JP2019132671A

JP2019132671A - Laser radar device

Info

Publication number: JP2019132671A
Application number: JP2018014241A
Authority: JP
Inventors: 裕一竹内; Yuichi Takeuchi; 吉田　直人; Naoto Yoshida; 直人吉田
Original assignee: Konica Minolta Inc
Current assignee: Konica Minolta Inc
Priority date: 2018-01-31
Filing date: 2018-01-31
Publication date: 2019-08-08

Abstract

To suppress the electric noise generated in a light projection unit from being propagated to a light receiving unit in a laser radar device in which the light projection unit and the light receiving unit are integrally fixed via a housing composed of an electro-conductive material.SOLUTION: Provided is a laser radar device in which a light projection circuit board 10 where a laser oscillator is mounted and a light receiving circuit board 20 where a light receiving element is mounted are integrally fixed via a housing 30 composed of an electro-conductive material, wherein an electro-conductive member 21 is arranged between the housing and the light receiving circuit board and an insulating member 22 is arranged between the housing and the electro-conductive member, the electro-conductive member being electrically connected to a ground pattern (20G) included in the light receiving circuit board 20 and grounded to earth. Propagation to the light receiving circuit board is suppressed by a capacitor formed by the housing, the insulating member and the electro-conductive member.SELECTED DRAWING: Figure 1

Description

本発明は、レーザーレーダー装置に関する。 The present invention relates to a laser radar device.

近年、対象にパルス発光するレーザー光を投光し対象からの反射光を受光して対象までの距離等を検出するレーザーレーダー(ライダー（LIDAR（Light Detection and Ranging、Laser Imaging Detection and Ranging）)装置が利用されている。
レーザーレーダー装置の受光部では、投光に対して例えば１０^−９程度と弱い光を受光しなければならないが、投光部と受光部との相対的配置を固定するために、投光部と受光部とが導電性材料からなる筐体を介して一体的に固定された場合に、投光部で発生した電気ノイズが受光部に伝搬するという問題がある。
特許文献１にあっては、光源の発熱により、受光素子の温度が上昇し、特性に影響を与えることを防止するために、一般的な金属ハウジングに熱伝導率が低いホルダーを介して受光素子を付設することで、光源の熱を遮断し、受光素子への影響を抑えた。 In recent years, a laser radar (LIDAR (Light Detection and Ranging, Laser Imaging Detection and Ranging)) device that detects the distance to the target by projecting a pulsed laser beam to the target and receiving the reflected light from the target Is being used.
The light receiving unit of the laser radar device must receive light as weak as about 10 ^−9, for example, with respect to the light projection, but in order to fix the relative arrangement of the light projecting unit and the light receiving unit, When the light receiving unit is integrally fixed via a casing made of a conductive material, there is a problem that electrical noise generated in the light projecting unit propagates to the light receiving unit.
In Patent Document 1, in order to prevent the temperature of the light receiving element from being increased due to heat generated by the light source and affecting the characteristics, the light receiving element is inserted into a general metal housing through a holder having low thermal conductivity. By attaching, the heat of the light source was cut off and the influence on the light receiving element was suppressed.

特開２００３−３６５５３号公報JP 2003-36553 A

しかしながら、特許文献１に記載の発明にあっては、熱の伝搬を抑制することを目的としており、電気ノイズの伝搬を抑制するためには最適化されていない。 However, the invention described in Patent Document 1 aims to suppress the propagation of heat and is not optimized to suppress the propagation of electrical noise.

本発明は以上の従来技術における問題に鑑みてなされたものであって、投光部と受光部とが導電性材料からなる筐体を介して一体的に固定されたレーザーレーダー装置において、投光部で発生した電気ノイズが受光部に伝搬することを抑制することを課題とする。 The present invention has been made in view of the above problems in the prior art, and in a laser radar device in which a light projecting unit and a light receiving unit are integrally fixed via a housing made of a conductive material, It is an object of the present invention to suppress electrical noise generated at the light receiving portion from propagating to the light receiving portion.

