JPH0564114B2 - - Google Patents
Info
- Publication number
- JPH0564114B2 JPH0564114B2 JP20760885A JP20760885A JPH0564114B2 JP H0564114 B2 JPH0564114 B2 JP H0564114B2 JP 20760885 A JP20760885 A JP 20760885A JP 20760885 A JP20760885 A JP 20760885A JP H0564114 B2 JPH0564114 B2 JP H0564114B2
- Authority
- JP
- Japan
- Prior art keywords
- voltage
- transistor
- constant current
- print head
- current
- 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.)
- Expired - Lifetime
Links
- 238000000034 method Methods 0.000 claims description 4
- 238000001514 detection method Methods 0.000 claims description 2
- 238000010586 diagram Methods 0.000 description 4
- 230000020169 heat generation Effects 0.000 description 4
- 230000010354 integration Effects 0.000 description 3
- 230000007423 decrease Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
- B41J2/315—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of heat to a heat sensitive printing or impression-transfer material
- B41J2/32—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of heat to a heat sensitive printing or impression-transfer material using thermal heads
- B41J2/35—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of heat to a heat sensitive printing or impression-transfer material using thermal heads providing current or voltage to the thermal head
Landscapes
- Electronic Switches (AREA)
Description
【発明の詳細な説明】
技術分野
本発明は印字ヘツド駆動装置に関し、特に通電
転写方式における印字ヘツドの定電流駆動装置に
関する。TECHNICAL FIELD The present invention relates to a print head drive device, and more particularly to a constant current drive device for a print head in an electrical transfer method.
従来技術
通電転写方式におけるプリンタに使用されるリ
ボンは第２図に示す如き等価回路で表わされる。
すなわち、帰還電極としてのアースと通電用電極
２４−１〜２４−ｎとの間には、各電極に夫々対
応した個別の抵抗部２１−１〜２１−ｎと、これ
ら抵抗部２１−１〜２１−ｎに共通する共通抵抗
部２２とにより表わされる。Prior Art A ribbon used in a printer using an electric transfer method is represented by an equivalent circuit as shown in FIG.
That is, between the ground as a return electrode and the current-carrying electrodes 24-1 to 24-n, there are individual resistance parts 21-1 to 21-n corresponding to each electrode, and these resistance parts 21-1 to 21-n. 21-n.
ｎ個の等価抵抗２１−１〜２１−ｎのうちのｍ
個に印字信号に応じて選択的に定電流２５を流す
と、等価抵抗２２に流れる電流２６はｍに比例す
るので、当該抵抗２２の端子２７の電圧もｍに比
例することになる。よつて、ｍが大きくなれば、
端子２７の電圧が上昇するために等価抵抗２１に
定電流２５を流し続けるには、電極２４により大
きな電圧を印加する必要がある。この様な負荷を
従来の定電流駆動回路（第３図参照）に接続した
場合、全ての等価抵抗２１−１〜２１−ｎに定電
流２５を流すためには、電圧源の電圧は高電圧と
ならざるを得ない。 m of n equivalent resistances 21-1 to 21-n
When a constant current 25 is selectively applied to each print signal according to the print signal, the current 26 flowing through the equivalent resistance 22 is proportional to m, so the voltage at the terminal 27 of the resistance 22 is also proportional to m. Therefore, if m becomes large,
In order to keep the constant current 25 flowing through the equivalent resistance 21 because the voltage at the terminal 27 increases, it is necessary to apply a larger voltage to the electrode 24. When such a load is connected to a conventional constant current drive circuit (see Figure 3), the voltage of the voltage source must be a high voltage in order to flow the constant current 25 through all equivalent resistances 21-1 to 21-n. I have no choice but to do so.
