JPH04145679A - Laser driver of laser scanning unit - Google Patents
Laser driver of laser scanning unitInfo
- Publication number
- JPH04145679A JPH04145679A JP2269788A JP26978890A JPH04145679A JP H04145679 A JPH04145679 A JP H04145679A JP 2269788 A JP2269788 A JP 2269788A JP 26978890 A JP26978890 A JP 26978890A JP H04145679 A JPH04145679 A JP H04145679A
- Authority
- JP
- Japan
- Prior art keywords
- light
- laser
- signal
- light amount
- setting
- 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
- 238000003384 imaging method Methods 0.000 claims description 2
- 108091008695 photoreceptors Proteins 0.000 claims description 2
- 238000010586 diagram Methods 0.000 description 4
- 239000003990 capacitor Substances 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 1
Landscapes
- Dot-Matrix Printers And Others (AREA)
- Laser Beam Printer (AREA)
- Exposure Or Original Feeding In Electrophotography (AREA)
- Facsimile Scanning Arrangements (AREA)
- Semiconductor Lasers (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明はレーザドライバに関し、特に電子写真装置に用
いられるレーザ走査ユニットのレーザドライバに関する
。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a laser driver, and particularly to a laser driver for a laser scanning unit used in an electrophotographic apparatus.
従来、レーザ走査ユニットのレーザドライバは、レーザ
ダイオード（以下、ＬＤという）から出射される光量を
検出し、この光量と予め設定した基準値とを比較する比
較回路と、比較した信号を基にコンデンサに充電又は放
電を行って、所定の電圧を一定時間保持するピークホー
ルド回路と、コンデンサの端子電圧に対応する光量でＬ
ＤをｏＮｌｏＦＦを行うＯＮ／ＯＦＦ回路と、長時間Ｌ
ＤをＯＦＦにした状態では、再びＬＤをＯＮにした際、
大電流が流れないようにコンデンサを強制的に放電させ
る保護回路とを備えていた。Conventionally, a laser driver of a laser scanning unit includes a comparison circuit that detects the amount of light emitted from a laser diode (hereinafter referred to as LD) and compares this amount of light with a preset reference value, and a capacitor based on the compared signal. A peak hold circuit that charges or discharges the voltage and holds a predetermined voltage for a certain period of time, and
An ON/OFF circuit that performs oNloFF and a long-time L
When D is turned OFF, when LD is turned ON again,
It was equipped with a protection circuit that forced the capacitor to discharge to prevent large currents from flowing.
上述した従来のレーザ走査ユニットのレーザドライバは
、全て、アナログ信号による制御のため、ＬＤの近傍に
これらの制御回路を設置する必要があった。このため、
レーザ走査ユニットヲ小さくすることが困難となり、外
形の設計に対する制約を受けるという欠点があった。All of the laser drivers of the conventional laser scanning units described above are controlled by analog signals, so it is necessary to install these control circuits near the LD. For this reason,
This has the disadvantage that it is difficult to make the laser scanning unit small, and there are restrictions on the external design.
本発明は、レーザダイオードと、このレーザダイオード
から出射される光を感光体上に走査し、且つ、結像させ
る走査結像手段と、前記レーザダイオードを駆動するレ
ーザ駆動手段とを備えたレーザ走査ユニットのレーザド
ライバにおいて、前記レーザダイオードの出射する光量
と予め設定した基準値とを比較し、２値の信号を出力す
る光量比較回路と、前記光量比較回路からの信号情報に
基づいて前記レーザダイオードをＯＮ／ＯＦＦさせ、所
定の光量に設定する光量設定回路とより構成されている
。The present invention provides a laser scanning device comprising a laser diode, a scanning imaging means for scanning light emitted from the laser diode onto a photoreceptor and forming an image, and a laser driving means for driving the laser diode. The laser driver of the unit includes a light amount comparison circuit that compares the amount of light emitted by the laser diode with a preset reference value and outputs a binary signal; It is composed of a light amount setting circuit that turns on/off the light and sets the light amount to a predetermined amount.
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ブロック図である。第
１図において、本発明のレーザドライバはＬＤ２と、こ
の光量を設定する光量設定回路１と、ＬＤ２の出射した
光量を検知するフォトダイオード（ＰＤ）３と、フォト
ダイオード（ＰＤ）３からの検知信号を入力する光量比
較回路４とから構成されている。FIG. 1 is a block diagram showing one embodiment of the present invention. In FIG. 1, the laser driver of the present invention includes an LD 2, a light amount setting circuit 1 that sets the amount of light, a photodiode (PD) 3 that detects the amount of light emitted from the LD 2, and a detection circuit from the photodiode (PD) 3. It is composed of a light quantity comparison circuit 4 to which a signal is input.
