JP7519738B1 - Light-emitting device - Google Patents

Abstract

[Problem] To provide a light emitting device having a sharp peak in a wavelength range sandwiching a peak wavelength. [Solution] The light emitting device comprises a plurality of solid-state light sources that emit light with different peak wavelengths and are mounted on a substrate having a wiring pattern, and a phosphor having a fluorescent substance, which is arranged in the traveling direction of the light emitted from the plurality of solid-state light sources and is transmissible through the light emitted from the plurality of solid-state light sources, a first solid-state light source of the plurality of solid-state light sources is a light source having a peak wavelength in the range of 280 nm or less, and a second solid-state light source of the plurality of solid-state light sources different from the first solid-state light source is a light source having a peak wavelength between 420 nm and 470 nm. [Selected Figure] Figure 1

Description

The present invention relates to a light-emitting device.

In recent years, there has been a growing movement to eliminate the use of mercury for environmental protection purposes, including in ultra-high pressure mercury lamps, low pressure mercury lamps, metal halide lamps, and fluorescent lamps. Even in the industrial sector, which was previously exempt from restrictions on mercury use, there is a growing movement to stop using mercury.

In addition, inspection processes that use interference fringes have been introduced into the manufacturing processes for liquid crystal panels and functional films. In inspections that use interference fringes, light sources with characteristics that have sharp peaks in the wavelength ranges that sandwich the peak wavelength are still used. For example, three-wavelength fluorescent lamps that use red, green, and blue light are used.

JP 2006-349576 A

Furthermore, recently, even the production of three-wavelength fluorescent lamps has been discontinued, and light sources combining red, green, and blue LEDs, or light sources combining red, green, and blue laser diodes, etc., are being sold as alternative light sources. However, light sources combining red, green, and blue LEDs have characteristics that are dull and broad in the wavelength range that sandwiches the peak wavelength of each LED (especially green), making it difficult to form interference fringes with clear differences in light and dark (sharp interference fringes).

On the other hand, a light source that combines red, green, and blue laser diodes has a sharp peak in the wavelength range surrounding the peak wavelength, and can also form interference fringes with clear light and dark differences. However, because it emits laser light, it requires careful handling of not only direct light but also reflected light, and its introduction requires effort, time, and cost.

The present invention has been made in consideration of the above points. Its purpose is to provide a light-emitting device that has a sharp peak in a wavelength region that includes the peak wavelength.

The light emitting device according to the present invention is characterized in that
A plurality of solid-state light sources that emit light having different peak wavelengths and are mounted on a substrate having a wiring pattern;
a phosphor having a fluorescent substance, the phosphor being disposed in a traveling direction of light emitted from the plurality of solid-state light sources and capable of transmitting the light emitted from the plurality of solid-state light sources;
a first solid-state light source among the plurality of solid-state light sources is a light source that emits light having a peak wavelength in a range of 280 nm or less, which functions as excitation light for the phosphor and is converted by the phosphor into at least red and green visible light ,
A second solid-state light source of the plurality of solid-state light sources, which is different from the first solid-state light source, is a light source that emits light having a peak wavelength between 420 nm and 470 nm .

It has a sharp peak in the wavelength range surrounding the peak wavelength.

1 is a cross-sectional view showing a configuration of a light-emitting device according to an embodiment of the present invention. 1 is a plan view showing a configuration of a light emitting device according to an embodiment of the present invention. 2 is a block diagram showing a control circuit for controlling dimming of solid-state light sources 100a and 100b. FIG. FIG. 13 is a plan view showing a configuration of a modified example of a light emitting device in which a plurality of solid-state light sources are arranged in a line. FIG. 13 is a plan view showing a configuration of a modified example of a light emitting device in which a plurality of solid-state light sources are arranged in a circle.

