JP5721069B2 - LED rider device - Google Patents

Description

  The present invention relates to an LED rider device. More specifically, the present invention relates to a rider apparatus using an LED light source.

  A lidar device is a device that can measure the indoor gas concentration and the state of dust in the atmosphere using light. In recent years, the demand and importance of measuring the indoor state and the like are increasing. .

  Lasers are often used as the light source for lidar devices, but lasers are often very large devices, which are troublesome to carry and install, and can check the conditions of indoor gas concentrations and atmospheric dust. In many cases, it is difficult to measure easily depending on the weight and size.

  On the other hand, as a light source of this rider device, for example, the following Non-Patent Documents 1 to 3 propose a technique using an LED as a light source of a rider device.

Tatsuo Shiina and Gotetsu Koyama, "LED Rider Proposal", Proceedings of the 27th Laser Sensing Symposium, 84-85, 2009 Tatsuo Shiina and Gotetsu Koyama, “Development of LED Light Source Pulse Light Source”, Proceedings of the 27th Laser Sensing Symposium, 86-87, 2009 M.M. Koyama, T .; Shiina, “Light” Source Module for LED Lidar ”, proceedings of 25th International Laser Radar Conference, S01P-32-1-4 (2010)

  However, the bullet-type LED light source used in the techniques described in Non-Patent Documents 1 to 3 has a low collimating property, and there still remains a problem to be solved in the performance as an actual device.

  In general, a conventional rider has a so-called blind area that cannot be observed, and this blind area appears in short-distance measurement, and there is a problem that short-distance measurement is difficult.

  In view of the above problems, an object of the present invention is to provide an LED rider device that can be reduced in size and weight, has a smaller blind area, and has practical performance as an actual device.

  The LED lidar device according to the first aspect of the present invention that solves the above-described problems makes the LED light source that emits light and the light emitted by the LED light source parallel, and the light that is scattered by the measurement object and returns. A condensing lens, a hole for arranging a bullet-type LED light source is formed, a mirror arranged to be inclined with respect to the optical axis of the LED light source, and a light shield formed with a pinhole for transmitting light reflected by the mirror And a light receiving device that receives light transmitted through the pinhole of the light shielding filter.

  According to the present invention, it is possible to provide an LED rider apparatus that can be reduced in size and weight, has a smaller blind area, and has practical performance as an actual apparatus.

It is the schematic of the LED rider apparatus which concerns on embodiment. It is an enlarged view near the bullet-type LED light source of the LED rider device according to the embodiment. It is a figure which shows the result of the LED rider apparatus which concerns on an Example.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention can be implemented in many different forms, and is not limited to the following embodiments and examples.

  FIG. 1 is a schematic view of an LED rider apparatus (hereinafter referred to as “this apparatus”) 1 according to the present embodiment. As shown in the figure, the present apparatus 1 makes the bullet-type LED light source 2 that emits light and the light emitted by the bullet-type LED light source 2 parallel, and the light that is scattered and returned by the measurement object among the light. A condensing lens 3 and a hole 41 in which the bullet-type LED light source 2 is disposed are formed, and a mirror 4 that is inclined with respect to the optical axis 21 of the bullet-type LED light source 2 and light reflected by the mirror 4 are transmitted. A light blocking filter 5 in which a pinhole 51 is formed, a light receiving device 5 that receives light transmitted through the pinhole 51 of the light blocking filter 5, and a bandpass filter 7 disposed between the light receiving device 6 and the light blocking filter 5. And having.

  In the present embodiment, the bullet-type LED light source 2 is a bullet-shaped LED (Light Emitting Diode), and specifically, an LED element made of a semiconductor and emitting light is covered with a transparent resin in the form of a bullet. Say things. The bullet-type LED has a spherical tip, and the emitted light can be spread in advance.

  In the present embodiment, the lens 3 can collimate the light emitted from the bullet-type LED light source 2 and can collect the light that is scattered by the measurement object and returns. That is, in the present embodiment, the same lens can be used as it is for the transmission lens and the reception lens, and it is not necessary to arrange a mirror or the like at the tip of the transmission / reception lens, and there is almost no so-called blind area.

  In this embodiment, as described above, the lens 3 is limited as long as it can collimate the light emitted from the bullet-type LED light source 2 and collect light scattered by the measurement object and returning from this light. However, for example, a Fresnel lens is useful in that it can be further downsized.

  In the present embodiment, the mirror 4 is a member that can reflect light, and has a hole 41 in which the bullet-type LED light source 2 is disposed, and is inclined with respect to the optical axis 21 of the bullet-type LED light source 2. Are arranged. The optical axis 21 of the bullet-type LED light source 2 is an axis that is the center of light emitted from the bullet-type LED light source 2, and the light spreads symmetrically with respect to this axis.

