JP2019186139A - Illuminating device - Google Patents

Abstract

To obtain an illuminating device that is compact as a whole and restrains a deterioration in brightness.SOLUTION: An illuminating device comprises a laser light source for emitting light, a condenser lens for condensing the light emitted from the laser light source, a rod integrator for multiply reflecting and emitting the light condensed by the condenser lens, a phosphor for using a portion of the light incident from the rod integrator as excitation light and emitting the light, and an illuminating lens for controlling the distribution of the light emitted from the phosphor.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an illumination device having a laser light source.

  2. Description of the Related Art Conventionally, illumination apparatuses that use laser light include an illumination apparatus that includes a phosphor composed of a fluorescent member that emits laser light as excitation light. Laser light is light having a sharp peak in the light density distribution, and the portion with high light density has high energy density. For this reason, in a lighting device equipped with a phosphor, if the phosphor is continuously irradiated with the laser light, phosphor particles contained in the phosphor deteriorate. In the lighting device in which the phosphor particles are deteriorated, there is a problem that sufficient brightness cannot be obtained and the lifetime of the lighting device is shortened.

  In order to solve this problem, there has been proposed an illumination device that rotates a phosphor and prevents laser light from continuing to irradiate only a specific region of the phosphor (see, for example, Patent Document 1).

JP 2013-37867 A

  Since the illumination device disclosed in Patent Document 1 needs to be provided with a rotation mechanism for rotating the phosphor, the illumination device becomes complicated and large.

  The present invention has been made in order to solve the above-described problems, and provides an illuminating device in which the entire device is small and brightness deterioration is suppressed.

  The illumination device according to the present invention includes a laser light source that emits light, a condensing lens that condenses the light emitted from the laser light source, and a rod that multiple-reflects and emits the light collected by the condensing lens. An integrator; a phosphor that emits light using part of light incident from the rod integrator as excitation light; and an illumination lens that controls light distribution of the light emitted from the phosphor.

  According to the present invention, the amount of light is optimally adjusted by multiple reflection of light in the rod integrator, and the light density distribution at the condensing point on the incident surface of the phosphor is lower than the value that deteriorates the phosphor, and is uniform. Distribution. Therefore, the entire apparatus is small, and brightness deterioration due to phosphor deterioration can be suppressed.

It is a side view which shows the example of 1 structure of the illuminating device which concerns on Embodiment 1 of this invention. It is an external appearance perspective view which shows the entrance plane side of the rod integrator shown in FIG. It is an external appearance perspective view which shows the output surface side of the rod integrator shown in FIG. It is a side perspective view for demonstrating the effect | action of the rod integrator shown in FIG. It is a figure which shows the light density distribution in the entrance plane of the rod integrator shown in FIG. It is a figure which shows the light density distribution in the output surface of the rod integrator shown in FIG. It is a figure which shows the example of 1 structure of the illuminating device of a comparative example. It is a figure which shows the light density distribution in the entrance plane of the fluorescent substance shown in FIG. It is a figure which shows the light density distribution in the entrance plane of the fluorescent substance shown in FIG.

Embodiment 1 FIG.
(Configuration of lighting device)
A configuration of the lighting apparatus according to the first embodiment will be described with reference to the drawings. In the drawings to be referred, for convenience of explanation, three axes of the X axis, the Y axis, and the Z axis are indicated by arrows in order to specify the direction. FIG. 1 is a side view showing a configuration example of a lighting apparatus according to Embodiment 1 of the present invention.

  The illumination device 10 includes a laser light source 1, a phosphor 2, a condenser lens 3, an illumination lens 4, and a rod integrator 5. A laser light source 1, a condenser lens 3, a rod integrator 5, a phosphor 2 and an illumination lens 4 are disposed along the optical axis OAX. The rod integrator 5 is installed between the condenser lens 3 and the phosphor 2.

  The laser light source 1 is a semiconductor laser light source. The laser light source 1 is, for example, a blue semiconductor laser light source that emits blue laser light. The condensing lens 3 condenses the light emitted from the laser light source 1 on the incident surface of the rod integrator 5. The condensing lens 3 is disposed so that the focal point is located on the incident surface of the rod integrator 5.

