JP3930900B2 - Lighting device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an illuminating device using a plurality of LED lamps or LED chips as a light source used in an optical apparatus such as a microscope, an exposure apparatus, a projector, and a spectroscopic instrument, and a microscope using the illuminating apparatus.
[0002]
[Prior art]
Conventional optical devices use almost a single light source, and when the light intensity is increased, the intensity of the light source itself is increased, that is, a large light source is employed. As means for increasing the light intensity, Patent Document 1 discloses a rod integrator provided with a partial introduction portion, and Patent Document 2 discloses a rod integrator having the same number of incident end faces as the light source. Both of these are expensive because of complex processing on the incident end face of the rod integrator. Due to recent technological advances, inexpensive and high-brightness LED chips that can be used as LED lamps have been developed, and their application fields are expanding.
[0003]
A conventional fluorescent microscope uses a large lamp such as a mercury lamp, selects only light having a wavelength used as excitation light with a filter, and uses only a small part of the light emitted from the light source. . Although the above problem is solved when an LED is used, a high-brightness LED has been developed, but the amount of light is insufficient when a single LED is used. However, when multiple are used, uneven illumination occurs. In general, the Koehler illumination method is widely used as a microscope illumination method for both transmission observation and fluorescence observation. The critical illumination method for forming an image of a light source on a sample has not been widely used in spite of many advantages such as high resolution in the depth direction. This is because when the light source part of the illumination lamp is imaged, the filament and arc image of the lamp appear in the sample, resulting in illumination spots. To solve this problem, there is a method of inserting a scatterer in order to eliminate this illumination spot. For example, a frost bulb or a fluorescent tube is used.
[0004]
As an illumination device using LEDs, Patent Document 3 discloses a rod integrator in which a plurality of LEDs are used as a basic unit constituting an LED display, and in order to avoid interference with adjacent units and to equalize light brightness. And the use of light pipes. As a microscope illumination device using LEDs, Patent Document 4 describes a method of directly diffusing a microscope observation sample using a plurality of LEDs, a diffractive optical element, and a lens. Further, as a microscope illumination method, Patent Document 5 describes a method of easily switching between a microscope Kohler illumination method and a critical illumination method by detaching and inserting a lens group from an optical system.
[0005]
[Patent Document 1]
JP-A-5-72627 [Patent Document 2]
JP 2000-75407 A [Patent Document 3]
Japanese Patent Laid-Open No. 10-319873 [Patent Document 4]
JP 2002-189174 A [Patent Document 5]
Japanese Patent Laid-Open No. 10-232353
[Problems to be solved by the invention]
By the way, with a single LED lamp or LED chip, there is a problem of insufficient light quantity depending on the application, and when a plurality of LED lamps are mounted at a high density, heat dissipation is also a problem. Further, in the conventional microscope illumination method, the scattered light from the scatterer spreads in all directions, and only a part of this can be used for sample illumination, so a sufficient amount of light cannot be secured. In other words, there was a problem of darkness. In addition, since the scatterer is thicker than necessary, there is a problem that the resolution in the thickness direction does not increase even if the scatterer is regarded as a pseudo-planar light source and an image is formed on the sample. In particular, when a critical illumination method is employed in fluorescence microscope observation, it is expected that both sensitivity and resolution will be increased, but it is not popular due to the above problems and price problems.
The object of the present invention has been made in view of the above circumstances, and uses a plurality of LED lamps or integrates LED chips, and these light beams are incident on a rod integrator and have high light intensity and uniformity. An object of the present invention is to provide an illuminating device that uses various emitted light.
Another object of the present invention is to adopt an LED lamp as a light source, which enables observation with high resolution and sensitivity, and a uniform illumination device that is free of illumination spots, has high light utilization efficiency, and is low in power consumption. Is to provide a microscope.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a lighting device according to a first aspect of the present invention includes a heat conductive electrode substrate, and a plurality of LED chips mounted directly on the heat conductive electrode substrate to directly connect them electrically and thermally. And an LED chip assembly in which one electrode of each LED chip is connected by a bonding wire to a wiring pattern insulated from the thermally conductive electrode substrate by an insulating film ;
A condensing lens that condenses the luminous flux from the LED chip assembly;
A rod integrator that enters a light beam collected by the condenser lens into an incident end surface, superimposes the light beams of a plurality of LED chips inside, adds light intensity, and generates a planar light source on the output end surface; It is characterized by being.
