smaller compared to FIG. 24, in which the focal position in the X-axis direction is moved by about 100 μm in the -Z-axis direction with respect to the light emitting surface of the light source 1a. can be confirmed. From this, it is considered preferable to align the focal position in the X-axis direction, where the divergence angle of the light source is large, with the light emitting surface of the light source. In other words, in the Y-axis direction where the divergence angle is small, the depth of focus is deeper than in the X-axis direction where the divergence angle is large, the sensitivity to the focal position is lower, and the influence on the illuminance distribution is smaller. It is thought that it is preferable to adjust the focus to the focal position.

Furthermore, from FIG. 29, it can be confirmed that when the collimating lens 3 and the optical deflection element 212 of Embodiment 3 are further moved by 50 μm in the +Z-axis direction, the area where the light intensity is 20% or more expands in the X-axis direction. It can be seen that it is preferable to prioritize the focus position in the X-axis direction over the focus position in the Y-axis direction.

<Correction of focus position in X-axis direction and Y-axis direction>
As explained above, when the optical deflection element 212 having an inclined incident surface is used, reverse ray tracing is performed in which light rays are incident on the collimating lens 3 from the +Z-axis direction to the -Z-axis direction in the X-axis direction and the Y-axis direction. It can be seen that when doing this, the focal position is different, and when focusing in the Y-axis direction, the X-axis direction becomes blurred on the evaluation surface. Regarding the difference between the focal positions in the X-axis direction and the Y-axis direction, the surface on the +Z-axis direction side of the collimating lens 3 is not an aspherical surface that is rotationally symmetrical with respect to the Z-axis, but the curvature of the ZX plane is greater than the curvature of the YZ plane. It is assumed that by increasing the size, it becomes possible to move the focus position in the X-axis direction in the +Z-axis direction, and it becomes possible to bring it closer to the focus position in the Y-axis direction. In other words, it is considered that it is good to make the surface of the parallelizing lens 3 on the +Z-axis direction side an anamorphic aspheric surface. For example, on the +Z-axis side surface of the collimating lens 3, the same conic constant and aspherical coefficient as in the YZ plane may be used in the ZX plane, and only the curvature may be increased. For example, the radius of curvature of the YZ plane may be 4.90 mm, and the radius of curvature of the ZX plane may be 4.81 mm. Note that the incident surface, that is, the surface on the −Z-axis direction side may have a shape that is rotationally symmetrical about the Z-axis. For example, a spherical concave shape with a radius of curvature of 43.7 mm may be used.

<Embodiment 4: Illuminance distribution when using anamorphic aspheric surface>
FIG. 31 shows the illuminance distribution when the +Z-axis direction side surface of the collimating lens 3 is an anamorphic aspherical surface in the light source device of the fourth embodiment. That is, FIG. 31 shows an anamorphic aspheric surface in which the curvature of the ZX plane is larger than the curvature of the YZ plane on the +Z axis direction surface of the collimating lens 3, for example, the radius of curvature of the YZ plane is 4.90 mm, and the curvature of the ZX plane is 4.90 mm. The illuminance distribution of light on the evaluation surface at a distance of 2000 mm from the light source 1a and the light source 1b is shown when the radius is 4.81 mm and both the light source 1a and the light source 1b are turned on. Note that the divergence angles of the light source 1a and the light source 1b are as follows: 1/e ² in the X-axis direction (RY direction) is ± approximately 37°, and 1/e ² in the Y-axis direction (RX direction) is ± The angle was approximately 5°. In FIG. 31, the horizontal axis indicates the X-axis (mm), the vertical axis indicates the Y-axis (mm), and the intensity of light is expressed divided into five gradations. Note that the brightest white color represents 100% intensity.

In the illuminance distribution in the X-axis direction in Fig. 31, when the optical axis C1 is set to 0 mm, the continuous area where the light intensity is 80% or more is uniform in the range of -0.4 mm to +0.5 mm (0.9 mm). It can be seen that the light is reaching . Furthermore, it can be seen that the region where the light intensity is 20% or more is in the range of -1.5 mm to +1.5 mm (3.0 mm). It can be confirmed that the width in the X-axis direction is slightly narrower than the illuminance distribution in FIG. 17.