  In the mirror 4 according to the present embodiment, the hole 41 is formed as described above, and the bullet-type LED light source 2 is disposed in the region of the hole 41, and the light of the bullet-type LED light source 2 is transmitted from the hole 41 to the above-mentioned. It can be emitted to the lens 3. In this case, it is preferable that the bullet-type LED light source 2 does not protrude from the reflection surface of the mirror 4. By doing so, it is possible to prevent the light reflected from the mirror from being absorbed or scattered by the bullet-type LED light source 2 before entering the light shielding filter 5.

  Further, in the present embodiment, the mirror 4 is disposed so as to be inclined with respect to the surface 32 perpendicular to the optical axis 21 of the bullet-type LED light source 2 and the optical axis 31 of the lens 3. By arranging in this way, the light returned by the scattering is reflected in the process of being collected by the lens 3, is completely condensed after changing its direction, and enters the light receiving device 6. In this embodiment, since the bullet-type LED light source 2 is used, the bullet-type LED light source 2 is arranged at the position where the light returned by the scattering is collected due to the effect of the transparent resin of the bullet-type LED light source 2. The position is farther from the lens than the position. Therefore, in this embodiment, by arranging the bullet-type LED light source 2 at a position close to the mirror, light can be widely emitted without being interrupted by the mirror, while the light returned by scattering is reflected off the mirror and separated. Light can be collected and detected at the position.

  In this embodiment, the angle at which the mirror 4 is tilted is not particularly limited, and can be adjusted as appropriate as long as the amount of received light can be adjusted and the light receiving device 6 can be disposed compactly and without waste. For example, it is preferable that the angle β formed by the reflecting surface 42 of the mirror and the surface 32 perpendicular to the optical axis 21 of the bullet-type LED light source 2 or the optical axis 31 of the lens is in the range of 30 degrees to 60 degrees, It is preferably in the range of 50 degrees or more and 55 degrees or less, and most preferably 45 degrees.

  Further, in the present embodiment, the size of the mirror 4 can be appropriately adjusted depending on the size of the lens 3, and is not limited, but even the light returning to the edge of the lens 3 is reflected by the mirror 4. It is preferable to make it possible.

  Moreover, in this embodiment, it is preferable that the hood 43 is attached to the side surface 42 of the hole formed in the mirror 4. FIG. 2 shows a partially enlarged view of the bullet-type LED light source 2 and the mirror 4 when the hood 43 is provided. The hood 43 according to the present embodiment is preferably a member that absorbs light or suppresses reflection of light. For example, black paper, black paint (matte), and non-woven paper can be used. In the present embodiment, by providing the hood, it is possible to prevent the light emitted from the bullet-type LED light source 2 from being directed toward the light receiving device 6 by the hole side surface 42.

  In the present embodiment, the light receiving device 6 is a device that can capture light reflected from the outside of the device such as the atmosphere and measure the amount of light received. The light receiving device 6 is not limited to this, but is preferably configured to include, for example, a PMT (PhotoMultiplier Tube) and a photon counter connected to the PMT. By doing so, light energy is converted into electric energy by the PMT, and photons can be counted.

  In the present embodiment, a light blocking filter 5 is provided between the light receiving device 6 and the mirror 4 for taking only light reflected from the outside of the device into the light receiving device 6 and blocking other light. A pinhole 51 is formed in the light shielding filter 5, and the position of the pinhole 51 is adjusted so that the light reflected by the mirror 4 and focused on the pinhole 51 is focused, thereby adversely affecting the measurement. The light can be removed.

  In the present embodiment, a band pass filter 7 is provided between the light receiving device 6 and the mirror 4. In this apparatus, by passing through the band pass filter 7, light having a wavelength in a necessary range can be taken in, and more accurate measurement can be performed. It should be noted that if the wavelength of the cannonball type LED light source is sufficient, it is not necessary to provide this bandpass filter.

  Further, in this apparatus, there is a possibility that a part of the light irradiated to the lens 3 side with the bullet-type LED light source 2 is reflected by the lens 3 and further reflected by the mirror 4 and enters the light receiving device 6. Therefore, in this apparatus, it is preferable to shift the optical axis of the bullet-type LED light source 2 and the optical axis of the lens. The angle in this case can be adjusted as appropriate. For example, when the divergence angle of the bullet-type LED light source 2 is α, it is preferably shifted within a range of 0.5α to 2α, more preferably α or more. 2α or less. By setting it within this range, the present apparatus has an effect that the amount of light emitted from the bullet-type LED light source 2 is reflected to the light receiving device 6 side even if it is reflected by the lens. Here, the divergence angle of the bullet-type LED light source 2 refers to the full width at half maximum at which the light intensity is half of the maximum intensity.

  The apparatus 1 preferably further includes a housing 8 for housing and installing the LED light source 2, the lens 3, the mirror 4, the light shielding filter 5, the light receiving device 6, and the band pass filter 7. By providing the housing 8 in this way, there is an advantage that the system is fixed and can be carried as a unit.

