JPH04107888A - Led driver lsi - Google Patents
Led driver lsiInfo
- Publication number
- JPH04107888A JPH04107888A JP2226170A JP22617090A JPH04107888A JP H04107888 A JPH04107888 A JP H04107888A JP 2226170 A JP2226170 A JP 2226170A JP 22617090 A JP22617090 A JP 22617090A JP H04107888 A JPH04107888 A JP H04107888A
- Authority
- JP
- Japan
- Prior art keywords
- temperature
- led
- value
- reference voltage
- voltage
- 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.)
- Pending
Links
- 238000012937 correction Methods 0.000 description 5
- 238000000034 method Methods 0.000 description 3
- 238000009529 body temperature measurement Methods 0.000 description 2
- 238000001454 recorded image Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
Landscapes
- Dot-Matrix Printers And Others (AREA)
- Printers Or Recording Devices Using Electromagnetic And Radiation Means (AREA)
- Led Devices (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明はLEDドライバLSIに関し、特にファクシミ
リ等の電子写真記録に用いるLED記録ヘッド用LED
ドライバLSIに関する。[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an LED driver LSI, and particularly to an LED for an LED recording head used in electrophotographic recording such as a facsimile.
Regarding driver LSI.
高性能ファクシミリ受信機等の電子写真記録方式として
高記録速度、高解像度等の長所から、最近、発光ダイオ
ード(以下LED)を記録幅一杯に配列したLEDアレ
ーを光源とするLEDアレー記録方式が採用される例が
多くなっている。As an electrophotographic recording method for high-performance facsimile receivers, etc., due to its advantages such as high recording speed and high resolution, the LED array recording method, which uses an LED array in which light emitting diodes (hereinafter referred to as LEDs) are arranged to cover the full recording width, is used as a light source has recently been adopted. There are many cases where this is the case.
LEDアレーを主要構成要素とするLED記録ヘッドは
、記録幅一杯に一列に並べた数十個のLEDからなるL
EDアレーと、その両側もしくは片側に配列されたLE
Dドライバ回路がら構成される。The LED recording head, which has an LED array as its main component, is an L head consisting of several dozen LEDs arranged in a line across the entire recording width.
ED array and LE arranged on both sides or one side of it
It consists of a D driver circuit.
LEDドライバ回路は通常LSI化され、LEDアレー
を構成する個々のLEDの発光量のばらつきを小さくす
るために、一般には、定電流駆動方式が用いられる。The LED driver circuit is usually implemented as an LSI, and a constant current drive method is generally used in order to reduce variations in the amount of light emitted by the individual LEDs forming the LED array.
従来のこの種の定電流駆動方式のLEDドライバLSI
の一例を第2図に示す。Conventional constant current drive type LED driver LSI of this type
An example is shown in FIG.
なお、第2図の回路には、LED駆動回路のみを示して
おり、データの入出力用の回路は省略しである。Note that the circuit in FIG. 2 shows only the LED driving circuit, and the data input/output circuit is omitted.
第2図を参照すると、従来のLEDドライバLSIは、
駆動部5と、LEDアレー6、基準電圧源VRと、抵抗
器Rとで構成されていた。Referring to FIG. 2, the conventional LED driver LSI is
It was composed of a driving section 5, an LED array 6, a reference voltage source VR, and a resistor R.
駆動部5は、演算増幅器OP1と、トランジスタMl、
Qlと、ドライバ回路51〜5nから構成されていた。The drive unit 5 includes an operational amplifier OP1, a transistor Ml,
Ql and driver circuits 51 to 5n.
トランジスタQlは、各ドライバ回路のトランジスタで
カレントミラー回路を構成する。The transistor Ql constitutes a current mirror circuit with the transistors of each driver circuit.
ドライバ回路51〜5nは、それぞれ、カレントミラー
回路の他の一方を構成するトランジスタQ5i2(i=
1〜n)と、CMOSスイッチ回路55i1から構成さ
れていた。The driver circuits 51 to 5n each have a transistor Q5i2 (i=
1 to n) and a CMOS switch circuit 55i1.
