JP2019095366A - Light guide body unit and light sensor - Google Patents

Abstract

To provide a light guide body unit for a sensor and a light sensor, capable of improving detection accuracy of light reflected from an object to be detected.SOLUTION: A light guide body unit 1 for a sensor has a light guide body 10 which includes: a light emitting region 10a where a light emitting element is installed; and a light receiving region 10b where a light receiving element is installed. In the light guide body unit, detection light emphasizing means is provided, by which light is made to enter the light receiving region 10b from the light emitting region 10a and also enter the light receiving region 10b by being reflected against light intensity detected by the light receiving element from the object to be detected and the light intensity detected by the light receiving element is relatively improved.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a sensor light guide unit and an optical sensor including the light guide unit.

  2. Description of the Related Art Conventionally, liquid crystal displays have been used, for example, in central information displays (CIDs) of automobiles and car navigation systems. These liquid crystal display devices may be provided with a sensor for activating a display function when a finger of a person approaches the display surface to operate a touch panel or the like provided in the liquid crystal display device. When the sensor detects a human finger, display of a hidden display unit is activated in a pause state such as screen display or an icon or a touch button.

  For example, Patent Document 1 describes a display device provided with a backlight device provided with an infrared sensor function. The backlight device includes an infrared light emitting element and an infrared light receiving element, and infrared light emitted from the light emitting element is incident on the light guide plate of the backlight device and is irradiated to the outside from the infrared transmitting region of the display panel. The infrared light reflected by the detection subject, incident on the light guide plate and guided to the light receiving element is received.

JP, 2015-225423, A

    However, in the structure of the conventional infrared sensor as described in Patent Document 1, in addition to the infrared light reflected by the detection target, a part of the infrared light emitted from the light emitting element is a light guide Directly to the light receiving element. In this case, there is a problem that the light reaching the light receiving element becomes noise to lower the detection accuracy of the sensor. In particular, when there is a restriction in the arrangement of the light source or the base, as in a display device for vehicles, this problem is significant because the light guide needs to be enlarged.

    The present invention is a light guide unit for a sensor that can reduce noise and improve detection accuracy of an infrared sensor when guiding reflected light from a detection target to a light receiving element, and such a light guide unit It aims at providing an infrared sensor provided with.

The sensor light guide unit of the present invention is
A light emitting region in which a light emitting element is installed;
And a light guide including a light receiving area in which the light receiving element is installed,
The light from the light emitting area enters the light receiving area, and the light intensity detected by the light receiving element is reflected from the object to be detected and enters the light receiving area, and the light intensity detected by the light receiving element A sensor light guiding unit provided with detection light emphasizing means for relatively improving

  According to the sensor light guide unit, the light emitted from the light emitting element by the detection light emphasizing means is prevented or suppressed from being guided in the light guide and incident on the light receiving area, or the detected light The detection efficiency of the sensor can be improved by improving the detection intensity of the reflected light from the body.

In the sensor light guide unit,
While the said light emission area | region is equipped with the light emission part in which the installation location of the light emitting element was provided,
The detection light emphasizing unit further includes a wedge-shaped portion located closer to the light receiving area than the light output portion,
In the wedge-shaped portion, the distance between the outer end surface of the light guide and the inner end surface opposite to the light guide surface, which becomes the light irradiation surface to the outside of the light guide, becomes gradually smaller from the light output portion side Thus, the outer end surface and the inner end surface may be inclined to each other.

  According to the sensor light guide unit, in the wedge-shaped portion, the reflection angle of light multiply reflected between the outer end face and the inner end face of the light guide is gradually changed to emit light from the outer end face As a result, it is possible to improve the light emission property of the light from the irradiation surface, to suppress the light incidence to the light receiving area, and to improve the detection efficiency of the sensor.

  In the sensor light guide unit, at least one of the outer end surface and the inner end surface of the wedge-shaped portion may form an inclined surface which is inclined with respect to the outer end surface of the light receiving area.

  In the sensor light guide unit, the detection light emphasizing means includes a light collecting part whose width is narrowed from the base end to the tip as the detection light emphasizing means, and the installation place of the light receiving element is the light collecting part It may be provided at the tip of the light portion.

  According to the sensor light guide unit, the detection light reflected from the object to be detected and entering the light receiving area is condensed at the light collecting portion, and the intensity when detected by the light receiving element is improved. The detection light rate of the sensor can be improved.

