JP3042951B2 - Light quantity stabilizing device in image input device - Google Patents
Light quantity stabilizing device in image input deviceInfo
- Publication number
- JP3042951B2 JP3042951B2 JP30373793A JP30373793A JP3042951B2 JP 3042951 B2 JP3042951 B2 JP 3042951B2 JP 30373793 A JP30373793 A JP 30373793A JP 30373793 A JP30373793 A JP 30373793A JP 3042951 B2 JP3042951 B2 JP 3042951B2
- Authority
- JP
- Japan
- Prior art keywords
- light
- light source
- constant current
- emitting diode
- circuit
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Image Input (AREA)
- Facsimile Scanning Arrangements (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は画像入力装置における光
量一定化装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for stabilizing the amount of light in an image input device .
【０００２】[0002]
【従来の技術】発光ダイオード等の光源からの光を被写
体に照射してその反射光或は透過光をイメージセンサで
受光する画像入力装置は、硬貨判別装置などに用いら
れ、光源の明るさが重要な要素となる。ところが、光源
は、温度変化及び経時変化により明るさが変化する。従
来は、サーミスタにより温度補償を行う温度補償部付き
の定電流回路を用いて光源の発光量を一定に制御する装
置や、マイクロコンピュータを用いてソフトウェアで
光源の発光量を一定に制御する装置が良く使用されて
いる。2. Description of the Related Art An image input device that irradiates a subject with light from a light source such as a light emitting diode and receives reflected light or transmitted light by an image sensor is used for a coin discriminating device or the like. It is an important factor. However, the brightness of the light source changes due to a change in temperature and a change with time. Conventionally, there have been devices that control the light emission of the light source using a constant current circuit with a temperature compensation unit that performs temperature compensation using a thermistor, and devices that control the light emission of the light source to constant using software using a microcomputer. Well used.
【０００３】また、特開平５ー１７６１２２号公報に
は、光源の使用累積時間と光量のとの関係を記憶する記
憶手段と、前記光源の使用累積時間を計測する使用累積
時間測定手段と、この使用累積時間測定手段で測定した
使用累積時間により前記記憶手段の記憶内容を参照して
前記光源の光量を求めこの光量を定常値として前記光源
の光量を制御する光量制御手段と、定常光量値が前記光
源の寿命に対応する所定値より小さい設定値に達したこ
とにより前記光源が寿命に達した旨のステータス情報を
出力するステータス情報出力手段とを備えたことを特徴
とするイメージセンサの光量一定化装置が記載されて
いる。Japanese Patent Application Laid-Open No. 5-176122 discloses a storage means for storing the relationship between the cumulative use time of a light source and the amount of light, a cumulative use time measuring means for measuring the cumulative use time of the light source, Light amount control means for controlling the light amount of the light source by obtaining the light amount of the light source with reference to the storage content of the storage means based on the cumulative use time measured by the cumulative use time measuring means, and controlling the light amount of the light source as a steady value, A status information output unit that outputs status information indicating that the light source has reached the end of its life when the set value has reached a set value smaller than a predetermined value corresponding to the life of the light source. An apparatus is described.
【０００４】さらに、特開平３ー７６０３４号公報に
は、記録用光ビームの光源としての半導体レーザと再生
用光ビームとしての発光ダイオードとを有する２光源方
式の光学的情報記録再生装置において、発光ダイオード
から出射され記録媒体で反射された光ビームを受光する
光検出器と、この光検出器の検出信号の出力手段と、こ
の出力手段からの出力値と所定の発光出力のための基準
値との差に応じた信号を出力する手段と、この差信号を
ゼロレベルに戻すように発光ダイオードの駆動電流を制
御する手段とを備えたことを特徴とする光学的情報記録
再生装置が記載されている。Japanese Patent Application Laid-Open No. 3-76034 discloses a two-light source type optical information recording / reproducing apparatus having a semiconductor laser as a light source of a recording light beam and a light emitting diode as a reproducing light beam. A photodetector for receiving a light beam emitted from the diode and reflected by the recording medium; output means for a detection signal of the photodetector; an output value from the output means and a reference value for a predetermined light emission output; An optical information recording / reproducing apparatus, comprising: means for outputting a signal corresponding to the difference between the two, and means for controlling the drive current of the light emitting diode so as to return the difference signal to zero level. I have.