In addition, in the illuminance distribution in the Y-axis direction, if the optical axis C1 is 0 mm, the continuous area where the light intensity is 80% or more is uniform in the range of -9.9 mm to +9.9 mm (19.8 mm). It can be seen that the light is reaching. Furthermore, it can be seen that the region where the light intensity is 20% or more is in the range of -12.5 mm to +12.6 mm (25.1 mm). From this, it can be confirmed that the width in the Y-axis direction is slightly wider than the illuminance distribution in FIG. 17.

From the above, it can be confirmed that an illuminance distribution substantially similar to the illuminance distribution shown in FIG. 17 of the light source device 100 of Embodiment 1 using the optical deflection element 2 can be obtained. This confirmed the effect of the anamorphic aspheric surface. Moreover, when compared with the illuminance distribution in the defocused case shown in FIG. 30, it can be confirmed that the spread of the illuminance distribution in the X-axis direction is further suppressed. In addition, it is preferable that the collimating lens 3 has an aspherical shape in the ZX plane and the YZ plane, and when either one is a spherical surface, for example, a toroidal surface suppresses the spread in the X-axis direction but causes aberrations. This has a large influence, and the efficiency of using light that reaches the vicinity of the optical axis C1 of the evaluation surface decreases.

The anamorphic aspherical surface described in the fourth embodiment shows a case where the conic constant and aspherical coefficient of the YZ plane and the ZX plane are the same, and only the radius of curvature is different. Note that although the conic constant and aspherical coefficient of the YZ plane and the ZX plane may have different shapes, there is a concern that the shapes will become complicated and affect workability.

In addition, although we have explained the surface shape of the parallelizing lens 3 on the +Z-axis side, the surface shape on the +Z-axis side is an aspherical shape that is rotationally symmetrical about the Z-axis, and the surface shape of the ZX plane with respect to the surface in the -Z-axis direction is The curvature may be larger than the curvature of the YZ plane. For example, the surface on the +Z-axis side is an aspherical surface rotationally symmetrical about the Z-axis with a radius of curvature of 4.90 mm, and the surface on the -Z-axis side is an aspherical surface with a radius of curvature of 4.90 mm. It may be a concave toroidal surface with a radius of curvature of 43.7 mm on the YZ plane and 70 mm on the ZX plane. The surface shape on the -Z axis side is concave, that is, has a negative curvature, so the curvature is larger on the ZX plane than on the YZ plane. Note that the curvature is the reciprocal of the radius of curvature.

<When the surface in the -Z axis direction is a toroidal surface>
FIG. 32 shows an illuminance distribution when the −Z-axis side surface of the collimating lens 3 is a toroidal surface as a modification of the light source device of the fourth embodiment. That is, FIG. 32 shows a concave toroidal surface with a radius of curvature of 43.7 mm on the YZ plane and 70 mm on the ZX plane on the -Z axis side surface of the collimating lens 3, and a concave toroidal surface with a radius of curvature of 70 mm on the The illuminance distribution of light on the evaluation surface at a distance of 2000 mm from the light source 1a and the light source 1b is shown when the surface shape is a rotationally symmetrical aspherical surface and both the light source 1a and the light source 1b are turned on. Note that the divergence angles of the light source 1a and the light source 1b are as follows: 1/e ² in the X-axis direction (RY direction) is ± approximately 37°, and 1/e ² in the Y-axis direction (RX direction) is ± The angle was approximately 5°. In FIG. 32, the horizontal axis indicates the X-axis (mm), the vertical axis indicates the Y-axis (mm), and the intensity of light is divided into five gradations. Note that the brightest white color represents 100% intensity.

