DE2410569C2 - Circuit arrangement for recording image information on electrosensitive paper - Google Patents

Description

The invention relates to a circuit arrangement for recording image information on electrosensitive Paper, in particular on metal recording paper, according to the category of the main claim.

There are already devices of this type known at which a large number of writing electrodes is designed as a so-called electrode comb. For controlling a special character generator is used for each individual writing electrode, with all Character generators control the individual writing electrodes at the same time. The simultaneous control In this process, the writing electrodes have the disadvantage of bridging between them Writing electrodes with it, which means that writing errors cannot be avoided. The required circuit configuration b5 wall for these known devices is very large.

It has also been proposed to control the individual writing electrodes one after the other.

In this case, however, a control process is dependent on the previous one. This can lead to errors such as were generated by an interference pulse, multiply, which results in a certain susceptibility to failure of this device

From DE-OS 20 23 719 is an electrographic; hes Known printing system in which with the help of a high voltage latent images can be generated on a recording medium. The pictures are made using of a toner made visible The circuit arrangement of this known device contains a control circuit for a multiple electrodcngcbilde, in which the Writing trodes can be steered via two coordinates. The control signals are generated by a character generator generated, an analog-to-digital converter is not used and there is also no division and Evaluation of the various binary number outputs of an analog-digital converter. Besides, this one is well known Relatively complex arrangement, among other things. because they are for a different, more complex recording method is determined.

The invention is based on the object one of the Arrangement according to main patent no. 22 15 519 corresponding circuit arrangement for recording To create image information on electrosensitive paper with the least possible amount of circuitry Aufwind allows safe and exact control of the writing electrodes without bridging even when recording analog input signals. In addition to the measure that the individual Writing electrodes are each driven individually one after the other, this is to be achieved in that the control process door of a writing electrode is made independent of control processes on others Writing electrodes.

This object is achieved according to the invention by the characterizing features of claim 1. The compared to the solution of the main patent with the invention achieved advantages exist in particular, that through the successive and independent control of the individual writing electrodes both erroneous records due to bridging between the individual writing electrodes ^ as Incorrect records can also be avoided by multiplying a single control error. With direct access to a single writing electrode, rapid recording is possible. in the In contrast to the known devices, analog input signals can be evaluated Circuit can be made very easily by a few, commercially available integrated components are built.

An embodiment of the invention is shown in the drawing and is described in more detail below. The analog input signal containing the information to be recorded is fed via an input terminal 10 to an 8-bit analog-digital converter 11 (MD converter). Such a Λ-D converter is commercially available as an integrated component. In the cycle of a clock frequency, which is fed to the Λ-D converter II via a second input terminal 12, the respective analog voltage is converted into 8-bit Bmarworte, which are present at the 8 binary number outputs of the Λ-D converter. The binary number outputs 1 to 4 of the Λ-D converter 11 are connected to corresponding binary number inputs A. B, C, D of 16 demultiplexers 13 to 28. Inputs with the same designation are connected to one another. For the sake of simplicity, only 3 of these are shown in the drawing

sixteen demultiplexers are shown, the first two demultiplexers 13,14 and the last demultiplexer 28. Demultiplexer, as they are for the present circuit are required are commercially available. Through the 16 possible variations of one at the entrance of one Demultiplexer 4-bit words attached to each 16 outputs of the demultiplexer 13 to 28 can be controlled optionally. This results in a total number of 256 demultiplexer outputs. Each of these demultiplexer outputs is via an amplifier 29 connected to a writing electrode 30. These 256 writing electrodes form the so-called electrode comb. An electrosensitive paper is attached to the electrode comb consisting of the writing electrodes 30 31, in particular registration metal paper, passed by. This paper is connected to ground. Such electro-sensitive Papers usually consist of a carrier paper on which a black lacquer and over it a thin metal layer is placed. The electrode comb slides over this metal layer Writing electrodes 30 is actuated by one of the demultiplexer outputs, a current flows through them Write electrode 30 in the metal layer on the electrosensitive Paper 31. As a result, the metal layer evaporates at the point in question and places the one underneath black lacquer layer free as a dark point. Transistors are preferably used as amplifiers 29 used, the bases of which are controlled by the demultiplexer outputs. The switching path of such The transistor connects a write electrode 30 to a burnout voltage source not shown in detail in the drawing. The amplifiers 29, which effectively amplify the output signals of the demultiplexers 13 to 28, can therefore also be referred to as controllable switches.

The binary number outputs 5-8 of the Λ-D converter II are connected to corresponding binary number inputs A, B ₁ C, D of a further demultiplexer 32. The commercially available type can also be used for the demultiplexer 32. The 16 outputs of the demultiplexer 32, which can optionally be activated by 4 binary words at the inputs A to D , are each connected to the first release inputs Gl of the 16 demultiplexers 13 to 28.

