TW201636725A - Lens and projection image display device - Google Patents

Abstract

The invention provides a lens capable of inhibiting the influence of back focal length variation even if there is environment change at low cost, and a projection image display device using the lens. The invention determines the length T of a leg portion of a collimating lens (COL) by satisfying equation (1). The leg portion (LG) stretches by the length of T±△T in response to environmental temperature variation. Therefore, the invention can inhibit back focal length variation. Furthermore, because the collimating lens (COL) has a pair of cuts (CT), a laser chip (CP) would not be sealed by the collimating lens (COL) even if an end portion of the leg portion (LG) is connected to a stem portion (ST), and the laser chip (CP) can be cooled by letting in external air from the cuts (CT). This invention inhibits temperature rise of the collimating lens (COL) and effectively inhibits the back focal length variation. In this invention, BF refers to a distance (mm) measured from an optical surface of a light source side to a light concentration location, and [Phi] is a lens outer diameter (mm).

Description

Lens and projection image display device

The present invention relates to a projection image display device and a lens used therein.

In recent years, development of projection image display devices using semiconductor lasers or LEDs (Light Emitting Diodes) for light sources has been widely practiced for the purpose of miniaturization and weight reduction. In a projection image display device using a semiconductor laser, in particular, a scanning type projection image display device in which an RGB laser and a MEMS mirror are combined, the number of parts can be reduced, and it is also easy to achieve miniaturization. Therefore, it is attracting attention.

As an example of the projection image display device, a light beam emitted from a light source for projecting an image is converted into a parallel beam by a collimator lens, and then illuminates a MEMS mirror having a function of scanning two-dimensionally. Finally, the portrait is formed on the screen. In this case, since the collimator lens is made of plastic, it is possible to mass-produce a high-precision lens at a low price, and therefore it is possible to produce a projection image display device at a low price. However, the general plastic collimator lens has a cause Problems caused by environmental changes.

Specifically, the refractive index changes or expansion/contraction of the plastic material caused by the temperature change of the environment, or the wavelength shift of the light beam emitted from the light source, the focal length changes after the collimating lens Therefore, the parallelism of the light beam emitted from the collimator lens changes, and as a result, the beam diameter at a specific projection position also has a large change. Therefore, when such a collimator lens is used in a projection image display device, image quality deterioration may occur. In response to such a problem, by using an actuator for driving, the collimator lens is moved in the optical axis direction in response to the amount of change in the back focus caused by the temperature change, and it is possible to emit parallel from the collimator lens. The light beam, however, has a problem of increasing the number of parts or increasing the size of the device.

On the other hand, in Patent Document 1, a technique is disclosed in which a diffraction structure is applied to a collimator lens, and a change in the back focus can be reduced even if the ambient temperature changes, and the projection image display device can be reduced. The deterioration of the image quality is suppressed.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent No. 5488803

[Patent Document 2] International Publication No. 2014/0733305

However, when a collimating lens having a diffraction structure is formed by injection molding using a mold, it is caused by difficulty in mold processing technology and forming technique, and a front end is generated at the diffraction step portion. The difference between the vertical edge or the addition of a tapered shape and the ideal shape has a problem that the actual diffraction efficiency becomes lower than the design value. In particular, if the amount of phase difference that determines the phase function of the diffraction structure is larger, the above-described situation becomes more remarkable. In the collimator lens of Patent Document 1, although a diffraction structure is provided to reduce the change in the back focus, the diffraction efficiency is set to be high with respect to three wavelengths of RGB. The amount of step, and the number of diffraction bands there are also increased. That is, the number of the diffraction step portions and the tapered region are increased, and the diffraction efficiency due to the loss of the light amount occurs. In other words, since the utilization efficiency of the light beam emitted from the laser light source is low, it is necessary to set the laser light source to a higher output power, which causes a problem that the temperature is further increased. The increase in cost or the enlargement of the projection image display device.

On the other hand, in Patent Document 2, it is described that the light source and the optical surface of the lens are caused by the expansion/contraction of the plastic leg portion due to the temperature change by fixing the leg portion of the lens to the substrate. The spacing between the two changes, so it is advantageous for the out-of-focus correction, that is, for the change in the back focus. However, it is not explicitly stated as to how the length of the lens foot is to be set for the benefit of the back focus change. Moreover, the lens disclosed in Patent Document 2 is a cover. (cap) type, so when used to cover the light source, heat is accumulated between the light source and the lens, and the temperature of the lens exceeding the desired ambient temperature rises, so that it is necessary to use a material having higher heat resistance, and There are flaws that lead to higher costs. Alternatively, in order to avoid the influence caused by the temperature rise of the lens exceeding the desired ambient temperature, it is necessary to excessively increase the number of the ring belts of the diffraction structure at the expense of the diffraction efficiency.

The present invention has been made in view of the problems of the prior art, and an object thereof is to provide a lens which is inexpensive and which can appropriately suppress the influence of a back focus change even if an environmental change occurs, and A projection image display device having the same is used.

In order to achieve at least one of the above objects, a lens that reflects one of the aspects of the present invention is a lens for a projection image display device, characterized in that the lens is a plastic that is integrally formed. And a lens portion that converts a light beam emitted from the light source into parallel light or convergence light, and a leg portion that holds the lens portion, wherein the leg portion is configured to support the base portion of the light source At least a part of the end portion of the leg portion is fixed, and at least one of the leg portions is formed with an opening or a cut, and the length T (mm) of the leg portion in the optical axis direction satisfies the following formula: BF ≦T≦Φ(1), where BF is the distance (mm) from the optical surface of the light source side to the light collecting position, and Φ is the outer diameter (mm) of the lens.