In the illuminance distribution in the X-axis direction in Fig. 32, when the optical axis C1 is set to 0 mm, the continuous area where the light intensity is 80% or more is uniform in the range of -0.4 mm to +0.4 mm (0.8 mm). It can be seen that the light is reaching . Furthermore, it can be seen that the region where the light intensity is 20% or more is in the range of −1.3 mm to +1.3 mm (2.6 mm). It can be confirmed that the width in the X-axis direction is slightly narrower than the illuminance distribution in FIG. 17 .

In addition, in the illuminance distribution in the Y-axis direction, if the optical axis C1 is 0 mm, the continuous area where the light intensity is 80% or more is uniform in the range of -10.1 mm to +10.0 mm (20.1 mm). It can be seen that the light is reaching. Furthermore, it can be seen that the region where the light intensity is 20% or more is in the range of -12.5 mm to +12.5 mm (25.0 mm). From this, it can be confirmed that the width in the Y-axis direction is slightly wider than the illuminance distribution in FIG. 17.

From the above, it can be confirmed that an illuminance distribution substantially similar to the illuminance distribution shown in FIG. 17 of the light source device 100 of Embodiment 1 using the optical deflection element 2 can be obtained. This confirmed the effect of the toroidal surface. Moreover, when compared with the illuminance distribution in the defocused case shown in FIG. 30, it can be confirmed that the spread of the illuminance distribution in the X-axis direction is further suppressed.

Here, in the fourth embodiment, the −Z-axis direction side surface of the collimating lens 3 and the +Z-axis direction side surface have different shapes, but the shape is not limited to this, and the collimating lens 3 has different shapes. 3, the curvature of the ZX plane may be greater than the curvature of the YZ plane.

The toroidal surface exhibiting the effect in the modification of the fourth embodiment shows the case where the conic constant=0 and the aspherical coefficient=0 in the ZX plane and the YZ plane. There is a concern that having a conic constant and an aspherical coefficient will complicate the shape. In other words, the ZX plane and the YZ plane are toroidal surfaces having different spherical curvatures or radii of curvature. Note that the third embodiment has a greater effect than the first embodiment in that the +Z-axis side surface of the collimating lens 3 is made an anamorphic aspherical surface, or the -Z-axis direction side is made a toroidal surface. However, as shown in the illuminance distribution in FIG. 17, even when the optical deflection element 2 has an inclined surface on the +Z-axis side, the convergence position of the light beam on the X-axis direction and the condensation position on the Y-axis direction are different. are different, and by making the +Z-axis side surface of the collimating lens 3 an anamorphic aspheric surface, the illuminance distribution width on the evaluation surface in the X-axis direction may be narrowed. Further, the surface of the collimating lens 3 on the −Z-axis direction side may be a toroidal surface.

<When anamorphic aspheric surface is applied to Embodiment 1>
The collimating lens 3 of the light source device 100 of Embodiment 1 may have the same conic constant and aspherical coefficient as the YZ plane on the +Z-axis direction side in the ZX plane, and may have an anamorphic aspherical surface by increasing only the curvature. . For example, the radius of curvature of the YZ plane is 4.90 mm, and the radius of curvature of the ZX plane is 4.895 mm. Note that the incident surface, that is, the surface on the −Z-axis direction side may have a shape that is rotationally symmetrical about the Z-axis. For example, a spherical concave shape with a radius of curvature of 43.7 mm may be used.

FIG. 33 shows the illuminance distribution of light on the evaluation surface at a distance of 2000 mm from the light source 1a and the light source 1b when both the light source 1a and the light source 1b are turned on. Note that the divergence angles of the light source 1a and the light source 1b are as follows: 1/e ² in the X-axis direction (RY direction) is ± approximately 37°, and 1/e ² in the Y-axis direction (RX direction) is ± The angle was approximately 5°. In FIG. 33, the horizontal axis indicates the X-axis (mm), the vertical axis indicates the Y-axis (mm), and the intensity of light is expressed divided into five gradations. Note that the brightest white color represents 100% intensity.