According to the first aspect of the present invention, a plurality of inexpensive LED chips can be mounted at a high density as compared with the LED lamp, so that the size and mass production can be achieved, and the cost of the light source device can be reduced.
[0008]
The invention of claim 2 is characterized in that, in the description of claim 1, heat radiation means is thermally coupled to the surface of the thermally conductive electrode substrate opposite to the surface on which the LED chip is disposed .
According to the invention of claim 2, a large current can be allowed to flow through the LED chip with improved heat dissipation efficiency, and a longer life can be achieved.
[0009]
According to a third aspect of the present invention, in order to increase the amount of light by cascading the illuminating devices according to the first aspect, the light beams emitted from the emission end faces of the rod integrators of the plurality of illuminating devices are condensed to form a single rod integrator The planar light source is generated on the exit end face of the single rod integrator .
According to the invention of claim 3, it is possible to cope with a shortage of light quantity by increasing the light quantity by increasing the number of LED chips by connecting the lighting devices in multiple stages.
[0011]
The invention according to claim 5 is characterized in that the lighting devices according to any one of claims 1 to 4 are cascade-connected.
According to the invention of claim 5, by connecting the lighting devices in multiple stages, the number of LED lamps or LED chips can be increased to increase the amount of light, so that the shortage of light can be dealt with.
[0012]
According to a sixth aspect of the present invention, there is provided a microscope for illuminating a sample with light from an illuminating device and forming an image of transmitted light or fluorescence from the sample and observing the light source. A rod integrator that makes a luminous flux emitted from an LED incident on an incident end face, superimposes the luminous flux inside to add and uniformize the light intensity of each LED, and generates a uniform planar light source on an emission end face. And an optical system that forms an image of a planar light source generated at the exit end of the rod integrator and critically illuminates the sample.
According to the sixth aspect of the present invention, when light beams emitted from a plurality of LED lamps are introduced into the incident end surface of the rod integrator, they are reflected multiple times inside the rod integrator, and the light beams from the respective LED lamps are superimposed and added and are made uniform at the same time. Since it is emitted from the exit end face, critical illumination without illumination unevenness becomes possible.
[0013]
A seventh aspect of the present invention is that, in the sixth aspect, the light source is disposed on the thermally conductive electrode substrate and the thermally conductive electrode substrate, and the lead frame on which the LED chip is mounted is electrically and thermally connected to the thermally conductive electrode substrate. And a plurality of LED lamps directly connected to each other.
According to the invention of claim 7, the operational effects of the inventions of claim 2 and claim 6 are produced.
[0014]
The invention of claim 8 is the LED chip assembly according to claim 6, wherein the light source is directly and electrically connected thermally by mounting a plurality of LED chips directly on the heat conductive electrode substrate, and the LED chip assembly. And a condensing lens that condenses the luminous flux from the lens.
According to the invention of claim 8, the operational effects of the inventions of claims 3 and 6 are produced.
[0015]
The invention of claim 9 is a microscope for illuminating a sample with light from an illuminating device capable of selecting Koehler illumination and critical illumination , and forming an image of reflected light from the sample for observation.
The lighting device and a light source comprising a plurality of LED, the incident on the incident end face of the light flux emanating from each LED, and homogenized by adding the light intensity of each LED and superimposes the light beams inside, the exit end face A rod integrator that generates a uniform planar light source, and while maintaining a distance between the light source and the rod integrator, the position of the exit end of the rod integrator is moved to a field stop position or an aperture stop position, and Koehler illumination and critical illumination And an optical system that images a planar light source generated on the exit end face of the rod integrator to Koehler illumination or critical illumination of the sample .
According to the ninth aspect of the present invention, when the light beams emitted from the plurality of LED lamps are introduced into the incident end face of the rod integrator, they are multiple-reflected inside the rod integrator, and the light beams from the respective LED lamps are superposed and added simultaneously and made uniform. Since it is emitted from the exit end face, Koehler illumination or critical illumination without illumination unevenness is possible, and observation with a deep focal depth and observation with a shallow focal depth can be switched by a simple operation during observation.
[0016]
A tenth aspect of the present invention is that, in the ninth aspect, a light source is disposed on the thermally conductive electrode substrate and the thermally conductive electrode substrate, and a lead frame on which an LED chip is mounted is electrically and thermally connected to the thermally conductive electrode substrate. It is characterized by being a plurality of LED lamps connected together.