以上の課題を解決するための請求項１記載の発明は、レーザー発振器が実装された投光回路基板と、受光素子が実装された受光回路基板とが導電性材料からなる筐体を介して一体的に固定されたレーザーレーダー装置であって、
前記筐体と前記受光回路基板との間に、導電性部材が配置され、
前記筐体と前記導電性部材との間に、絶縁性部材が配置されて両者を絶縁し、
前記導電性部材が、前記受光回路基板に含まれる接地パターンに電気的に接続して接地されたレーザーレーダー装置である。 The invention described in claim 1 for solving the above-mentioned problems is that the light projecting circuit board on which the laser oscillator is mounted and the light receiving circuit board on which the light receiving element is mounted are integrated via a casing made of a conductive material. Fixed laser radar device,
A conductive member is disposed between the housing and the light receiving circuit board,
An insulating member is disposed between the housing and the conductive member to insulate both,
In the laser radar device, the conductive member is grounded by being electrically connected to a ground pattern included in the light receiving circuit board.

請求項２記載の発明は、前記投光回路基板からの投光路と、前記受光回路基板への受光路とが、前記筐体内で同軸に配置された請求項１に記載のレーザーレーダー装置である。 The invention according to claim 2 is the laser radar device according to claim 1, wherein a light projecting path from the light projecting circuit board and a light receiving path to the light receiving circuit board are arranged coaxially in the housing. .

本発明によれば、投光回路基板から筐体に印加される電気ノイズは、投光回路基板と受光回路基板との間に、筐体と絶縁性部材と導電性部材とでつくられるキャパシタにより、受光回路基板への伝搬が抑制される。
レーザー発振器の発振パルス幅等の電気的特性に応じて同キャパシタのインピーダンスが大きくなるようにその電気的特性を選択し、電気ノイズ伝搬量を縮小することができる。 According to the present invention, the electrical noise applied to the housing from the light projecting circuit board is caused by the capacitor formed by the housing, the insulating member, and the conductive member between the light projecting circuit board and the light receiving circuit board. Propagation to the light receiving circuit board is suppressed.
The electrical characteristics can be selected according to the electrical characteristics such as the oscillation pulse width of the laser oscillator so that the impedance of the capacitor is increased, and the electric noise propagation amount can be reduced.

本発明の一実施形態に係るにレーザーレーダー装置を示す模式図である。It is a mimetic diagram showing a laser radar device concerning one embodiment of the present invention. 本発明の一実施形態に係るにレーザーレーダー装置の受光部の断面図である。It is sectional drawing of the light-receiving part of the laser radar apparatus based on one Embodiment of this invention. 本発明の一実施形態に係るにレーザーレーダー装置の受光部の切断図である。It is a cutaway view of a light receiving part of a laser radar device according to an embodiment of the present invention. 実施例に係るレーザーレーダー装置についての電気伝搬ノイズの測定結果と導電性部材（アルミ）の厚みとの関係を示すグラフである。It is a graph which shows the relationship between the measurement result of the electric propagation noise about the laser radar apparatus which concerns on an Example, and the thickness of an electroconductive member (aluminum).

以下に本発明の一実施形態につき図面を参照して説明する。以下は本発明の一実施形態であって本発明を限定するものではない。 An embodiment of the present invention will be described below with reference to the drawings. The following is one embodiment of the present invention and does not limit the present invention.