According to the present invention, for maintaining the foot of the aforementioned lens portion When the ambient temperature changes, the expansion/contraction occurs, and the refractive index change and the shape change due to the lens portion generated at the same time and the wavelength shift of the light emitted from the light source are caused. The amount of change in the back focus is counteracted, and the change in the exit angle of the beam emitted from the lens is suppressed. As a result, it is possible to suppress a change in the beam diameter at the projection position. In particular, by setting the value T of the formula (1) to the upper limit or lower, the lens can be stably formed, which contributes to miniaturization of the device. Further, by setting the value of the formula (1) to the lower limit or higher, there is an effect of reducing the beam diameter change at the projection position. Further, since the leg portion is formed with an opening or a cutout at least in one of the leg portions, the air can be ventilated between the outside and the inside of the leg portion through the opening or the cutout. . As a result, it is possible to suppress the temperature rise inside the leg portion and prevent the lens portion from being overheated, and it is not necessary to select a plastic material having high heat resistance. In addition, since the temperature rise inside the leg portion can be suppressed, the length T of the leg portion can be set to be equal to or less than the upper limit, and the increase in size of the device and the improvement in the ease of forming the lens can be suppressed. Further, from the viewpoint of allowing air to accumulate more efficiently, it is preferable that the slit is cut from the end surface of the leg portion to the height of the light source surface on the light source side.

In the above-described lens, it is preferable that the leg portion is formed with at least two places, and the cutout portion extending from the end portion toward the lens portion is formed. By forming the aforementioned cuts at least at two locations, one of them can be between the outside and the inside of the aforementioned foot. The use of the air is used as an air inlet, and the other side is used as an air outlet. Therefore, efficient ventilation is possible. Moreover, by making a cut, the moldability of the said lens can be improved. Further, from the viewpoint of promoting convection of air, it is preferable that at least two places are cut so that the opening or the cutout is placed on the opposite side with the optical axis interposed therebetween.

Further, it is preferable that the shape when viewed from the optical axis direction with respect to the lens is at least two linear portions which are slightly parallel to each other with the optical axis interposed therebetween. When the shape of the lens is observed from the optical axis direction, at least two linear portions which are slightly parallel to each other with the optical axis are provided, and the heated air is more easily discharged. Further, by using this lens in a projection image display device or the like, it is possible to obtain an effect that the height can be lowered. In addition, "slightly parallel" means that the relative angle of two straight lines is within ±5 degrees. Further, from the viewpoint of making the above-described effects more remarkable, the distance between the two straight portions which are slightly parallel is preferably within a range of 0.7 times to 2 times the diameter of the optical surface of the lens.

Further, preferably, the thickness of the leg portion increases from the end portion toward the lens portion. When the lens is molded by a mold, the mold release property is improved by providing a so-called drawn tapered portion in which the thickness of the leg portion is increased from the end portion toward the lens portion.

Further, preferably, a diffraction structure is formed in the lens portion. If a diffraction structure is provided at the aforementioned lens portion, it is possible to adjust the back focus change caused by the change in the environmental temperature. Department The amount of change in the subsequent focal length is adjusted in accordance with the phase difference amount of the phase function of the diffraction structure, and the change in the back focus can be more effectively suppressed by complementing the expansion/contraction of the aforementioned foot portion. The diffraction structure is such that the diffraction efficiency is close to the design value when the lens is formed by injection molding, for example, when the diffraction step of the primary diffracted light is generated within the effective diameter of the lens, Preferably, it is set such that the minimum width of the diffraction ring band becomes a phase difference of 5 μm or more. Further, in order to reduce the variation in the diffraction efficiency due to the ambient temperature, it is preferable to set the number of diffractions by the diffraction step to be 5 times or less.

The projection image display device is characterized in that a light source and a lens that converts a light beam from the light source into parallel light or convergence light are used.

Preferably, in the above-described projection image display device, the light source and the lens system are provided with a plurality of pairs, and the straight line passing through the center of the adjacent light source is moved in parallel to the aforementioned foot in the optical axis direction of the lens. At the side of the portion, the straight line that has been moved by a certain amount passes through the opening or the cut of the foot portion.

According to the present invention, since the opening or the cutout of the leg portion adjacent to the lens is disposed at a position opposite to each other, for example, by providing a forced fan or the like and transmitting through the opposite opening or cutting In the absence of a large amount of ventilation per unit time along the aforementioned straight line, efficient ventilation is possible. Further, it is preferable that two or more of the openings or the cuts are provided, and the straight line does not overlap with the opening or the portion other than the cut. For example, when the same lens is staggered by 90 degrees In the case of arrangement, if the heat from the light source of one of the lenses contacts only a part of the leg portion of the adjacent lens, uneven temperature variation in the leg portion is caused, and the optical characteristics are affected. However, since this problem does not occur, it is ideal.

Further, preferably, the light source and the lens system are provided with a plurality of pairs, and when the line passing through the center of the adjacent light source is moved in parallel to the side of the foot in the optical axis direction of the lens, the foregoing The straight line does not pass through the opening or cut of the aforementioned foot.