A conversion signal output G of the AD converter 11 is connected to the input of a monostable switching stage 33, the output of which is connected to the second enable inputs C? 2 the demultiplexer 13 to 28 is connected. A conversion signal at output G appears when the conversion of an analog signal at input terminal 10 into an 8-bit binary word at the outputs of AD converter 11 has been completed.

The terms 0 signal and 1 signal should be introduced to describe the mode of operation. A 0 signal has a potential which corresponds approximately to the ground potential and a 1-signal has a potential which corresponds to in the order of magnitude of the supply voltage.

After each clock pulse at terminal 12, as already described, the analog signal present at terminal 10 is converted into an 8-bit binary word at the output of AD converter 11. This 8-bit binary word is divided into two 4-bit binary words for processing, the first being applied to outputs 1 to 4 and the second to outputs 5-8. Through the cisic 4-bit binary words present at the outputs (-4 of the A- D converter 11, the binary number entries A to D of the demultiplexers 13 to 28 are controlled One of the 16 outputs of each demultiplexer 13 to 28 is controlled The same output is used for each demultiplexer A 0 signal changes This only happens when both release inputs G1, G 2 have a 0 signal

As a result of the second 4-bit binary word present at the outputs 5 to 8 of the AD converter 11, one of the 16 outputs of the demultiplexer 32 changes its potential from a 1 signal to a 0 signal. In one of the 16 demultiplexers 13 to 28, the first release input G 1 is therefore set from a 1 signal to an 0 signal. The monostable switching stage 33 is started by a conversion signal at the output C of the Λ-D converter 11, ie its output changes its potential from a 1 signal to a 0 signal. As a result, one of the 16 demultiplexers 13 to 28, the first release input of which is on a 0 signal, has both release inputs G 1, G 2 on a 0 signal. In this one demultiplexer, the output controlled by the first 4-bit word is released, ie the write current is released. This write current flows for the duration of the hold time of the monostable switching stage 33. The change in the write time that is possible as a result allows the point size to be changed. This point size is limited by the fact that after a certain time, even when the writing voltage is continuously applied, the metal layer of the electrosensitive paper around the writing electrode is completely burned off and current can no longer flow.

Of the two, by breaking down the 8-bit binary word The resulting 4-bit binary words are used for the synchronous control of a specific one The output of each of the 16 demultiplexers 13 to 28 and the second 4-bit binary word are used to determine which Demultiplexer should come into action. The activation time is determined by monostable switching stage 33.

The number of writing electrodes is limited by the number of outputs of the / 4-D converter 11. With η binary number outputs, the maximum possible number of writing electrodes is 2 ". Such an n-bit binary word is converted into an x- bit binary word undy-bit binary word broken down where χ + y - n. This results in the number of demultiplexers required as 2 * and the number of outputs from each of these demultiplexers as 2 ". In the exemplary embodiment described, / 3 = 8 and χ = y = 4.

With the new device it is possible to record any binary-coded information, each Pixel must be represented by a binary word, in the example shown by an 8-bit word. It is thus possible to use analog signals (via the / 4-D converter) as well as alpha-numeric characters - after processing by a suitable circuit - as well as grabs record phical representations.

1 sheet of drawings

Claims (4)

Patent claims: 1. Circuit arrangement for recording image information on electrosensitive paper, in particular recording metal paper, using a group of individual writing electrodes which are electrically isolated from one another and are each controlled one after the other via a controllable switch, the writing electrodes being controlled by binary signals , which are decoded in a decoding circuit, so that each of the individual binary signals is assigned to one of the controllable switches at the output of the decoding circuit and the switch-on duration of each individual writing electrode is preferably selected to be shorter than the time after which the burn-out process ends by itself , according to patent 22 15 519, where an analog voltage is applied as input information, characterized in that this is fed to an analog-digital converter (11) that a first number (x) of binary number outputs of the analog-digital converter (U) with the data inputs (A to D) is connected by at least two demultiplexers (13 to 28) and that a second number (y) of binary number outputs of the analog-digital converter (U) are provided for controlling release inputs (G 1) of the demultiplexers (13 to 28). 2 Circuit arrangement according to Claim 1, characterized in that the analog-digital converter a clock signal controlling the conversion of the analog voltage into a binary number is supplied 3. Circuit arrangement according to claim 1 or 2, characterized in that the binary number outputs of the analog-digital converter (H) corresponding to the second number / V) are connected to the inputs (A to fine demultiplexer (32), the outputs of which are connected to the enable input (G 1) each one of the demultiplexers (13 to 28) are connected. 4. Circuit arrangement according to one of the preceding claims, characterized in that the conversion signal output (C) of the analog-digital converter (11) is connected to a monostable switching stage (33). the output of which is connected to the interconnected, second enable inputs (G 2) of the demultiplexers (13 to 28) for control of the writing electrodes.