U.S. Philips Corporation

Ulf Rothgordt

Hans-Dieter Hinz

Ernst Bunge

Franz Schinke

Herbert Piotrowski

Bernd Ehlers

Gerrit Verspui

Klaus Witter

Raymond G Schayes

Gerhard Renelt

Hans D Hinz

Herbert Lobl

Gerhard Jost

HansDieter Hinz

Pieter Homan

The invention relates to a printing device for electrophoretic recording by means of electrodes which are relatively movable with respect to an image carrier. Between the image carrier and electrodes, a liquid developer fluid is present in which the electrodes are immersed. Recording takes place under the influence of a control voltage (U.sub.ST) causing adherence of electrophoretic pigment to the image carrier. In order to enable point-like (matrix-like) recording, the surface of the image carrier is electrically conductive and the developer fluid at the area of the electrodes is continuously exchanged to maintain the electrophoretic pigment supply.

Printing device for electrophoretic recording

A method of liquid development of charge images formed on a surface of a tape-like record carrier, for example by an electrostatic printer. The record carrier is simultaneously sprayed with developer liquid in two flows which are directed towards each other. As a result, two separate, uniform and oppositely directed flow zones meeting at one common turbulent flow zone are obtained. Both during pre-development and final developement the charge images are brought into contact with a large quantity of fresh developer liquid.

Method and apparatus for liquid electrostatic development of charge

In facsimile transmission by means of a redundancy reducing coding, for example run-length coding, a distance affects the entire remaining portion of the picture line. End-of-line control characters are therefore transmitted for line synchronization. As these characters are possibly also disturbed and the picture lines to be printed would then completely be lost, a fixed number of different end-of-line control characters are used in cyclic sequence from line to line. This enables the recognition of various successive disturbed picture lines, lost end-of-line control characters as well as end-of-line control characters artificially produced by a disturbance, so that the correct number of picture lines is always printed. Corrected picture lines are printed instead of the picture lines which were received in a disturbed manner, for example by taking over the contents of adjacent picture lines.

Method and arrangement for facsimile picture transmission

In facsimile transmission the sequences of picture elements having the same luminance are transmitted in coded form. The code words have, in general, different lengths and no ambiguous beginning or end marking respectively. Consequently, in case of a disturbance during the transmission not only the luminance values are generally falsified but also the plurality of successive picture elements so that in situ of the receipt picture lines appear which are too long or too short. In accordance with the invention it is now proposed in the case of a picture line which was received in a disturbed manner to compare it to one or both adjacent picture lines respectively, to take-over the portions having an adequate correlation, and, as regards the place of the disturbed portion to shift the end of the disturbed picture line in such a way that the definite line gets the prescribed length and to replace the portions of insufficient correlation by the corresponding information of one of the two adjacent picture lines. This comparison can be done relative to the two ends of the disturbed picture line. It is particularly favorable for the comparison that the picture elements of each picture line are grouped in equal groups and to check if the ratio of the number of, for example, black picture elements having a corresponding position in adjacent lines relative to the total number of black elements in the groups of the two lines together, remains below a given threshold value (decorrelation).

Method and arrangement for correcting errors in facsimile transmission

With the facsimile transmission of pictures the run-lengths (plurality of successive picture elements of the same luminance value) are often transmitted in coded form to save transmission time and transmission bandwidth respectively. Herein the shortest run-length is often allocated to the shortest code word. In accordance with the invention every run-length having the value 1 is either extended to the value 2 or suppressed and the shortest code word is then allocated in a corresponding manner to the run-length 2. As a result the total length of the transmitted code words for a document is considerably reduced. Extension is done such that one picture element is extended to the left to the detriment of the preceding run-length having the opposite luminance value provided this preceding run-length still contains thereafter at least two picture elements and that in the other case one picture element is extended to the right to the detriment of the next run-length provided the latter retains at least the value 2 and that otherwise the run-length having the value 1 is suppressed. It is true that the resolution is slightly reduced, however only for the very thin lines which is fully acceptable and in many cases hardly noticeable.