According to the present invention, since the opening or the cutout of the leg portion adjacent to the lens is disposed at a position that does not face each other, it is possible to make one of the sides by, for example, natural convection. When the heated air flowing out of the opening or the cutout flows into the other opening or the cutout, the temperature rise of the other lens portion can be suppressed. Further, from the viewpoint of convection of air and miniaturization in the height direction of the projection image display device, it is preferable that two or more openings or cutouts are provided, and when the lens is observed from the optical axis direction, The shape is at least two straight lines which are slightly parallel to each other with the optical axis interposed therebetween. For example, when the same lens is shifted by 90 degrees, if the heat from the light source of one of the lenses contacts only a part of the leg of the adjacent lens, it will result in no in the foot. Uniform temperature changes affect optical properties, but they are ideal because they do not.

According to the present invention, it is possible to provide a lens which is inexpensive and which can suppress the influence of the back focus change even if environmental changes occur, and a projection image display device using the same.

1‧‧‧Laser light source

2‧‧‧Scanning Department

3‧‧‧Scan mirror

3a‧‧‧reflecting surface

4‧‧‧Fixed frame

5‧‧‧ drive source

5a‧‧‧Piezoelectric components

5b‧‧‧electrode

6‧‧‧ movable frame

7‧‧‧Twist rod

8‧‧‧Projected mirror

20‧‧‧Scanning Optics

20a‧‧‧Shell components

22‧‧‧Two-way beam splitter

23‧‧‧Two-way spectroscope

24‧‧‧Mirror

25‧‧‧Mirror

27‧‧‧Mirror

40‧‧‧Mobile terminals

40a‧‧‧ face

41‧‧‧Projection surface

100‧‧‧Projector

BF‧‧‧ Distance from the optical side of the light source to the position of the light collection

COL‧‧ ‧ collimating lens

CP‧‧‧Semiconductor laser chip

CT‧‧‧ cut

FL‧‧‧Flange

FP‧‧‧ face

FR‧‧‧ framework

L‧‧‧ Straight line

LD‧‧‧ wire

LG‧‧ ‧ foot

LS‧‧‧Lens Department

SM‧‧‧Deputy Installation Department

ST‧‧‧ cadres

T‧‧‧The length of the foot

Fig. 1 is a view showing a state in which a projector according to the present embodiment is mounted in a mobile terminal.

Fig. 2 is a view for explaining the configuration of the scanning optical system according to the embodiment.

FIG. 3 is a view corresponding to a cross section taken along line III-III of FIG. 2. FIG.

Fig. 4 is a plan view showing a scanning portion of the scanning optical system shown in Fig. 2.

Fig. 5 is a cross-sectional view showing a part (drive unit) of the scanning unit shown in Fig. 4 in an enlarged manner.

Fig. 6 is a view showing an enlarged display of the laser light source unit 1-R.

Fig. 7 is a view showing the collimator lens COL used in the laser light source section 1-R from the light source side.

Fig. 8 is a view in which the configuration of Fig. 7 is cut by a line VIII-VIII and observed from the direction of the arrow.

Fig. 9 is a view showing a modification of the embodiment.

Fig. 10 is a view showing a modification of the embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Referring to Fig. 1, a projector 100 that is a projection image display device is suitable, for example, if it is mounted on a mobile terminal such as a mobile phone or a PDA (Personal Digital Assistant). Therefore, the projector 100 is miniaturized to such an extent that it can be accommodated in a small space in the mobile terminal 40.

As the light source of the projector 100, a semiconductor laser that generates laser light is used, and the laser light is scanned in the horizontal direction (H direction) and the vertical direction (V direction) on the projection surface 41 to be input. The portrait information to the projector 100 is projected on the projection surface 41. The projection surface 41 may be a separately prepared screen, but may be a screen other than the screen. For example, a wall surface or the like may be used as the projection surface 41.

Further, regarding the reproduction of the hue of the portrait information input to the projector 100, the intensity of the red, green, and blue laser light, which are the three primary colors of light, is intensity-modulated, and then the changes are made. Synthesize and proceed. In this case, the wavelength of the red laser light is set to, for example, about 640 nm, and the wavelength of the green laser light is set to, for example, about 530 nm. Further, the wavelength of the blue laser light is set, for example, to about 450 nm.

Referring to FIGS. 2 to 5, the scanning optical system 20 is configured to synthesize and scan the red, green, and blue laser light after they are converted into parallel beams. In other words, the scanning optical system 20 includes the laser light source unit 1, the scanning unit 2, and a mirror. A plurality of optical components are incorporated in a specific box member (frame) 20a. In addition, in FIGS. 2 and 3, the laser light is indicated by a 2-point chain line.

The laser light source unit 1 is a laser light for generating red, green, and blue light. Hereinafter, the laser light source unit 1 that generates red laser light is referred to as a laser light source unit 1-R, and the laser light source unit 1 that generates green laser light is referred to as a laser light source unit 1-G. Further, the laser light source unit 1 that generates blue laser light is referred to as a laser light source unit 1-B.

The laser light source unit 1-R is formed of a red semiconductor laser having a high luminous intensity and capable of high-speed modulation of intensity. The red semiconductor laser as the laser light source portion 1-R is in the form of a CAN package, and a laser wafer is mounted on a heat sink base called a dry (STEM).

Fig. 6 is a view showing an enlarged display of the laser light source unit 1-R. In FIG. 6, the laser light source unit 1-R is provided with a flat-shaped stem (base portion) ST to which nickel plating and gold plating are applied to a SPC material which is a metal made of metal, and is disposed in the stem portion. a submount SM at the center on the ST, a semiconductor laser wafer (light source) CP disposed on the submount SM, and four wires LD (one of which are respectively mounted at the stem ST) It is connected to the base of the submount SM, and the two are connected to the semiconductor laser CP, and the remaining one is connected to a monitor (not shown). At the laser light source portion 1-R, a collimator lens COL is mounted. If the power is supplied via the wire LD, the red semiconductor laser is illuminated, and the emitted beam is directly incident on the beam. Straight lens COL, and is converted into a slightly parallel beam.

