JP2014052657A - Projection video display apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projection video display apparatus which, in using a light source in which a fluorescent substance is made to emit light by excitation light, improves a lifetime of the light source with the fluorescent substance without causing an increase in size of the apparatus.SOLUTION: A projection video display apparatus includes: an excitation light source group for emitting excitation light; a base material on which a fluorescent substance for emitting fluorescent light by incidence of the excitation light is applied; a first light intensity detector for detecting the intensity of the excitation light; a second light intensity detector for detecting the intensity of the fluorescent light; a control device for determining whether or not to move the base material on the basis of a detection value of the first and the second light intensity detectors; and a moving device for moving the base material in accordance with an indication of the control device. When the ratio of a decrease in the intensity of the fluorescent light to a decrease in the intensity of the excitation light exceeds a prescribed value, the control device may give the indication to the moving device so as to move the base material. Furthermore, the control device may move the base material in the direction orthogonal to the direction of the incident light axis in which the excitation light is incident on the base material.

Description

  The present invention relates to a projection display apparatus.

  In this technical field, a light source device has been proposed that emits light with high efficiency even when excitation light emitted from a solid light source is visible light (see Patent Document 1). In Patent Document 1, visible light having lower energy than ultraviolet light is irradiated as excitation light on a phosphor, and the phosphor is adhered to a circular base material that can be rotationally controlled, so that the excitation light is applied to one place of the phosphor. Prevents irradiation.

JP 2009-277516 A

  According to Patent Document 1, excitation light is always irradiated on the circumference of the disk, which is insufficient for improving the life of the phosphor. Note that if the excitation light is irradiated to a position far from the center of rotation, the actual irradiation area can be enlarged, but there is a problem that the shape of the disk becomes large and the apparatus becomes large.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a projection display apparatus that improves the life of a phosphor light source without increasing the size of the apparatus.

  In order to solve the above problems, one of the desirable embodiments of the present invention is as follows.

  The projection display apparatus includes an excitation light source group that emits excitation light, a base material coated with a phosphor that emits fluorescence light upon incidence of excitation light, and a first light intensity that detects the intensity of excitation light. A control device that determines whether or not to move the substrate based on the detection values of the detector, the second light intensity detector that detects the intensity of the fluorescent light, and the first and second light intensity detectors And a moving device for moving the substrate in accordance with an instruction from the control device.

  ADVANTAGE OF THE INVENTION According to this invention, the projection type video display apparatus which improved the lifetime of the fluorescent light source can be provided, without causing the enlargement of an apparatus.

The figure which shows a part of illumination optical system of a present Example. 1 is a schematic configuration diagram of an optical system of a projection display apparatus. The figure which shows a part of illumination optical system of a prior art.

  Hereinafter, the present embodiment will be described with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the same part and the description is abbreviate | omitted about what was once demonstrated.

  Here, a right-handed rectangular coordinate system is introduced. In the drawings, from left to right in the drawing, that is, the light traveling direction of the optical axis 100 in each drawing is taken as the Z axis, and the axis parallel to the drawing in the plane perpendicular to the Z axis is taken as the X axis. The axis toward the front is the Y-axis (however, in FIGS. 1B, 1C, and 3B, the axis from the front to the back of the page is the X-axis). The direction parallel to the X axis is the “X direction”, the direction parallel to the Y axis is the “Y direction”, the direction parallel to the Z axis is the “Z direction”, and the polarized light whose polarization direction is the X direction is “X polarized light”. The polarized light whose polarization direction is the Y direction is referred to as “Y-polarized light”.

  First, in order to make the difference between the present embodiment and the prior art easier to understand, the prior art (Patent Document 1) will be described. FIG. 3 is a diagram showing a part of a conventional illumination optical system.

  In FIG. 3A, the excitation light emitted from the excitation light source group 5 becomes substantially parallel light by the collimating lens group 6 and enters the dichroic mirror 7. The dichroic mirror 7 has a characteristic of transmitting the wavelength range of excitation light and reflecting the wavelength range of fluorescent light. Therefore, the excitation light passes through the dichroic mirror 7, passes through the condenser lens 4, and then enters the disk 1 on which the phosphor 3 is applied. The curvature of the condensing lens 4 is set so that the incident parallel light is condensed at one place of the disk 1.

  The disk 1 is a circular base material whose rotation can be controlled with the rotation element 2 as a central axis. The phosphor 3 on the disk 1 excited by the excitation light emits fluorescent light in the direction of the condenser lens 4. After passing through the condenser lens 4, the fluorescent light becomes substantially parallel light, is reflected by the dichroic mirror 7, and enters the projection lens side.