In the illuminance distribution in the X-axis direction in Fig. 33, when the optical axis C1 is set to 0 mm, the continuous area where the light intensity is 80% or more is uniform in the range of -0.5 mm to +0.5 mm (1.0 mm). It can be seen that the light is reaching . Furthermore, it can be seen that the region where the light intensity is 20% or more is in the range of −1.8 mm to +1.8 mm (3.6 mm). As compared with FIG. 17, it can be confirmed that the spread of the width in the X-axis direction of the region where the light intensity is 80% or more is slightly narrower.

In addition, in the illuminance distribution in the Y-axis direction, when the optical axis C1 is set to 0 mm, the continuous area where the light intensity is 80% or more is uniform in the range of -8.8 mm to +8.8 mm (17.6 mm). It can be seen that the light is reaching. Furthermore, it can be seen that the region where the light intensity is 20% or more is in the range of -11.5 mm to +11.5 mm (23.0 mm). From this, it can be confirmed that the spread of the width in the Y-axis direction is approximately equal when compared with the illuminance distribution in FIG. 17.

From the above, when an anamorphic aspherical surface is applied to the collimating lens 3 of the light source device 100 of Embodiment 1, the illuminance distribution in the X-axis direction is It can be confirmed that the distribution becomes narrower, albeit slightly. This confirmed the effect of the anamorphic aspheric surface.

Note that the anamorphic aspheric surface applied to the collimating lens 3 of the light source device 100 of the first embodiment, which can obtain the same effect as the fourth embodiment, has the same conic constant and aspheric coefficient on the YZ plane and the ZX plane, and has a curvature of The case where only the radius differs is shown.

Furthermore, as explained using FIG. 27, in the light source device 100 of Embodiment 1, the condensing position of the light beam in the X-axis direction is assumed to be located on the +Z-axis direction side from the light emitting surface of the light source. Considering the intensity distribution (light distribution) of the light source from the illuminance distribution results in Figure 33, it is thought that the condensing position of the light ray in the X-axis direction is located on the -Z-axis direction side from the light emitting surface. It is thought that the effect was obtained by making the curvature larger than the curvature of the YZ plane.

<When toroidal surface is applied to Embodiment 1>
The collimating lens 3 of the light source device 100 of Embodiment 1 has an aspherical surface shape on the +Z-axis side that is rotationally symmetrical about the Z-axis, and the curvature of the ZX plane with respect to the surface in the -Z-axis direction is the YZ plane. It is also possible to make the curvature larger than that to form a toroidal surface. For example, the surface on the +Z-axis side is an aspherical surface that is rotationally symmetrical about the Z-axis with a radius of curvature of 4.90 mm, and the surface on the -Z-axis side is an aspherical surface that is rotationally symmetrical about the Z-axis with a radius of curvature of 4.90 mm. It may be a concave toroidal surface with a plane radius of curvature of 43.7 mm and a ZX plane radius of curvature of 50 mm. The surface shape on the -Z axis side is concave, that is, has a negative curvature, so the curvature is larger on the ZX plane than on the YZ plane.

FIG. 34 shows the illuminance distribution of light on the evaluation surface at a distance of 2000 mm from the light source 1a and the light source 1b when both the light source 1a and the light source 1b are turned on. Note that the divergence angles of the light source 1a and the light source 1b are as follows: 1/e ² in the X-axis direction (RY direction) is ± approximately 37°, and 1/e ² in the Y-axis direction (RX direction) is ± The angle was approximately 5°. In FIG. 34, the horizontal axis indicates the X-axis (mm), the vertical axis indicates the Y-axis (mm), and the intensity of light is divided into five gradations. Note that the brightest white color represents 100% intensity.

In the illuminance distribution in the X-axis direction in Fig. 34, when the optical axis C1 is set to 0 mm, the continuous area where the light intensity is 80% or more is uniform in the range of -0.3 mm to +0.3 mm (0.6 mm). It can be seen that the light is reaching . Furthermore, it can be seen that the region where the light intensity is 20% or more is in the range of -1.3 mm to +1.3 mm (2.6 mm). It can be confirmed that the width in the X-axis direction is narrower than the illuminance distribution in FIG. 17.