第３図の定電流駆動回路を参照するに、電圧源
３６の電圧は、ツエナーダイオード３１と抵抗３
２とによる直列回路により分圧定電圧化されてい
る。このツエナーダイオード３１により定電圧が
定電流源となるｎ個のPNPトラジスタ３５−１
〜３５−ｎのベース・エミツタ間の各バイアス電
圧となるが、この場合各トラジスタのベースに
は、印字信号に応じてオンオフ制御されるスイツ
チ３４−１〜３４−ｎを夫々介してツエナーダイ
オード３１の一端電圧が印加されている。また各
トランジスタのエミツタには、エミツタ抵抗３３
−１〜３３−ｎを夫々介してツエナーダイオード
３１の他端電圧が印加されている。そして、各ト
ランジスタのコレクタから定電流が印字ヘツドの
通電用電極２４−１〜２４−ｎへ対応して供給さ
れるようになつている。 Referring to the constant current drive circuit shown in FIG.
The divided voltage is made constant by a series circuit with 2 and 2. n PNP transistors 35-1 whose constant voltage becomes a constant current source by this Zener diode 31
~ 35-n, but in this case, the base of each transistor is connected to a Zener diode 31 via switches 34-1 to 34-n, which are controlled on and off according to the print signal. A voltage is applied to one end. In addition, an emitter resistor 33 is provided at the emitter of each transistor.
The voltage at the other end of the Zener diode 31 is applied through -1 to 33-n, respectively. A constant current is supplied from the collector of each transistor to the current-carrying electrodes 24-1 to 24-n of the printing head.
かかる構成において、定電流源としてのトラン
ジスタ３５での損失を考えると、全ての等価抵抗
２１−１〜２１−ｎに定電流を流す場合、各電極
２４の電圧は最高となり、トランジスタ３５のエ
ミツタ・コレクタ間電圧は最小となり、トランジ
スタ３５の損失は最小すなわち発熱は最小とな
る。しかし、ただひとつの等価抵抗２１に定電流
２５を流した場合、電極２４の電圧は最低とな
り、トランジスタ３５の損失は最大、すなわち発
熱最大となるため、トランジスタ３５−１〜３５
−ｎには大許容損失のトランジスタが必要であつ
た。従つて回路の大規模化を招き、集積化を困難
にしていた。 In such a configuration, considering the loss in the transistor 35 as a constant current source, when a constant current is passed through all the equivalent resistances 21-1 to 21-n, the voltage of each electrode 24 becomes the highest, and the emitter of the transistor 35 The voltage between the collectors becomes the minimum, and the loss of the transistor 35 becomes the minimum, that is, the heat generation becomes the minimum. However, when the constant current 25 is passed through only one equivalent resistance 21, the voltage of the electrode 24 is the lowest, and the loss of the transistor 35 is the maximum, that is, the heat generation is maximum.
-n required a transistor with large allowable loss. This led to an increase in the scale of the circuit, making integration difficult.
発明の目的
本発明の目的は、負荷抵抗の変動とは無関係に
常に定電流源トランジスタの損失を迎えて発熱を
抑制するようにして回路の集積化に適した印字ヘ
ツドの駆動装置を提供することである。OBJECTS OF THE INVENTION It is an object of the present invention to provide a print head drive device that is suitable for circuit integration and that suppresses heat generation due to constant current source transistor loss regardless of changes in load resistance. It is.
発明の構成
本発明による印字ヘツド駆動装置は、通電転写
方式における印字ヘツドの各通電用電極に夫々対
応して定電流を供給する複数の定電流回路を有す
る印字ヘツド駆動装置であつて、前記通電用電極
の各電圧のうち最大電圧値を検出する最大電圧検
出手段と、この検出電圧に応じて前記定電流回路
の電源電圧を制御する電源電圧制御手段とを含む
ことを特徴としている。Structure of the Invention A print head drive device according to the present invention is a print head drive device having a plurality of constant current circuits that supply a constant current corresponding to each current-carrying electrode of a print head in a current transfer method, The present invention is characterized in that it includes a maximum voltage detection means for detecting the maximum voltage value among the voltages of the electrodes, and a power supply voltage control means for controlling the power supply voltage of the constant current circuit according to the detected voltage.