  The sensor light guide unit may further include a light absorbing member disposed at least on the inner end face side of the light receiving area as the detection light emphasizing means.

  According to the sensor light guide unit, light which has entered the light receiving area from the light emitting area is attenuated by the light absorbing member in the process of multiple reflection, and the detection efficiency of the sensor is improved.

  An optical sensor according to the present invention is an optical sensor including the sensor light guide unit, a light emitting element provided in the light emitting area, and a light receiving element provided in the light receiving area. Here, the light emitting element may be an infrared light emitting element, and the light receiving element may be an infrared light receiving element.

  According to the light sensor having the above configuration, since the sensor light guide unit of the present invention is provided, the detection light rate can be improved.

  According to the present invention, since the sensor light guide unit includes the detection light emphasizing means and the detection efficiency of the detection light is improved, the optical sensor can be made into a highly accurate device.

It is a disassembled perspective view which shows the structure of the optical sensor which comprises the light guide unit for sensors concerning one Embodiment of this invention. It is a top view of the optical sensor shown in FIG. FIG. 3 is a plan view in the vicinity of a wedge-shaped portion indicated by a frame III in the optical sensor of FIG. FIG. 3 is a plan view in the vicinity of a light collecting portion indicated by a frame IV in the light sensor of FIG. 2. FIG. 5 is a view showing an optical path of reflected light (detection light) from a detection subject in the same portion as FIG. 4. It is a top view which shows the light guide unit for sensors concerning another embodiment of this invention. It is a top view for demonstrating the dimension design of the light guide for sensors of this invention. It is a figure which shows the optical sensor which comprises the light guide unit for sensors in a prior art.

  A light guide unit for a sensor according to the present invention emits light (for example, infrared light) and receives a reflected light of the light to thereby use the light guide unit used in an optical sensor for detecting an object to be detected The light guide includes a light emitting area in which the light emitting element is installed and a light receiving area in which the light receiving element is installed. When the light guided in the light emitting area enters the light receiving area and is received by the light receiving element, the reflected light from the object to be detected (detection light) becomes noise and lowers the detection accuracy of the sensor. In the present invention, light is emitted from the light emitting area to the light receiving area, and the intensity of light detected by the light receiving element is reflected from the object to be detected and enters the light receiving area and detected by the light receiving element Detection light emphasizing means are provided which relatively increase the light intensity.

  Hereinafter, configurations of a light guide unit for a sensor according to the present invention and an optical sensor including the light guide unit will be described with reference to the drawings. In the drawings, the same reference numerals are given to the common components, and the description is omitted. The drawings are for explanation and do not limit the actual dimensional ratio of each part.

FIG. 1 is a schematic perspective view showing the configuration of a sensor light guide unit 1 according to an embodiment of the present invention and an optical sensor 2 including the light guide unit. The light guide unit 1 includes a plate-like light guide (light guide member) 10 and a light absorbing member 11 installed on the light guide 10. The light guide 10 has a light emitting area 10 a in which at least one light emitting element 20 is installed, and a light receiving area 10 b in which the light receiving element 21 is installed, and emits light from the light emitting element 20. When Idemitsu the irradiation light L _E from (irradiated surface) 10c is irradiated onto the sensing member 3, the reflected light L _R from the detection object 3 is incident on the light guide 10, the light receiving element 21 as the detection light It is detected. Here, the outer end surface 10 c refers to an end surface facing the detection target 3. Although not shown, the light emitting element 20 and the light receiving element are respectively connected to a power supply and a sensor control unit.

  FIG. 2 is a plan view of an optical sensor 2 provided with the light guide unit 1 shown in FIG. In the present embodiment, the outer end face 10c of the light guide 10 has a flat and linear contour, but the outline of the inner end face 10d which is the end face opposite to the outer end face 10c (opposite the outer end face 10c) Different in area. The outer side surface 10m is flat without bending. The light emitting region 10a includes a light emitting portion 10e provided with the installation place of the light emitting element 20, and a wedge shaped portion 10f located closer to the light receiving region 10b than the light emitting portion 10e. In the light emitting portion 10e, the distance between the outer end surface 10c and the inner end surface 10d is substantially constant, but in the wedge-shaped portion 10f, the inclined surface 10g in which the distance between the outer end surface 10c and the inner end surface 10d gradually decreases toward the light receiving region It is formed. In the light receiving area 10b, the inner end face 10d constitutes an inclined side face 10h, and a light collecting part 10k is formed whose width gradually narrows from the base end 10i to the tip end 10j. The light absorbing member 11 is disposed outside the side surface 10 h of the light receiving area 10 b and the inclined surface 10 g of the wedge-shaped portion 10 f. At least one light emitting element 20 is disposed on the inner end face 10d side of the light emitting part 10e, and the light receiving element 21 is disposed on the tip end 10j side of the focusing part 10k of the light receiving region 10b.