According to the invention of claim 10, the effects of the inventions of claims 2 and 9 are produced.
[0017]
The invention of claim 11 is the LED chip assembly according to claim 10, wherein the light source is electrically and thermally connected by directly mounting a plurality of LED chips on a thermally conductive electrode substrate, and the LED chip assembly. And a condensing lens for condensing the luminous flux.
According to the invention of claim 11, the effects of the inventions of claim 3 and claim 9 are produced.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a conceptual diagram illustrating the principle of the illumination device of the present invention. Light beams from the plurality of LED lamps L1 to Ln are condensed on the incident end face of the rod integrator. At this time, the LED lamps L1 to Ln are arranged so that the light beam is incident within the light receiving angle of the rod integrator. The light beam incident on the incident end of the rod integrator is multiple-reflected inside the rod integrator, and the light beams from the individual LED lamps are superimposed and added, and are made uniform at the same time. When the directivity of each LED lamp is sharp, it is sufficient to arrange the optical axis of the LED lamp, that is, the emission direction, toward the incident end surface of the rod integrator. When the directivity is dull, the light from each LED lamp is condensed on the incident end face of the rod integrator using a lens or a mirror. In the present invention, the number of LED lamps spatially arranged is limited by the limitation of the light receiving angle of the rod integrator. Therefore, when the amount of light is further insufficient, the illumination device is connected in multiple stages (cascade) as shown in FIG. 2 to increase the amount of light by increasing the number of LED lamps.
[0024]
FIG. 3 is a block diagram of the first reference example of the present invention . FIG. 4 is a diagram showing an assembled state of the LED lamp 1 to the thermally conductive electrode substrate. In this embodiment, a plurality of LED lamps 1 are arranged on a thermally conductive electrode substrate 2 made of, for example, a copper plate, and are installed so that the optical axis of the LED lamp 1 faces the incident end face of the rod integrator 3. A lead frame 11 on which one of the cathode and anode electrodes of the LED chip 10 of each LED lamp 1 is mounted is electrically connected to the thermally conductive electrode substrate 2. The fixing surface of the LED lamp 1 of the heat conductive electrode substrate 2 is formed in a concave spherical surface, and the insulating film 4 is affixed. The lead frame 11 penetrates the insulating film 4 and is electrically connected to the heat conductive electrode substrate 2. The other lead frame 12 is connected to a wiring pattern 7 provided on the surface of the insulating film 4. In this reference example, it is bonded to a copper thermally conductive electrode substrate by soldering, but it is also possible to use an adhesive that conducts electricity and heat well. By this thermal coupling, the heat generated from the LED chip 10 can be efficiently released.
[0025]
In order to release heat from the heat conductive electrode substrate 2, the heat conductive electrode substrate is provided with heat radiating means. One specific example of the heat dissipating means is shown in FIG. In this example, a Peltier element 8 is disposed on the back surface of the thermally conductive electrode substrate 2, a radiator 5 is provided on the Peltier element 8, and each is thermally coupled, and the radiator 5 is further cooled by a cooling fan 6. Has been. In this embodiment, 16 bullet-type LED lamps 1 having a sharp directivity with a viewing angle of ± 6 degrees are used and arranged in a grid pattern. Any number of LED lamps 1 having other shapes and performances can be arranged arbitrarily.
[0026]
FIG. 5 shows a configuration diagram of a second reference example of the present invention . In the second reference example , a plurality of LED lamps 1 are arranged on a flat thermally conductive electrode substrate 2 so that their optical axes are parallel to each other. Between the LED lamp 1 and the rod integrator 3, a condenser lens 9 that condenses the luminous flux of each LED lamp 1 at the incident end of the rod integrator 3 is installed. According to the present embodiment, it is not necessary to adjust the optical axis of each LED lamp 1 to face the incident end of the rod integrator 3. Since the luminous flux can be guided, it is effective when the directivity of the LED lamp 1 is dull.