  The rod integrator 5 equalizes the light density distribution of the light incident from the condenser lens 3 and emits it to the phosphor 2. The phosphor 2 transmits a part of the light incident from the laser light source 1 and absorbs the non-transmitted light as excitation light to emit light. For example, the phosphor 2 is excited by light incident from the laser light source 1 and generates yellow fluorescence. The phosphor 2 is disposed in the immediate vicinity of the light exit surface of the rod integrator 5 so that the light entrance surface is located on the light exit surface of the rod integrator 5. For example, the incident surface of the phosphor 2 may be in contact with the exit surface of the rod integrator 5. The illumination lens 4 controls the light distribution by combining the yellow fluorescence excited by the phosphor 2 and the light transmitted through the phosphor 2 without being absorbed by the phosphor 2.

  2 and 3 are diagrams showing a configuration example of the rod integrator shown in FIG. FIG. 2 is an external perspective view showing an incident surface side of the rod integrator shown in FIG. FIG. 3 is an external perspective view showing the exit surface side of the rod integrator shown in FIG.

  As shown in FIGS. 2 and 3, the rod integrator 5 is a pipe-like element including a casing 51 having a square cross section perpendicular to the optical axis OAX shown in FIG. 1. The length of each side of the square of the cross-sectional shape of the housing 51 is set so that the area of the incident surface 56 of the rod integrator 5 is equal to the area of the condensing spot by the condensing lens 3. Therefore, the laser light emitted from the laser light source 1 enters the rod integrator 5 at a rate close to 100%.

  As shown in FIG. 2, four reflecting plates 55 that reflect light are provided on the inner wall of the casing 51. Specifically, since the casing 51 shown in FIG. 2 is a rectangular parallelepiped, two combinations of two reflecting plates 55 facing each other in parallel are provided on the inner wall of the casing 51. The reflection plate 55 is, for example, a mirror. As shown in FIG. 3, a light shielding plate 54 is provided on the light exit surface 52 of the rod integrator 5. The light shielding plate 54 has a circular opening 53 inscribed in a square having a cross-sectional shape. The light incident from the incident surface 56 shown in FIG. 3 is multiple-reflected by the reflection plate 55 in the casing 51 and then exits from the opening 53 of the exit surface 52 shown in FIG.

  In the first embodiment, the case where the cross-sectional shape of the casing 51 of the rod integrator 5 is a square has been described with reference to FIGS. 2 and 3, but the cross-sectional shape is not limited to a square. The cross-sectional shape of the housing 51 may be a rectangle including a square and a rectangle. Moreover, the cross-sectional shape of the housing | casing 51 is not restricted to a rectangle, The rod integrator 5 should just be the structure which can carry out multiple reflection of the light in a reflective surface.

(Operation of lighting device)
Next, the operation of the lighting apparatus 10 according to the first embodiment will be described with reference to FIG. When the laser light is incident on the condenser lens 3 from the laser light source 1, the condenser lens 3 condenses the incident laser light on the incident surface 56 of the rod integrator 5. The light that has entered the rod integrator 5 propagates while being multiple-reflected by the reflector 55 provided on the inner wall of the rod integrator 5.

  Here, the operation of the rod integrator 5 will be described with reference to FIGS. FIG. 4 is a side perspective view for explaining the operation of the rod integrator shown in FIG. FIG. 5 is a diagram showing a light density distribution on the entrance surface of the rod integrator shown in FIG. FIG. 6 is a diagram showing a light density distribution on the exit surface of the rod integrator shown in FIG.

  As described with reference to FIGS. 2 and 3, the rod integrator 5 includes a casing 51 having a square cross-sectional shape, and a pipe-shaped element in which a reflection surface composed of the reflection plate 55 is formed on the inner wall. It is. Therefore, the light incident on the rod integrator 5 propagates through the rod integrator 5 while being repeatedly reflected on the inner wall surface of the rod integrator 5, as shown in FIG. The light propagating through the rod integrator 5 becomes a light beam having a uniform light density distribution near the emission surface 52 due to the superposition effect due to multiple reflection. When the light beam having a uniform light density distribution passes through the opening 53 of the light shielding plate 54 provided on the emission surface 52, the light beam has a circular cross-sectional shape and is reflected on the phosphor 2 positioned in the immediate vicinity of the emission surface 52. Incident.