In addition, in the illuminance distribution in the Y-axis direction, when the optical axis C1 is set to 0 mm, the continuous area where the light intensity is 80% or more is uniform in the range of -9.1 mm to +9.0 mm (18.1 mm). It can be seen that the light is reaching. Furthermore, it can be seen that the region where the light intensity is 20% or more is in the range of −11.3 mm to +11.3 mm (22.6 mm). From this, it can be confirmed that the spread of the width in the Y-axis direction is approximately equal when compared with the illuminance distribution in FIG. 17.

From the above, it is confirmed that when a toroidal surface is applied to the collimating lens 3 of the light source device 100, the illuminance distribution in the X-axis direction becomes narrower compared to the illuminance distribution in FIG. 17 when no toroidal surface is applied. can. This confirmed the effect of the toroidal surface.

Note that the toroidal surface applied to the collimating lens 3 of the light source device 100 of the first embodiment, which can obtain the same effect as the fourth embodiment, has a conic constant = 0 and an aspheric coefficient = 0 in the ZX plane and the YZ plane. The case is shown below. There is a concern that having a conic constant and an aspherical coefficient will complicate the shape. In other words, the ZX plane and the YZ plane are toroidal surfaces with different spherical curvatures (or radii of curvature).

Furthermore, as explained using FIG. 27, in the light source device 100 of Embodiment 1, the condensing position of the light beam in the X-axis direction is assumed to be located on the +Z-axis direction side from the light emitting surface of the light source. Considering the intensity distribution (light distribution) of the light source from the results of the illuminance distribution in Fig. 34, it is thought that the condensing position of the light ray in the X-axis direction is located on the -Z-axis direction side from the light emitting surface. It is thought that the effect was obtained by making the curvature larger than the curvature of the YZ plane.

<When the inclined surface in Embodiment 3 is a curved surface>
If the inclined surface on the −Z-axis direction side of the light deflection element 212 of the light source device 2101 of the third embodiment shown in FIG. 20 is not a flat surface but a curved surface, for example, the curved surface on the +Y-axis direction side from the optical axis C1 is It is a spherical or aspherical surface whose center of curvature is located in the +Y-axis direction from the center of the light source 1a, and the light beam emitted from the light source 1a is deflected in the +Y-axis direction and emitted. At this time, the larger the curvature, the stronger the influence of deflection. As an example of this measure, in order to make the light rays emitted from the collimating lens 3 parallel to the optical axis C1, for example, in the collimating lens 3, the collimating lens By setting the center of curvature of 3 in the -Y axis direction, the light ray traveling in the +Y axis direction is deflected in the -Y axis direction, thereby making it possible to make the light ray parallel to the optical axis C1.

In other words, the collimating lens 3 is placed on a curved surface on the +Y-axis direction side from the optical axis C1, and the center of curvature of the collimating lens 3 is on the -Y-axis direction, and the parallelizing lens 3 is placed on a curved surface on the -Y-axis side from the optical axis C1. By setting the curvature center of the collimating lens 3 in the +Y-axis direction and integrating two lenses with different curvature center positions, the apparent length of the light source in the Y-axis direction can be shortened, similar to the illuminance distribution in Fig. 17. It becomes possible to do so.

Note that considering the manufacturing cost of making the -Z-axis direction side inclined surface of the optical deflection element 212 a curved surface and the manufacturing cost of integrating lenses with different centers of curvature, the first embodiment, the third embodiment, or Embodiment 4 is considered to be more preferable.

