Device and method for densitometric and/or colourmetric measurements.

Various specific devices for performing densitometric, or colorimetric, known measurements of prints or printing plates, these are designed so that the measurements can only be performed by a single coordinate (x) and for a single type of measurement.

These devices are for their specific orientation and thus due to the fact that they are not suitable for further measurement or control, while expensive in relation to their limited field of application. Furthermore, these known devices require a perfectly flat bearing surface and a perfect guidance of the mobile carrier for the measuring head so that a high accuracy is given relative to the distance between the measuring head and the surface to be inspected, a minimal change in this distance would have measurement errors. There are further specific devices for exclusively densitometric measurements according to two coordinates (x, y) is known.

The invention has as its object to provide a device which is suitable to carry out various measurements and any visual inspections using procedures applicable which programming the measurements of the positions and the quality control are generally easier.

This object is achieved by the use of a known positioning device is proposed, which consists of guides, carriages, stepper motors, which are suitable positioning and re-positioning of measuring heads and / or a video camera and / or a light source for a light spot, according to three mutually perpendicular axes lying (x, y, z) to perform one of which (z) perpendicular to the supporting surface, for example for a printed sheet, or for a printing plate, extends.

In order to achieve the maximum accuracy of the distance between the measuring head and the surface to be inspected, the invention proposes for the movement of the measuring and / or controlling perpendicular (z) to the support surface a possibly adjustable spacer member to be provided. This allows the use of less precisely machined bearing surfaces without thereby suffering the accuracy of the measured data.

Besides the measurement by displacement perpendicular to the bearing surface and use an adjustable spacer, the invention provides for the exchange of the measuring heads and / or the recording or monitoring bodies before and that automatically takes place in a similar manner as the replacement of the pens on a plotter or by hand, without the fixed construction of several measuring heads and / or control bodies on the same support and the development of additional, less frequently used, specific measuring heads to exclude.

Because of these features of positioning the attachment of various heads is possible suitable for measurements and / or controls which only specifically developed devices or not it still provided devices are possible today.

On the support for the measuring heads according to the invention as measuring heads can be for the purpose of presetting the ink supply and limitation of the Committee at the start of printing, constructed for the detection of the density of the printing plates.

Of course densitometric measurements on the control strip of prints are possible in which, as in previously known devices, the advantage is these measurements at several strip and in particular also at certain locations within the printed area to carry out, with the possibility of these measuring points exactly (stored ), the purpose of the following controls, "later". According to the invention, it is possible to provide the measuring heads for colorimetric measurements which in the case of non-standard colors, eg for packaging printing ( "house color") and flexo printing is advantageous. It is furthermore possible to provide specific filters equipped measuring heads which are suitable special colors (eg bronze color) to detect by densitometry and / or provide measuring heads for performing densitometry measurements on six-color printing (after Küppers).

The installation of a video camera on the support of the positioning device according to the invention allows the monitoring and correction of registration marks or other characters which are suitable to achieve the exact coverage of the individual inks. This video camera allows furthermore a visual control of elements which are provided on the pressure-control strips as well as concerning the resolution of printing plates; Checks which are hitherto performed by Lupe.

By providing a light source for projecting a light point is provided on the to be tested, printed sheet or the printing plate, the programming of the controls is facilitated by by the perfectly coaxially opposite to the optical axis of the measuring heads light beam, for example the determination of the position of the pressure control strip, or the individual gradations of this, is facilitated.

The device allows also because it has a positioning device which allows any point on the material under test to reach and retrieve exactly the retrofitting of new measurement and / or control bodies.

The invention will be explained with reference to an, in the accompanying drawing schematically illustrated preferable embodiment of an apparatus according to the invention, this presentation is purely descriptive, not limiting purpose.

The Fig.1 shows a perspective view of a positioning device for the construction of measuring heads and / or a video camera and / or a light source for projecting a light spot, while the device is connected to a computer with keyboard and screen.

The support surface 1 is provided with a lateral stop 2 and a rear stop 2a for the exact placing of printed sheets 7, printing plates or other objects to be inspected. To the support surface 1 guides 3 including the engine and engine are mounted to the movement y of the transverse guide to obtain 4, which in turn is equipped with a drive for the movement x of the carriage 5, said a motor mechanism for displacing such a carrier for the building measuring heads 9 and / or control bodies has; this can be at the own holders 9a and possibly automatically, such as the pens on a plotter, be removed from the carrier. The transverse guide 4 is in the lateral stops 2 parallel direction y displaced during the movement x of the carriage 5 in parallel with the rear stop and 2a, the movement for the wearer 6 perpendicular to bearing surface. 1

This positioning device thus makes it possible, measurements, visual controls and displays at any point of the printed sheet 7, or printing plates which rest by means of suitable measuring heads and / or recording devices, which are attached to the carrier 6 on the platen 1, perform in particular at each point of the individual printed areas 7b, on one or more control strips 7a, at registration marks and the like. By storing the data of the individual measurement points, it is possible the same measurements at the measurement points identical to carry out the following Druckbättern. intends to carry out in particular for the programming of the measuring points at which you can measurements a point of light serve what is projected by a mounted on the carrier 6 light source coaxially to the optical axis of the measuring heads. For the transmission of impulses to the computer 8 are already in the guides 3 in the transverse guide 4 and the carriage 5 existing electrical connections available. The carrier 6 can be inventively equipped with one or more measuring heads which are all or in part by other measuring heads, by a video camera and / or a light source replaceable. According to the invention the precision of certain measurements (densitometric measurements) are given by the use of a possibly adjustable spacing element which exactly defines the distance when approaching the sensing surface. This mechanical spacer can be replaced according to the invention by an electric limit switch or by an electronic distance measurement.

The change of measuring heads 9 can be manually carried out by a 9 Einschnappbefestigung with the necessary electrical contacts or automatically, by filing and Entnehmung of the measuring heads of a holder 9a.