  FIG. 3 is a plan view in the vicinity of the wedge-shaped portion 10 f indicated by a frame III in FIG. 2, in which the optical path of the guided light is indicated by a broken line. In this portion, since the inner end face 10d is inclined with respect to the outer end face 10c, light incident on the wedge-shaped portion 10f from the light output portion 10e is gradually reflected in the wedge-shaped portion 10f while the reflection angle is gradually increased. It is changed and emitted from the outer end face 10c (irradiated surface) when the critical angle is exceeded. Therefore, as compared with the case where the outer end face 10c and the inner end face 10d are parallel to each other, the light amount of the light emitted from the outer end face 10c increases, and as a result, the intensity of the detection light reflected from the detection object 3 (FIG. 1) To increase. Further, the amount of light emitted is increased, the light entering the light receiving area 10b is prevented, or the intensity (light amount) of light entering the light is reduced. Due to these effects, the wedge-shaped portion 10 f functions as a detection light emphasizing means. Furthermore, in the present embodiment, since the light absorbing member 11 is installed on the inner end face 10d side (the inclined surface 10g side), for example, light emitted from the side surface of the light output portion 10e enters the wedge shape portion 10f. Thus, the light can be prevented from being guided to the light receiving area 10b. The light absorbing member 11 also serves as detection light emphasizing means by absorbing unnecessary light other than the detection light.

  FIG. 4 is a plan view of the light guide unit 1 shown by a frame IV in FIG. In the present embodiment, the inner end face 10d of the light guide 10 forms a side face 10h which is an inclined surface in which the inclination angle changes discontinuously. Although the drawing shows an example of the light collecting portion 10k in which the inclination angle changes once, the light collecting portion 10k may have a constant side inclination angle depending on the size and design. The inclination angle may be changed twice or more, or the inclination angle may be changed continuously. In any case, it is preferable that the inclination angle of the side surface 10h with respect to the outer end surface 10c be gradually reduced from the proximal end 10i to the distal end 10j of the light collecting portion 10k.

  As shown by a broken line in FIG. 4, when light is incident from the light emitting area 10a to the light receiving area 10b, the incident light is guided while being multiple-reflected by the light collecting section 10k. The light having a critical angle is emitted from the side surface 10 h and absorbed by the light absorbing member 11. Therefore, even if light is incident from the light emitting area 10a to the light receiving area 10b, the amount of light gradually decreases, and the intensity detected by the light receiving element 21 becomes small. In addition, the light absorbing member 11 plays a role of preventing light from entering the outside of the light collecting unit (for example, the light emitting region 10a) to the light collecting unit 10k.

  In the same part as FIG. 4, the optical path of the light (detection light) reflected from the detection object 3 (FIG. 1) and entering the light receiving area 10b is indicated by a broken line in FIG. As seen in FIG. 5, the light collecting portion 10k is configured to narrow in width from the base end portion 10i to the tip end portion 10j so that light reflected by the side surface 10h is collected at the tip end. It is designed. For this reason, the detection accuracy of the reflected light from a to-be-detected body can be improved. As described above, the condensing unit 10 k functions as a detection light emphasizing unit by condensing the detection light on the light receiving element 21 while suppressing or preventing the light as noise from reaching the light receiving element 21. .

  The present invention is not limited to the embodiments described above, and the shape of the light guide can be changed. Although the embodiment in which the outer end face 10 c is flat is shown in FIGS. 1 to 5, in the wedge-shaped portion 10 f, the outer end face 10 c may form an inclined surface.