<<<<<Outline of the Present Invention>>>>
<<First feature>>
According to a first feature,
A plurality of solid-state light sources that emit light having different peak wavelengths and are mounted on a substrate having a wiring pattern;
a phosphor having a fluorescent substance, the phosphor being disposed in a traveling direction of light emitted from the plurality of solid-state light sources and capable of transmitting the light emitted from the plurality of solid-state light sources;
a first solid-state light source of the plurality of solid-state light sources is a light source having a peak wavelength in a range of 280 nm or less;
A light emitting device is provided, wherein a second solid-state light source of the plurality of solid-state light sources, different from the first solid-state light source, is a light source having a peak wavelength between 420 nm and 470 nm.

A light emitting device can be provided that can emit light having a peak wavelength in the range of 280 nm or less and light having a peak wavelength between 420 nm and 470 nm using a solid-state light source. Light having a peak wavelength in the range of 280 nm or less can be used as excitation light to be converted to light of another wavelength and emitted. Light having a peak wavelength between 420 nm and 470 nm can be emitted as an alternative to blue light. It can replace the 436 nm blue light that is the emission line spectrum of mercury. The spectrum of a three-wavelength fluorescent lamp can be easily reproduced using a solid-state light source.

Both the light emitted from the first solid-state light source and the light emitted from the second solid-state light source reach the phosphor. The light emitted from the first solid-state light source functions as excitation light for the phosphor. Meanwhile, the light emitted from the second solid-state light source simply passes through the phosphor. The light-emitting device includes a light source that emits light to be converted into excitation light by the phosphor, and a light source that emits light that is simply passed through without being converted into excitation light. In this way, by emitting both excitation light and direct light from the light source, it is possible to provide a light-emitting device that efficiently emits light in a wide wavelength range with a simple configuration.

<<Second feature>>
A second feature is the first feature,
The phosphor contains a phosphor that emits green light and red light using light having a wavelength of at least 200 nm or more and 280 nm or less as excitation light. By setting the excitation light range to 200 nm or more and 280 nm or less, phosphors for general fluorescent lamps can be efficiently excited.

<<Third feature>>
A third feature, in the first feature, is
The phosphor contains a phosphor that emits blue light, green light, and red light using light having a wavelength of at least 200 nm or more and 280 nm or less as excitation light. By setting the excitation light range to 200 nm or more and 280 nm or less, general fluorescent lamp phosphors can be efficiently excited. In addition, since the phosphor emits not only green light and red light but also blue light, it can supplement or enhance the light emitted from the second solid-state light source.

<<Fourth feature>>
A fourth feature is the first feature,
The light-transmitting element may further include a light-transmitting element that is disposed between the solid-state light source and the phosphor and does not transmit light of 300 nm or less.

It can prevent unwanted light from being emitted.

<<Fifth feature>>
A fifth feature, in the first feature, is
At least one of the plurality of solid-state light sources is a light-emitting diode (LED).

<<Sixth Feature>>
A sixth feature, in the first feature, is
At least one of the solid-state light sources is a laser diode.

<<Seventh Feature>>
A seventh feature, in the first feature, is
the first solid-state light source is a deep ultraviolet light source and the second solid-state light source is a blue light source;
The light source device further includes a control unit that controls dimming of the first solid-state light source and dimming of the second solid-state light source independently of each other.

The balance between the brightness of the light emitted from the first solid-state light source and the brightness of the light emitted from the second solid-state light source can be adjusted. For example, the brightness of the light emitted from the first solid-state light source and the brightness of the light emitted from the second solid-state light source can be made uniform.

<<<<<Details of this embodiment>>>>
Hereinafter, an embodiment will be described with reference to the drawings.

<<<Light-emitting device 10>>>
Fig. 1 is a cross-sectional view showing the configuration of a light emitting device 10 according to the present embodiment. Fig. 2 is a plan view showing the configuration of the light emitting device according to the present embodiment.

The light emitting device 10 mainly includes a solid-state light source 100 (solid-state light sources 100a and 100b), a substrate 140, a phosphor 160, a light-transmitting member 180, and a wall body 190.