  In FIG. 3B, the excitation light is condensed on the irradiation region 31 on the disk 1. In order to prevent the excitation light from being always collected at one place of the phosphor 3, the disk 1 rotates around the rotating element 2. Compared with the case where excitation light is always collected at one place of the phosphor 3 (without rotation of the disk 1), the circumference of the circumference becomes an irradiation region, and the life of the phosphor is improved.

  Next, this embodiment will be described. FIG. 1 is a diagram showing a part of the illumination optical system of the present embodiment. In this embodiment, the illumination optical system refers to a portion excluding the projection lens 22 and the screen 120 in FIG.

  In FIG. 1A, the excitation light emitted from the excitation light source group 5 receives the incidence of fluorescent light, the phosphor 3 emits fluorescent light, and then the fluorescent light is incident on the projection lens side in FIG. It is the same as the description.

The disk 1 is a circular base material whose rotation is controllable with the rotation element 2 as a central axis, and is connected via a connecting part 40 to a moving device 42 that can move the disk 1 in the Z direction. The connecting portion 40 has a hole, and the positioning pin 41 is passed through the hole. Therefore, the control device 60 can move the disk 1 in the Z direction by operating the moving device 42.

A first light intensity detector 50 that detects the intensity of the excitation light emitted from the excitation light source group 5 is disposed on the rear surface of the disk 1. Further, in order to detect the excitation light intensity on the rear surface of the disk 1, the base material of the disk 1 is a transmissive base material, and a region (non-fluorescent material region 30) to which no phosphor is bonded is provided. Further, a second light intensity detector 51 for detecting the intensity of the fluorescent light is disposed on the projection lens side of the dichroic mirror 7.

The first light intensity detector 50 and the second light intensity detector 51 each transmit a light intensity monitoring result to the control device 60. The control device 60 determines whether or not to move the disk 1 based on the received monitoring result.

With actual use of the projection display apparatus, both the excitation light source and the phosphor gradually deteriorate, and the brightness as the projection display apparatus also decreases. When the excitation light source is deteriorated, the excitation light output is reduced, so the output of the fluorescent light emitted by the excitation is also reduced in proportion to the reduction in the excitation light intensity, and the brightness of the projection display apparatus is reduced. Even when only the phosphor is deteriorated, the output of the fluorescent light is lowered, and the brightness of the projection display apparatus is lowered.

When the phosphor is greatly deteriorated, a decrease in the fluorescence light intensity is detected as compared with a decrease in the excitation light intensity. Therefore, the control device 60 determines that the disk 1 is moved when the ratio of the decrease in the fluorescence light intensity to the decrease in the excitation light intensity exceeds a predetermined value.

Next, the control device 60 moves the disk 1 in the Z direction by about the laser irradiation size (for example, 1 to 2 mm). For example, when the application width of the phosphor 3 is 10 mm and the laser irradiation size is 2 mm, the excitation light irradiation possible positions are five (the number of movements is four times). In other words, the life is about five times longer than when not moving in the Z direction (Patent Document 1).

The storage device 61 stores the application width of the phosphor 3, the laser irradiation size, the position on the circumference that is the current condensing position, and the control device 60, based on these pieces of information, the moving device 42. Is instructed to move the disk 1. If it is determined that there is no longer a position to be moved, the user may be notified to replace the disk 1 via the user interface.

Note that the control device 60 always rotates the disk while the projection display apparatus is operating (during laser irradiation). This is because the excitation light used here is a high wattage (20 to 30 W), and if the heat is concentrated at one point without rotating, the silicon adhesive for bonding the phosphor to the substrate is burned in an instant. In order to always rotate, the non-fluorescent substance region 30 passes through the condensing position once per rotation. Therefore, the first light intensity detector 50 can reliably detect the excitation light intensity.

FIG. 1B shows a state in which the phosphor 3 is bonded to the disk 1. On the surface of the disk 1, there are a region to which the phosphor 3 is adhered (indicated by oblique lines), an irradiation region 31 in the phosphor 3, and a non-phosphor region to which the phosphor 3 is not adhered. 30 is provided. When the disk 1 rotates and the non-fluorescent material region 30 passes through the irradiation region 31, the first light intensity detector 50 detects the excitation light intensity. The non-fluorescent material region 30 is desirably as wide as the irradiation region 31 in order to prevent a decrease in the amount of light flux.

FIG. 1C shows an example when the position of the disk is moved in the Z direction. The radial width of the region where the phosphor 3 is bonded is large enough to accommodate a plurality of irradiation regions 31 in the radial direction. By moving the position of the disk by the same size as the irradiation region 31, it is possible to irradiate the phosphor in a region other than the deteriorated phosphor region with the excitation light, so that the output of the fluorescent light increases, Brightness can be restored. That is, the lifetime as a light source can be improved.

