【考案の詳細な説明】[Detailed explanation of the idea]
この考案は炎感知器における受光盤に関するも
のである。炎は紫外線から赤外線に至る広い波長
範囲の光を放射する。然し可視光線より赤外線ま
での光は炎のみでなく、光、太陽光、バーナー炉
壁の赤熱などあらゆる所に存在するため、可視〜
赤外の範囲の光を捉えて火災を報知しようとする
と、火災でないものを火災として報じてしまう誤
動作を起す。そこで、炎中の微弱な紫外線を高感
度で捉えて火災を報じるために紫外線検出管が用
いられる。
然し、この紫外線検出管には指向特性と云うも
のがあつて、紫外線検出管の光に対する向きによ
り感知性能が異る性質がある。即ち、第１図イに
示すように該検知管ａの陽極Ｐと陰極Ｋとを結ぶ
線PKが、光の来る方向Ｌに対し直交する場合の
感知状況は第１図イに示すような線図になるとす
ると、該検出管ａが90°回転し、前記線PKが前記
方向Ｌと一直線をなす場合には、その感知状況は
第１図ロに示す線図となる。
このため、火災検知器における該検出管ａは、
第２図に示すように、受光鏡ｂの中心部に立設
し、受光鏡ｂの反射面により、該検出管ａに直接
当らなかつた光も該反射面で反射して該検出管ａ
に当るようにし、少しでも多くの光が該検出管ａ
に当るようにしている。
然し、この反射面が深く、又曲率が一様である
と、第３図に示すような折角反射面で捉えた光ｌ
も検出管ａに当らない方向に反射されてしまう場
合があるし、検出管ａの受光部Ｏを中心とする光
の受入角θも比較的に小さい。この考案は叙上の
事実に鑑み、叙上の受入角θも大きくでき、光が
多量に検出管ａに当るようにした、炎感知器にお
ける受光盤を提供するのをその目的とする。
この考案に係る炎感知器における受光盤１の構
成を、第４、第５図に示す一実施例に基づいて説
明すると、第４図に示すように、平底２の周辺が
次第に彎曲して立上つている形状をなし、中心
に、第５図に明示するように、紫外線検出管ａの
突出用透孔３を有し、内面が微細な梨地面をなす
ものである。なお、４はフランジ部、５は取付螺
子用透孔を示す。なお又梨地面につくる方法は、
アルミニユーム材の場合に例を取れば、サンドブ
ラストで行い後にアルマイト処理をする。
この実施例は叙上のような構成を有し、平底２
に続いて周辺が彎曲して立上つているので、周辺
に当つた光は中心の紫外線検出管ａの方に集り易
いし、仮令、方向的には受光盤１に当つて該検出
管ａに当らずにそれて行く光でも受光盤１の反射
面が微細な梨地面となつているので乱反射を起こ
し、一部該検出管ａに当るようになり、該検出管
ａに当る光量を多くすることができるし、中央を
平底としたので該検出管ａに対する集光角θを大
きく取ることができ、従つてこの点からも光量を
増すことができる。
今、同一断面形状の受光盤１をアルミ材で作
り、この考案におけるように微細な梨地面にした
ものＡと、従来のように鏡面にしたものＢとにつ
き、該感知器より一定の距離離れた箇処に発生さ
せた炎を感知するまでの時間、及びその感知時間
短縮率を実験により求めた数値は下表の通りであ
り、
This invention relates to a light receiving panel in a flame detector. Flames emit light in a wide range of wavelengths, from ultraviolet to infrared. However, light ranging from visible light to infrared rays exists not only in flames, but also in light, sunlight, the red heat of burner furnace walls, and so on.
If an attempt is made to detect a fire by detecting light in the infrared range, a malfunction will occur in which something that is not a fire will be reported as a fire. Therefore, ultraviolet detection tubes are used to detect the weak ultraviolet rays in flames with high sensitivity and report fires. However, this ultraviolet detection tube has a so-called directional characteristic, and its sensing performance differs depending on the direction of the ultraviolet detection tube with respect to the light. That is, when the line PK connecting the anode P and cathode K of the detection tube a is perpendicular to the direction L of the light as shown in Fig. 1A, the sensing situation is as shown in Fig. 1A. If the detection tube a is rotated by 90 degrees and the line PK is in line with the direction L, the sensing situation will be as shown in the diagram shown in FIG. 1B. Therefore, the detection tube a in the fire detector is
As shown in FIG. 2, a light receiving mirror b is erected at the center, and by the reflecting surface of the light receiving mirror b, light that does not directly hit the detection tube a is also reflected by the reflecting surface, and the light that does not directly hit the detection tube a is reflected by the reflecting surface of the light receiving mirror b.
so that as much light as possible hits the detection tube a.
