JP2005062735A - Method for designing reflector, reflector, light emission lamp equipped with same, luminaire, and projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a reflector whose thermal cracking is avoided, and to provide a light emission lamp, a luminaire, and a projector equipped with the reflector. <P>SOLUTION: The reflector is made of a base material which transmits ultraviolet rays and infrared rays and the shape of the base material is so determined that stress generated on the top and reverse side of the base material owing to heat that a substrate receives does not exceed 10×10<SP>6</SP>pascals. For example, the base material is made semi-spherical and a condition of 10×10<SP>6</SP>pascals>E×(α×H×t)/äρ×2π(r+t/2)<SP>2</SP>} is met, where (r) is the radius in the spherical surface of the base material, (t) the thickness of the spherical surface of the base material, H the quantity of heat that the base material receives, E the Young's modulus of the base material, ρ the heat conductivity of the base material, and α the coefficient of linear expansion of the base material. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical reflecting mirror, a light-emitting lamp including the reflecting mirror, an illumination device, and a projector.

In a light emitting lamp, for efficient use of light, a reflecting mirror (also referred to as a sub-reflecting mirror or a second reflecting mirror) that returns light emitted from a bulb part having a built-in discharge electrode back to the bulb part. (For example, refer to Patent Document 1).
JP-A-8-31382 (second page, FIG. 1)

Heat generated in the bulb is transmitted to the reflecting mirror. In particular, when the reflecting mirror is disposed near the bulb portion, the reflecting mirror is exposed to a high temperature, and the reflecting mirror easily breaks due to the high temperature. Therefore, care must be taken to avoid the cracking.
The present invention has been made in view of this problem, and an object of the present invention is to provide a reflecting mirror that avoids cracking due to heat, and to provide a light-emitting lamp, an illuminating device, and a projector including the reflecting mirror.

  The reflecting mirror design method of the present invention determines the base material constituting the reflecting mirror from the materials that transmit ultraviolet rays and infrared rays, and the stress generated on the front and back of the base material due to the amount of heat received by the substrate, The size of the base material is determined so as to be smaller than a stress that causes cracking in the base material. With such a design, even when the reflecting mirror is arranged in the vicinity of the bulb of the light emitting lamp, it is possible to avoid the cracking of the reflecting mirror caused by heat. Moreover, various materials can be used as the base material of the reflecting mirror.

In addition, the base material has a hemispherical shape, the inner radius of the base material is r, the spherical surface thickness of the base material is t, the amount of heat received by the base material is H, the Young's modulus of the base material is E, When the thermal conductivity of the substrate is ρ and the linear expansion coefficient of the substrate is α,
10 × 10 ⁶ Pascal> E · (α · H · t) / {ρ · 2π (r + t / 2) ² }
The spherical inner radius r and the spherical thickness t are determined so that Accordingly, it is possible to determine the size of the hemispherical reflector in which cracking due to heat is avoided by using various substrate materials.

The reflecting mirror of the present invention is composed of a hemispherical base material that transmits ultraviolet rays and infrared rays, the inner radius of the base is r, the spherical thickness of the base is t, and the amount of heat received by the base is H, when the Young's modulus of the substrate is E, the thermal conductivity of the substrate is ρ, and the linear expansion coefficient of the substrate is α,
10 × 10 ⁶ Pascal> E · (α · H · t) / {ρ · 2π (r + t / 2) ² }
It is characterized by that. As a result, even when the reflecting mirror is arranged in the vicinity of the bulb of the light emitting lamp, cracking of the reflecting mirror due to heat is avoided.
The substrate may be selected from any of quartz, sapphire, translucent alumina, crystallized glass, crystal, borosilicate glass, borosilicate crown glass, and white plate glass.

  The light-emitting lamp of the present invention is a light-emitting lamp including a bulb portion in which a discharge electrode is incorporated and a sub-reflecting mirror that returns light emitted from the bulb portion back to the bulb portion. It is characterized by comprising the reflecting mirror described above.

  An illuminating device of the present invention includes a bulb portion in which a discharge electrode is built, a main reflector that is behind the bulb portion and directs light emitted from the bulb portion, and is located in front of the bulb portion. An illuminating device including a sub-reflecting mirror that returns light emitted from the bulb portion to the bulb portion again includes the reflecting mirror described in any one of the above.