  Although the position of the first light intensity detector 50 is the rear surface of the disk 1 and the position of the second light intensity detector 51 is the rear surface of the dichroic mirror, this position can be used as long as the excitation light intensity can be detected. It is not limited to. Also, the direction in which the disk is moved is not limited to the Z direction as long as it can move so as to avoid the degraded region of the phosphor 3.

  In the said Example, although the object which apply | coats fluorescent substance was demonstrated as a disk, it is not limited to a disk, For example, a polygon-shaped base material may be sufficient.

  Next, the illumination optical system of the projection display apparatus will be described. FIG. 2 is a schematic configuration diagram of an optical system of the projection display apparatus. When distinguishing elements arranged in the optical path of each color light, R, G, and B representing the color light are added after the reference numerals, and when it is not necessary to distinguish, the subscript of the color light is omitted.

First, the principle of applying red light and green light to liquid crystal display elements (hereinafter referred to as liquid crystal panels) 17R and 17G with uniform illuminance will be described.

A blue laser is used as the excitation light source. This is because the light emission area of the light source is small, so that it is easy to collect and collimate light. The blue excitation light emitted from the excitation light source group 5 becomes substantially parallel by the collimating lens group 6 and enters the dichroic mirror 7. The dichroic mirror 7 has characteristics of transmitting blue light and reflecting green light and red light. Therefore, the blue excitation light passes through the dichroic mirror 7, is condensed by the condenser lens 4, and is condensed on the disk 1. The yellow light including the components of green light and red light generated by the yellow phosphor 3 is emitted from the disk 1, passes through the condenser lens 4, becomes parallel, is reflected by the dichroic mirror 7, and is converted into a polarization conversion integrator. 70 is incident.

The polarization conversion integrator 70 includes an optical integrator that performs uniform illumination including the first lens group 8 and the second lens group 9, and a polarization beam splitter array that converts light into a linearly polarized light with the polarization direction aligned with a predetermined polarization direction. and a polarization conversion element 10 combined with a λ / 2 plate. Light from the second lens group 9 is substantially aligned by a polarization conversion element 10 into linearly polarized light in a predetermined polarization direction, for example, the Y direction. The projected images of the lens cells of the first lens group 8 are superimposed on the liquid crystal panels 17R and 17G by the condenser lens 11 and the collimating lenses 15R and 15G, respectively.

At that time, the yellow light passing through the condenser lens 11 is separated into red light and green light by the dichroic mirror 12. Since the dichroic mirror 12 has characteristics of transmitting green light and reflecting red light, among yellow light incident on the dichroic mirror 12, green light passes through the dichroic mirror 12 and is reflected by the reflection mirror 13. It becomes substantially parallel by the collimating lens 15G, and after further removing the X-polarized light by the incident polarizing plate 16G, it enters the liquid crystal panel 17G. On the other hand, the red light is reflected by the dichroic mirror 12, reflected by the reflecting mirror 14, becomes substantially parallel by the collimating lens 15R, and after further removing the X-polarized light by the incident polarizing plate 16R, enters the liquid crystal panel 17R.

In this manner, the liquid crystal panel can be uniformly illuminated while aligning light having a random polarization direction from the excitation light source group 5 with a predetermined polarization direction (here, Y-polarized light).

  Next, the principle of irradiating blue light to the liquid crystal panel 17B with uniform illuminance will be described.

  An LED is used as the blue light source. This is because, unlike lasers, there is less danger to eyes, less visibility, less contribution to brightness, and longer life.

  By using a blue laser that is easy to collect and collimate as an excitation light source and using an LED as a light source for projection, the effect of reducing the risk to eyes while maintaining the brightness of the light Play.

The blue light emitted from the LED 19 is incident on the multiple reflection element 20 disposed immediately thereafter. The blue light is reflected by the multiple reflection element 20 a plurality of times, and becomes light having a uniform illuminance distribution on the exit aperture surface of the multiple reflection element 20. The shape of the exit aperture surface of the multiple reflection element 20 is substantially similar to that of the liquid crystal panel 17B. The blue light emitted from the multiple reflection element 20 becomes substantially parallel by the collimator lens 15B and enters the incident polarizing plate 16B. Since the light emitted from the LED is light having a random polarization direction, the X-polarized light is removed by the incident polarizing plate 16B, and only the Y-polarized light passes and enters the liquid crystal panel 17B.