  The phosphor deterioration threshold value Dth shown in FIG. 5 and FIG. 6 is a threshold value that is a criterion for determining whether or not the phosphor 2 is deteriorated with respect to the light density. The light density distribution on the incident surface 56 is represented by a parabola having a sharp peak, as shown in FIG. In the light density distribution shown in FIG. 5, the peak value is larger than the phosphor deterioration threshold value Dth. On the other hand, as shown in FIG. 6, the light density distribution on the exit surface 52 is uniform with a flat top and a cylindrical top hat shape. The light density distribution on the emission surface 52 has a maximum value lower than the phosphor deterioration threshold value Dth.

  The rod integrator 5 has an effect of converting light having a non-uniform light density distribution into a uniform light beam having a top hat-like light density distribution. Further, the circular opening 53 of the light shielding plate 54 converts the cross-sectional shape of the light beam emitted from the rod integrator 5 from a rectangle to a circle. The effect when the cross-sectional shape of the emitted light beam is circular will be described. When the phosphor 2 is irradiated with light while the cross-sectional shape of the light beam is rectangular, the axial symmetry of light emission is lost in the phosphor 2. In this case, the light beam after exiting the illumination lens 4 also loses its axial symmetry and anisotropy occurs in the illumination. In contrast, the circular opening 53 of the light shielding plate 54 converts the cross-sectional shape of the light beam from a rectangle to a circle, thereby preventing anisotropy in illumination. “Anisotropy occurs in illumination” means that the gloss of the same object illuminated by illumination varies depending on the viewing direction.

  Due to the above-described action, the light incident on the rod integrator 5 propagates through the rod integrator 5 to become a light flux having a uniform light density distribution, and passes through the opening 53 of the light shielding plate 54 so that the cross-sectional shape is circular. It is converted into a light beam and irradiated onto the phosphor 2.

  In FIG. 1, a part of the light incident on the phosphor 2 from the rod integrator 5 is absorbed by the phosphor 2 as excitation light, causing the phosphor 2 to emit yellow light. On the other hand, of the light incident on the phosphor 2, the light that is not absorbed by the phosphor 2 passes through the phosphor 2. Light transmitted through the phosphor 2 and yellow light emission generated by the phosphor 2 are mixed and emitted from the phosphor 2 to the outside. The light emitted from the phosphor 2 is mixed with laser light and yellow fluorescence to become white light. The white light emitted from the phosphor 2 is controlled in light distribution by the illumination lens 4 and is emitted outside the illumination device 10 as illumination light.

  Next, the illuminating device 10 of this Embodiment 1 is demonstrated in contrast with the illuminating device of a comparative example. FIG. 7 is a diagram illustrating a configuration example of a lighting device of a comparative example. About the illuminating device 100 of a comparative example, the same code | symbol is attached | subjected to the structure same as the structure shown in FIG. 1, and the detailed description is abbreviate | omitted.

  As illustrated in FIG. 7, the illumination device 100 of the comparative example does not include the rod integrator 5 in the configuration illustrated in FIG. 1. In the case of the illumination device 100, the condenser lens 3 condenses the laser light emitted from the laser light source 1 directly on the incident surface of the phosphor 2.

  FIG. 8 is a diagram showing a light density distribution on the incident surface of the phosphor shown in FIG. FIG. 9 is a diagram showing a light density distribution on the incident surface of the phosphor shown in FIG. For comparison, FIGS. 8 and 9 show the effective irradiation area Var and the phosphor deterioration threshold value Dth. The effective irradiation area Var is a region that is incident on the phosphor 2 among regions where the phosphor 2 is irradiated with light.

  In the case of the illumination device 100 of the comparative example, the condensing point on the incident surface of the phosphor 2 exhibits a light density distribution having a sharp peak in the effective irradiation area Var as shown in FIG. In the phosphor 2, degradation of the phosphor 2 does not occur in a region other than the effective irradiation area Var, but the phosphor 2 is degraded in the sharp peak portion because the light density is larger than the phosphor degradation threshold Dth. . As a result, the brightness emitted from the illumination lens 4 is deteriorated.