Fig. 7 is a view of the collimator lens COL used in the laser light source section 1-R from the light source side, and Fig. 8 is a view in which the configuration of Fig. 7 is cut by the line VIII-VIII. And make a picture of the observation from the direction of the arrow. In the figure, a collimator lens (lens) COL is obtained by integrally molding a transparent polyolefin resin (but is not limited thereto), and is provided by a central lens portion LS, and The flange portion FL extending in the direction orthogonal to the optical axis and the pair of leg portions LG extending from the flange portion FL in the optical axis direction are formed around the periphery. When the collimator lens COL is observed from the optical axis direction, the portion of the flange portion FL that covers the optical axis and is opposed to each other (the portion sandwiched by the leg portion LG) is a substantially parallel straight portion LN. Further, the pair of leg portions LG are formed at a linearly symmetrical position, and are formed with a pair of cutout CTs extending from the leg portion LG toward the lens portion LS and extending to the flange portion FL. The thickness of the leg portion LG gradually increases from the end portion thereof to the flange portion FL. By forming the drawing taper portion at the leg portion LG in this manner, it is easy to pull the collimator lens COL out of the mold at the time of injection molding. Here, the distance T (mm) from the vertex of the side surface of the lens portion LS to the end of the leg portion LG is the length of the leg portion LG. The length T (mm) of the foot is such that the following formula is satisfied.

Here, BF represents the distance (mm) from the optical surface of the light source side to the light collecting position, and Φ represents the outer diameter (mm) of the lens.

In Fig. 6, the optical axis of the lens portion LS is combined with the semiconductor The ejection center of the body laser wafer CP is overlapped to be arranged, and the end surface of the leg LG is attached to the surface FP of the stem ST. Since the focal length after the lens portion LS is appropriately set with respect to the length T of the leg portion LG, it is only necessary to fix the end surface of the leg portion LG to the surface FP of the stem portion ST to be ejected from the semiconductor laser wafer CP. The light beam is incident on the lens portion LS and is converted into a specific magnification to be emitted. Further, a diffraction structure may be provided at the lens portion LS.

In FIG. 2, the laser light source unit 1-G is formed of a green semiconductor laser of a CAN package form having a high luminous intensity and capable of high-speed modulation of intensity, and the structure thereof is coupled to the laser light source unit 1 -R is slightly the same, but the shape of the lens portion LS of the collimator lens COL may be changed in accordance with the wavelength of the light source of the green semiconductor laser.

The laser light source unit 1-B is formed of a blue semiconductor laser having a high luminous intensity and capable of high-speed modulation of intensity, and has a structure similar to that of the laser light source unit 1-R. However, the shape of the lens portion LS of the collimator lens COL may be changed in accordance with the wavelength of the light source of the blue semiconductor laser.

Further, the scanning unit 2 is configured to perform two-dimensional scanning of the laser light that has been converted into parallel beams and combined, and at least has the laser light to be combined toward the projection surface 41 (refer to FIG. 1). The reflected scanning mirror 3 is reflected. The inclination angle (reflection angle) of the scanning mirror 3 is variably changed, and the two-dimensional scanning of the combined laser light by the scanning unit 2 is performed by changing the inclination angle of the scanning mirror 3.

Here, in the present embodiment, the scanning mirror 3 is used. The MEMS (Micro Electro Mechanical System) is incorporated, and the MEMS incorporated in the scanning mirror 3 is used as the scanning unit 2. Further, the scanning unit 2 is slightly flat and has a small thickness, and its outer shape is slightly square in shape (see FIG. 2) (the length of one side is about 1 cm).

As a specific structure, as shown in FIG. 4, the scanning unit 2 is formed of a structure obtained by performing an etching process or the like on a substrate, and is integrally provided with a fixed surface in addition to the scanning mirror 3. Frame 4, drive unit 5, movable frame 6, and the like. In addition, in the following description, the axis which cuts the center of the scanning mirror 3 in the lateral direction of FIG. 4 is taken as the X-axis, and the center of the scanning mirror 3 is cut in the longitudinal direction of FIG. The axis is the Y axis. In other words, the point where the X-axis and the Y-axis are orthogonal to each other is taken as the center of the scanning mirror 3.

The fixing frame 4 is a portion corresponding to the outer edge of the scanning unit 2, and surrounds the other portions (the scanning mirror 3, the driving unit 5, the movable frame 6, and the like).

The drive unit 5 is separated from the fixed frame 4 in the X-axis direction, and is coupled to the fixed frame 4 in the Y-axis direction. Further, the driving unit 5 includes four unimorph structures, and the four single-wafer structures are symmetrical with each of the X-axis and the Y-axis as symmetry axes, and are separated from each other. The status is configured. In addition, as shown in FIG. 5, the single-wafer structure of the drive unit 5 is generally a piezoelectric element (a polarization treatment is performed on a sintered body using PZT or the like as a raw material) 5a by a pair of electrodes 5b. Hold it and stick it It is formed by attaching to the region of the crucible substrate which becomes the driving portion 5.

In the drive unit 5, when a voltage is applied to the pair of electrodes 5b, the piezoelectric element 5a held by the pair of electrodes 5b is elongated or contracted. On the other hand, if the piezoelectric element 5a is elongated or contracted, the area of the substrate in which the driving portion 5 is extended or contracted. That is, the drive unit 5 is driven by being supplied with electric power.

