JPS63221061A

JPS63221061A - Printer

Info

Publication number: JPS63221061A
Application number: JP62056329A
Authority: JP
Inventors: Kiyoshi Sensui; 泉水　清; Yoshiaki Tangesaka; 丹下坂　義敬
Original assignee: NIPPON DENKI DATA KIKI KK; NEC Corp
Current assignee: NIPPON DENKI DATA KIKI KK; NEC Corp
Priority date: 1987-03-10
Filing date: 1987-03-10
Publication date: 1988-09-14

Abstract

PURPOSE:To obtain an electrophotographic printer imparting printing density reduced in change even when the voltage of a power source changes, by reading the change in drive voltage to change a pulse width so as to correct said voltage. CONSTITUTION:The printing data from a logical part is sent out to a shift register 1. LED 3 being a light emitting element is driven by a transistor 2, and a pair of transistors and LED are arranged in a row corresponding to the number of printing figures to constitute an LED array. A numeral 4 is a power source line supplying a power source to an LED element and a numeral 5 is a condenser suppressing the instantaneous variation of voltage and a numeral 6 is an A/D converter detecting the variation in the voltage of the power source line 4 to input the same to a microprocessor 7. For example, when the voltage Vcc of the power source drops, the voltage drop is detected by the A/D converter 6 and a driving pulse width is increased by the microprocessor 7 so as to compensate said voltage drop.

Description

【発明の詳細な説明】〔産業上の利用分野〕本発明は電子写真式によるプリンタｌに関し、特にその
光源部であるＬＥＤヘッドに関するものである。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrophotographic printer l, and particularly to an LED head that is a light source section thereof.

[Conventional technology]

従来は、ＬＥＤ駆動電源の変動に対しての補償機ｍ１に
有してはいなかった。Conventionally, the compensator m1 did not have a compensator for fluctuations in the LED driving power source.

[Problem that the invention seeks to solve]

上述した従来のＬＥＤ駆動方法は、Ｌｈ：Ｄ［動電源の
変動を察知できないので、点灯される単一のＬＥＤの数
が多くなり、それが連続で続くような場合には、しだい
に光量が低下し、それに合わせて印字濃度も低下すると
いう欠点があった。The conventional LED driving method described above is Lh:D [Since fluctuations in the dynamic power source cannot be detected, the number of single LEDs that are turned on increases, and if this continues continuously, the amount of light gradually decreases. There was a drawback that the print density also decreased accordingly.

[Means for solving problems]

本発明によるプリンタ装置は、シフトレジスターと、−
次元のＬＥＤアレイとＬＥＤへの電源ラインの電圧を検
出し、そのアナログ値をディジタル変換する７ナロ糸イ
ジタル変換器と、当該の値をパルス幅に換算するマイク
ロプロセッサ−と、各々のＬＥＤを駆動するＬＥＤ駆動
回路とを有している。A printer device according to the present invention includes a shift register;
A 7-narrow digital converter that detects the voltage of the power line to the three-dimensional LED array and the LED and converts the analog value to digital, a microprocessor that converts the value into a pulse width, and drives each LED. It has an LED drive circuit.

〔Example〕

本発明の一実施例を図面を参考にして説明する。 An embodiment of the present invention will be described with reference to the drawings.

第１図において、１はシフトレジスターでアリ、論理部
からの印字データがここに送出される。２は、ＬＥＤ’
ｉ−駆動するトランジスターである。３は、発光素子で
あるＬＥＤである。この一対のトランジスターとＬＥＤ
が印字桁数分だけ１列に並んで、ＬＥＤプレイを構成し
ている。４は、各々のＬＥＤ素子へ電源を供給する電源
ラインであり、５Ｆｉ、瞬間的な電圧変動を抑止するコ
ンデンサーである。６は、電源ライン４の電圧変動を検
出し、ディジタル値に変換して、マイクロプロセッサ−
へ入力するアナログ＝ディジタル変換器である。In FIG. 1, 1 is a shift register, to which print data from the logic section is sent. 2 is LED'
It is an i-driven transistor. 3 is an LED which is a light emitting element. This pair of transistors and LED
are lined up in a line corresponding to the number of printed digits to form an LED play. 4 is a power line that supplies power to each LED element, and 5Fi is a capacitor that suppresses instantaneous voltage fluctuations. 6 detects the voltage fluctuation of the power supply line 4, converts it into a digital value, and sends it to the microprocessor.
It is an analog-to-digital converter that inputs to the

７は、ディジタル変換器６からの値に従い、ＬＥＤの駆
動パルス幅を可変させる制御を行うマイクロプロセッサ
−である。7 is a microprocessor that performs control to vary the driving pulse width of the LED according to the value from the digital converter 6.