LEDアレー6は、n個のLEDD1〜Dnから構成さ
れていた。The LED array 6 was composed of n LEDs D1 to Dn.
次に、第2図に示した従来のLEDドライバLSIの動
作について説明する。Next, the operation of the conventional LED driver LSI shown in FIG. 2 will be explained.
各ドライバ回路51〜5nのカレントミラー回路を構成
するトランジスタQ1に流れる電流工は、抵抗器Rの抵
抗値Rと、基準電圧源VRの電圧値VRにより、次式で
与えられる。The current flowing through the transistor Q1 constituting the current mirror circuit of each of the driver circuits 51 to 5n is given by the following equation based on the resistance value R of the resistor R and the voltage value VR of the reference voltage source VR.
I=VR/R(1)
このとき、たとえばドライバ回路51のCMOSスイッ
チ回路5511がオン状態であれば、トランジスタQ5
12にも同様に電流Iが流れる。I=VR/R (1) At this time, for example, if the CMOS switch circuit 5511 of the driver circuit 51 is in the on state, the transistor Q5
Similarly, current I flows through 12 as well.
ただし、Ql、Q512のトンランジスタサイズは同じ
とする。なお、ドライバ回路51〜5nのCMOSスイ
ッチ回路5511〜55n1は、端子T1〜Tnから入
力される入力データによりオン、オフされる。 演算増
幅器OPIと、そのバッファ増幅器であるトランジスタ
M1は、電源VDD等の外部要因による電流Iの変動を
抑圧するための安定化回路である。However, it is assumed that the transistor sizes of Ql and Q512 are the same. Note that the CMOS switch circuits 5511 to 55n1 of the driver circuits 51 to 5n are turned on and off by input data input from the terminals T1 to Tn. The operational amplifier OPI and the transistor M1, which is its buffer amplifier, are a stabilizing circuit for suppressing fluctuations in the current I caused by external factors such as the power supply VDD.
トランジスタQ2の電流Iは、LEDアレー6のLED
DIに供給されこれを駆動するものであった。The current I of the transistor Q2 is the LED of the LED array 6.
It was supplied to the DI to drive it.
ドライバ回路52〜5nについても、CMOSスイッチ
回路8521〜55nlがオン状態となることにより同
様の動作を行なうものであった。The driver circuits 52 to 5n perform similar operations when the CMOS switch circuits 8521 to 55nl are turned on.
上述した従来のLEDドライバLSIは、常時一定の電
流を供給するものであった。The conventional LED driver LSI described above always supplies a constant current.
しかし、LEDは、温度により発光量が変化する。−例
として、駆動電流を一定とすると、25℃から70℃に
変化すると、発光量は、20〜30%減少し、また、2
5℃から0℃に変化すると、発光量は、20〜30%増
加するという欠点があった。However, the amount of light emitted by LEDs changes depending on the temperature. - As an example, if the drive current is constant, when the temperature changes from 25°C to 70°C, the amount of light emission decreases by 20-30%;
There was a drawback that when changing from 5°C to 0°C, the amount of light emission increased by 20 to 30%.
LED記録ヘッドの使用条件では、70℃程度に温度上
昇することは普通である。この場合、LEDの発光量が
20〜30%減少するため、反転現像の場合の記録画像
が薄くなるという欠点があった。Under the usage conditions of an LED recording head, it is normal for the temperature to rise to about 70°C. In this case, since the amount of light emitted from the LED is reduced by 20 to 30%, there is a drawback that the recorded image in the case of reversal development becomes thinner.
すなわち、環境温度により、記録画像の濃淡が影響され
るという欠点があった。That is, there was a drawback that the density of the recorded image was affected by the environmental temperature.