Further, as shown in FIG. 4, the movable frame 6 is a frame having a slightly rhombic shape positioned inside the driving portion 5. Both ends of the movable frame 6 on the X-axis are coupled to the drive unit 5, and the other portions are separated from the drive unit 5. Thereby, the movable frame 6 is rotatable around the X-axis.

Inside the movable frame 6, a torsion bar 7 extending in a pair along the Y-axis direction is provided. The pair of torsion bars 7 are arranged to overlap the Y-axis and to be symmetrical with respect to the X-axis. Further, one end of each of the pair of torsion bars 7 is coupled to the end portion of the movable frame 6 on the Y-axis.

Further, the scanning mirror 3 is disposed between the other ends of each of the pair of torsion bars 7, and is supported by the other end. Therefore, the scanning mirror 3 rotates around the X-axis together with the movable frame 6, and rotates around the Y-axis with the torsion bar 7 as a rotation axis. Further, the scanning mirror 3 is formed in a substantially circular shape, and is obtained by attaching a reflective film made of gold or aluminum or the like to a region of the ruthenium substrate which becomes the scanning mirror 3.

The scanning unit 2 of the present embodiment has the above-described general structure. Further, the scanning operation of the scanning unit 2 is performed by adjusting the timing of driving (stretching) the four driving units 5 and causing the scanning mirror 3 to vibrate around the X-axis and around the Y-axis. For example, the frequency when vibrating around the X-axis is set to about 60 Hz, and the frequency when vibrating around the Y-axis is set to about 30 kHz.

When the component numbers of 5-1 to 5-4 are attached to each of the four drive units 5 and specifically described, when the scanning mirror 3 is vibrated around the X-axis, the drive unit 5-1 and the drive unit 5-1 are 5-3 is one of the groups, and the driving portions 5-2 and 5-4 are taken as another group, and the positive and negative voltages applied to each of one group and the other group are reversed. In this case, if the driving portions 5-1 and 5-3 which are one of the groups are deformed in the direction of elongation, the driving portions 5-2 and 5-4 which are the other group are deformed toward the contraction direction. When the driving portions 5-1 and 5-3 which are one of the groups are deformed in the direction of contraction, the driving portions 5-2 and 5-4 which are the other group are deformed in the direction of elongation. Thereby, the scanning mirror 3 vibrates around the X-axis together with the movable frame 6, and the slope of the scanning mirror 3 changes around the X-axis. Further, since the torsion direction of the torsion bar 7 is a direction orthogonal to the direction of the vibration around the X-axis, it does not affect the vibration around the X-axis of the scanning mirror 3.

Further, when the scanning mirror 3 is vibrated around the Y-axis, the driving portions 5-1 and 5-2 are taken as one group, and the driving portions 5-3 and 5-4 are taken as another group, and One group and another group The positive and negative voltages applied by each of them are reversed. In this case, if the driving portions 5-1 and 5-2 which are one of the groups are deformed in the direction of elongation, the driving portions 5-3 and 5-4 which are the other group are deformed toward the contraction direction. When the driving portions 5-1 and 5-2 which are one of the groups are deformed in the direction of contraction, the driving portions 5-3 and 5-4 which are the other group are deformed in the direction of elongation. Thereby, the scanning mirror 3 vibrates around the Y-axis together with the movable frame 6, and the slope of the scanning mirror 3 changes around the Y-axis.

At this time, if the scanning mirror 3 is tilted around the Y-axis only by deforming the driving portion 5, the variation of the inclination of the scanning mirror 3 around the Y-axis is reduced. Therefore, when the scanning operation is actually performed, the frequency of the applied voltage to the driving unit 5 is set so that the scanning mirror 3 resonates by the frequency of the voltage applied to the driving unit 5. Further, the vibration around the Y-axis of the scanning mirror 3 is performed with the torque bar 7 as a reference.

By operating the scanning unit 2 as described above, the scanning mirror 3 can be rotated around the two axes orthogonal to each other, and the combined laser light can be made by one scanning mirror 3 2D scanning. Therefore, in response to the image signal input to the projector, the red, green, and blue laser light source sections are individually turned off, and the projection surface can be formed by the combination of the emitted laser light. A color portrait is displayed on 41.

Further, in the present embodiment, the red, green, and blue laser light is configured to adopt the same as shown in FIGS. 2 and 3. The light path (the 2 chain chain in the picture). That is, after the red, green, and blue laser light is parallelized, the red, green, and blue laser light is directed toward the scanning by reflecting the plurality of optical components. The mirror 3 is advanced. Further, when the optical path between the two optical components that are different from each other is one optical path, the normal direction N of the reflecting surface 3a of the scanning mirror 3 in the non-driving state is referred to (refer to Fig. 3), and the plane including at least two optical paths is orthogonal. Hereinafter, the optical paths of the red, green, and blue laser beams will be described in detail.

First, inside the box member 20a, the laser light source sections 1-G, 1-R, and 1-B are sequentially arranged side by side from the upper side of FIG. 2 toward the lower side. Further, the laser light source units 1-R, 1-G, and 1-B are in such a manner that the respective emission directions are in the same direction, and the respective emission directions are opposite to the non-driving state of the scanning mirror 3. The reflecting surfaces 3a are arranged in parallel and arranged. Further, the laser light source units 1-R, 1-G, and 1-B are placed in a plane view (refer to FIG. 2) so that one of the parts overlaps with the scanning unit 2. In addition, the laser light source units 1-R, 1-G, and 1-B are in a state in which most of the respective light-emitting sides are completely overlapped with the scanning unit 2.