<<Solid-state light source 100 (solid-state light sources 100a and 100b)>>
When power is supplied to the solid-state light source 100, the solid-state light source 100 emits light having a wavelength in a range including a predetermined peak wavelength. The solid-state light source 100 can be, for example, an LED or a laser diode. The solid-state light source 100 includes solid-state light sources 100a and 100b. The solid-state light source 100a emits light having a peak wavelength in a range of 280 nm or less. The solid-state light source 100b emits light having a peak wavelength between 420 nm and 470 nm. In the following description, when the solid-state light sources 100a and 100b are not distinguished from each other or cannot be distinguished from each other, they will be simply referred to as the solid-state light source 100.

The solid-state light sources 100a and 100b are both disposed on the surface 142 of the substrate 140. The solid-state light sources 100a and 100b are disposed at fixed positions different from each other. The solid-state light sources 100a and 100b are disposed at a distance d apart. The solid-state light sources 100a and 100b are disposed so that their optical axes are parallel.

The solid-state light source 100a has a light-emitting unit 102a that emits light having a peak wavelength in the range of 280 nm or less. The solid-state light source 100a is configured with a surface-mount package (SMD package). The solid-state light source 100b has a light-emitting unit 102b that emits light having a peak wavelength between 420 nm and 470 nm. The solid-state light source 100b is configured with a chip-on-board substrate (COB substrate) or a surface-mount package (SMD package). The light-emitting units 102a and 102b have LED chips or laser diode chips.

The light emitting surfaces (not shown) of the light emitting units 102a and 102b are positioned with their backs to the substrate 140. The light emitted from the light emitting units 102a and 102b travels in a direction away from the substrate 140 toward the phosphor 160 and the light transmitting member 180. The solid-state light source 100a has an electrode (not shown) and is electrically connected to the light emitting unit 102a. The solid-state light source 100b has an electrode (not shown) and is electrically connected to the light emitting unit 102b. The electrodes of the solid-state light sources 100a and 100b are further electrically connected to a wiring pattern formed on the substrate 140. The solid-state light sources 100a and 100b are supplied with power via a wiring pattern (not shown) formed on the substrate 140.

<<Substrate 140>>
In this embodiment, the substrate 140 is a substantially flat (thin) member. The substrate 140 extends in a plane. The substrate 140 has a size that allows the solid-state light sources 100a and 100b to be arranged side by side.

For heat dissipation, the substrate 140 is preferably made of a material with high thermal conductivity, for example, a metal such as an aluminum substrate. However, the substrate 140 is not limited to this and may be made of resin, ceramics, etc.

The substrate 140 has a surface 142 and a back surface 144 opposite the surface 142. The surface 142 faces the phosphor 160 and the light transmitting member 180. A wiring pattern (not shown) is formed on the surface 142 or the back surface 144. The wiring pattern is a conductor for supplying power to the solid-state light source 100. Note that, instead of forming a wiring pattern on the surface 142 or the back surface 144 of the substrate 140, power may be supplied to the solid-state light source 100 by connecting a lead wire or the like.

<<Phosphor 160>>
The phosphor 160 is disposed at a position spaced apart from the solid-state light source 100. Specifically, the phosphor 160 is formed by being applied to the lower surface 182 of the light-transmitting member 180. The phosphor 160 has a flat film-like shape. The light-transmitting member 180 is disposed parallel to the substrate 140, and the phosphor 160 is also disposed parallel to the substrate 140. The phosphor 160 is provided so as to cover the solid-state light source 100.

The phosphor 160 is disposed facing the light emitting portions 102a and 102b of the solid-state light source 100. The phosphor 160 is large enough to cover both the solid-state light sources 100a and 100b. The optical axes of the solid-state light sources 100a and 100b extend perpendicular to the plane in which the phosphor 160 extends. The light emitted from the solid-state light source 100 travels toward the phosphor 160 and illuminates the entire surface of the phosphor 160.

<Fluorescent particles>
The phosphor 160 includes phosphor particles (not shown) that are a fluorescent material. The phosphor particles are excited by light having a predetermined peak wavelength and emit light with a longer wavelength than the peak wavelength (in other words, light close to infrared light).