図１にレーザーレーダー装置の構成例を示す。
図１に示すようにレーザーレーダー装置１は、レーザーダイオードなどのレーザー発振器が実装された投光回路基板１０と、受光素子が実装された受光回路基板２０とが導電性材料からなる筐体３０を介して一体的に固定された構成を有する。
筐体３０は箱状で内部に光学部品等が配置される。
投光回路基板１０は筐体３０の内部にレーザー光を出射するように筐体３０の外面にアルミ板などの導電性部材１１を介して固定されている。
受光回路基板２０は筐体３０の内部に入射したレーザー光を受光するように筐体３０の外面にアルミ板などの導電性部材２１、さらに樹脂板などの絶縁性部材２２を介して固定されている。導電性部材２１は、筐体３０と受光回路基板２０との間に配置されている。絶縁性部材２２は、筐体３０と導電性部材２１との間に配置されており、絶縁性部材２２は、筐体３０と導電性部材２１とを絶縁する。
投光回路基板１０からの投光路Ｌ１と、受光回路基板２０への受光路Ｌ２とが、筐体３０内の少なくとも投光・集光口３１で同軸に配置された構成である。このような場合、投光回路基板１０と受光回路基板２０との相対的配置を固定するために、共通の筐体３０への固定構造が適用される。 FIG. 1 shows a configuration example of a laser radar device.
As shown in FIG. 1, a laser radar device 1 includes a housing 30 in which a light projecting circuit board 10 on which a laser oscillator such as a laser diode is mounted and a light receiving circuit board 20 on which a light receiving element is mounted are made of a conductive material. Through a fixed structure.
The housing 30 has a box shape, and optical components and the like are disposed therein.
The light projecting circuit board 10 is fixed to the outer surface of the housing 30 via a conductive member 11 such as an aluminum plate so as to emit laser light into the housing 30.
The light receiving circuit board 20 is fixed to the outer surface of the housing 30 via a conductive member 21 such as an aluminum plate and an insulating member 22 such as a resin plate so as to receive laser light incident on the inside of the housing 30. Yes. The conductive member 21 is disposed between the housing 30 and the light receiving circuit board 20. The insulating member 22 is disposed between the housing 30 and the conductive member 21, and the insulating member 22 insulates the housing 30 from the conductive member 21.
The light projecting path L <b> 1 from the light projecting circuit board 10 and the light receiving path L <b> 2 to the light receiving circuit board 20 are arranged coaxially at least at the light projecting / condensing port 31 in the housing 30. In such a case, in order to fix the relative arrangement of the light projecting circuit board 10 and the light receiving circuit board 20, a fixing structure to the common housing 30 is applied.

導電性部材２１は、受光回路基板２０に含まれる接地パターン２０Ｇに電気的に接続して接地されている。例えば、図２に示すように導電性材料からなる固定ネジ２３を介して接地パターン２０Ｇが導電性部材２１に接続されている。
投光回路基板１０及び受光回路基板２０は、筐体３０に設けられた孔部３２，３３にそれぞれ位置決めされる。図３(a)に示すように絶縁性部材２２に凸型の嵌合部２０Ｈを形成して孔部３３に嵌め入れて位置決めしてもよいし、図３(b)に示すようにフラットな形状として位置決め用の凹凸を形成せずに、位置決め後固定してもよい。これにより受光素子２０Ｒが筐体３０に対して位置決めされる。 The conductive member 21 is electrically connected to the ground pattern 20G included in the light receiving circuit board 20 and grounded. For example, as shown in FIG. 2, the ground pattern 20 </ b> G is connected to the conductive member 21 through a fixing screw 23 made of a conductive material.
The light projecting circuit board 10 and the light receiving circuit board 20 are respectively positioned in holes 32 and 33 provided in the housing 30. A convex fitting portion 20H may be formed in the insulating member 22 as shown in FIG. 3 (a), and may be positioned by being fitted into the hole 33, or may be flat as shown in FIG. 3 (b). You may fix after positioning, without forming the unevenness | corrugation for positioning as a shape. Thereby, the light receiving element 20 </ b> R is positioned with respect to the housing 30.

投光回路基板１０は、光学調整感度が高いため、雰囲気温度の変化で熱膨張をさけるよう金属(導電性部材１１)を介して筐体３０に固定している。
筐体３０も光学調整の維持のため、金属（導電性材料）を適用している。
したがって、投光回路基板１０でのレーザー発振時に発生する電気ノイズが筐体３０まで伝搬する。
受光回路基板２０は、投光回路基板１０の光学調整感度に比べて鈍感であるため、熱膨張係数の小さな絶縁性部材２２を使用している。筐体３０と絶縁性部材２２と導電性部材２１とにより、キャパシタがつくられ、このキャパシタにより、投光回路基板１０から筐体３０に印加される電気ノイズの受光回路基板２０への伝搬を抑制する。 Since the light projecting circuit board 10 has high optical adjustment sensitivity, the light projecting circuit board 10 is fixed to the housing 30 through a metal (conductive member 11) so as to avoid thermal expansion due to a change in ambient temperature.
A metal (conductive material) is also applied to the housing 30 in order to maintain optical adjustment.
Therefore, electrical noise generated during laser oscillation in the light projecting circuit board 10 propagates to the housing 30.
Since the light receiving circuit board 20 is less sensitive than the optical adjustment sensitivity of the light projecting circuit board 10, an insulating member 22 having a small thermal expansion coefficient is used. The housing 30, the insulating member 22, and the conductive member 21 form a capacitor, and this capacitor suppresses propagation of electrical noise applied from the light projecting circuit board 10 to the housing 30 to the light receiving circuit board 20. To do.