Further, although not shown in FIG. 2, near the scanning mirror 3 (refer to FIG. 3), a projection mirror configured to project the synthesized laser light to the scanning mirror 3 is disposed. 8. That is, by the projection mirror 8, the combined laser light is reflected toward the scanning mirror 3.

As a specific light path, the red laser light is emitted from the laser light source unit 1-R, and sequentially passes through the collimator lens COL, the dichroic beam splitter 22, the dichroic beam splitter 23, the meander mirror 24, The meandering mirror 25 and the projection mirror 8 are incident on the scanning mirror 3 by being reflected at the projection mirror 8.

In addition, the collimator lens COL is used to convert laser light from divergent light into slightly parallel light. The meandering mirrors 24 and 25 are simply for changing the direction in which the laser light is directed. The dichroic beam splitter 22 is configured to transmit green laser light and reflect red laser light, and has a function of synthesizing green and red laser light by being configured as shown in FIG. . The dichroic beam splitter 23 is configured to transmit green and red laser light and reflect the blue laser light, and has a green, red, and blue color by being configured as shown in FIG. Laser light is used as a composite function.

The red laser light is set to be slightly parallel light by the collimator lens COL, and then the optical paths other than the projection mirror 8 (after the zigzag mirror 25) are placed in the same plane. That is, the red laser light is set to be slightly parallel light by the collimating lens COL, and sequentially passes through the dichroic beam splitter 22, the dichroic beam splitter 23, and the zigzag mirror in the same plane. 24 and a meandering mirror 25.

The green laser light is emitted from the laser light source portion 1-G, and sequentially passes through the collimator lens COL, the meander mirror 27, the dichroic beam splitter 22, the dichroic beam splitter 23, the zigzag mirror 24, and the meandering reflection. The mirror 25 and the projection mirror 8 are reflected by the projection mirror 8, It is injected into the scanning mirror 3.

Further, the meandering mirror 27 is simply a member for changing the direction in which the laser light is directed.

This green laser light is set to be slightly parallel light by the collimator lens COL, and then the optical paths other than the projection mirror 8 (after the zigzag mirror 25) are placed in the same plane. That is, the green laser light is set to be slightly parallel light by the collimating lens COL, and sequentially passes through the zigzag mirror 27, the dichroic beam splitter 22, 23, and the meandering reflection in the same plane. The mirror 24 and the meandering mirror 25 are provided.

The blue laser light is sequentially emitted from the laser light source unit 1-B, and sequentially passes through the collimator lens COL, the dichroic beam splitter 23, the meandering mirror 24, the meandering mirror 25, and the projection mirror 8, and It is incident on the scanning mirror 3 by being reflected at the projection mirror 8. In addition, the collimator lens COL is used to convert laser light from divergent light into slightly parallel light.

This blue laser light is set to be slightly parallel light by the collimator lens COL, and then the optical paths other than the projection mirror 8 (after the zigzag mirror 25) are placed in the same plane. That is, the blue laser light is sequentially set to be slightly parallel light by the collimating lens COL, and sequentially passes through the dichroic beam splitter 23, the meandering mirror 24, and the zigzag mirror in the same plane. 25.

Further, in the present embodiment, all of the red, green, and blue laser light are made before and after the projection mirror 8 (the zigzag The optical paths other than the mirrors 25 are located in the same plane, and this plane is orthogonal to the normal direction N (refer to FIG. 3) of the reflecting surface 3a of the scanning mirror 3 in the non-driving state. Further, at least a part of the optical path included in the plane described above is disposed in a region on the scanning unit 2. However, all of the red, green, and blue laser light is set such that the optical path is located in the region on the scanning portion 2 immediately before being incident on the meandering mirror 24, and is in the region of the tortuous mirror 25 After the reflection, the optical path is again placed in the area on the scanning unit 2.

Further, by arranging various optical components in such a manner as to be in a general state as shown in FIGS. 2 and 3, red, green, and blue laser light is incident on the scanning mirror 3 until it is incident on the scanning mirror 3. Each of them will be reflected four times. That is, the red laser light is reflected by the order of the dichroic mirror 22, the meandering mirror 24, the meandering mirror 25, and the projection mirror 8, so the number of reflections is four times. Since the green laser light is reflected by the order of the meandering mirror 27, the meandering mirror 24, the meandering mirror 25, and the projection mirror 8, the number of reflections is four times. Since the blue laser light is reflected by the order of the dichroic mirror 23, the meandering mirror 24, the meandering mirror 25, and the projection mirror 8, the number of reflections is four times. Further, in the plane orthogonal to the normal direction N of the reflection surface 3a of the scanning mirror 3 in the non-driving state, the red, green, and blue laser light beams are each reflected three times.

Further, in the plane observation (refer to FIG. 2), a part of each of the laser light source sections 1-R, 1-G, and 1-B is made to be in phase with the scanning section 2. overlapping. In particular, most of the respective light-emitting sides of the laser light source sections 1-R, 1-G, and 1-B are completely overlapped with the scanner section 2. Therefore, all of the red, green, and blue laser light is in a region where the optical path is located on the scanning unit 2 immediately after being emitted.

As described above, by arranging one of the respective optical paths of the laser light of red, green, and blue (until the optical path immediately before reaching the meandering mirror 24) in the region on the scanning unit 2, it is possible to A scanning optical system 20 that has been further miniaturized is obtained. Further, in the scanning optical system, when the plane is observed (refer to FIG. 2), the outer dimension is about 18 mm × about 24 mm, and the thickness is about 7 mm.