FIG. 6 is a plan view showing a portion in the vicinity of another light collecting portion 10k and a wedge-shaped portion 10f of the light guide unit for sensor of the present invention. In the present embodiment, of the outer end surface 10c of the light guide 10, an outer end surface 10c ₁ of the light exit portion 10e, although the outer end surface 10c ₃ of the light-receiving region 10b are parallel to each other, the outer end face 10c of the wedge-shaped portion 10f ₂ Is inclined with respect to both, and forms an inclined surface 10 n.
On the other hand, the inner end surface 10d ₂ of the wedge-shaped portion 10f is parallel to the outer end surface 10c ₁ and Uchitanmen 10d ₁ of the light exit portion. The wedge-shaped portion 10f may be provided with both an inclined surface 10n on the outer end surface side and an inclined surface 10g on the inner end surface side, as shown in FIG. 7 below. If only the luminous efficiency is considered, it is preferable that the inclined surface be formed only on the outer end face 10 c side of the light guide 10 as in the present embodiment.

In the embodiment shown in FIGS. 1 to 5, the light absorbing member 11 inside the wedge-shaped portion 10f is arranged, in this embodiment, faces the inner end surface 10d ₂ of the wedge-shaped portion 10f of FIG. 6 A specular reflection member 12 having a reflection surface 12a is disposed. By installing the specular reflection member 12, the light emitted from the inner end face 10 d ₂ of the wedge-shaped portion 10 f is specularly reflected to allow the wedge-shaped portion 10 f to reenter light while maintaining the angle, and the outer end face 10 c ₂ It can be emitted from the surface 10n).

FIG. 7 is a plan view of the light-condensing part 10k of the light guide 10 and a portion in the vicinity of the wedge-shaped part 10f. The drawings are for the purpose of illustration and do not reflect the actual dimensional ratio. In the embodiment of FIG. 7, although the outer end face side of the wedge-shaped portion 10f is the inclined face 10n and the inner end face is the inclined face 10g, the limitation described below is also when the inclined face is formed on only one side. Applicable When the plate-like light guide 10 is viewed from the lateral direction along the outer end surface 10c ₁ of the light-receiving portion 10e, when the longitudinal direction perpendicular thereto, the inclined surface 10n whereas lateral θ _At an angle of _L2 , the inclined surface 10g is inclined at an angle of θ _L1 with respect to the lateral direction. FIG. 7 shows that the light reflected at the total reflection angle θ _R1 on the inclined surface 10 n is reflected three times at the reflection angles θ _R2 , θ _R3 and θ _R4 on the side surface 10 h of the light collecting part 10 k. It is indicated by a broken line. The ratio of the vertical width t ₁ (minimum width of the ridge-shaped portion 10 f) of the ridge-shaped portion 10 f at the boundary with the light receiving region 10 b to the width W ₁ of the ridge-shaped portion 10 f is 0 <t ₁ / w ₁ <1 It is preferable to be about .16. Here longitudinal width t _1, it is desirable to reduce to production limits. By reducing the t _1, increasing the frequency of multiple reflection, it is possible to Idemitsu more light.

At that time, the inclination angles θ _L1 and θ _L2 from the lateral direction of the inclined surfaces 10 g and 10 n of the wedge-shaped portion 10 f are preferably smaller than the critical angle of the light guide 10, and each is preferably 0 to 45 degrees . The inclination angle theta ₁ of the condensing section side 10h of the base end vicinity, the condenser portion 10k, When the time of the reflection of the n-th Idemitsu begins, it is preferred that satisfy the following condition.

θ ₁ <(180 (n−1) + 2θ _R 1 −θ _{L 2} ) / (2 n −1)

Here, θ _R1 is the total reflection angle at the inclined surface 10 n (the outer end face 10 c ₂ of the wedge-shaped portion 10 f), θ _L2 is the tilt angle of the inclined surface 10 n, and n is light collected from the wedge-shaped portion 10 f It is the number of times of reflection at the light portion 10k.

  FIG. 8 is a diagram illustrating an embodiment of a light sensor having a light guide in the prior art. In a), in the light guide 10, a slit S1 is provided from the inner end face 10d side at the boundary between the light emitting area 10a and the light receiving area 10b, and light entering the light receiving area 10b from the light emitting area 10a is provided in the slit S1. The light absorbing member 11 is inserted in order to suppress. In b), the slit S2 is provided also from the outer end face 10c side, and the light absorbing member 11 is inserted. Thereby, the light entering from the light emitting area 10a to the light receiving area 10b is further suppressed.