第２図は、印字ドツトａを横軸にして、ＬＥＤ駆ｍｔ源
電圧変動と、補正後のパルス幅を縦軸に表わしたもので
るり、グラフ２１ｔｉ、電源電圧の変動を、グラフ２２
は、補正後のパルス幅を概含的に表わしている。In Figure 2, the printed dot a is plotted on the horizontal axis, and the LED driving mt source voltage fluctuation and the corrected pulse width are plotted on the vertical axis.
roughly represents the corrected pulse width.

今、１５００　　ドツト分の印字が実行され、電源電圧
が＃ＩＯ，５Ｖ低下したとする。この変化により、電流
値も約１０九減少して、それにつれて、照射光量の減少
、印字濃度の減少となる。ところが、本発明においては
、電源電圧Ｖｃｃ　の低下をアナログ＝ディジタル変換
器６で検出し、これを補う形で１イクロプロセツサーに
よ）、駆動パルス幅が増加される。ＩＯＸの電圧減少に
対しては、１０Ｘのパルス幅の増加となシ、グラフよシ
２２０μＳの駆動パルス幅となることがわかる。Now, assume that printing for 1500 dots has been executed and the power supply voltage has decreased by #IO, 5V. Due to this change, the current value also decreases by about 109, and accordingly, the amount of irradiated light and the print density decrease. However, in the present invention, a decrease in the power supply voltage Vcc is detected by the analog-to-digital converter 6, and to compensate for this, the drive pulse width is increased by the microprocessor. As the voltage of IOX decreases, the pulse width increases by 10X, and the graph shows that the drive pulse width becomes 220 μS.

〔Effect of the invention〕

以上説明した様に、本発明は、駆動電圧の変化を読み取
シ、それを補正する様にパルス幅を変化させることによ
り、電源電圧か変動しても、印字濃度の変化の少ないＬ
ＥＤアレイを光源とする電子写真プリンタを提供するこ
とが可能となる。As explained above, the present invention reads changes in the drive voltage and changes the pulse width to compensate for the changes in the drive voltage.
It becomes possible to provide an electrophotographic printer using an ED array as a light source.

[Brief explanation of drawings]

第１図は本発明の構成を示す機能図である。第２図は印
字ドツト数に対する電源電圧変動と、パルス幅の補正を
示すグラフである。１・・・・−・シフトレジスタ、２・・・・・・トラン
ジスタ、３・・・・・・発光素子（ＬＥＤ）、４・・・
・・・電源供給線、５・・・・・・コンデンサー、６・
・・・・・アナロダ−ディジタル変換器、７・・・・・
・マイクロプロセッサ−１８・・出・駆動回路、２１・
・・・・・電圧変動、２２・・・・・・補正パルス幅。FIG. 1 is a functional diagram showing the configuration of the present invention. FIG. 2 is a graph showing power supply voltage fluctuations and pulse width corrections with respect to the number of printed dots. 1...Shift register, 2...Transistor, 3...Light emitting element (LED), 4...
...Power supply line, 5... Capacitor, 6.
...Analoger-digital converter, 7...
・Microprocessor-18・・Output/drive circuit, 21・
...Voltage fluctuation, 22...Correction pulse width.

Claims

[Claims]

In an electrophotographic printer that uses a one-dimensional LED array as a light source, there is an analog-to-digital converter that detects the LED drive power supply voltage and converts it into a digital signal, and a microprocessor that inputs the data and changes the LED drive pulse width accordingly. and a circuit that drives an LED driving transistor using a signal from the processor.