The solid-state light source 100a emits light with a peak wavelength in the range of 280 nm or less. The light emitted from the solid-state light source 100a is used as excitation light, and the excited fluorescent particles are converted to long-wavelength light and emitted. In this embodiment, the same fluorescent particles as those used in wavelength fluorescent lamps are used. Specifically, Tokyo Chemical Laboratory's red phosphor "YOX", green phosphor "CAT", blue phosphor "BAM", etc. can be used.

The phosphor 160 uses the light emitted from the solid-state light source 100a as excitation light and contains fluorescent particles that emit green visible light, fluorescent particles that emit red visible light, and fluorescent particles that emit blue visible light.

The phosphor 160 may contain phosphor particles that emit green visible light and phosphor particles that emit red visible light using the light emitted from the solid-state light source 100a as excitation light. The type of phosphor particles contained in the phosphor 160 may be determined appropriately according to the wavelength of the light emitted from the solid-state light source 100a and the wavelength of the light converted by the phosphor particles.

Even when using a solid-state light source, the spectrum of a three-wavelength fluorescent lamp can be reproduced almost perfectly by using the same phosphor as that used in fluorescent lamps.

<<Light transmitting member 180>>
The light transmitting member 180 is disposed at a distance of a height h from the substrate 140. The light transmitting member 180 has a flat thin plate shape. The light transmitting member 180 is disposed parallel to the substrate 140. The light transmitting member 180 has a lower surface 182 and an upper surface 184. The phosphor 160 is applied to the lower surface 182.

The light-transmitting member 180 does not transmit light of 300 nm or less. In other words, a material that does not transmit light of 300 nm or less is used for the light-transmitting member 180. Specifically, a float glass plate or glass with a long-pass filter is used for the light-transmitting member 180.

The light that passes through the phosphor 160 immediately enters the lower surface 182 of the light-transmitting member 180, where light of 300 nm or less is attenuated, and only light of wavelengths longer than 300 nm is emitted from the upper surface 184. With this configuration, light with a peak wavelength of 280 nm, which is harmful to the human body and is used to excite the phosphor 160, is not emitted from the light-emitting device 10. It is possible to provide a light-emitting device that emits light with a spectrum roughly equivalent to that of a three-wavelength fluorescent lamp, while blocking light around 280 nm that is harmful to the human body, without using mercury.

Since the light that has passed through the phosphor 160 immediately enters the lower surface 182, all of the light that has passed through the phosphor 160 can be guided to the light-transmitting member 180. In this way, it is possible to prevent light from leaking to the outside from the light-emitting device 10 through the gap between the phosphor 160 and the light-transmitting member 180.

<<Wall body 190>>
The wall 190 stands along a direction away from the surface 142 of the substrate 140. The wall 190 has a lower end 192 and an upper end 194. The surface 142 of the substrate 140 is positioned at the lower end 192 of the wall 190. More specifically, the wall 190 stands around the periphery of the surface 142 of the substrate 140. The phosphor 160 is positioned at the upper end 194 of the wall 190.

The wall 190 is made of a non-conductive and non-translucent material. By providing the wall 190, it is possible to prevent the light emitted from the solid-state light source 100 from leaking out of the light-emitting device 10. The wall 190 may be formed integrally with the substrate 140 or may be formed separately.

The inner surface of the wall 190 may be made of a material that reflects light. In this way, the light emitted from the solid-state light source 100 can be actively guided to the phosphor 160 and the light-transmitting member 180, allowing for effective use.

The wall 190 allows a certain gap h to be formed between the substrate 140 and the phosphor 160. The gap h can be appropriately determined according to the light distribution characteristics of the solid-state light sources 100a and 100b, the distance d between the solid-state light sources 100a and 100b, and the like. The gap h can be determined so that the light emitted from the solid-state light source 100 illuminates the entire surface of the phosphor 160.