  On the other hand, as shown in FIG. 9, in the illumination device 10 of the first embodiment, the light density distribution at the condensing point on the incident surface of the phosphor 2 becomes uniform within the effective irradiation area Var, and the top It has a hat-like distribution. In FIG. 9, for reference, the light density distribution on the incident surface of the phosphor 2 in the comparative example is indicated by a dotted line.

  Here, “a uniform top-hat light density distribution within the effective irradiation area Var” means that the center of the light density distribution is lower than the phosphor deterioration threshold Dth as shown in FIG. This means that the distribution is close to the light density at the center from the center to the periphery. In addition, an ideal light density distribution at the focal point of the incident surface of the phosphor 2 will be described with reference to FIG. 9 in a shape approximate to a cylinder surrounded by the effective irradiation area Var and the phosphor deterioration threshold Dth. The light density distribution is such that the height of the cylinder is lower than the phosphor deterioration threshold value Dth.

  As shown in FIG. 9, the light density distribution of the light irradiated onto the phosphor 2 of the illumination device 10 is different from the light intensity distribution having a sharp peak as shown in FIG. 8, and is a portion higher than the phosphor deterioration threshold Dth. There is no. Therefore, in this Embodiment 1, deterioration of the fluorescent substance 2 can be suppressed. As a result, it is possible to suppress the deterioration of brightness in the light emitted from the illumination lens 4. Moreover, in the illuminating device 10 of this Embodiment 1, the density distribution of the light irradiated to the fluorescent substance 2 is a top hat-shaped uniform distribution. Therefore, in the first embodiment, the effective irradiation area Var of the phosphor 2 can be efficiently irradiated with light.

  As described above, in the illumination device 10 according to the first embodiment, the condensing lens 3 condenses between the condensing lens 3 that condenses the light emitted from the laser light source 1 and the phosphor 2. It has a rod integrator 5 that emits light by multiple reflection.

  In the first embodiment, the amount of light is optimally adjusted by multiple reflection of light in the rod integrator 5 provided between the condenser lens 3 and the phosphor 2, and the condensing point on the incident surface of the phosphor 2. The light density distribution at is lower than the phosphor deterioration threshold value Dth and becomes a uniform distribution. Therefore, not only can the deterioration of the phosphor 2 be suppressed, but the phosphor 2 can be efficiently irradiated with light. In addition, the illumination device 10 according to the first embodiment can reduce the size of the entire device as compared with the case where the rotation mechanism of the phosphor 2 is provided, and can suppress brightness degradation due to phosphor degradation with a simple configuration.

  In the first embodiment, the rod integrator 5 has been described as a hollow element in which a mirror is provided on the inner wall of the casing 51. However, light propagates through the interior by total reflection, such as a square glass rod. An element in which a transparent solid member is provided in the housing 51 may be used. In this case, since the light is totally reflected inside the glass and propagates, no light absorption loss occurs on the reflecting surface, and the light efficiency can be further increased.

  DESCRIPTION OF SYMBOLS 1 Laser light source, 2 Phosphor, 3 Condensing lens, 4 Illumination lens, 5 Rod integrator, 10 Illumination device, 51 Case, 52 Output surface, 53 Opening part, 54 Light-shielding plate, 55 Reflection plate, 56 Incidence surface, 100 Lighting device.

Claims (3)

A laser light source that emits light;
A condensing lens for condensing light emitted from the laser light source;
A rod integrator that multiple-reflects and emits the light collected by the condenser lens; and
A phosphor that emits light by using a part of light incident from the rod integrator as excitation light;
An illumination lens for controlling the light distribution of the light emitted from the phosphor;
A lighting device. The rod integrator is
A casing whose surface perpendicular to the optical axis is rectangular;
A reflector provided on the inner wall of the housing;
A light shielding plate provided on the light exit surface of the housing and having a circular opening;
The lighting device according to claim 1, comprising: The rod integrator is
A casing whose surface perpendicular to the optical axis is rectangular;
A solid member provided in the housing, in which incident light propagates by total reflection;
A light shielding plate provided on the light exit surface of the housing and having a circular opening;
The lighting device according to claim 1, comprising:

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