<Embodiment 5: Example of three or more light sources>
FIG. 35 is a diagram showing a schematic configuration of a light source device 100A according to the fifth embodiment. As shown in FIG. 35, it is possible to increase the number of light sources to three or more. In the example shown in FIG. 35, in addition to the light source 14a (first light source) and light source 14b (second light source) arranged symmetrically with respect to the optical axis C1, a light source 14c (third light source) is further arranged on the optical axis C1. light sources) are placed. When using such a light source group 14, a light deflection element 20 as shown in FIG. 35 can be used. The optical deflection element 20 shown in FIG. 35 has a first optical surface 20c on the optical axis C1 that has no inclination with respect to a reference plane (XY plane) perpendicular to the optical axis C1, and a first optical surface 20c on both sides thereof with respect to the reference plane. It includes a second optical surface 20a and a third optical surface 20b having a slope. The first optical surface 20c emits the light beam emitted from the light source 14c from the optical deflection element 20 at the same angle in the +Z-axis direction. The second optical surface 20a emits the light beam emitted from the light source 14a in the +Z-axis direction at an angle in the +Y-axis direction, for example, like the light beam 501cc in FIG. The third optical surface 20b emits the light beam emitted from the light source 14b in the +Z-axis direction at an angle in the -Y-axis direction. Note that the second optical surface 20a moves the virtual focal point of the light source 14a in the +Z-axis direction, and the third optical surface 20b moves the virtual focal point of the light source 14b in the +Z-axis direction. Moving. Therefore, the following adjustment may be made to align the Z-axis direction position with the virtual convergence points of both. That is, the air equivalent length may be adjusted by moving the first optical surface 20c in the +Z-axis direction. Further, the light source 14c may be moved in the +Z-axis direction.

By adopting such a configuration, it becomes possible to further improve the light utilization efficiency near the optical axis C1.

Although the example shown in FIG. 35 shows an example in which the optical surface for light deflection is arranged on the light incidence side, it is also possible to provide the optical surface on the light exit side. By adopting such a configuration, it becomes possible to further improve the light utilization efficiency near the optical axis C1.

It is also possible to substitute a similar deflection function using a mirror. In this case, when replacing the optical deflection element 20 shown in FIG. A mirror is provided at a portion corresponding to the optical surface 20b. Further, as in the case of FIG. 35, the light source 14c may be moved in the +Z-axis direction so as to match the Z-axis direction position of the virtual condensing points of the light sources 14a and 14b. Therefore, in the present disclosure, a "light deflection element" in a broad sense includes a member (in this example) that adjusts the apparent length of the entire light source in the Y-axis direction in the arrangement direction of the light sources by deflecting light using reflection. In this case, the above-mentioned mirror) is also included. Note that in order to obtain the effects of the fifth embodiment, a configuration in which the number of light sources is two or more is preferable. Further, by using the collimating lens 3 of the fourth embodiment, it is possible to obtain the effects of the fourth embodiment.

Although the present disclosure has been described in detail, the above description is illustrative in all aspects, and the present disclosure is not limited thereto. It is understood that countless variations not illustrated can be envisioned without departing from the scope of this disclosure.

Note that within the scope of the disclosure, the embodiments of the present disclosure can be freely combined, or the embodiments can be modified or omitted as appropriate.

Claims (10)