<<<<Dimming Control of Solid-State Light Sources 100a and 100b>>>
FIG. 3 is a block diagram showing a control circuit for controlling the dimming of the solid-state light sources 100a and 100b.

The control circuit mainly includes a power supply unit, constant current circuits 110a and 110b, and a control unit 120.

<<Power supply>>
The power supply device has a power supply unit (not shown). The power supply unit supplies a power supply voltage to the solid-state light sources 100a and 100b. The power supply unit mainly has a switching power supply (not shown) or the like, and rectifies power from a commercial power supply to output a constant DC power supply voltage. The power supply unit may have a switching power supply or a linear power supply. It is sufficient for the power supply unit to supply a constant power supply voltage to the solid-state light sources 100a and 100b. Furthermore, a constant voltage circuit (not shown) having a DC/DC converter or the like may be configured to supply a stable constant voltage power supply to the solid-state light sources 100a and 100b.

<<Control Unit 120>>
The control unit 120 mainly includes a processor (such as a CPU (Central Processing Unit)), a ROM (Read Only Memory), a RAM (Random Access Memory), a communication interface, and the like (not shown).

The control unit 120 outputs dimming value signals a and b to the constant current circuits 110a and 110b to instruct the dimming (brightness) of the solid-state light sources 100a and 100b. The solid-state light sources 100a and 100b emit light with a brightness according to the dimming value.

The control unit 120 stores a dimming value indicating the dimming of the solid-state light sources 100a and 100b. The dimming value is determined by a preliminary experiment or the like and is stored in advance in a ROM, a RAM, or the like. The present invention is not limited to this, and the dimming value may be appropriately supplied to the control unit 120 by an operation by an operator or an instruction signal from an external control device (not shown) while the light-emitting device 10 is in operation.

<<Constant current circuits 110a and 110b>>
The constant current circuits 110a and 110b supply a constant current to the solid-state light sources 100a and 100b.

The constant current circuits 110a and 110b mainly include an operational amplifier and a FET (field-effect transistor) (not shown). Note that instead of a FET, other current amplification elements that control the current may be used. The constant current circuits 110a and 110b may be of the so-called sink type.

The dimming value signal a output from the control unit 120 is supplied to the constant current circuit 110a, and the dimming value signal b is supplied to the constant current circuit 110b. The constant current circuit 110a generates a constant current according to the dimming value indicated by the dimming value signal a and supplies it to the solid-state light source 100a. The constant current circuit 110b generates a constant current according to the dimming value indicated by the dimming value signal b and supplies it to the solid-state light source 100b.

As mentioned above, the dimming value is a value for specifying the brightness of the light emitted from the solid-state light sources 100a and 100b. If the dimming value is small, the current value flowing through the solid-state light sources 100a and 100b is also small, and the solid-state light sources 100a and 100b emit dimmer light. On the other hand, if the dimming value is large, the current value flowing through the solid-state light sources 100a and 100b is also large, and the solid-state light sources 100a and 100b emit brighter light.

The dimming values of both solid-state light source 100a and solid-state light source 100b can be determined so that the light emitted from light-emitting device 10 has a spectral distribution suitable for inspection to detect defects, etc., and a balance can be achieved between the brightness of the light emitted from solid-state light source 100a and the brightness of the light emitted from solid-state light source 100b. As described above, the dimming value can be determined by a preliminary experiment or the like, or can be adjusted as appropriate while light-emitting device 10 is in operation.

In addition, in the case of so-called pulse lighting, in which the solid-state light source 100a is repeatedly turned on and off at predetermined intervals, it is necessary to synchronize the timing of turning the solid-state light source 100a on or off with the timing of turning the solid-state light source 100b on or off. The processor of the control unit 120 can appropriately adjust the timing of outputting the dimming value signal a and the timing of outputting the dimming value signal b according to the intensity and wavelength distribution of the light emitted by the solid-state light source 100a and the intensity and wavelength distribution of the light emitted by the solid-state light source 100b. The solid-state light sources 100a and 100b can be made to emit light simultaneously, or one can be made to emit light with a delay or advancement relative to the other.