  As described above, the LED rider device according to the present embodiment can be reduced in size and weight, has a smaller blind area, and has practical performance as an actual device.

  In this embodiment, a bullet-type LED light source is used. However, there is no particular limitation as long as the focal position of the scattered light returns to a position away from the position of the light source. For example, a surface-emitting LED is used. It may be a light source.

  Hereinafter, the apparatus according to the above-described embodiment was actually created and its effect was confirmed. This will be described below.

  This device forms a housing with a width of 230 mm, a depth of 230 mm, and a height of 210 mm, and a bullet-type LED light source, a Fresnel lens, a mirror, a PMT, and a light blocking filter in which pinholes are formed are installed in a predetermined arrangement. .

  In this example, a bullet-type LED light source having a wavelength of 392 nm and a diameter of 3 mm was used. In order to oscillate the LED, a composite circuit of an astable multivibrator circuit and a monostable multivibrator was created, and a pulse excitation signal was input to the LED drive circuit. As a result, the pulse drive circuit can be reduced in size to 30 mm × 45 mm. Note that this bullet-type LED light source causes a large current to flow during pulse driving, so there is a slight wavelength shift compared to continuous wave driving, but there is no significant effect.

  In the present embodiment, the Fresnel lens is arranged at a position 180 mm away from the bullet-type LED light source, and collimates the light emitted from the bullet-type LED light source. The beam diameter was 60 mm, and the beam divergence angle was 9.5 mrad. Note that light of 190 mm × 190 mm (f = 140 mm) was used assuming that the light reflected from the outside of the apparatus naturally spreads out from the beam diameter.

  In the present embodiment, the mirror has a plate shape of 120 mm × 60 mm and a hole is formed, and the bullet-type LED light source is arranged in the hole. The angle formed between the reflecting surface of the mirror and the bullet-type LED light source was set to 45.

  In this embodiment, PMT used is model number 1924P manufactured by Hamamatsu Photonics, a light-shielding filter is disposed on the front surface, and the diameter of the pinhole is 4 mm. As a result, the viewing angle (FOV) of this apparatus was 10.7 mrad.

  Next, operation check was performed about the created LED lidar apparatus. This operation was confirmed by first irradiating light to a hard target (wall) that was 6.4 m away from the lens of this apparatus.

  First, light was emitted from a bullet-type LED light source with a pulse width of 10.2 ns, 112 kHz, and 55 mW, and the signal was confirmed. FIG. 3 shows the result. As a result, a peak that seemed to be echo from the wall could be confirmed at a position of 6.4 m, which coincided with the actually measured value. As a result, it was confirmed that the LED rider apparatus according to this example can be reduced in size and weight, has a smaller blind area, and has practical performance as an actual apparatus.

(Example 2)
This embodiment differs from the first embodiment in that a hood with black paint is provided on the side surface of the mirror hole, and the optical axis of the bullet-type LED light source and the optical axis of the lens are shifted. Same as above.

  In the result shown in FIG. 3, a very strong peak is observed at a position of 0 m as shown in the figure. As described in the above embodiment, this is because there is a possibility that the bullet-type LED light source receives light reflected from the lens, and the bullet-type LED light source reflects on the hole side surface of the mirror and enters the light receiving device. I found that there is a possibility. Therefore, in this example, a hood was provided on the side surface of the mirror hole, and the same measurement as in Example 1 was performed by tilting the optical axis of the bullet-type LED light source and the optical axis of the lens by 10 degrees. The result is shown in FIG. In Examples 1 and 2, the hole is formed so that a cavity with a diameter of 4 mm penetrates through a mirror (thickness: 3 mm) with a 45 ° inclination, that is, parallel to the optical axis of the bullet-type LED light source. Is formed.

  As a result, it was confirmed that the strength at 0 m was very low compared with that before the improvement (Example 1), and the usefulness of this means could be confirmed.

  The present invention has industrial applicability as an LED rider device.

Claims (3)

A bullet-type LED light source that emits light;
A lens that collimates the light emitted by the LED light source and collects the light scattered back by the measurement object out of the light; and
A hole in which the LED light source is disposed, and a mirror that is disposed to be inclined with respect to the optical axis of the LED light source and that completely collects light after changing the direction of the returning light ;
A light shielding filter in which a pinhole for transmitting light reflected by the mirror is formed;
A light receiving device that receives light transmitted through the pinhole of the light shielding filter,
A rider device,
The LED light source does not protrude from the reflecting surface of the mirror,
When the light spread angle of the LED light source is α, the optical axis of the lens and the optical axis of the LED
The LED rider according to claim 1, wherein the angle β formed by the
apparatus. The L of claim 1, further comprising a band pass filter between the light shielding filter and the light receiving device.
ED rider device.   The LED rider apparatus according to claim 1, further comprising a hood on a side surface of the mirror.