【０００５】[0005]
【発明が解決しようとする課題】上記装置では、サー
ミスタにより温度補償を行う温度補償部付きの定電流回
路を用いて光源の発光量を一定に制御するので、光源の
発光量が光源の寿命により減少してしまう。また、上記
装置では、マイクロコンピュータを用いてソフトウェ
アで光源の発光量を一定に制御するので、回路構成が複
雑になってコストアップになり、ソフトウェアの作成も
必要になる。また、上記イメージセンサの光量一定化装
置では、記憶手段に記憶されている光源の使用累積時
間と光量のとの関係を参照して光源の定常光量を光源の
使用累積時間に応じて決め、光源が寿命に達した旨のス
テータス情報を出力するので、光源の経時変化に対する
対策として有効であるが、光源の明るさが温度変化によ
り変化してしまう。In the above device, the light emission amount of the light source is controlled to be constant by using a constant current circuit having a temperature compensator for performing temperature compensation by a thermistor. Will decrease. Further, in the above-described apparatus, since the amount of light emitted from the light source is controlled to be constant by software using a microcomputer, the circuit configuration becomes complicated, the cost increases, and software must be created. Further, in the light amount stabilizing device of the image sensor, the steady light amount of the light source is determined in accordance with the cumulative use time of the light source with reference to the relationship between the cumulative use time of the light source and the light amount stored in the storage means. Outputs the status information indicating that the life has expired, which is effective as a countermeasure against a temporal change of the light source. However, the brightness of the light source changes due to a temperature change.
【０００６】さらに、上記光学的情報記録再生装置で
は、発光ダイオードから出射され記録媒体で反射された
光ビームを受光する光検出器と、この光検出器の検出信
号の出力手段と、この出力手段からの出力値と所定の発
光出力のための基準値との差に応じた信号を出力する手
段と、この差信号をゼロレベルに戻すように発光ダイオ
ードの駆動電流を制御する手段とを備えたので、温度変
化に対する対策として有効であるが、光源の明るさが経
時変化により変化してしまう。Further, in the above optical information recording / reproducing apparatus, a photodetector for receiving a light beam emitted from a light emitting diode and reflected by a recording medium, output means for a detection signal of the photodetector, and output means for the output signal Means for outputting a signal corresponding to the difference between the output value from the reference signal and the reference value for the predetermined light emission output, and means for controlling the drive current of the light emitting diode so as to return the difference signal to zero level. Therefore, it is effective as a countermeasure against a temperature change, but the brightness of the light source changes over time.
【０００７】そこで、上記各装置を組み合わせて光源の
明るさを経時変化と温度変化の両方に対して変化しない
ようにすることが考えられるが、これは複雑な構成が強
いられ、しかも、実際の使用にあたっては使用温度条件
（例えば０℃〜６０℃等）、耐用期間を満足させる必要
がある。本発明は、上記欠点を改善し、構成が簡単で光
源の発光量制御をソフトウェアによる制御無しに経時変
化と温度変化の両方に対して安定に行うことができる画
像入力装置における光量一定化装置を提供することを目
的とする。Therefore, it is conceivable to combine the above devices so that the brightness of the light source does not change with time and with temperature. In use, it is necessary to satisfy a use temperature condition (for example, 0 ° C. to 60 ° C.) and a service life. The present invention improves the above disadvantage, image can be performed stably with respect to both the aging and temperature change the light emission amount control arrangement is simple source without software control
It is an object of the present invention to provide a constant light amount device in an image input device .
【０００８】[0008]
【課題を解決するための手段】上記目的を達成するた
め、請求項１記載の発明は、光源からの光を被写体に照
射してその反射光或いは透過光をイメージセンサで光電
変換するようにした画像入力装置において、前記イメー
ジセンサとは異なる、前記光源の明るさを検出するフォ
トセンサと、前記光源に定電流を供給する定電流回路
と、前記フォトセンサの出力信号を増幅する増幅回路
と、この増幅回路の出力信号と所定の設定値との差をと
って該差により前記定電流回路の定電流を可変する差動
増幅器とを備え、前記フォトセンサの出力により前記定
電流回路の定電流を可変するようにして前記光源の発光
量を一定にするように制御するようにしたものである。In order to achieve the above object, the invention according to claim 1 irradiates light from a light source to a subject.