[0027]
The rod integrator 3 is an optical propagating body in which a light beam introduced from an incident end repeats multiple reflections and propagates to the exit end. In the rod integrator 3 shown in FIG. 6, a clad 30 formed of an optical material having a low refractive index surrounds a core body 31 formed of an optical material having a high refractive index, like an optical fiber. In the rod integrator 3 shown in FIG. 7, the core 31 is formed of a glass rod or a plastic rod that can provide ambient air with a cladding function and allow total reflection on the surface. The rod integrator 3 shown in FIG. 8 is a mirror rod made of a mirror such as a glass or plastic surface coated with a metal such as aluminum. The rod integrator 3 shown in FIG. 9 is a typical example of a structure in which the rod integrator is formed in a tapered shape in which the cross-sectional area decreases from the incident end 3A toward the exit end 3B. The tapered rod integrator acts to reduce the light flux and increase the light intensity. The shape narrowed down to a taper can be used to fabricate a fiber light source by optically coupling the exit end to an optical fiber. As an application example of the tapered rod integrator, a point light source shown in FIG. 10 or a linear light source shown in FIG. 11 can be created. A point light source can easily obtain parallel light by adding a lens. In addition, the tapered shape is also applied to the structure of only the core of FIG. 7 or the structure in which the core surface of FIG. 8 is mirrored. The shape of the rod integrator is not limited to a cylinder or a prism, and can be a curved line other than a straight line.
[0028]
The configuration of the incident end of the rod integrator 3 will be described. At the incident end of the core body 31 of the rod integrator 3, as shown in FIG. 12, a condensing lens 33 for enlarging the light receiving angle is arranged in contact with the incident end surface, or formed on the convex lens 34 shown in FIG. ing. FIG. 14 shows a structure in which the core material of the core body 31 of the rod integrator 3 and the LED lamp 1 are integrated by molding.
The configurations of the entrance end and the exit end of these rod integrators 3 can be selectively applied to the above-described embodiments such as the structure with or without the cladding 30 and the mirror 32.
[0029]
Examples of the present invention will be described. FIG. 15 is a perspective view of an LED chip integrated body constituting this embodiment , and FIG. 14 is a partial cross-sectional view of the LED chip integrated body. In the LED chip integrated body, a plurality of LED chips 9 are directly mounted on the thermally conductive electrode substrate 2 by adhesion and are electrically and thermally connected. An insulating film 4 provided with a wiring pattern 7 is pasted on the surface of the thermally conductive electrode substrate 2. The other electrode of each LED chip 9 is connected to the wiring pattern 7 via a chip resistor 14 by a bonding wire 13. Although not shown in the drawing, the whole or at least the LED chip 9 and the bonding wire 13 are covered with a transparent resin for protection.
[0030]
The LED chip integrated body can be used in place of the aforementioned LED lamp. In addition, many LED chip assemblies are not only excellent in heat dissipation efficiency because the LED chip 7 is directly thermally coupled to the thermally conductive electrode substrate 2 without a lead frame, but are also suitable for mass production.
[0031]
An example of a microscope employing the illumination device of the present invention will be described. FIG. 17 is a schematic diagram of a microscope. The microscope illuminates the sample surface through the objective lens 42 by making the light from the illumination device 50 into parallel light by the field lens 40 and reflecting it to the dichroic mirror 41. The transmitted light or fluorescence from the sample surface is imaged on the imaging surface by the imaging lens 43 through the objective lens 42 and the dichroic mirror 41 and observed.
[0032]
The illumination device 50 is arranged so that the exit end of the rod integrator 3 matches the field stop position of the microscope. As a result, a uniform planar light source having no luminance unevenness generated at the exit end of the rod integrator 3 is imaged on the observation surface of the sample, thereby realizing critical illumination. As a result, critical illumination without illumination unevenness is possible, and observation with a shallower depth of focus is possible compared to Koehler illumination. This is because the focal depth of observation is proportional to the product of the focal depth of illumination and the focal depth of imaging.
[0033]
The present invention is applicable to both transmitted light illumination and epi-illumination such as fluorescence observation. Since the depth of focus is shallow, an optical slice image can be obtained. It is also possible to acquire a plurality of optical slice images while shifting the observation surface in the depth direction, and reconstruct a three-dimensional stereoscopic image from these optical slice images by an image processing technique. Further, the exit angle of the rod integrator can adjust the refractive index of the material, so that it can be transmitted to the field lens arranged in front of the rod integrator without loss of light energy.
[0034]
Illumination switching means for moving the illumination device 50 to the field stop position and the aperture stop position in the direction of the arrow shown in the figure is provided. The illumination switching means switches the Kohler illumination and the critical illumination by moving the position of the exit end of the rod integrator 3 to the field stop position or the aperture stop position while keeping the distance between the light source 1 and the rod integrator 3. Koehler illumination is achieved by matching the exit end of the rod integrator to the aperture stop position.