（実施例）
以上の実施形態に従ってレーザーレーダー装置を実施し、さらに導電性部材２１にはアルミを使用し、絶縁性部材２２には樹脂を使用し、導電性部材２１の厚みと絶縁性部材２２の厚み（ｄ）を合計した総厚（Ｌ）を３．５ｍｍとし、導電性部材２１の厚み（Ｌ−ｄ）を図４に示すように３．５から０．５とした場合の電気伝搬ノイズの測定結果を同図に示す。
図４に示すように導電性部材２１の厚みを２．５ｍｍ、絶縁性部材２２の厚みを１ｍｍとした場合にノイズの抑制効果が最大となった。
投光回路基板１０では数十Ａを超える電流がノイズとなり、受光回路基板２０側へ伝搬し、受光回路基板２０で検出する受光信号に影響を与え得る。
ノイズ周波数により、絶縁性部材２２、導電性部材２１の厚みを決める必要がある。本実施例では、投光回路基板１０でのレーザー発振のパルス幅が１０ｎｓから５ｎｓの場合であるため、ノイズ周波数は50MHz〜300MHz程度となる。そのため、絶縁性部材２２の厚みを１ｍｍとし、全体の厚み（Ｌ）の３．５ｍｍに対して導電性部材２１の厚みを２．５ｍｍとした場合にノイズの抑制効果が最大となった。 (Example)
The laser radar apparatus is implemented according to the above embodiment, and the conductive member 21 is made of aluminum, the insulating member 22 is made of resin, and the thickness of the conductive member 21 and the thickness of the insulating member 22 (d ) Is a total thickness (L) of 3.5 mm, and the thickness (Ld) of the conductive member 21 is 3.5 to 0.5 as shown in FIG. Is shown in FIG.
As shown in FIG. 4, when the thickness of the conductive member 21 is 2.5 mm and the thickness of the insulating member 22 is 1 mm, the noise suppressing effect is maximized.
In the light projecting circuit board 10, a current exceeding several tens of A becomes noise, propagates to the light receiving circuit board 20 side, and may affect a light receiving signal detected by the light receiving circuit board 20.
It is necessary to determine the thickness of the insulating member 22 and the conductive member 21 based on the noise frequency. In this embodiment, since the pulse width of the laser oscillation in the light projecting circuit board 10 is 10 ns to 5 ns, the noise frequency is about 50 MHz to 300 MHz. Therefore, when the thickness of the insulating member 22 is 1 mm and the thickness of the conductive member 21 is 2.5 mm with respect to the total thickness (L) of 3.5 mm, the noise suppressing effect is maximized.

