GB2119200A

GB2119200A - Scribe density control means for picture scanner

Info

Publication number: GB2119200A
Application number: GB08309674A
Authority: GB
Inventors: Franz Arendt; Heinz Bielig
Original assignee: Heidelberger Druckmaschinen AG
Current assignee: Heidelberger Druckmaschinen AG
Priority date: 1982-04-20
Filing date: 1983-04-08
Publication date: 1983-11-09
Also published as: IT8321551V0; IT8321551U1; GB8309674D0; GB2119200B; FR2525356A1; JPS58170647U

Abstract

For the streakless production of half-tone or continuous-tone copies with scanners for picture production, a continuous procedure is made possible by connecting to a shaft (4) of the scribe density (ie. range of density between light and shadow) control means an electric miniature driving motor (8), e.g. with a connecting sleeve (5). This motor is controlled by a voltage regulator within the appropriate scribe density range so that any desired half-tone or continuous-tone copy can be made. <IMAGE>

Description

SPECIFICATION Scribe density control means for picture scanner This invention relates to a scanner for picture production for printing processes, having a scribe density control means for screened tones and half-tones.

Scanners are known for picture production which make printable reproductions in one operation directly form the original, either by looking on to or looking through the original, in one or more colours, or via intermediate stages of duplicate slide, photocomposing. A lamp illuminates through the original. After the beams have been directed through an optical system and a plurality of mirrors, they reach multipliers which convert the light into an electric voltage. The voltage is transmitted to amplifiers which direct the signals to the input stage of colour computers. Here there takes place logarithmization in order to obtain a voltage corresponding to the original. The output signals of the multipliers are used for colour correction. A distinction is made between white and black colour corrections.The electronic "correction mask" is formed from the difference between the separation channel and the mxture of the other channel; the mixture ratio is established by means of a balance controller, and the intensity of the masking by means of a correction intensity controller. The choice between a light or dark, between a hard and soft gradation is possible with the aid of gradation controllers for middle tones, lights and shadows. Undercolour removals which are required for wet-on-wet printing as well as regulation of coloured and neutral highlight and changes in focus are controllable. The thus calculated end signal with the incorporated changes and controls goes to a reversal stage where there is a selection for negative or positive separation, and white and black dots are specified by means of a scribe density controller.Afterwards the signal is passed to a final stage which supplies power for a scribe lamp, and a light signal is generated again from the electric voltage. This scribe lamp is employed in the exposure of a film clamped on to a scribe roller, and the film is then further processed.

The scribe density, i.e. the range of density between light and shadow, is regulated by hand by means of a scribe density controller on the scanner. The streakless production of continuous-tone and half-tone copies is thus not possible, even with very expensive types of scanner. It is proposed to control the production of half-tone or continuous-tone copies through special software programs.

It is an object of the present invention to make possible a continuous procedure in connection with the production of continuoustone or half-tone copies with scanners for picture production for printing processes.

According to the present invention, there is provided a scanner for picture production for printing processes, having a scribe density control means for screened tones and halftones, wherein a shaft of the scribe density control means is connected to the shaft of an electric motor, which, via a voltage regulator, provides control for any desired half-tone or continuous-tone copy within the appropriate scribe density range.

The shaft of the electric motor may be connected to the shaft of the scribe density control means by means of a connecting sleeve.

The motor may be clamped in an angled holder which is in contact with the front face of a switchbox of the scanner, thus preventing the motor from turning bodily.

The electric drive of the scribe density controller may comprise a controllable drive unit operating indirectly via a pulley or gears.

The device according to the invention permits the simple production of streakless continuous-tone or half-tone copies, and above all a uniform continuous-tone or half-tone copy.

Moreover, a miniature motor is considerably cheaper than the contemplated special development of software programs for the production of continuous-tone or half-tone copies.

Anembodiment of the invention is explained below with reference to the accompanying drawing, in which: Figure 1 is a front elevation of a scanner (light scanner 296 C) with a scribe density controller, and Figure 2 is a partially sectioned elevation on a larger scale showing a miniature driving motor mounted on the scribe density controller.

The scanner 1 as shown in Fig. 1 has a switchbox front face 2 with a scribe density control knob 3 in its initial position. Fig. 2 shows how, after the scribe density control knob 3 has been removed from the shaft 4 of a scribe density controller (by loosening a clamping screw, not shown), the shaft 4 of this controller is connected by means of a connecting sleeve 5 to the shaft 6 of a miniature driving motor 8. An angled metal clamping sleeve 7 which embraces the motor 8 serves to lock this motor. The metal clamping sleeve 7 is in contact with the switchbox front face 2. The motor 8 has a power connection 9 for its operation. It is possible to use as a miniature driving motor 8, for example, a motor of the type "Minimotor SA CH 6982 AGNO 06/1 100 emp", or any other controllable drive unit which works indirectly via a pulley.

LIST OF COMPONENTS 1 Scanner 2 Switchbox 3 Scribe density control knob 4 Shaft of scribe density controller 5 Connecting sleeve 6 Shaft of miniature driving motor 7 Metal clamping sleeve 8 Miniature driving motor 9 Power connection

Claims

1. Scanner for picture production for printing processes, having a scribe density control means for screened tones and half-tones, wherein a shaft of the scribe density control means is connected to the shaft of an electric motor, which, via a voltage regulator, provides control for any desired half-tone or continuous-tone copy within the appropriate scribe density range.

2 Scanner according to claim 1, wherein the shaft of the electric motor is connected to the shaft of the scribe density control means of a connecting sleeve.

3. Scanner according to claim 1 or 2, wherein the electric motor is clamped in an angled holder which is in contact with the front face of a switch box of the scanner, thus preventing the motor from turning bodily.

4. Scanner according to claim 1, 2 or 3, wherein the electric drive of the scribe density controller comprises a controllable drive unit operating indirectly via a pulley or gears.

5. Scanner according to claim 1, substantially as described with reference to the accompanying drawing.

CLAIMS (29Jul1983)

1. Scanner for picture production for printing processes, having a scribe density control means for screened tones and half-tones, wherein a shaft of the scribe density control means is connected to the shaft of an electric motor, and the motor is provided with a voltage regulator which (in use) selects a setting appropriate to any desired half-tone or continuous-tone copy within the appropriate scribe density range.