本発明のLEDドライバLSIは、LEDを列状に配列
したLEDアレーを用いる電子写真記録用LED記録ヘ
ッドを、基準電圧源の電圧値により設定される電流を出
力する定電流駆動回路により駆動するLEDドライバL
SIにおいて、前記LEDの温度を計測する温度計測手
段と、前記温度に対応する補正を行なった前記電圧値の
温度補正電圧値を予め記憶した記憶手段と、読出した前
記温度補正電圧値を出力する出力手段を有するものであ
る。The LED driver LSI of the present invention drives an LED recording head for electrophotographic recording using an LED array in which LEDs are arranged in a row, using a constant current drive circuit that outputs a current set by the voltage value of a reference voltage source. Driver L
In the SI, a temperature measurement means for measuring the temperature of the LED, a storage means for storing in advance a temperature correction voltage value of the voltage value corrected corresponding to the temperature, and outputting the read temperature correction voltage value. It has an output means.
次に、本発明について図面を参照して説明する。 Next, the present invention will be explained with reference to the drawings.
第1図は、本発明の一実施例を示す回路図である。FIG. 1 is a circuit diagram showing one embodiment of the present invention.
第1図を参照すると、本発明のLEDドライバLSIは
、従来と同様の駆動部5と、LEDアレー6と、抵抗器
Rに加えて、基準電圧源VRの代りに、温度センサ1と
、A/D変換器2と、EEPROM (電気的に記憶情
報の消去再書込みが可能な不揮発性メモリ)3と、D/
A変換器4とが追加された構成となっている。Referring to FIG. 1, the LED driver LSI of the present invention includes a drive section 5, an LED array 6, and a resistor R similar to the conventional one, and also includes a temperature sensor 1 and a temperature sensor A instead of a reference voltage source VR. /D converter 2, EEPROM (non-volatile memory in which stored information can be electrically erased and rewritten) 3, and
It has a configuration in which an A converter 4 is added.
次に、本実施例の動作について説明する。Next, the operation of this embodiment will be explained.
温度センサ1は、LEDアレー6内に設けられ、動作中
のLEDの温度を計測しその値を電圧値に変換するもの
である。The temperature sensor 1 is provided within the LED array 6 and measures the temperature of the LEDs during operation and converts the temperature into a voltage value.
温度センサ1の動作原理としては、バイポーラトランジ
スタのペースエミッタ間電圧VBHの温度検数を利用し
ている。The operating principle of the temperature sensor 1 is to utilize the temperature coefficient of the pace emitter voltage VBH of a bipolar transistor.
温度センサ1の出力は、電圧値で表わされた温度情報で
あり、A/D変換器2に入力され、ディジタル数値に変
換される。The output of the temperature sensor 1 is temperature information expressed as a voltage value, which is input to the A/D converter 2 and converted into a digital value.
ディジタル数値に変換された温度情報は、EEFROM
Bに入力され、EEFROMBのアドレスを指定してそ
の内容を読出す。Temperature information converted to digital values is stored in EEFROM.
B, the address of EEFROMB is specified and its contents are read.
EEFROMBには、予め、温度情報をアドレスとして
、LEDの発光量の温度特性を補償する値が書込まれて
いる。In EEFROMB, a value that compensates for the temperature characteristics of the amount of light emitted by the LED is written in advance using temperature information as an address.
EEFROMBから読出されたディジタル温度情報は、
D/A変換器4に入力され、電圧値に変換される。The digital temperature information read from EEFROMB is
The signal is input to the D/A converter 4 and converted into a voltage value.
D/A変換器4の出力電圧VROは、駆動部5の演算増
幅器OPIに入力される。The output voltage VRO of the D/A converter 4 is input to the operational amplifier OPI of the drive section 5.
このD/A変換器4の出力電圧、すなわち、温度補正基
準電圧VROは、前述の従来例における基準電圧VRに
相当するものであり、したがって、抵抗器Rとにより、
(1)式にに示す関係でVRをVROと読替えることに
より、LEDアレー6の各LEDの動作電流Iが決定さ
れる。The output voltage of this D/A converter 4, that is, the temperature-corrected reference voltage VRO corresponds to the reference voltage VR in the conventional example described above, and therefore, by the resistor R,
By replacing VR with VRO in the relationship shown in equation (1), the operating current I of each LED of the LED array 6 is determined.