  The projector according to the present invention includes a bulb portion in which a discharge electrode is incorporated, a main reflector that is behind the bulb portion and directs light emitted from the bulb portion, and is located in front of the bulb portion. In the projector for generating an image by projecting the illumination light from the illumination device including the secondary reflection mirror that returns the light emitted from the bulb unit to the bulb unit again, and entering the light modulation device, and projecting the image. One of the above-described sub-reflecting mirrors is provided as a reflecting mirror.

Embodiment 1
First, as shown in FIG. 1, a rectangular flat base material having an area A in the thickness direction center and a thickness t receives heat on the back surface (heat amount H), and the heat is conducted to the surface. think of. In this case, the temperature difference Δt between the front and back surfaces of the substrate can be expressed by Expression (1).
Δt = H · t / (ρ · A) (1)
When the dimension of the back surface of the substrate (for example, the long side) is d1, and the dimension of the substrate surface corresponding to this d1 is d2, the dimension changes between d1 and d2 due to the temperature difference Δt according to the equation (1). Difference Δd occurs. If the substrate front and back temperatures are the same, the dimensional change d is also the same, and no stress is generated on the substrate front and back. Here, the distortion is not defined with respect to the original dimensions d1 and d2, and the front and back in the case where there is a temperature difference between the front and back of the substrate with respect to the dimensional change d when the temperature of the front and back of the substrate is the same. The strain ε is defined using the difference Δd in the amount of dimensional change.

The difference Δd in the amount of dimensional change is
Δd = α · d · Δt = α · d · {(H · t / (ρ · A)} (2)
It becomes. Where α is the linear expansion coefficient of the substrate, ρ is the thermal conductivity of the substrate, and H is the amount of heat received by the base material. Further, the strain ε can be expressed by Expression (3).
ε = Δd / d = {α · d · H · t / (ρ · A)} / d = α · H · t / (ρ · A)
... Formula (3)
At this time, the stress σ generated on the front and back of the base material can be expressed by Expression (4).
σ = E · ε = E · {α · H · t / (ρ · A)} (4)
If the stress σ defined by this formula (4) is smaller than the stress that causes cracks in the substrate, cracks due to the heat of the substrate will not occur.

  A preferable reflecting mirror for reflecting visible light is that the base material constituting the reflecting mirror is a material that transmits ultraviolet rays and infrared rays. Therefore, usually, the material of the base material is first determined, and the size of the determined base material is set so that the stress σ represented by the formula (4) is smaller than the stress that causes the base material to crack. If determined, it is possible to prevent cracking of the reflecting mirror due to heat.

Next, as shown in FIG. 2, a reflecting mirror in which the base material is hemispherical, the inside radius of the base material is r, and the spherical surface thickness of the base material is t will be considered. When the base material is composed of a material that transmits ultraviolet rays and infrared rays having Young's modulus E, thermal conductivity ρ, and linear expansion coefficient α, and the amount of heat received by the base material is H, the stress σ in the equation (4) is It can be expressed as equation (5).
σ = E · [(α · H · t) / {ρ · 2π (r + t / 2) ² }] Equation (5)

  Next, as shown in FIG. 3, a reflector (sub-reflector or sub-reflector or mirror) is disposed so as to be close to and cover about half of the bulb portion 2 in which the discharge electrodes 1a and 1b of the light emitting lamp are incorporated. Consider 5) (also called second reflector). In this case, the amount of heat H received by the reflecting mirror 5 is determined according to the power consumption of the light-emitting lamp (hereinafter referred to as lamp power). Further, the energy distribution of the light emitting lamp with the reflecting mirror 5 and the type of the light emitting lamp without the reflecting mirror 5 as shown in FIG. Among these, the energy distribution of the light emitting lamp without the reflecting mirror 5 is obtained by actual measurement. On the other hand, the energy distribution of the light emitting lamp with the reflecting mirror 5 is obtained by calculation based on the energy distribution of the light emitting lamp without the reflecting mirror 5. For this purpose, first, the loss of visible light of the light emitting lamp with the reflecting mirror 5 is measured. Then, the loss of visible light is regarded as an increase in heat loss of the light-emitting lamp by the reflector 5, and the increase is allocated according to the energy distribution ratio of convection / conduction and radiation of the type without the reflector 5, and reflected. It adds to the energy distribution table | surface of a light emitting lamp of the type without the mirror 5. FIG. As for the energy of visible light, the loss of visible light is subtracted from the corresponding part without the reflecting mirror 5. The rest of the energy distribution of the light emitting lamp with the reflecting mirror 5 can be obtained by making it the same as the energy distribution of the type without the reflecting mirror 5.