Method and device for transmitting facsimile picture signals

An electrostatic printing device comprising a rotatable printing roller with stylus electrodes. In order to keep the distance of the images or of the recorded sheets small and the images themselves clear and pure, notably at the edges, the stylus electrodes are moved transversely of the longitudinal direction of the tape-like record carrier. The foil tape is at the same time continuously transported. Thus, the translatory movement of the printing roller supporting the stylus electrodes is eliminated.

Electrostatic printing device with air cushion guiding

In order to increase recording quality the electrode pin of a device for electrostatically printing characters consists of a whisker which is mounted to be electrically conductive in a metal holder. A whisker is by definition a monocrystalline member.

Electrostatic printing device with monocrystalline stylus

An electrode stylus which is arranged in an aperture of a rotatable printing roller is secured in a cylindrical insert of the roller by means of an electrode holder. The electrode holder comprises a constriction in the center, so that it is sub-divided into an adjusting portion which supports the electrode and which can be slightly bent, by means of adjusting screws, transversely of the jacket surface of the roller, and a fixing portion which can be fixed in an aperture in the insert by means of a fixing screw. The adjustment of the height of the stylus is effected, after the loosening of the fixing screw, by an arm which can be inserted into the insert and which is radially pivotable therein relative to the roller axis. Microscopic adjustment of the electrode stylus in the tangential as well as the radial direction relative to the roller is thus possible.

Adjustable mount for electrostatic printer stylus within cylindrical

In practice it is often desirable to represent only a given, selectable dynamic range of a measuring signal, preferably in logarithmic form. This is achieved in accordance with the invention in that from the measured value in the form of a binary number only the positions corresponding to the desired dynamic range are selected for forming the base number, the weight of the most significant bits having the value '1' being converted into a binary number. The mantissa is derived from the following positions, i.e. independent of the selected dynamic range, so that even when the most significant bit is in the last position, a mantissa comprising the full number of positions is formed. The magnitude of the dynamic range is chosen by omitting the correspondingly more significant positions of the base number formed for the maximum range. The position of the dynamic range can be shifted in that the inputs of the circuits for forming the base number and the mantissa are shifted with respect to the lines supplying the individual positions of the measured value.

Natural binary to logarithmic binary conversion device with means for

An electrostatic recording device in which an area on a record carrier is charged electrically. Electrodes are arranged on both sides of the carrier. The print electrodes arranged in groups on one side thereof serve to form the desirable charge image. The counter electrodes on the other side, serve to select the desirable print electrode group. The counter electrodes being arranged in spaced opposing relationship with portions of two groups of print electrodes. The print electrodes are arranged in even and odd groupings, with each alternating group set being electrically connected.

Electrostatic recording device

Method and apparatus for producing a grey-tone image having areas of different average density values which are given by an n-digit binary number, all the bits of the binary number being interrogated in parallel by clock patterns. For the area to be printed an elemental area containing 2.sup.n pulses is selected which is printed in a total cycle of 2.sup.n .sup.- 1 clock pulses of the clock pattern. In this total cycle, at each clock pulse the drive of each pair of dots is determined in a manner such that the most-significant bit of the binary number is always used for driving while the remaining bits are used a number of times which depends upon their positional values. For this purpose, for each position of the binary number the clock pattern has a number of clock pulses which corresponds to the value of this position. The clock pulses for the individual positions are non-uniformly distributed in time, however, no clock pulses for the second and any further positions of the binary number coincide in time. Before each new print line the pattern will if required be shifted by additional clock pulses.

Logic circuit for grey-tone printer

An electrostatic printer having electrodes which each are constructed as a needle arranged on a rotatable drum mounted for translatory movements. At the recording area the needle slides directly over the paper under pressure to cause the paper to be slightly pushed away. The width of the recorded track is identified by the contact surface area of the needle.

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Norderstedt, Germany

Ulf Rothgordt