実施例
以下、図面を用いて本発明の実施例を説明す
る。Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.
第１図は本発明の実施例のブロツク図であり、
第３図と同等部分は同一符号により示している。
図において、電圧源３６の電圧が可変インピーダ
ンス素子としてのPNPトラジスタ１のエミツ
タ・コレクタを介して各定電流源回路へ供給され
るようになつている。すなわち、トランジスタ１
のコレクタ出力点７の電圧が各定電流源トランジ
スタ３５−１〜３５−ｎのエミツタ抵抗３３−１
〜３３−ｎへ供給されており、また各トランジス
タ３５−１〜３５−ｎのベース・エミツタ間のバ
イアス電圧を決定するためのツエナーダイオード
３１と抵抗３２との直列回路へ供給されている。 FIG. 1 is a block diagram of an embodiment of the present invention.
Parts equivalent to those in FIG. 3 are indicated by the same reference numerals.
In the figure, the voltage of a voltage source 36 is supplied to each constant current source circuit through the emitter-collector of a PNP transistor 1 as a variable impedance element. That is, transistor 1
The voltage at the collector output point 7 of the emitter resistor 33-1 of each constant current source transistor 35-1 to 35-n
33-n, and also to a series circuit of a Zener diode 31 and a resistor 32 for determining the bias voltage between the base and emitter of each transistor 35-1 to 35-n.
定電流源トランジスタ３５−１〜３５−ｎの各
コレクタの電圧、すなわち各通電用電極２４−１
〜２４−ｎの電圧のうち最大電圧を検出すべく、
ダイオード５−１〜５−ｎが夫々設けられてい
る。各ダイオード５〜１〜５−ｎのアノードは各
電極２４−１〜２４−ｎに夫々対応して接続され
ており、カソードはすべて共通とされてNPNト
ランジスタ２のベース入力となつている。 The voltage of each collector of constant current source transistors 35-1 to 35-n, that is, each current-carrying electrode 24-1
In order to detect the maximum voltage among the voltages of ~24-n,
Diodes 5-1 to 5-n are provided, respectively. The anodes of the diodes 5 to 1 to 5-n are connected to the respective electrodes 24-1 to 24-n, respectively, and the cathodes thereof are all shared and serve as the base input of the NPN transistor 2.
このトランジスタ２のエミツタには、抵抗３２
の両端に並列に設けられたツエナーダイオード３
と抵抗４との直列回路における分圧出力が印加さ
れており、そのコレクタ出力に応じて先のトラン
ジスタ１のインピーダンスが制御されるようにな
つている。他の構成は第２図の例と同等でありそ
の説明は省略する。 A resistor 32 is connected to the emitter of this transistor 2.
Zener diode 3 installed in parallel on both ends of
A divided voltage output from a series circuit of a resistor 4 and a resistor 4 is applied, and the impedance of the transistor 1 is controlled according to the collector output. The other configurations are the same as the example shown in FIG. 2, and their explanation will be omitted.