ここで、A/D変換器2のビット構成およびEEFRO
MBの容量は任意に設定できる。Here, the bit configuration of A/D converter 2 and EEFRO
The MB capacity can be set arbitrarily.
−例として、LED記録ヘッドの温度補正範囲を一10
℃〜100℃とし、A/D変換器2が8ビツト、EEF
ROMBが256ワード×6ビツトとして、出力電圧値
は0.5■から31.5Vまで0.02V間隔で設定で
きるものとする。- As an example, the temperature correction range of the LED recording head is
℃ to 100℃, A/D converter 2 is 8 bits, EEF
It is assumed that the ROMB is 256 words x 6 bits, and the output voltage value can be set from 0.5V to 31.5V at intervals of 0.02V.
ここで、室温25℃にて基準光量を満足する電圧値VR
を1.0■とすると、温度70℃に対しては1.3V、
また、0℃に対しては0.7■の出力電圧となるように
EEFROMB内にデータを書込んでおく。Here, the voltage value VR that satisfies the reference light amount at room temperature 25°C
If it is 1.0■, then 1.3V for a temperature of 70℃,
Further, data is written in the EEFROMB so that the output voltage is 0.7 cm for 0°C.
温度変化によるLEDアレーの各LEDの光量変化を補
正するような電流値が得られるように、温度補正基準電
圧電圧VROを設定しておく6以上、本発明の詳細な説
明したが、本発明は上記実施例に限゛られることなく種
々の変形が可能である。The temperature correction reference voltage VRO is set so as to obtain a current value that corrects the change in light intensity of each LED of the LED array due to temperature change.6 Although the present invention has been described in detail above, the present invention is Various modifications are possible without being limited to the above embodiments.
以上説明したように本発明は、LEDの発光量の温度特
性を補正するよう、電流を制御する基準電圧の温度補正
電圧値を記憶手段にに記憶しておき、温度検出手段から
の周囲温度計測値に対応する前記温度補正電圧値を読出
して、LEDドライバ回路の出力電流値を決定する基準
電圧を制御することにより、LEDの発光量を周囲温度
に関係なく一定に保持てきるという効果がある。As explained above, the present invention stores the temperature correction voltage value of the reference voltage for controlling the current in the storage means so as to correct the temperature characteristics of the light emission amount of the LED, and the ambient temperature measurement from the temperature detection means is performed. By reading out the temperature-corrected voltage value corresponding to the temperature-corrected voltage value and controlling the reference voltage that determines the output current value of the LED driver circuit, the amount of light emitted by the LED can be kept constant regardless of the ambient temperature. .
PROM、4・・・D/A変換器、5・・・駆動部、6
・・・LEDアレー、51〜5n・・・ドライバ回路。PROM, 4...D/A converter, 5...Driver, 6
...LED array, 51-5n...driver circuit.