The reflected light or transmitted light is illuminated by an image sensor.
The image input apparatus adapted to convert the Image
Jisensa different from a photo sensor which detects the brightness of the light source, a constant current circuit for supplying a constant current to the light source, an amplifying circuit for amplifying the output signal of the photosensor, the output signal of the amplifier circuit and a differential amplifier for varying the constant current of the constant current circuit by difference taking the difference between the predetermined set value, the constant by the output of the photosensor
The light source emits light by changing the constant current of the current circuit.
The amount is controlled to be constant .
【０００９】[0009]
【作用】光源からの光が被写体に照射されてその反射光
或いは透過光がイメージセンサで光電変換される。前記
イメージセンサとは異なるフォトセンサが前記光源の明
るさを検出し、定電流回路が光源に定電流を供給する。
フォトセンサの出力信号が増幅回路により増幅され、差
動増幅器が前記増幅回路の出力信号と所定の設定値との
差をとって該差により前記定電流回路の定電流を可変す
る。これにより、前記フォトセンサの出力で前記定電流
回路の定電流が可変されて前記光源の発光量が一定にな
るように制御される。An object is irradiated with light from a light source, and the reflected light or transmitted light is photoelectrically converted by an image sensor. A photo sensor different from the image sensor detects the brightness of the light source, and a constant current circuit supplies a constant current to the light source.
The output signal of the photosensor is amplified by the amplifier circuit, and the differential amplifier takes the difference between the output signal of the amplifier circuit and a predetermined set value, and varies the constant current of the constant current circuit according to the difference. Thereby, the constant current of the constant current circuit is varied by the output of the photo sensor, and the light source is controlled such that the light emission amount of the light source becomes constant.
【００１０】[0010]
【実施例】図１は本発明の一実施例を示す。この実施例
は、硬貨判別用画像入力装置における光量一定化装置の
例１０であり、ループ系のフィードバック回路である。
画像入力装置は、光スキャナ１１で被写体を走査しなが
ら発光ダイオード（ＬＥＤ）からなる光源１２から被写
体に光を照射し、その反射光（もしくは透過光）をＣＣ
Ｄからなるイメージセンサで光電変換して図示しない画
像処理部で処理する。FIG. 1 shows an embodiment of the present invention. This embodiment is an example 10 of a light amount stabilizing device in a coin discriminating image input device, and is a loop-type feedback circuit.
The image input device irradiates a subject with light from a light source 12 composed of a light emitting diode (LED) while scanning the subject with an optical scanner 11, and reflects the reflected light (or transmitted light) to the CC.
The image data is photoelectrically converted by an image sensor made of D and processed by an image processing unit (not shown).
【００１１】この光スキャナ１１において、光源１２か
ら被写体に照射される光の光量は、光軸から外れた（被
写体へ照射された光を邪魔しない）位置に設けられたフ
ォトセンサ１３で検出されて発光ダイオード１２の発光
量に比例した光電流に光電変換され、本実施例１０はフ
ォトセンサ１３の出力信号によりスキャナ１１で検出す
る画像の明るさを一定に保つ。In the optical scanner 11, the amount of light emitted from the light source 12 to the subject is detected by a photo sensor 13 provided at a position off the optical axis (does not interfere with the light emitted to the subject). In the tenth embodiment, the brightness of the image detected by the scanner 11 is kept constant by the output signal of the photo sensor 13.