In the present embodiment, the dichroic beam splitter is used as a folding mirror. However, as a means for synthesizing the laser light, a dichroic beam splitter or a reflection pupil may be used.

Further, in the present embodiment, as described above, the laser light of red, green, and blue is configured to be reflected four times until it is incident on the scanning mirror 3, which makes it easy to perform. The compaction of the optical path is performed. Further, after the laser light of red, green, and blue is synthesized, the synthesized laser light is incident on the scanning mirror 3.

Further, in the present embodiment, as described above, the scanning unit 2 is configured by the MEMS in which the scanning mirror 3 is incorporated, and since the thickness of the scanning unit 2 can be reduced, it is easy to scan optically. The system 20 is thinned.

Moreover, in the present embodiment, as in the above, by It is configured such that the scanning mirror 3 can be rotated around the two axes orthogonal to each other, and the two-dimensional scanning of the combined laser light can be performed by one scanning mirror 3, and it is not necessary to borrow Two-dimensional scanning of the combined laser light is performed by the two scanning mirrors 3. As a result, since the installation space for the scanning mirror is reduced, it is possible to further reduce the size of the scanning optical system 20.

Further, in the present embodiment, as described above, the scanning mirror 3 is driven by the piezoelectric element 5a, and the piezoelectric element 5a can vibrate the scanning mirror 3 in a thin structure. The scanning unit 2 of the driving method is extremely thin.

Further, in the present embodiment, as described above, the respective emission directions of the laser light source sections 1-R, 1-G, and 1-B are configured to be opposite to the scanning mirror 3 of the non-driving state. When the reflecting surface 3a is parallel, it is possible to easily arrange at least two optical paths in a plane orthogonal to the normal direction N of the reflecting surface 3a of the scanning mirror 3 in the non-driving state. Further, by overlapping a part of each of the laser light source units 1-R, 1-G, and 1-B with the scanning unit 2, the plane area of the scanning optical system 20 can be easily reduced.

Further, in the present embodiment, as described above, the laser light source sections 1-R, 1-G, and 1-B are respectively constituted by a red semiconductor laser, a green semiconductor laser, and a blue semiconductor laser. Since the semiconductor laser system is small, the laser light source sections 1-R, 1-G, and 1-B can be reduced. Therefore, the plane area and thickness of the scanning optical system 20 can be easily further reduced.

In addition, referring to FIG. 1, if it is assumed that the mobile terminal 40 is placed on a setting table (not shown) and projected, it is configured to emit laser light from a surface 40a that faces the side opposite to the installation table side. The laser light can be advanced toward the projection surface 41 while the mobile terminal 40 is kept in a thin state. Further, in this case, it is not necessary to tilt the mobile terminal 40 at the time of projection.

Here, if the ambient temperature rises, the refractive index of the collimating lens COL decreases or thermal expansion, and the back focal length changes. Therefore, when the divergent light beam emitted from the laser light source is emitted from the lens portion LS of the collimator lens COL, it does not become a predetermined slightly parallel light beam, and there is a significant finite beam. On the other hand, according to the present embodiment, since the length T of the leg portion of the collimator lens COL is determined so as to satisfy the expression (1), the leg portion LG is stretched and contracted in response to changes in the ambient temperature (T). ±ΔT), whereby the amount of change in the back focus can be suppressed, and even when the ambient temperature is changed, it can be emitted from the collimator lens COL with a predetermined slightly parallel beam.

Further, since the collimator lens COL includes a pair of cutout CTs, the laser wafer CP is not collimated by the collimating lens COL even after the end portion of the leg portion LG is attached to the stem (STEM) portion ST. It is sealed and cooled by the outside air promoted by the cut CT, whereby the temperature rise of the collimator lens COL can be suppressed, so that the influence of the change of the back focus can be effectively suppressed. .

Further, when the laser light source unit is used as in the present embodiment When a plurality of sheets are used side by side, the cooling effect can be further improved by specially designing the arrangement of the adjacent collimating lenses COL. Here, the collimator lens COL is disposed as shown in FIG. 9 or FIG. For example, in the arrangement example shown in FIG. 9, if the straight line L passing through the center of the adjacent laser wafer CP is moved to the side of the leg portion LG in parallel with the height of the cutout CT, it is passed through The laser wafer CP is opposite to the CT of the collimating lens COL. When the collimator lens COL is disposed in such a manner, since the air passage can be formed along the straight line L, ventilation is performed by using a forced fan or the like (not shown), and the collimator lens COL is made. The heated air is easily dissipated from the CT cut, and the ventilation performance is improved. By performing such a heat countermeasure, the leg portion LG can be shortened, and a compacted projection image display device can be provided.

On the other hand, in the arrangement example shown in FIG. 10, if the straight line L passing through the center of the adjacent laser wafer CP is moved in parallel to the side of the leg portion LG, it is made to pass through the laser wafer CP. The position of the foot LG of the collimating lens COL (the position other than the CT is cut). In the case of utilizing natural convection, the air heated in the collimator lens COL is not dissipated along the straight line L, but is discharged by the CT that intersects with it. Therefore, the probability of entering the adjacent collimating lens COL is small, and the uniform temperature rise of each collimating lens can be ensured. By performing such a heat countermeasure, the leg portion LG can be shortened, and a compacted projection image display device can be provided.

Hereinafter, a suitable embodiment of the above embodiment is described. Give instructions. Hereinafter, it is the specification of the first embodiment.