なお、電気ノイズの伝搬等については以下が参考となる。
絶縁材の厚みdを通して、導電体である筐体３０の電気ノイズが伝搬(カップリング)する。
この現象は一般的なキャパシタ（Ｃ）とノイズの周波数（ω）で示すことができる。
Ｃ＝ε0＊ε＊Ｓ/ｄ・・・（式１）
但し、ε0：誘電率(真空)、ε：誘電率（絶縁性部材２２）、Ｓ:筐体３０との接触面積、ｄ: 絶縁性部材２２を介した筐体３０と導電性部材２１との距離
Ｚ＝１/（ｊωＣ)・・・（式２）但し、Ｚ:インピーダンス
以上の式１，２より、絶縁性部材２２の誘電率が低いと距離が短く、元のノイズの周波数が高いほど、インピーダンスが小さくなるため、電気ノイズの伝搬量が大きくなる。
ノイズ源の大きさ（Ｚに関係)、周波数(ω)に対応した、厚みｄ以上の絶縁性部材２２を使用することにより、伝搬ノイズを抑制することが可能である。
導電性部材２１の厚み（Ｌ−ｄ）は、受光回路基板２０のＧＮＤ部（２０Ｇ）の強化に効果がある。そのため導電性部材２１の厚みを、全体のＬに応じて大きくすることが望ましい。式２より、
Ｃ＜Ｚ＊ｊ＊ω
式１より、
ε0＊ε＊Ｓ/ｄ＜Ｚ＊ｊ＊ω
ｄ＞ε0＊ε＊Ｓ/(ｊω)
上限は、全体のＬとなるので、
ε0＊ε＊Ｓ/(ｊω) ＜ｄ＜Ｌ・・・（式３）
・絶縁材の厚みは誘電率を用いてｄ>0.15mm＊ε
・導電材の厚みＤ（＝Ｌ−ｄ）は、Noise ＝α＊Ｄ^(-a)
・α、a＝定数(材料、光学の構成により決まる値) The following is helpful for the propagation of electrical noise.
Through the thickness d of the insulating material, electrical noise of the housing 30 that is a conductor propagates (couples).
This phenomenon can be shown by a general capacitor (C) and noise frequency (ω).
C = ε0 * ε * S / d (Formula 1)
Where ε0: dielectric constant (vacuum), ε: dielectric constant (insulating member 22), S: contact area with the casing 30, d: between the casing 30 and the conductive member 21 via the insulating member 22. Distance Z = 1 / (jωC) (Expression 2) However, Z: Impedance From Expressions 1 and 2 above, the lower the dielectric constant of the insulating member 22, the shorter the distance and the higher the original noise frequency. Since the impedance is reduced, the propagation amount of electrical noise is increased.
Propagation noise can be suppressed by using the insulating member 22 having a thickness d or more corresponding to the size of the noise source (related to Z) and the frequency (ω).
The thickness (Ld) of the conductive member 21 is effective in strengthening the GND portion (20G) of the light receiving circuit board 20. Therefore, it is desirable to increase the thickness of the conductive member 21 in accordance with the entire L. From Equation 2,
C <Z * j * ω
From Equation 1,
ε0 * ε * S / d <Z * j * ω
d> ε0 * ε * S / (jω)
Since the upper limit is the entire L,
ε0 * ε * S / (jω) <d <L (Expression 3)
・ The thickness of the insulation material is calculated using the dielectric constant. D> 0.15mm * ε
・ Thickness D (= L-d) of conductive material is Noise = α * D ^ (-a)
・ Α, a = constant (value determined by material and optical configuration)

１レーザーレーダー装置
１０投光回路基板
１１導電性部材
２０受光回路基板
２０Ｇ接地パターン
２０Ｈ嵌合部
２０Ｒ受光素子
２１導電性部材
２２絶縁性部材
２３固定ネジ
３０筐体
３１投光・集光口
３２，３３孔部
Ｌ１投光路
Ｌ２受光路 DESCRIPTION OF SYMBOLS 1 Laser radar apparatus 10 Light projection circuit board 11 Conductive member 20 Light reception circuit board 20G Grounding pattern 20H Fitting part 20R Light receiving element 21 Conductive member 22 Insulating member 23 Fixing screw 30 Case 31 Light projection and condensing port 32, 33 Hole L1 Light Emitting Path L2 Light Receiving Path

Claims

A laser radar device in which a light emitting circuit board on which a laser oscillator is mounted and a light receiving circuit board on which a light receiving element is mounted are integrally fixed via a housing made of a conductive material,
A conductive member is disposed between the housing and the light receiving circuit board,
An insulating member is disposed between the housing and the conductive member to insulate both,
A laser radar device in which the conductive member is grounded by being electrically connected to a ground pattern included in the light receiving circuit board.

The laser radar device according to claim 1, wherein a light projecting path from the light projecting circuit board and a light receiving path to the light receiving circuit board are arranged coaxially in the housing.