かかる構成において、今、スイツチ３４−２を
はじめとする複数個のスイツチが選択的にオンと
なると、これ等オンとなつたスイツチに夫々対応
するトランジスタ３５−２をはじめとする複数個
のトランジスタが対応する負荷である等価抵抗２
１及び２２に定電流２５を供給する。このとき、
等価抵抗２１のばらつきによりいちばん高い電極
２４が電圧と抵抗器４の両端電圧とがトランジス
タ２で比較され、双方が等しく（ダイオード５の
順電圧とトランジスタ２のベース・エミツタ電圧
は無視する）なるようにトランジスタ１が抑制さ
れることによりトランジスタ１のインピーダンス
が制御されて、端子７の電圧が決まる。このとき
のトランジスタ３５のベース電圧は、最も高いト
ランジスタ３５のコレクタ電圧よりも定電圧ダイ
オード３の電圧だけ高い電圧に維持される。従つ
て、トランジスタ３５のエミツタ・コレクタ間電
圧は定電圧ダイオード３の電圧を十分小さく選べ
ば、常に低い電圧に保つことができる。すなわ
ち、トランジスタ３５の損失を最小に保つことが
できる。 In this configuration, when a plurality of switches including switch 34-2 are selectively turned on, a plurality of transistors including transistor 35-2 corresponding to the turned-on switches turn on. Equivalent resistance 2 which is the corresponding load
A constant current 25 is supplied to 1 and 22. At this time,
Due to the variation in the equivalent resistance 21, the voltage at the highest electrode 24 and the voltage across the resistor 4 are compared by the transistor 2, so that both are equal (ignoring the forward voltage of the diode 5 and the base-emitter voltage of the transistor 2). By suppressing transistor 1, the impedance of transistor 1 is controlled, and the voltage at terminal 7 is determined. At this time, the base voltage of the transistor 35 is maintained at a voltage higher than the highest collector voltage of the transistor 35 by the voltage of the constant voltage diode 3. Therefore, the emitter-collector voltage of the transistor 35 can always be kept low if the voltage of the constant voltage diode 3 is selected to be sufficiently small. That is, the loss of the transistor 35 can be kept to a minimum.
一方、トランジスタ１の損失は多少大きくなる
が、負荷の等価抵抗２１を駆動する数を増やして
いくと、トランジスタ１のエミツタ電流は増加す
るが、端子７の電圧は上昇してくるため、トラン
ジスタ１のエミツタ・コレクタ電圧は低下してい
くので、損失はさほど増加しないのである。 On the other hand, although the loss of transistor 1 increases somewhat, as the number of equivalent resistors 21 of the load is increased, the emitter current of transistor 1 increases, but the voltage at terminal 7 increases, so transistor 1 Since the emitter-collector voltage of is decreasing, the loss does not increase much.
すなわち、ダイオード群５−１〜５−ｎによつ
て通電用電極２４−１〜２４−ｎのうちの最大の
電圧値を検出してこの電圧値に応じて可変インピ
ーダンス素子１のインピーダンスを制御し、電圧
源３６の電圧をこのインピーダンスにより降下制
御するようにして、定電流源トランジスタ３５の
コレクタ・エミツタ間電圧を常に低い略一定の電
圧に維持するものである。 That is, the maximum voltage value of the current-carrying electrodes 24-1 to 24-n is detected by the diode groups 5-1 to 5-n, and the impedance of the variable impedance element 1 is controlled according to this voltage value. The voltage of the voltage source 36 is controlled to drop by this impedance, so that the collector-emitter voltage of the constant current source transistor 35 is always maintained at a low, substantially constant voltage.
電極２４−１〜２４−ｎのうちの最大電圧を検
出するようにしているのは、等価抵抗２１−１〜
２１−ｎのバラツキにより最大抵抗のものにも常
に定電流を流すに十分な電圧を定電流源が供給し
得ることが必要であるからであり、この最大等価
抵抗に電流を供給するトランジスタのコレクタ電
圧（すなわち最大電圧である）を検出して、この
電圧に応じて電源３６の電圧をインピーダンス１
により降下させつつ定電流源回路の端子７の電源
として用いているのである。 The maximum voltage of the electrodes 24-1 to 24-n is detected by the equivalent resistances 21-1 to 21-n.
This is because it is necessary for the constant current source to be able to supply a voltage sufficient to always cause a constant current to flow even through the maximum resistance due to variations in 21-n, and the collector of the transistor that supplies current to this maximum equivalent resistance. The voltage (that is, the maximum voltage) is detected, and the voltage of the power supply 36 is changed to an impedance of 1 according to this voltage.
It is used as a power source for the terminal 7 of the constant current source circuit while lowering the voltage.