  In the case of the lamp of FIG. 3, the heat loss energy due to radiation from the bulb 2 mainly affects the reflecting mirror 5 among the heat generated in the bulb 2. Table 2 shows the results obtained by proportionally calculating the heat loss energy due to this radiation according to the power consumption of the light emitting lamp. However, since the reflecting mirror 5 covers only about half of the bulb portion 2, the half value in Table 2 may be regarded as the amount of heat received by the reflecting mirror 5, and the amount of heat received by the reflecting mirror 5 thus obtained is It is shown in Table 3.

  The inventors assumed hemispherical reflecting mirrors 5 and conducted experiments on cracking due to heat. The experiment was performed under the conditions of the spherical inner diameter r = 0.068 m of the base material constituting the reflecting mirror 5, the spherical surface thickness t = 0.015 m of the base material, and the amount of heat received T = 20.7 W (when the lamp power is 165 W). With respect to various materials that transmit ultraviolet rays and infrared rays, experiments were conducted on cracking of the reflecting mirror 5. The base material used in the experiment is as shown in Table 4, and they have the Young's modulus, thermal conductivity, and linear expansion coefficient in Table 4. Moreover, the result of having calculated stress (sigma) of Formula (5) using those values was shown in FIG.

According to the experiment, cracks occur in the crystal (axial shaft), borosilicate glass, borosilicate crown glass (BK7), and white plate glass (B270) in which the stress σ of the formula (5) exceeds 10 × 10 ⁶ Pascal (10 Mpa). Occurred. However, cracks did not occur in quartz, super heat resistant crystallized glass (for example, trade name Neoceram), sapphire, translucent alumina, and crystallized glass having a stress σ of less than 10 × 10 ⁶ Pascals. This result is obtained by determining the spherical inner diameter r of the substrate and the spherical thickness t of the substrate so that the stress σ of the formula (5) does not exceed 10 × 10 ⁶ Pascals for each substrate. This shows that the breakage of the reflecting mirror 5 due to the above can be avoided. For example, even in the case of crystal (shaft), borosilicate glass, borosilicate crown glass (BK7), and white plate glass (B270) that have cracked under the above conditions, as shown in FIG. And the spherical wall thickness t can be determined to avoid cracking due to heat.

  In the first embodiment, the case where the reflecting mirror 5 has a hemispherical shape has been described as an example. However, the present invention is not limited to this shape, and is applicable to other shapes, for example, a spheroidal shape. it can.

Embodiment 2
Next, a light-emitting lamp provided with the reflecting mirror described in Embodiment 1 as a sub-reflecting mirror will be described. As the light-emitting lamp, there are a mercury lamp, a xenon lamp, a metal haloid lamp, and the like. Here, a mercury lamp will be described as an example. FIG. 6 is a configuration diagram of a mercury lamp 10A according to Embodiment 2 of the present invention. A mercury lamp 10A according to FIG. 6 has a bulb part 2 (including a substantially spherical shape) in which a pair of discharge electrodes 1a and 1b are built. The thickness of the valve portion 2 is substantially the same at any position. And it is integral with the valve part 2 on both sides of the valve part 2, and is provided with sealing parts 3a and 3b having the same diameter and length continuously extending from the valve part 2 to the left and right sides. The valve portion 2 and the sealing portions 3a and 3b are integrally formed of a transparent material such as quartz glass. Metal foils 14a and 14b made of molybdenum connected to the electrodes 1a and 1b are sealed inside the sealing portions 3a and 3b, and lead wires 15a and 15b connected to the outside are respectively connected to the metal foils 14a and 14b. Is provided. Furthermore, the reflecting mirror described in the first embodiment is arranged as the sub-reflecting mirror 6 in the sealing portion 3b. The sub-reflecting mirror 6 is close to the bulb portion 2 so as to cover almost half of the bulb portion 2, and is fixed to the sealing portions 3a and 3b with an inorganic material cement 31 or the like. In FIG. 6, description of mercury, rare gas, etc. enclosed in the valve unit 2 is omitted.