【００１２】本実施例はフォトセンサ１３の他に定電流
回路１４、抵抗１５、増幅回路１６、差動増幅器１７及
びアラーム用検出回路１８を有し、定電流回路１４はト
ランジスタ２０、抵抗２１、演算増幅器２２及びダイオ
ード２３により構成される。ここに、トランジスタ２０
のエミッタは抵抗２１を介してアースに接続され、トラ
ンジスタ２０のコレクタは発光ダイオード１２を介して
直流電源に接続される。発光ダイオード１２は定電流回
路１４から１０ｍＡ〜２０ｍＡの定電流Irが供給されて
発光し、フォトセンサ１３から出力される光電流が抵抗
１５により電圧に変換されて増幅回路１６により例えば
１．０Ｖになるまで増幅（調整）される。This embodiment has a constant current circuit 14, a resistor 15, an amplifier circuit 16, a differential amplifier 17, and an alarm detection circuit 18 in addition to the photo sensor 13, and the constant current circuit 14 includes a transistor 20, a resistor 21, It comprises an operational amplifier 22 and a diode 23. Here, the transistor 20
Is connected to the ground via a resistor 21, and the collector of the transistor 20 is connected to a DC power supply via a light emitting diode 12. The light emitting diode 12 emits light when a constant current Ir of 10 mA to 20 mA is supplied from the constant current circuit 14, and the photocurrent output from the photosensor 13 is converted into a voltage by the resistor 15, and is converted to, for example, 1.0 V by the amplifier circuit 16. It is amplified (adjusted) until it is.
【００１３】差動増幅器１７は増幅回路１６の出力信号
電圧とＬＥＤ電流リミット値設定回路１９からのＬＥＤ
電流リミット値とが入力されてこれらの差をとる。ここ
に、ＬＥＤ電流リミット値は発光ダイオード１２の電流
の上限値を決める値である。発光ダイオード１２は、定
格電流があり、かつ、温度により電流が変わる。例え
ば、発光ダイオード１２の定格電流は３０ｍＡであり、
６０℃では発光ダイオード１２の電流が１８ｍＡとな
る。そこで、ＬＥＤ電流リミット値設定回路１９は発光
ダイオード１２の定格電流の最低値を元にＬＥＤ電流リ
ミット値を設定し、例えばＬＥＤ電流リミット値を２．
０Ｖとする。従って、差動増幅器１７の出力側には１．
０Ｖの出力信号電圧が現れる。また、発光ダイオード１
２への電流Ｉrが通常使用に適する電流となるように増
幅回路１６の増幅度が設定され、これにより初期で通常
温度のときの発光ダイオード１２の明るさが決まる。増
幅回路１６の増幅度は発光ダイオード１２の明るさが初
期には当然余裕を持つように、すなわち、適正な使用範
囲の中で低めとなるように設定される。The differential amplifier 17 has an output signal voltage of the amplifier circuit 16 and an LED from the LED current limit value setting circuit 19.
The current limit value is input and the difference between them is calculated. Here, the LED current limit value is a value that determines the upper limit value of the current of the light emitting diode 12. The light emitting diode 12 has a rated current and the current changes depending on the temperature. For example, the rated current of the light emitting diode 12 is 30 mA,
At 60 ° C., the current of the light emitting diode 12 becomes 18 mA. Therefore, the LED current limit value setting circuit 19 sets the LED current limit value based on the minimum value of the rated current of the light emitting diode 12, and for example, sets the LED current limit value to 2.
0V. Therefore, 1 ..
An output signal voltage of 0V appears. Light emitting diode 1
The amplification degree of the amplifier circuit 16 is set so that the current Ir to 2 becomes a current suitable for normal use, and thereby, the brightness of the light emitting diode 12 at the time of the normal temperature is initially determined. The amplification degree of the amplifier circuit 16 is set such that the brightness of the light emitting diode 12 has a margin at the beginning, that is, it is lower in an appropriate use range.
【００１４】定電流回路１４においては、差動増幅器１
７の出力信号電圧が演算増幅器２２を介してトランジス
タ２０のベースに印加され、差動増幅器１７の出力信号
電圧に応じた定電流Ｉrが電源からトランジスタ２０お
よび抵抗２１を通して発光ダイオード１２に供給され
る。抵抗２１の電圧は演算増幅器２２にフィードバック
され、抵抗２１を例えば１００Ωとすれば増幅回路１６
の出力信号電圧が１Ｖの時には発光ダイオード１２には
１０ｍＡの電流Ｉrが流れる。増幅回路１６の出力信号
電圧が２Ｖの時には発光ダイオード１２には２０ｍＡの
電流が流れる。In the constant current circuit 14, the differential amplifier 1
7 is applied to the base of the transistor 20 via the operational amplifier 22, and a constant current Ir corresponding to the output signal voltage of the differential amplifier 17 is supplied from the power supply to the light emitting diode 12 through the transistor 20 and the resistor 21. . The voltage of the resistor 21 is fed back to the operational amplifier 22. If the resistor 21 is set to, for example, 100Ω, the amplification circuit 16
When the output signal voltage is 1 V, a current Ir of 10 mA flows through the light emitting diode 12. When the output signal voltage of the amplifier circuit 16 is 2 V, a current of 20 mA flows through the light emitting diode 12.