Subsequently, each color light whose degree of polarization is increased by the incident polarizing plate 16 (16R, 16G, 16B) whose transmission axis is the Y direction is the liquid crystal panel 17 (17R, 17G, 17B) constituting the light intensity modulation unit. Thus, modulation (light intensity modulation) is performed in accordance with a color video signal (not shown) to form an X-polarized optical image of blue light and red light and a Z-polarized optical image of green light.

The optical image is incident on the output polarizing plate 18 (18R, 18G, 18B). The outgoing polarizing plates 18R, 18G, and 18B are polarizing plates that have the X direction as the transmission axis, and the outgoing polarizing plate 18G is a polarizing plate that has the Z direction as the transmission axis. Thereby, an unnecessary polarized light component (here, Y-polarized light) is removed, and the contrast is increased.

The optical image is incident on the color synthesizing prism 21 which is color synthesizing means. At this time, the optical image of green light is incident as Z-polarized light (P-polarized light with respect to the dichroic film surface of the color synthesis prism 21). On the other hand, in the blue optical path and the red optical path, a ½λ wavelength plate (not shown) is provided between the output polarizing plates 18B and 18R and the color combining prism 21, so that the optical images of the X-polarized blue light and red light are After being converted into an optical image of Y-polarized light (S-polarized light with respect to the dichroic film surface that performs color composition of the color composition prism 21), the light enters the color composition prism 21. This is because the spectral characteristics of the dichroic film are taken into account, and the color is efficiently synthesized by so-called SPS synthesis in which green light is P-polarized light and red light and blue light are S-polarized light.

Subsequently, in the color synthesis prism 21, a dichroic film (dielectric multilayer film) that reflects blue light and a dichroic film (dielectric multilayer film) that reflects red light are substantially X-shaped at the interface of four right-angle prisms. It is formed in a shape (cross shape). Of the three incident surfaces of the color combining prism 21, blue light and red light (S-polarized light with respect to the dichroic film surface) incident on the opposite incident surfaces are crossed by the dichroic film for blue light and the red light. Each is reflected by the dichroic film. Further, the green light (P-polarized light with respect to the dichroic film surface) incident on the central incident surface travels straight. The optical images of these color lights are color-synthesized, and color video light (synthesized light) is emitted from the emission surface.

  Then, the combined light emitted from the color combining prism 21 is projected onto a transmission type or projection type screen 120 by a projection lens 22 such as a zoom lens, for example, thereby displaying an enlarged projected image. Become.

  Here, the liquid crystal display device (liquid crystal panel) has been described as an example of the video display device, but it goes without saying that the present invention can also be applied to a projection display device using a DMD (Digital Mirror Device) device.

DESCRIPTION OF SYMBOLS 1 ... Disk 2, 2 Rotating element, 3 ... Phosphor, 4 ... Condensing lens, 5 ... Excitation light source group, 6 ... Collimating lens group, 7 ... Dichroic mirror, 30 ... Non-fluorescent substance area, 31 ... Irradiation area, 32 DESCRIPTION OF SYMBOLS ... Phosphor area | region, 40 ... Connection part, 41 ... Positioning pin, 42 ... Moving device, 50 ... 1st light intensity detector, 51 ... 2nd light intensity detector, 60 ... Control apparatus, 61 ... Memory | storage device.

Claims (6)

An excitation light source group that emits excitation light; and
A substrate coated with a phosphor that emits fluorescent light upon incidence of the excitation light; and
A first light intensity detector for detecting the intensity of the excitation light;
A second light intensity detector for detecting the intensity of the fluorescent light;
A control device for determining whether or not to move the substrate based on detection values of the first and second light intensity detectors;
A projection display apparatus comprising a moving device for moving the base material in accordance with an instruction from the control device.   The said control apparatus issues the instruction | indication to the said moving apparatus to move the said base material, when the ratio of the fall of the intensity | strength of the said fluorescence light with respect to the fall of the intensity | strength of the said excitation light exceeds a predetermined value. Projection display device.   The projection display apparatus according to claim 2, wherein the moving device moves the base material in a direction orthogonal to an incident optical axis direction in which the excitation light enters the base material.   4. The projection display apparatus according to claim 1, wherein a surface of the base material that receives the excitation light includes a non-fluorescent region for transmitting the excitation light. 5. The area where the phosphor is applied includes an irradiation area where the excitation light is actually condensed,
5. The projection type according to claim 4, wherein a region to which the phosphor is applied is formed in a circular shape, and a radial width in the circular shape is large enough to accommodate a plurality of the irradiation regions in the radial direction. Video display device.   The projection display apparatus according to claim 1, wherein the excitation light source group is a blue laser, and further includes a light source for projecting an LED on a screen.

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