  It is preferable to provide a gap G between about 0.2 mm and about 1.5 mm between the bulb portion 2 and the sub-reflecting mirror 6. This is because the heat radiation of the bulb portion 2 on the side where the gap G is covered with the sub-reflecting mirror 6 is promoted. The back surface of the sub-reflecting mirror 6 transmits light incident from the reflecting surface side (infrared rays, ultraviolet rays, visible light leaking from the reflecting surface side, etc.) or light incident from the reflecting surface side. The sub-reflecting mirror 6 absorbs as little light as possible.

  In the case of the mercury lamp 10A, the light emitted by the discharge of the electrodes 1a and 1b is radiated from the inside of the bulb portion 2 to the outside, but the emitted light is emitted from the sub-reflecting mirror 6 at a portion where the sub-reflecting mirror 6 is present. The light is reflected, enters the inside of the bulb portion 2 again, and is radiated again from the side without the sub-reflecting mirror 6 to the outside of the bulb portion 2. During the operation of the mercury lamp 10A, the sub-reflecting mirror 6 receives heat, mainly radiant heat from the bulb portion 2, but the base material of the sub-reflecting mirror 6 is designed as in the first embodiment. Breaking of the mirror 6 is prevented.

Embodiment 3
FIG. 7 is a configuration diagram of an illumination device 100A according to Embodiment 3 of the present invention. The illumination device 100A includes a mercury lamp 10A with a sub-reflecting mirror 6, and a main reflecting mirror 20 that reflects light emitted backward from the bulb portion 2 of the mercury lamp 10A toward the front. The shape of the main reflecting mirror 20 can be a spheroidal surface shape, a rotating paraboloid shape, or the like. In the mercury lamp 10A, one end 3a of the sealing portion is inserted into the through hole 21 at the bottom of the main reflecting mirror 20, and is fixed integrally with the main reflecting mirror 20 by an inorganic adhesive 22 such as cement. Here again, the metal foils 14a and 14b made of molybdenum connected to the electrodes 1a and 1b are sealed in the respective sealing portions 3a and 3b, and the lead wires 15a and 15b connected to the outside are connected to the metal foils 14a and 14b. Are provided.

  When the main reflecting mirror 20 has a spheroid shape, the center between the electrodes 1a and 1b is usually positioned substantially at the same position as the position of the first focal point F1 of the main reflecting mirror 20. Further, since the reflecting surface of the sub-reflecting mirror 6 surrounds almost the front half of the bulb portion 2, the reflecting surface of the main reflecting mirror 20 may be large enough to cover the rear half of the bulb portion 2. Thereby, the main reflecting mirror 20 can be made considerably smaller than the case without the sub-reflecting mirror 6. In addition, this causes many portions of the mercury lamp 10 </ b> A to protrude outward from the reflection surface opening end of the main reflecting mirror 20.

  The illumination device 100A having the above configuration operates as follows. That is, the emitted light from the rear side of the bulb portion 2 is reflected by the main reflecting mirror 20 and travels forward of the illumination device 100A. Further, the light emitted from the front side of the bulb 2 is reflected by the sub-reflecting mirror 6 and returns to the bulb 2 again, and enters the main reflecting mirror 20 from there. The light also reaches the main reflecting mirror 20, is reflected there, and travels forward of the illumination device 100A. As a result, most of the light emitted from the bulb portion 2 can be used. According to the illumination device 100A of the third embodiment, cracks due to thermal distortion of the sub-reflecting mirror 6 used for effective use of light are prevented, and efficient supply of light is stably maintained. .