【００１５】発光ダイオード１２の発光量が環境変動
（温度変化）や経時変化により例えば２０％減少すれ
ば、増幅回路１６の出力信号電圧は０．８Ｖとなり、差
動増幅器１７の出力信号電圧が１．２Ｖとなる。このた
め、トランジスタ２０のコレクタから発光ダイオード１
２へ供給される電流Ｉrは２０％増加して１２ｍＡとな
り、発光ダイオード１２の発光量補正が行われる。発光
ダイオード１２の順電流対光量は図２に示すように使用
範囲においてほぼリニアである。If the light emission amount of the light emitting diode 12 is reduced by, for example, 20% due to environmental fluctuation (temperature change) or aging, the output signal voltage of the amplifier circuit 16 becomes 0.8 V and the output signal voltage of the differential amplifier 17 becomes 1 .2V. For this reason, the light emitting diode 1
The current Ir supplied to 2 increases by 20% to 12 mA, and the light emission amount of the light emitting diode 12 is corrected. The forward current versus the light amount of the light emitting diode 12 is substantially linear in the range of use as shown in FIG.
【００１６】発光ダイオード１２は環境変動による影響
を受け易いデバイスであり、図３及び図４に示すように
発光量が温度変化、経時変化により極端に変動する。と
ころが、発光ダイオード１２の発光量が温度変化、経時
変化により変動すれば、上述のように増幅回路１６の出
力信号電圧が減少して差動増幅器１７の出力信号電圧が
増加し、定電流回路１４の定電流Ｉrが増加して発光ダ
イオード１２の発光量補正が行われるので、発光ダイオ
ード１２の発光量が一定に保たれる。The light emitting diode 12 is a device which is easily affected by environmental changes. As shown in FIGS. 3 and 4, the light emission amount fluctuates extremely due to temperature change and aging. However, if the amount of light emitted from the light emitting diode 12 fluctuates due to a change in temperature or a change with time, the output signal voltage of the amplifier circuit 16 decreases and the output signal voltage of the differential amplifier 17 increases, as described above. Is increased and the light emission amount of the light emitting diode 12 is corrected, so that the light emission amount of the light emitting diode 12 is kept constant.
【００１７】また、アラーム用検出回路１８は、差動増
幅器１７の出力信号電圧を監視し、差動増幅器１７の出
力信号電圧を所定の電圧、例えば１．８Ｖと比較して発
光ダイオード１２の発光量が発光ダイオード１２の寿命
等により異常に低下して差動増幅器１７の出力信号電圧
が１．８Ｖ以上となった時にホストにアラームを出して
異常を知らせる。The alarm detection circuit 18 monitors the output signal voltage of the differential amplifier 17 and compares the output signal voltage of the differential amplifier 17 with a predetermined voltage, for example, 1.8 V, to emit light of the light emitting diode 12. When the output level abnormally decreases due to the life of the light emitting diode 12 or the like and the output signal voltage of the differential amplifier 17 becomes 1.8 V or more, an alarm is issued to the host to notify the host of the abnormality.
【００１８】なお、フォトセンサ１３は温度が上がると
出力値が上昇するという温度特性があるので、フォトセ
ンサ１３の温度補償を行う周知の温度補償手段が設けら
れ、この温度補償手段はフォトセンサ１３の温度特性と
は反対の温度特性（温度が上がると出力値が下降すると
いう温度特性）を有するサーミスタを用いてフォトセン
サ１３の温度補償を行う。Since the photosensor 13 has a temperature characteristic that the output value increases as the temperature rises, a well-known temperature compensating means for compensating the temperature of the photosensor 13 is provided. The temperature compensation of the photosensor 13 is performed using a thermistor having a temperature characteristic opposite to the temperature characteristic (a temperature characteristic in which the output value decreases as the temperature increases).