A light source device that irradiates light to an irradiation target in a Z-axis direction in an XYZ coordinate system including an X-axis, a Y-axis, and a Z-axis,
a first light source and a second light source that are arranged apart in the Y-axis direction in the XYZ coordinate system and emit light whose divergence angle in the Y-axis direction is smaller than the divergence angle in the X-axis direction in the XYZ coordinate system; a group of light sources that emit a luminous flux;
a collimating lens that collimates the light flux emitted by the light source group;
A first optical surface that is arranged between the light source group and the collimating lens in the Z-axis direction and is a plane that deflects the light emitted by the first light source, and a plane that deflects the light that is emitted by the second light source. an optical deflection element configured to have a concave shape toward the irradiation target in the Z-axis direction using a second optical surface, and deflect the light beam emitted from the light source group to make it enter the collimating lens. , the first light source is arranged to face the first optical surface in the Z-axis direction, and the second light source is arranged to face the second optical surface in the Z-axis direction. Light source device. The optical deflection element is
The light source device according to claim 1, wherein the light emitted from each of the first light source and the second light source is transmitted, refracted, and deflected in a direction away from the Z-axis direction of the collimating lens. The light emitted from the first light source and the second light source with an extension in the Y-axis direction exits the light deflection element with an extension in the Y-axis direction,
3. The light source device according to claim 1, wherein the light that has spread in the Y-axis direction and enters the collimating lens becomes parallel to the Z-axis direction and is emitted by the collimating lens. The optical deflection element is
The light source device according to claim 1, wherein the light emitted from each of the first light source and the second light source is reflected and deflected in a direction away from the Z-axis direction of the collimating lens. The light deflection element has a light reflecting surface,
The distance between the center of one light source among the first light source and the second light source and the Z axis is an interval y1ac,
The distance between the central part of the one light source and the reflective surface is a distance D4,
When the inclination angle of the reflective surface with respect to the Z axis is α9,
The distance D4 is
It is set based on the relational expression y1ac/D4=sin(2×|α9|),
5. The light source device according to claim 4, wherein an error of ±10% is allowed for the distance D4. When parallel light is incident on the collimating lens from the side opposite to the first light source and the second light source in the direction along the Z axis, the optical system including the collimating lens and the light deflecting element 6. The light source device according to claim 4, wherein a condensing position of the parallel light is located between the first light source, the second light source, and the optical deflection element. 7. The light source device according to claim 1, wherein the light source device has a ring-shaped illuminance distribution at a position closer to the collimating lens than a focal position of the collimating lens closer to the first light source and the second light source. further comprising a third light source disposed on the Z axis,
The optical deflection element is
In the Y-axis direction of the first light source and the second light source, the light emitted from each of the first light source and the second light source is deflected in a direction away from the Z-axis. 7. The light source device according to any one of 7. A collimating lens that collimates the incident light;
The light source includes a plurality of light sources arranged apart from each other in a direction away from the optical axis of the collimating lens, and diverges in a first direction and a second direction parallel to the direction away from the optical axis, which are orthogonal to each other as a whole. A group of light sources that emit light beams with different angles,
disposed between the light source group and the collimating lens in the direction of the optical axis, and in the first direction of the first direction and the second direction, the divergence angle of the light source group is smaller. , an optical deflection element that deflects the light emitted from each of the plurality of light sources in a direction away from the optical axis and causes it to enter the collimating lens,
The optical deflection element is
Has a light reflective surface,
reflecting the light emitted from each of the plurality of light sources and deflecting it in a direction away from the optical axis;
The distance between the center of one light source among the plurality of light sources and the optical axis is defined as an interval y1ac,
The distance between the central part of the one light source and the reflective surface is a distance D4,
When the inclination angle of the reflective surface with respect to the optical axis is α9,
The distance D4 is
It is set based on the relational expression y1ac/D4=sin(2×|α9|),
The distance D4 is a light source device in which an error of ±10% is allowed. A collimating lens that collimates the incident light;
The light source includes a plurality of light sources arranged apart from each other in a direction away from the optical axis of the collimating lens, and diverges in a first direction and a second direction parallel to the direction away from the optical axis, which are orthogonal to each other as a whole. A group of light sources that emit light beams at different angles,
disposed between the light source group and the collimating lens in the direction of the optical axis, and in the first direction of the first direction and the second direction, the divergence angle of the light source group is smaller. , an optical deflection element that deflects the light emitted from each of the plurality of light sources in a direction away from the optical axis and causes it to enter the collimating lens,
The optical deflection element is
Has a light reflective surface,
reflecting the light emitted from each of the plurality of light sources and deflecting it in a direction away from the optical axis;
When parallel light enters the collimating lens from the side opposite to the light source group in the direction along the optical axis, the collimating position of the collimated light by the optical system including the collimating lens and the light deflection element. is located between the plurality of light sources and the light deflection element.

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