続いて、本発明のレーザドライバの動作機能について説
明する。光量設定回路１には、印字装置の制御部（図示
せず）からレーザＯＮ／ＯＦＦ信号ａと光量設定信号す
とが入力される。そして、第２図に示すように、光量設
定信号ａのデユーティ−（Ｔｈ／Ｔ）に従ってＬＤ２に
流す電流が決定され、レーザＯＮ／ＯＦＦ信号すによっ
てＬＤ２をＯＮ又はＯＦＦにする。フォトダイオード（
以下、ＰＤという）３はＬＤ２の出射した光量を検知し
、光量比較回路４はＰＤ３の検知信号を入力すると共に
、基準値である基準光量電圧Ｃとを比較し、第３図に示
すように ｕＨ”および“Ｌ”レベルの２値の光量比較
信号ｄが制御部にフィードバックされる。そして、本発
明のレーザドライバは、制御部によりディジタル信号で
ある光量比較信号ｄに基づいて、ＬＤ２を所定の光量で
出射するように動作する。Next, the operational functions of the laser driver of the present invention will be explained. A laser ON/OFF signal a and a light amount setting signal S are inputted to the light amount setting circuit 1 from a control section (not shown) of the printing device. Then, as shown in FIG. 2, the current to be passed through the LD 2 is determined according to the duty (Th/T) of the light amount setting signal a, and the LD 2 is turned on or off by the laser ON/OFF signal. Photodiode(
(hereinafter referred to as PD) 3 detects the amount of light emitted by the LD 2, and the light amount comparison circuit 4 inputs the detection signal of the PD 3 and compares it with the reference light amount voltage C, which is a reference value. The binary light amount comparison signal d of "uH" and "L" level is fed back to the control unit. Then, in the laser driver of the present invention, the control unit controls the LD2 to a predetermined value based on the light amount comparison signal d which is a digital signal. It operates to emit light with the amount of light.
以上説明したように本発明のレーザ走査ユニットのレー
ザドライバによれば、ＬＤの光量とその基準値とを比較
し、この比較信号を基にしてデユーティ−を調節したデ
ィジタル信号により光量を設定するため、これらの制御
回路をＬＤの近傍に設置する必要もなく、従って、レー
ザ走査ユニットを小さくすることが可能となり、外形の
設計に対する制約を減らせることができるという効果が
ある。As explained above, according to the laser driver of the laser scanning unit of the present invention, the light intensity of the LD is compared with its reference value, and the light intensity is set by a digital signal whose duty is adjusted based on this comparison signal. There is no need to install these control circuits near the LD, and therefore the laser scanning unit can be made smaller, which has the effect of reducing restrictions on external design.
第１図は本発明の一実施例を示すブロック図、第２図は
光量設定回路に送出される光量設定信号を説明する図、
第３図は光量比較回路が送出する光量比較出力信号を示
す図である。
１・・・光量設定回路、２・・・レーザダイオード（Ｌ
Ｄ）、３・・・フォトダイオード（ＰＤ）、４・・・光
量比較回路。
ａ・・・レーザＯＮ／ＯＦＦ信号、
ｂ・・・光
置設定信号、
Ｃ・・・基準光量電圧、
ｄ・・・光量比較信
′５０FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a diagram explaining a light amount setting signal sent to a light amount setting circuit,
FIG. 3 is a diagram showing a light amount comparison output signal sent out by the light amount comparison circuit. 1... Light intensity setting circuit, 2... Laser diode (L
D), 3... Photodiode (PD), 4... Light amount comparison circuit. a...Laser ON/OFF signal, b...Optical position setting signal, C...Reference light amount voltage, d...Light amount comparison signal '50
Claims (1)
れる光を感光体上に走査し、且つ、結像させる走査結像
手段と、前記レーザダイオードを駆動するレーザ駆動手
段とを備えたレーザ走査ユニットのレーザドライバにお
いて、前記レーザダイオードの出射する光量と予め設定
した基準値とを比較し、２値の信号を出力する光量比較
回路と、前記光量比較回路からの信号情報に基づいて前
記レーザダイオードをＯＮ／ＯＦＦさせ、所定の光量に
設定する光量設定回路とを備えたことを特徴とするレー
ザ走査ユニットのレーザドライバ。A laser driver for a laser scanning unit, which includes a laser diode, a scanning imaging device that scans light emitted from the laser diode onto a photoreceptor and forms an image, and a laser drive device that drives the laser diode. a light amount comparison circuit that compares the amount of light emitted by the laser diode with a preset reference value and outputs a binary signal; and a light amount comparison circuit that turns on/off the laser diode based on signal information from the light amount comparison circuit. 1. A laser driver for a laser scanning unit, comprising: a light amount setting circuit for setting the light amount to a predetermined light amount.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2269788A JPH04145679A (en) | 1990-10-08 | 1990-10-08 | Laser driver of laser scanning unit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2269788A JPH04145679A (en) | 1990-10-08 | 1990-10-08 | Laser driver of laser scanning unit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH04145679A true JPH04145679A (en) | 1992-05-19 |
Family
ID=17477169
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2269788A Pending JPH04145679A (en) | 1990-10-08 | 1990-10-08 | Laser driver of laser scanning unit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH04145679A (en) |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5145992A (en) * | 1974-10-17 | 1976-04-19 | Nippon Electric Co | Handotaireezano parusuhenchokairo |
| JPS59147568A (en) * | 1983-02-10 | 1984-08-23 | Canon Inc | Controller for quantity of light |
| JPS63147645A (en) * | 1986-07-22 | 1988-06-20 | Ricoh Co Ltd | Output control apparatus of semiconductor laser |
-
1990
- 1990-10-08 JP JP2269788A patent/JPH04145679A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5145992A (en) * | 1974-10-17 | 1976-04-19 | Nippon Electric Co | Handotaireezano parusuhenchokairo |
| JPS59147568A (en) * | 1983-02-10 | 1984-08-23 | Canon Inc | Controller for quantity of light |
| JPS63147645A (en) * | 1986-07-22 | 1988-06-20 | Ricoh Co Ltd | Output control apparatus of semiconductor laser |
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