Embodiment 4
FIG. 8 is a configuration diagram of a projector including the above-described illumination device 100A. This optical system includes an illumination optical system 300 including an illumination device 100A including a mercury lamp 10A, a main reflection mirror 20, and a sub-reflection mirror 6, and means for adjusting light emitted from the illumination device 100A to predetermined light, Color light separation optical system 380 having dichroic mirrors 382, 386, reflection mirror 384, etc., incident side lens 392, relay lens 396, relay optical system 390 having reflection mirrors 394, 398, and field lens 400 corresponding to each color light, 402 and 404, liquid crystal panels 410R, 410G, and 410B as light modulation devices, a cross dichroic prism 420 that is a color light combining optical system, and a projection lens 600.

  Next, the operation of the projector having the above configuration will be described. First, outgoing light from the rear side of the center of the bulb portion 2 of the mercury lamp 10A is reflected by the main reflecting mirror 20 and travels forward of the illumination device 100A. Also, the outgoing light from the front side of the center of the bulb portion 2 is reflected by the sub-reflecting mirror 6 and returns to the main reflecting mirror 20, then goes to the main reflecting mirror 20, where it is reflected and goes forward of the illumination device 100 </ b> A.

  The light exiting the illumination device 100A enters the concave lens 200, where the traveling direction of the light is adjusted substantially parallel to the optical axis 1 of the illumination optical system 300, and then each small lens of the first lens array 320 constituting the integrator lens. 321 is incident. The first lens array 320 divides incident light into a plurality of partial light beams corresponding to the number of small lenses 321. Each partial light beam exiting the first lens array 320 is incident on a second lens array 340 constituting an integrator lens having small lenses 341 respectively corresponding to the small lenses 321. Then, the emitted light from the second lens array 340 is condensed in the vicinity of the corresponding polarization separation film (not shown) of the polarization conversion element array 360. At this time, light is adjusted by a light shielding plate (not shown) so that light is incident only on a portion corresponding to the polarization separation film in the incident light to the polarization conversion element array 360.

  In the polarization conversion element array 360, the light beam incident thereon is converted into the same type of linearly polarized light. Then, a plurality of partial light beams whose polarization directions are aligned by the polarization conversion element array 360 enter the superimposing lens 370, where the partial light beams that irradiate the liquid crystal panels 410R, 410G, and 410B overlap on the corresponding panel surface. Adjusted to fit.

  The color light separation optical system 380 includes first and second dichroic mirrors 382 and 386, and has a function of separating light emitted from the illumination optical system into red, green, and blue color light. The first dichroic mirror 382 transmits the red light component of the light emitted from the superimposing lens 370 and reflects the blue light component and the green light component. The red light transmitted through the first dichroic mirror 382 is reflected by the reflection mirror 384, passes through the field lens 400, and reaches the liquid crystal panel 410R for red light. The field lens 400 converts each partial light beam emitted from the superimposing lens 370 into a light beam parallel to the central axis (principal ray). The field lenses 402 and 404 provided in front of the other liquid crystal panels 410G and 410B operate in the same manner.

  Further, of the blue light and green light reflected by the first dichroic mirror 382, the green light is reflected by the second dichroic mirror 386 and reaches the green light liquid crystal panel 410 </ b> G through the field lens 402. On the other hand, the blue light passes through the second dichroic mirror 386, passes through the relay optical system 390, that is, the incident side lens 392, the reflection mirror 394, the relay lens 396, and the reflection mirror 398, and further passes through the field lens 404. The light reaches the light liquid crystal panel 410B. The reason why the relay optical system 390 is used for blue light is to prevent a decrease in light use efficiency due to light divergence or the like because the optical path length of blue light is longer than the optical path length of other color lights. is there. That is, this is to transmit the partial light beam incident on the incident side lens 392 to the field lens 404 as it is. The relay optical system 390 is configured to pass blue light out of the three color lights, but may be configured to pass other color light such as red light.

  The three liquid crystal panels 410R, 410G, and 410B modulate each incident color light according to the given video information to form an image of each color light. A polarizing plate is usually provided on the light incident surface side and the light emitting surface side of the three liquid crystal panels 410R, 410G, and 410B.