In addition, the light guide unit 1 according to the embodiment of the present invention shown in FIG. 1 and the light guide unit shown in FIG. Optical simulation of the intensity of the light received by the light receiving element in the state where the light emitting element is installed, the state where the detected body is installed, and the state where the detected body is not installed for light intensity _{I N} of light), the ratio of light intensity _{I D} of the detection light incident on the light-receiving area is reflected from the sensing object, in the example of FIG. 8a) 0.62, 1.22 in the example of FIG. 8b) While it was 102.8 in the example of FIG.

  In addition, although the above-mentioned embodiment demonstrated the case where a flat plate-like light guide was used, a plate surface may be bent or it may be curving. Alternatively, when the plate thickness is large as compared with the size of the light emitting element and the light receiving element, the thickness on the inner end face side may be thinner than the thickness on the outer end face side.

  Although the light guide member which comprises the light guide 10 which comprises the light guide unit 1 may be glass, resin, such as a polycarbonate and a polymethyl methacrylate (PMMA), may be sufficient. The light absorbing member 11 may be black paper, carbon tape or the like. An LED or the like can be used as the light emitting element. The light receiving element is selected according to the wavelength of light emitted from the light emitting element. For example, when the light emitting element is an infrared light LED, a light receiving element that detects infrared light is used.

  The optical sensor provided with the light guide unit for sensor of the present invention can be used, for example, as a sensor for activating various electronic components (for example, image display devices) for vehicle use, and has a detection accuracy compared to a conventional sensor. Can be a sensitive sensor.

1 light guide unit 2 light sensor 10 light guide 10a light emitting region 10b receiving regions 10c outer end face 10c ₁ outer end face 10d in the end face 10d ₁ light exit portion of the outer end surface 10c ₃ light receiving area of the outer end surface 10c ₂ wedge-shaped portion of the light exit portion Inner end face 10d ₂楔 -shaped inner end face 10e Light-emitting part 10f 部 -shaped part 10g inclined surface 10i base end 10j tip 10h side 10k light collecting part 10m outer surface 10n inclined surface 11 light absorbing member 20 light emitting element 21 light receiving element S1, S2 slit

Claims (6)

A light emitting area (10a) in which the light emitting element is installed;
And a light guide including a light receiving area (10b) in which the light receiving element is installed,
The light from the light emitting area (10a) enters the light receiving area (10b), and the intensity of light detected by the light receiving element is reflected from the detection object and enters the light receiving area (10b), A sensor light guide unit provided with detection light emphasizing means for relatively improving the intensity of light detected by the light receiving element. In the sensor light guide unit according to claim 1,
The light emitting region (10a) includes a light emitting portion (10e) provided with the installation place of the light emitting element,
The detection light emphasizing means further includes a wedge-shaped portion (10f) located closer to the light receiving area (10b) than the light emitting portion (10e),
When the distance between the outer end face (10c) of the light guide and the inner end face (10d) opposed thereto, which serves as a light irradiation surface to the outside of the light guide, is the light emitting part at the wedge-shaped part (10f) The outer end surface (10c) and the inner end surface (10d) are inclined to each other so that the diameter gradually decreases from the (10e) side to the light receiving region (10b) side.
Sensor light guide unit. The sensor light guide unit according to claim 2, wherein at least one of the outer end face (10c ₂ ) and the inner end face (10d ₂ ) of the wedge-shaped portion (10f) is the outer end face (10b) of the light receiving region (10b). Forming an inclined surface (10 g, 10 n) inclined with respect to 10 c ₃ ),
Sensor light guide unit. The sensor light guide unit according to any one of claims 1 to 3.
As the detection light emphasizing means, the light receiving area (10b) includes a light collecting part (10k) whose width is narrowed from the proximal end (10i) to the distal end (10j), and the installation location of the light receiving element is A sensor light guide unit provided at the tip end (10j) of the light collector. The sensor light guide unit according to any one of claims 1 to 4.
A light guide unit for a sensor, comprising a light absorbing member (11) installed at least on the inner end face (10d) side of the light receiving area (10b) as the detection light emphasizing means. The sensor light guide unit (1) according to any one of claims 1 to 5,
An optical sensor comprising: a light emitting element (20) installed in the light emitting area (10a); and a light receiving element (21) installed in the light receiving area (10b).

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