こうすることにより、定電流供給条件が一番厳
しいトランジスタのコレクタ電圧に応じて電流源
回路の電源電圧（端子７の電圧）が変化制御され
る。よつて、常に定電流２５を供給可能としつつ
定電流電源回路の電源電圧が上下して、各トラン
ジスタのコレクタ・エミツタ間電圧を従来に比し
常に小とし得ることになるのである。 By doing so, the power supply voltage of the current source circuit (the voltage at the terminal 7) is controlled to change according to the collector voltage of the transistor whose constant current supply condition is the most severe. Therefore, the power supply voltage of the constant current power supply circuit increases and decreases while always being able to supply the constant current 25, and the voltage between the collector and emitter of each transistor can always be made smaller than in the conventional case.
発明の効果
以上説明したように、本発明によれば、負荷抵
抗の変動とは無関係に常に定電流源のドライブト
ランジスタの損失を低く抑え、発熱をひとつのト
ランジスタに集約できるため、ドライブトランジ
スタに大許容損失のトランジスタを使う必要がな
くなり回路の集積化にも貢献する。Effects of the Invention As explained above, according to the present invention, the loss of the drive transistor of a constant current source can be kept low regardless of changes in load resistance, and heat generation can be concentrated in one transistor, so that the drive transistor can be greatly reduced. This eliminates the need to use transistors with high power dissipation and contributes to circuit integration.
第１図は本発明の実施例の回路図、第２図は印
字リボンの等価回路図、第３図は従来の印字ヘツ
ド駆動装置の回路図である。
主要部分の符号の説明、１……可変インピーダ
ンストランジスタ、５−１〜５−ｎ……ダイオー
ド、３４−１〜３４−ｎ……スイツチ、３５−１
〜３５−ｎ……定電流トランジスタ、３６……電
圧源。
FIG. 1 is a circuit diagram of an embodiment of the present invention, FIG. 2 is an equivalent circuit diagram of a print ribbon, and FIG. 3 is a circuit diagram of a conventional print head driving device. Explanation of symbols of main parts: 1...Variable impedance transistor, 5-1 to 5-n...Diode, 34-1 to 34-n...Switch, 35-1
~35-n...constant current transistor, 36...voltage source.
Claims (1)
電極に夫々対応して定電流を供給する複数の定電
流回路を有する印字ヘツド駆動装置であつて、前
記通電用電極の各電圧のうち最大電圧値を検出す
る最大電圧検出手段と、この検出電圧に応じて前
記定電流回路の電源電圧を制御する電源電圧制御
手段とを含むことを特徴とする印字ヘツド駆動装
置。1. A print head drive device that has a plurality of constant current circuits that supply constant current corresponding to each of the current-carrying electrodes of a print head in the current transfer method, in which the maximum voltage value of each of the voltages of the current-carrying electrodes is A print head driving device comprising: maximum voltage detection means for detecting a maximum voltage; and power supply voltage control means for controlling a power supply voltage of the constant current circuit according to the detected voltage.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP20760885A JPS6266955A (en) | 1985-09-19 | 1985-09-19 | Printing head driving device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP20760885A JPS6266955A (en) | 1985-09-19 | 1985-09-19 | Printing head driving device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6266955A JPS6266955A (en) | 1987-03-26 |
| JPH0564114B2 true JPH0564114B2 (en) | 1993-09-13 |
Family
ID=16542597
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP20760885A Granted JPS6266955A (en) | 1985-09-19 | 1985-09-19 | Printing head driving device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6266955A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0731719U (en) * | 1993-11-19 | 1995-06-16 | 三ツ星ベルト株式会社 | Wide Toothed Belt for Transport |
-
1985
- 1985-09-19 JP JP20760885A patent/JPS6266955A/en active Granted
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0731719U (en) * | 1993-11-19 | 1995-06-16 | 三ツ星ベルト株式会社 | Wide Toothed Belt for Transport |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6266955A (en) | 1987-03-26 |
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