  The three colors of modulated light emitted from each of the liquid crystal panels 410R, 410G, and 410B enter a cross dichroic prism 420 having a function as a color light combining optical system that combines these modulated lights to form a color image. In the cross dichroic prism 420, a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are formed in an approximately X shape at the interface of four right-angle prisms. These dielectric multilayer films combine the three colors of red, green, and blue modulated light to form combined light for projecting a color image. The synthesized light synthesized by the cross dichroic prism 420 finally enters the projection lens 600 and is projected and displayed as a color image on the screen.

  According to the projector, the efficient use of light is stably maintained by the action of the illumination device 100A including the sub-reflecting mirror in which measures against cracking due to heat are taken.

  The reflector of the present invention can be used as a sub-reflector of a light-emitting lamp, and the light-emitting lamp and illumination device of the present invention can be used as a light source for various optical devices.

The external view of a flat base material. The external view of the hemispherical base material which is a reflecting mirror. The block diagram of a mercury lamp. Comparison of stress for each material generated on the front and back of the reflector The comparison figure of the radius in a spherical surface and spherical surface thickness for every material which makes the stress which generate | occur | produces in the front and back of a reflective mirror 10 Mpa. The block diagram which shows the mercury lamp which concerns on Embodiment 2 of this invention. The block diagram which shows the illuminating device which concerns on Embodiment 3 of this invention. FIG. 10 is a configuration diagram showing an optical system of a projector according to a fourth embodiment of the invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a, 1b ... Electrode, 2 ... Valve | bulb part, 3a, 3b ... Sealing part, 5 ... Reflecting mirror, 6 ... Sub-reflecting mirror, 10A ... Mercury lamp, 20 ... Main reflecting mirror, 100A ... Illuminating device.

Claims (7)

  The stress that causes the base material to crack due to the stress that occurs on the front and back of the base material due to the amount of heat received by the base material is determined from the material that transmits ultraviolet and infrared rays. A method of designing a reflecting mirror, wherein the size of the substrate is determined so as to be smaller. The base material has a hemispherical shape, the inner radius of the base material is r, the spherical surface thickness of the base material is t, the amount of heat received by the base material is H, the Young's modulus of the base material is E, and the base material Where ρ is the thermal conductivity and α is the linear expansion coefficient of the substrate,
10 × 10 ⁶ Pascal> E · (α · H · t) / {ρ · 2π (r + t / 2) ² }
The method of designing a reflecting mirror according to claim 1, wherein the radius r and the spherical thickness t are determined so that It is composed of a hemispherical base material that transmits ultraviolet rays and infrared rays, the inner radius of the base is r, the spherical thickness of the base is t, the amount of heat received by the base is H, and the Young of the base is When the rate is E, the thermal conductivity of the substrate is ρ, and the linear expansion coefficient of the substrate is α,
10 × 10 ⁶ Pascal> E · (α · H · t) / {ρ · 2π (r + t / 2) ² }
Reflector characterized by that.   4. The reflecting mirror according to claim 3, wherein the substrate is made of any one of quartz, sapphire, translucent alumina, crystallized glass, crystal, borosilicate glass, borosilicate crown glass, and white plate glass.   5. The light emitting lamp comprising a bulb portion in which a discharge electrode is built in and a sub-reflecting mirror that returns light emitted from the bulb portion to the bulb portion again, the sub-reflecting mirror according to claim 3 or 4. A light-emitting lamp comprising a reflecting mirror.   A bulb portion having a discharge electrode built therein; a main reflector that is behind the bulb portion and directs light emitted from the bulb portion; and a front reflector that is located forward of the bulb portion and emitted from the bulb portion. An illuminating device comprising a sub-reflecting mirror that returns the light again to the bulb portion, wherein the sub-reflecting mirror includes the reflecting mirror according to claim 3 or 4.   A bulb portion having a discharge electrode built therein; a main reflector that is behind the bulb portion and directs light emitted from the bulb portion; and a front reflector that is located forward of the bulb portion and emitted from the bulb portion. In a projector that generates illumination images by projecting illumination light from an illuminating device including a sub-reflecting mirror that returns the reflected light back to the bulb unit, and projects the image as the sub-reflecting mirror, the claim Item 5. A projector comprising the sub-reflecting mirror according to Item 3 or 4.

Images