【００１９】この実施例では、定電流回路１４から発光
ダイオード１２に定電流を供給し、発光ダイオード１２
の明るさをフォトセンサ１３により検出してフォトセン
サ１３の出力信号を増幅回路１６により増幅し、差動増
幅器１７により増幅回路１６の出力信号とＬＥＤ電流リ
ミット値との差をとってその差により定電流回路１４の
定電流を可変するので、発光ダイオード１２の発光量を
温度変化及び経時変化の両方に対して安定に制御でき、
かつ、ソフトウェアによる制御無しに実現できる。しか
も、構成が簡単で、低コストにできる。さらに、サーミ
スタによる温度補償付きの定電流回路を用いて光源の発
光量を一定に制御する装置に比べて精度良く発光ダイオ
ード１２の発光量を制御でき、また、発光ダイオードの
寿命を延ばすことができる。なお、本発明は、上記実施
例に限定されるものではなく、硬貨判別用画像入力装置
に限らず、発光ダイオードなどの光源を使用する、あら
ゆる装置に適用することが可能である。In this embodiment, a constant current is supplied from the constant current circuit 14 to the light emitting diode 12, and the light emitting diode 12
The output signal of the photosensor 13 is amplified by the amplifier circuit 16, and the difference between the output signal of the amplifier circuit 16 and the LED current limit value is obtained by the differential amplifier 17. Since the constant current of the constant current circuit 14 is variable, the light emission amount of the light emitting diode 12 can be controlled stably with respect to both the temperature change and the change with time.
And it can be realized without software control. Moreover, the configuration is simple and the cost can be reduced. Further, the light emission amount of the light emitting diode 12 can be controlled with higher accuracy than a device that controls the light emission amount of the light source to be constant using a constant current circuit with temperature compensation by a thermistor, and the life of the light emitting diode can be extended. . The present invention is not limited to the above embodiment, and is not limited to the image input device for coin discrimination, but can be applied to any device using a light source such as a light emitting diode.
【００２０】[0020]
【発明の効果】以上のように請求項１記載の発明によれ
ば、光源からの光を被写体に照射してその反射光或いは
透過光をイメージセンサで光電変換するようにした画像
入力装置において、前記イメージセンサとは異なる、前
記光源の明るさを検出するフォトセンサと、前記光源に
定電流を供給する定電流回路と、前記フォトセンサの出
力信号を増幅する増幅回路と、この増幅回路の出力信号
と所定の設定値との差をとって該差により前記定電流回
路の定電流を可変する差動増幅器とを備え、前記フォト
センサの出力により前記定電流回路の定電流を可変する
ようにして前記光源の発光量を一定にするように制御す
るようにしたので、光源の発光量を温度変化及び経時変
化の両方に対して安定に制御でき、かつ、ソフトウェア
による制御無しに実現できる。しかも、構成が簡単で、
低コストにできる。さらに、サーミスタによる温度補償
付きの定電流回路を用いて光源の発光量を一定に制御す
る装置に比べて精度良く光源の発光量を制御でき、ま
た、光源の寿命を延ばすことができる。As described above, according to the first aspect of the present invention, there is provided an image input apparatus in which light from a light source is irradiated onto a subject and reflected light or transmitted light is photoelectrically converted by an image sensor. A photosensor that detects the brightness of the light source, a constant current circuit that supplies a constant current to the light source, an amplifier circuit that amplifies an output signal of the photosensor, and an output of the amplifier circuit, which is different from the image sensor. A differential amplifier that takes a difference between the signal and a predetermined set value and varies the constant current of the constant current circuit according to the difference, wherein the constant current of the constant current circuit is varied by the output of the photosensor. Therefore, the light emission amount of the light source is controlled so as to be constant, so that the light emission amount of the light source can be controlled stably with respect to both temperature change and temporal change, and without control by software. It can be current. Moreover, the configuration is simple,
Cost can be reduced. Further, the light emission amount of the light source can be controlled more accurately than the device that controls the light emission amount of the light source to be constant using a constant current circuit with temperature compensation by a thermistor, and the life of the light source can be extended.
【図１】本発明の一実施例を示すブロック図である。FIG. 1 is a block diagram showing one embodiment of the present invention.