(Specification of light source)

Source wavelength: 450nm

Horizontal diffusing angle θ// of the outgoing beam (half-value full angle): 8.5°

The vertical direction of the exit beam is θ⊥ (half the full angle): 23.0°

Wavelength change with respect to temperature change (d λ/dT): 0.05 nm / ° C

(Specification of collimating lens)

Lens outer diameter (Φ): 4.0mm

Length of the foot (T): 2.0mm

Focal length: 1.6mm

Distance from the optical surface of the light source side to the light collecting position (BF): 1.516 mm

Number of openings: 0.4

(Characteristics of resin materials for collimating lenses)

Refractive index change (dn/dT) for temperature change: -9.0×10 ^-5 /°C

Linear expansion coefficient: 7.0 × 10 ^-5

In Table 1, the lens data of the first embodiment is shown. In the table, Ri is a radius of curvature, and di is a position in the optical axis direction from the i-th surface to the i+1th surface, and ni is a refractive index of each surface. In addition, in the following description (including the lens data of the table), there is a case where a power multiplier of 10 (for example, 2.5 × 10 ^-3 ) is expressed by E (for example, 2.5 × E ^-3 ). . Further, when the coordinates of the central portion of the light exit surface of the light source (laser wafer) are used as the origin, and the line perpendicular to the exit surface passing through the origin is used as the optical axis, the optical surface of the collimator lens is formed. The axisymmetric aspherical surfaces defined by the equations in Equation 2 are defined by the equations shown in Equation 2, respectively, around the optical axis.

Here, X(H) is the distance from the origin in the optical axis direction, κ is the conic coefficient, Ai is the aspheric coefficient, and H is the distance from the optical axis in the vertical direction of the optical axis (radius). , r is the radius of curvature.

With respect to the above-described embodiment and the first comparative example having the same specifications but no foot portion with respect to the embodiment, in Table 3, the projection position is increased when the temperature is increased by 30 ° C from the design temperature. The beam path at the place is compared and displayed. In the first embodiment, since the leg portion is provided at the collimator lens, the interval between the light source side optical surface and the light collecting position is increased by 0.0042 mm due to the expansion when the temperature rises by 30 °C. According to this, as shown in Table 3, it can be seen that, in the first embodiment, it is possible to effectively suppress the change in the beam diameter before and after the temperature change as compared with the first comparative example.

In addition, as the second to fifth embodiments, in the above-described embodiment, those having a length of the leg portion of 1.8 mm, 2.5 mm, 3.0 mm, and 3.8 mm are prepared as In the second and third comparative examples, in the above-described embodiment, when the length of the leg portion is 1.0 mm, it is set to 5 mm, and when the temperature is increased by 30 ° C compared with the design temperature. The change in beam path at the projected position was investigated. As a result, it has been found that in the second to fifth embodiments, the change in the beam system can be effectively suppressed as in the first embodiment. Further, in the second comparative example, the length of the leg portion was short, and the change in the beam system was not sufficiently suppressed. Further, in the third comparative example, a large number of molding defects occurred, and it was found that the yield was deteriorated.

The present invention can be easily understood from the embodiments and examples described in the specification, and the present invention is not limited to the embodiments and examples described in the specification. Other embodiments, examples, and modifications are also included. The description, the embodiments, and the examples of the specification are intended to be illustrative only, and the scope of the invention is shown by the scope of the claims.

1-R‧‧‧Laser light source

BF‧‧‧ Distance from the optical side of the light source to the position of the light collection

COL‧‧ ‧ collimating lens

CP‧‧‧Semiconductor laser chip

FP‧‧‧ face

LD‧‧‧ wire

LG‧‧ ‧ foot

LS‧‧‧Lens Department

SM‧‧‧Deputy Installation Department

ST‧‧‧ cadres

Claims (8)

A lens for a projection image display device, characterized in that the lens is a plastic lens integrally formed, and is configured to convert a light beam emitted from a light source into parallel light or a convergent light. a lens portion and a leg portion for holding the lens portion, wherein the leg portion is formed to fix at least a part of an end portion of the leg portion with respect to a base portion supporting the light source, and at least in one of the leg portions There is an opening or a cut, and the length T (mm) of the aforementioned optical axis of the foot is such that the following formula is satisfied: Here, BF is a distance (mm) from the optical surface of the light source side to the light collecting position, and Φ is a lens outer diameter (mm). The lens according to claim 1, wherein the leg portion is formed with at least two places, and the slit extending from the end portion toward the lens portion is formed. The lens according to the first aspect of the invention, wherein the lens is viewed from the optical axis direction and has at least two linear portions that are slightly parallel to each other with the optical axis interposed therebetween. The lens according to claim 1, wherein the thickness of the leg portion increases from the end portion toward the lens portion. The lens according to claim 1, wherein the lens portion is formed with a diffraction structure. A projection image display device comprising: a light source; and a light beam converted from the light source into parallel light or a convergent light, as described in any one of claims 1 to 5. lens. The projection image display device according to claim 6, wherein the light source and the lens system are provided with a plurality of pairs, and a line passing through a center of the adjacent light source is moved in parallel to the light of the lens When the foot portion is in the axial direction, the straight line that has been moved by a certain amount passes through the opening or the cut of the leg portion. The projection image display device according to claim 6, wherein the light source and the lens system are provided with a plurality of pairs, and a line passing through a center of the adjacent light source is moved in parallel to the light of the lens When the leg portion is in the axial direction, the straight line does not pass through the opening or the cut of the leg portion of the two adjacent lenses.