Claims (1)
記録用LED記録ヘッドを、基準電圧源の電圧値により
設定される電流を出力する定電流駆動回路により駆動す
るLEDドライバLSIにおいて、 前記LEDの温度を計測する温度計測手段と、前記温度
に対応する補正を行なった前記電圧値の温度補正電圧値
を予め記憶した記憶手段と、読出した前記温度補正電圧
値を出力する出力手段を有することを特徴とするLED
ドライバLSI。[Claims] An LED driver LSI that drives an LED recording head for electrophotographic recording using an LED array in which LEDs are arranged in a row by a constant current drive circuit that outputs a current set by the voltage value of a reference voltage source. A temperature measuring means for measuring the temperature of the LED, a storage means for storing in advance a temperature-corrected voltage value of the voltage value corrected according to the temperature, and an output for outputting the read temperature-corrected voltage value. LED characterized in that it has a means
Driver LSI.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2226170A JPH04107888A (en) | 1990-08-28 | 1990-08-28 | Led driver lsi |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2226170A JPH04107888A (en) | 1990-08-28 | 1990-08-28 | Led driver lsi |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH04107888A true JPH04107888A (en) | 1992-04-09 |
Family
ID=16840975
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP2226170A Pending JPH04107888A (en) | 1990-08-28 | 1990-08-28 | Led driver lsi |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH04107888A (en) |
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1996037862A1 (en) * | 1995-05-22 | 1996-11-28 | OCé PRINTING SYSTEMS GMBH | Optical character generator for an electrographic printer or copier |
US5963242A (en) * | 1996-01-22 | 1999-10-05 | Fuji Xerox Co., Ltd. | Image recording apparatus with an array light source |
JP2002116481A (en) * | 2000-07-25 | 2002-04-19 | Fuji Photo Film Co Ltd | Stroboscopic device for camera, electronic camera and light emission head |
JP2002175046A (en) * | 2000-12-07 | 2002-06-21 | Sony Corp | Image display device |
JP2005516728A (en) * | 2002-01-30 | 2005-06-09 | ソシエテ サテレク | Electro-optical device for photopolymerization of composite materials |
JP2009042773A (en) * | 2000-07-25 | 2009-02-26 | Fujifilm Corp | Flash device of camera and electronic camera |
JP2012243885A (en) * | 2011-05-18 | 2012-12-10 | Oki Data Corp | Reference voltage generation circuit, drive unit, print head and image forming apparatus |
JPWO2011030381A1 (en) * | 2009-09-10 | 2013-02-04 | 三菱電機株式会社 | LED lighting device for headlamp and headlamp lighting system for vehicle |
JP2013219633A (en) * | 2012-04-10 | 2013-10-24 | Fuji Electric Co Ltd | Circuit for driving power transistor |
-
1990
- 1990-08-28 JP JP2226170A patent/JPH04107888A/en active Pending
Cited By (15)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1996037862A1 (en) * | 1995-05-22 | 1996-11-28 | OCé PRINTING SYSTEMS GMBH | Optical character generator for an electrographic printer or copier |
US5963242A (en) * | 1996-01-22 | 1999-10-05 | Fuji Xerox Co., Ltd. | Image recording apparatus with an array light source |
US10326970B1 (en) | 2000-07-25 | 2019-06-18 | Fujifilm Corporation | Electronic flash, electronic camera and light emitting head |
JP2009042773A (en) * | 2000-07-25 | 2009-02-26 | Fujifilm Corp | Flash device of camera and electronic camera |
JP2002116481A (en) * | 2000-07-25 | 2002-04-19 | Fuji Photo Film Co Ltd | Stroboscopic device for camera, electronic camera and light emission head |
US8421910B2 (en) | 2000-07-25 | 2013-04-16 | Fujifilm Corporation | Electronic flash, electronic camera and light emitting head |
US10250863B2 (en) | 2000-07-25 | 2019-04-02 | Fujifilm Corporation | Electronic flash, electronic camera and light emitting head |
US8634021B2 (en) | 2000-07-25 | 2014-01-21 | Fujifilm Corporation | Electronic flash, electronic camera and light emitting head |
US8675124B2 (en) | 2000-07-25 | 2014-03-18 | Fujifilm Corporation | Electronic flash, electronic camera and light emitting head |
US9479751B2 (en) | 2000-07-25 | 2016-10-25 | Fujifilm Corporation | Electronic flash, electronic camera and light emitting head |
JP2002175046A (en) * | 2000-12-07 | 2002-06-21 | Sony Corp | Image display device |
JP2005516728A (en) * | 2002-01-30 | 2005-06-09 | ソシエテ サテレク | Electro-optical device for photopolymerization of composite materials |
JPWO2011030381A1 (en) * | 2009-09-10 | 2013-02-04 | 三菱電機株式会社 | LED lighting device for headlamp and headlamp lighting system for vehicle |
JP2012243885A (en) * | 2011-05-18 | 2012-12-10 | Oki Data Corp | Reference voltage generation circuit, drive unit, print head and image forming apparatus |
JP2013219633A (en) * | 2012-04-10 | 2013-10-24 | Fuji Electric Co Ltd | Circuit for driving power transistor |
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