I try to hit it. However, if this reflective surface is deep and has a uniform curvature, the light captured by the reflective surface as shown in Figure 3 will be
The light may also be reflected in a direction that does not hit the detection tube a, and the acceptance angle θ of the light centered on the light receiving portion O of the detection tube a is also relatively small. In view of the above-mentioned facts, the purpose of this invention is to provide a light-receiving panel for a flame detector, which allows the above-mentioned acceptance angle θ to be made large so that a large amount of light hits the detection tube a. The structure of the light receiving plate 1 in the flame detector according to this invention will be explained based on an embodiment shown in FIGS. 4 and 5. As shown in FIG. It has a rising shape, has a through hole 3 in the center for protruding the ultraviolet detection tube a, as shown in FIG. 5, and has a fine satin surface on its inner surface. Note that 4 indicates a flange portion, and 5 indicates a through hole for a mounting screw. Furthermore, the method of making it on the pear surface is as follows.
For example, in the case of aluminum material, it is sandblasted and then anodized. This embodiment has the configuration as described above, and has two flat bottoms.
Since the periphery is curved and rises next to the periphery, the light that hits the periphery tends to concentrate towards the central ultraviolet detection tube a; Even if the light deviates without hitting the detection tube 1, since the reflective surface of the light receiving plate 1 has a fine pear-shaped surface, it causes diffuse reflection and some of the light hits the detection tube a, increasing the amount of light that hits the detection tube a. Since the center is flat-bottomed, the convergence angle θ with respect to the detection tube a can be set large, and the amount of light can also be increased from this point of view. Now, light receiving panels 1 with the same cross-sectional shape are made of aluminum material, one with a fine matte surface as in this invention, and the other with a mirror surface as in the past, B. They are placed at a certain distance from the sensor. The table below shows the time it takes to detect the flame generated at the location and the detection time reduction rate determined through experiments.
【表】
感知時間を短縮することができた。なお上表にお
いて毎回の試験毎に感知時間にバラツキのあるの
は炎発生状態を均等に保ち難いためである。
なお、第４図に示すように紫外線検出管ａの受
光部０を中心とし集光角θを160゜にするための受
光盤１の深さは下記の式より簡単に算出できる。
Ｄ＝Ｒ tan（90゜−160゜／２）＋Ｔ
但し Ｄ…受光盤１の深さ
Ｒ…受光盤１の半径
Ｔ…受光部０の高さ
この考案は叙上のような構成、作用を有するか
ら、火災感知器が対面する比較的広範囲の領域内
に発生する微弱な紫外線も、従来よりも短時間に
感知できる、炎感知器における受光盤を提供する
ことができる。[Table] It was possible to shorten the sensing time. In the table above, there is variation in the detection time for each test because it is difficult to maintain an even flame generation state. Incidentally, as shown in FIG. 4, the depth of the light receiving plate 1 in order to set the light collecting angle θ to 160° with the light receiving portion 0 of the ultraviolet detection tube a as the center can be easily calculated using the following formula. D=R tan (90° - 160°/2) + T However, D...Depth of light receiving plate 1 R...Radius of light receiving plate 1 T...Height of light receiving part 0 This invention has the above-mentioned configuration and operation. Therefore, it is possible to provide a light receiving panel for a flame detector that can detect weak ultraviolet rays generated within a relatively wide area facing the fire detector in a shorter time than before.
【図面の簡単な説明】[Brief explanation of the drawing]
第１図は紫外線検出管の指向特性の説明図、第
２図は炎感知器の斜視図、第３図は従来の受光鏡
の欠点の説明図、第４図はこの考案に係る炎感知
器における受光盤の縦断面図、第５図はその正面
図を夫々示し、２は平底、３は紫外線検出管の突
出用透孔を夫々示す。
Fig. 1 is an explanatory diagram of the directional characteristics of the ultraviolet detection tube, Fig. 2 is a perspective view of the flame detector, Fig. 3 is an explanatory diagram of the drawbacks of the conventional light receiving mirror, and Fig. 4 is the flame detector according to this invention. FIG. 5 is a longitudinal cross-sectional view of the light receiving plate, and FIG. 5 is a front view thereof, 2 is a flat bottom, and 3 is a through hole for protruding an ultraviolet detection tube.