[0035]
It is desirable to image a thin planar light source generated at the exit end of the above rod integrator on the sample observation surface, but in order to produce inexpensively, a thin film scatterer is simply placed at the aperture stop position. Critical lighting can be realized. The thin-film scatterer has a thinner scattering layer than the conventional frosted glass or opal glass, and the scattering angle can be limited. There is a thin film scatterer using surface relief hologram technology that can be used for this purpose, for example, “Light Shaping Diffuser” manufactured by Physical Optics Corporation (CA.USA).
[0036]
【The invention's effect】
According to the illuminating device of the present invention, light beams from a plurality of LED lamps can be superposed by a rod integrator, and the light intensity can be added to be used as an illuminating device that generates a uniform planar light source . The illumination device becomes a uniform light source without illumination unevenness. In addition, by thermally coupling the lead frame on which the LED chip is mounted, or the LED chip itself to the thermally conductive electrode substrate, the heat dissipation effect is improved and a large current can flow through the LED, increasing the light intensity. At the same time, deterioration due to heat generation can be suppressed and the life can be extended.
According to the microscope of the present invention, a light source from a plurality of LED lamps is superimposed by a rod integrator, and the intensity of the light is added to generate a uniform planar light source. Therefore, it is easy to adapt it based on a conventional microscope that is more widespread. In addition, by providing illumination switching means for switching between Kohler illumination and critical illumination, observation with a deep focal depth and observation with a shallow focal depth can be switched by a simple operation during observation.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram illustrating the principle of a lighting device according to the present invention.
FIG. 2 is a diagram showing an application example in which the illumination devices of the present invention are cascade-connected.
FIG. 3 is a configuration diagram of a first reference example of the present invention.
FIG. 4 is a diagram showing an assembled state of an LED lamp to a thermally conductive electrode substrate.
FIG. 5 is a configuration diagram showing a second reference example ;
FIG. 6 is a diagram showing an embodiment of a rod integrator.
FIG. 7 is a view showing a modification of the rod integrator.
FIG. 8 is a view showing another modification of the rod integrator.
FIG. 9 is a view showing another modification of the rod integrator.
FIG. 10 is a diagram showing an example of a point light source using a tapered rod integrator.
FIG. 11 is a diagram showing an example of a linear light source using a tapered rod integrator.
FIG. 12 is a diagram showing an embodiment of a rod integrator light receiving angle enlarging means.
FIG. 13 is a view showing a modified example of the rod integrator light receiving angle enlarging means.
FIG. 14 is a view showing a structure in which an LED is integrated with an incident end of a rod integrator by molding.
FIG. 15 is a perspective view of an LED chip integrated body.
FIG. 16 is a partial cross-sectional view of an LED chip integrated body.
FIG. 17 is a schematic diagram of a microscope employing the illumination device of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... LED lamp, 2 ... Thermally conductive electrode board, 3 ... Rod integrator, 4 ... Insulating film, 5 ... Radiator, 7 ... Wiring pattern, 10 ... LED chip, 11, 12 ... Lead frame, 30 ... Cladding body, 31 ... Core body, 32 ... Mirror, 50 ... Illumination device.

Claims (3)

A thermally conductive electrode substrate;
A plurality of LED chips are directly mounted on the thermally conductive electrode substrate and directly connected electrically and thermally, and one electrode of each LED chip is insulated from the thermally conductive electrode substrate by an insulating film. LED chip integrated body connected to the wiring pattern by bonding wires ;
A condensing lens that condenses the luminous flux from the LED chip assembly;
A rod integrator that injects the light beam collected by the condenser lens into the incident end surface, superimposes the light beams of a plurality of LED chips inside, adds light intensity, and generates a planar light source on the output end surface ;
A lighting device comprising: 2. The lighting device according to claim 1, wherein the heat dissipating means is thermally coupled to the surface of the thermally conductive electrode substrate opposite to the surface on which the LED chip is disposed . In order to increase the amount of light by cascading the illumination devices according to claim 1, the light beams emitted from the emission end surfaces of the rod integrators of the plurality of illumination devices are collected and incident on the incidence end surface of a single rod integrator, An illumination device , wherein a planar light source is generated on an emission end face of the single rod integrator .

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