<<<Modification 1>>>
4 is a plan view showing a configuration of a modified example of a light emitting device in which a plurality of solid-state light sources 100a and 100b are arranged in a line. By arranging the solid-state light sources 100a and 100b in the longitudinal direction, a light source equivalent to a long fluorescent lamp can be provided.

<<<Modification 2>>>
5 is a plan view showing the configuration of a modified example of a light emitting device in which a plurality of solid-state light sources 100a and 100b are arranged in a circle. By arranging the solid-state light sources 100a and 100b in a circle, it becomes possible to illuminate and inspect objects of shapes that were difficult to inspect with conventional integrally formed fluorescent lamps. Note that the arrangement is not limited to a circle, and may be an ellipse, an oval, a rectangle, a zigzag, a lattice, or any other suitable shape depending on the shape of the object to be inspected.

<<<Modification 3>>>
The wavelength of the light emitted from the solid-state light sources 100a and 100b is not limited to the above, but may be any wavelength that can function as excitation light for conversion to a desired wavelength by the phosphor 160, and may be appropriately determined depending on the characteristics of the phosphor 160. The packages of the solid-state light sources 100a and 100b are not limited to the above, but may be appropriately selected depending on the brightness, heat dissipation performance, and the like.

The solid-state light source 100 may include not only solid-state light sources 100a and 100b but also other solid-state light sources.

The light-emitting device 10 shown in Figs. 1 and 2 has one each of solid-state light sources 100a and 100b. This is not limiting, and the number of solid-state light sources 100a and 100b may be multiple. Furthermore, the number of solid-state light sources 100a and the number of solid-state light sources 100b do not have to be the same.

<<<<<Scope of the embodiment>>>>
As described above, the present embodiment has been described. However, the description and drawings forming a part of this disclosure should not be understood as being limiting. Various embodiments not described here are included.

To provide a light-emitting device that emits light with a spectrum roughly equivalent to that of a three-wavelength fluorescent lamp without using mercury.

REFERENCE SIGNS LIST 10, 20, 30 Light emitting device 100, 100a, 100b Solid-state light source 140 Substrate 160 Phosphor 180 Light-transmitting member 190 Wall

Claims (7)

A plurality of solid-state light sources that emit light having different peak wavelengths and are mounted on a substrate having a wiring pattern;
a phosphor having a fluorescent substance, the phosphor being disposed in a traveling direction of light emitted from the plurality of solid-state light sources and capable of transmitting the light emitted from the plurality of solid-state light sources;
a first solid-state light source among the plurality of solid-state light sources is a light source that emits light having a peak wavelength in a range of 280 nm or less, which functions as excitation light for the phosphor and is converted by the phosphor into at least red and green visible light ,
A light emitting device, wherein a second solid-state light source of the plurality of solid-state light sources, which is different from the first solid-state light source, is a light source that emits light having a peak wavelength between 420 nm and 470 nm. The light-emitting device according to claim 1, wherein the phosphor contains a phosphor material that emits green light and red light using light having a wavelength of at least 200 nm and no more than 280 nm as excitation light. The light-emitting device according to claim 1, wherein the phosphor contains a fluorescent substance that emits blue light, green light, and red light using light having a wavelength of at least 200 nm and no more than 280 nm as excitation light. The light-emitting device according to claim 1, further comprising a light-transmitting member disposed between the solid-state light source and the phosphor, the light-transmitting member not transmitting light of 300 nm or less. The light emitting device according to claim 1, wherein at least one of the plurality of solid-state light sources is an LED. The light emitting device according to claim 1, wherein at least one of the plurality of solid-state light sources is a laser diode. the first solid-state light source is a deep ultraviolet light source and the second solid-state light source is a blue light source;
The light emitting device according to claim 1 , further comprising a control unit configured to control dimming of the first solid-state light source and dimming of the second solid-state light source independently of each other.