【図２】発光ダイオードの順電流対発光量特性を示す特
性図である。FIG. 2 is a characteristic diagram showing a forward current vs. light emission amount characteristic of a light emitting diode.
【図３】発光ダイオードの温度特性を示す特性図であ
る。FIG. 3 is a characteristic diagram showing a temperature characteristic of a light emitting diode.
【図４】発光ダイオードの経時特性を示す特性図であ
る。FIG. 4 is a characteristic diagram showing a temporal characteristic of a light emitting diode.
１２ 発光ダイオード １３ フォトセンサ １４ 定電流回路 １５ 抵抗 １６ 増幅回路 １７ 差動増幅器 Reference Signs List 12 light emitting diode 13 photo sensor 14 constant current circuit 15 resistor 16 amplifier circuit 17 differential amplifier
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 昭61−240775（ＪＰ，Ａ) 特開 平３−280780（ＪＰ，Ａ) 実開 昭52−62017（ＪＰ，Ｕ) 実開 平６−54355（ＪＰ，Ｕ) (58)調査した分野(Int.Cl.7，ＤＢ名) H04N 1/04 - 1/207 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-240775 (JP, A) JP-A-3-280780 (JP, A) Fully open 1975-62017 (JP, U) Really open 6- 54355 (JP, U) (58) Fields surveyed (Int. Cl. 7 , DB name) H04N 1/04-1/207
Claims (1)
光或いは透過光をイメージセンサで光電変換するように
した画像入力装置において、前記イメージセンサとは異
なる、前記光源の明るさを検出するフォトセンサと、前
記光源に定電流を供給する定電流回路と、前記フォトセ
ンサの出力信号を増幅する増幅回路と、この増幅回路の
出力信号と所定の設定値との差をとって該差により前記
定電流回路の定電流を可変する差動増幅器とを備え、前
記フォトセンサの出力により前記定電流回路の定電流を
可変するようにして前記光源の発光量を一定にするよう
に制御するようにしたことを特徴とする画像入力装置に
おける光量一定化装置。An object is irradiated with light from a light source and reflected therefrom.
Light or transmitted light is photoelectrically converted by an image sensor
In the image input device , the image sensor is different from the image sensor.
Comprising a photosensor for detecting the brightness of the light source, a constant current circuit for supplying a constant current to the light source, an amplifying circuit for amplifying the output signal of the photosensor, setting the output signal and a predetermined of the amplifier circuit and a differential amplifier for the variable constant current of the constant current circuit by difference taking the difference between the value, before
The constant current of the constant current circuit is determined by the output of the photo sensor.
Variable so that the light emission amount of the light source is constant.
A light amount stabilizing device in an image input device , characterized in that the light amount stabilizing device is controlled.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP30373793A JP3042951B2 (en) | 1993-12-03 | 1993-12-03 | Light quantity stabilizing device in image input device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP30373793A JP3042951B2 (en) | 1993-12-03 | 1993-12-03 | Light quantity stabilizing device in image input device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH07162597A JPH07162597A (en) | 1995-06-23 |
| JP3042951B2 true JP3042951B2 (en) | 2000-05-22 |
Family
ID=17924668
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP30373793A Expired - Fee Related JP3042951B2 (en) | 1993-12-03 | 1993-12-03 | Light quantity stabilizing device in image input device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3042951B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8077137B2 (en) | 2006-06-29 | 2011-12-13 | Samsung Led Co., Ltd. | Liquid crystal display backlight driving system with light emitting diodes |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4082547B2 (en) * | 1999-02-26 | 2008-04-30 | 矢崎総業株式会社 | Power supply control device for light emitting element |
| US20090160833A1 (en) | 2007-12-21 | 2009-06-25 | Microvision, Inc. | Laser Projection White Balance Tracking |
| CN112204379A (en) * | 2018-06-04 | 2021-01-08 | 默克专利股份公司 | Calibration device for a light detector and setting device for setting calibration points for a calibration device |
-
1993
- 1993-12-03 JP JP30373793A patent/JP3042951B2/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8077137B2 (en) | 2006-06-29 | 2011-12-13 | Samsung Led Co., Ltd. | Liquid crystal display backlight driving system with light emitting diodes |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH07162597A (en) | 1995-06-23 |
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