Configuration for Detecting a Physical Parameter at a Stack of Sheets Lying on Top of One Another

Abstract

A configuration for detecting a physical parameter at a stack of sheets resting on top of each other obtains signals from inside a stack in a wireless manner. At least one sensor that responds to changes in the parameter, is disposed between two sheets in the stack and is connected to a stationary evaluation unit. The sensor and the evaluation unit are connected by a wireless connection.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority, under 35 U.S.C. §119, of German Patent Application DE 10 2007 020 975.6, filed May 5, 2007; the prior application is herewith incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a configuration for detecting a physical parameter at a stack of sheets resting on top of each other. The configuration includes at least one sensor that responds to changes in the parameter, is inserted between two sheets in the stack and is connected to a stationary evaluation unit.

In sheet-fed printing presses, it is known to control driers as a function of measured values of temperature and humidity. Sensors disposed on a flat mount constructed like a blade or rod are used to measure the temperature and the humidity in a delivery stack. During printing, the mount, also known as a stack blade, is inserted between the upper sheets of the stack to obtain readings from inside the stack. Lines connect the sensors to a power supply and to an evaluation unit for evaluating the measured values. Inserting and retracting the stack blade may cause damage to the sheet surface and to a printed image.

It is known to use sensors that are equipped with a transponder in order to detect physical parameters at moving parts or in closed spaces. The measured values are transmitted to a stationary evaluation unit through a wireless connection. Power supply lines or signal lines are not required.

German Published, Non-Prosecuted Patent Application DE 10 2006 036 510 A1 discloses a control device for a drier. The control device processes signals that indicate the temperature and humidity of sheets. The signals are transmitted by wireless sensors that revolve on a chain conveyor for conveying the sheets. The sensor is equipped with a thermoelectric converter that is directed to a source of thermal radiation of the drier for power supply purposes.

German Published, Non-Prosecuted Patent Application DE 101 44 103 A1 discloses obtaining operating parameters such as temperature or humidity of a roller or cylinder through the use of a wireless sensor. The sensor signals are used to control a machine or installation.

BRIEF SUMMARY OF THE INVENTION

It is accordingly an object of the invention to provide a configuration for detecting a physical parameter at a stack of sheets lying or resting on top of one another, which overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type and with which signals can be obtained from inside the stack in a wireless manner.

With the foregoing and other objects in view there is provided, in accordance with the invention, a configuration for detecting a physical parameter at a stack of sheets resting on top of each other. The configuration comprises at least one sensor inserted between two sheets in the stack for responding to changes in the parameter, as well as a stationary evaluation unit. A wireless connection is provided between the at least one sensor and the evaluation unit.

The sensor is used to directly or indirectly detect a desired physical parameter inside the stack. A sensor sensing temperature and/or humidity changes can be used to control a drier in a printing press. The signals of a sensor sensing pressure changes can be used to determine the height of the stack, the application of ink, varnish, dampening solution and powder. The signals of the pressure sensor can be used to obtain actuating signals for a device for exchanging a stack and signals for controlling the application of ink, varnish, dampening solution and powder. A device positioned adjacent the stack may be provided for inserting the sensor between two sheets in the stack.

In accordance with another feature of the invention, the wireless connection between the sensor and the evaluation unit may be a radio connection. Alternatively, the wireless connection may be an optical connection or an acoustic connection.

In accordance with a concomitant feature of the invention, it is furthermore possible for the sensor to be a microsensor to be placed on a sheet before the sheet is deposited on the stack or while the sheet is being deposited on the stack. The outer dimensions of such a microsensor are less than 1 mm. When the stack is transferred to a further processing station, the microsensor remains in the stack. An autarkic microsensor is capable of continuously providing signals of the physical parameter. The temperature and/or humidity in the stack, in particular, can be measured continuously.

Other features which are considered as characteristic for the invention are set forth in the appended claims.

Although the invention is illustrated and described herein as embodied in a configuration for detecting a physical parameter at a stack of sheets lying on top of one another, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.

The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE VIEW OF THE DRAWING

The FIGURE of the drawing is a diagrammatic, perspective view of a stack of sheets and a configuration for measuring temperature in the stack of sheets.

DETAILED DESCRIPTION OF THE INVENTION

Referring now in detail to the single FIGURE of the drawing, there is seen a diagrammatic representation of a configuration for measuring temperature in a stack 1 in a delivery of a sheet-fed printing press. The stack 1 is formed of a plurality of sheets 2 stacked on top of each other. The sheets 2 carry a printed image. The sheets pass through a drier 3 before they are deposited on the stack 1. The drier 3 is connected to a control unit 4 for processing signals of measured values indicating the temperature in the stack 1. The measured signals are obtained by sensors 5.1-5.4. The strip-like sensors 5.1-5.4 have been inserted into the stack 1 through the use of an inserting device 10 that inserts the sensors 5.1-5.4 in such a way that a respective temperature measuring element 6 is placed between two sheets 2 at distances a and b from lateral surfaces of the stack 1 and at a distance c from each other. Ends of the sensors facing away from the measuring element 6 project from a lateral surface 7 of the stack. Each of these ends has an antenna of a transponder for a signal of the measured temperature. The transponders are autarkic in terms of power supply. The control unit 4 is connected to a transmitter/receiver unit 8. The transmitter 8 is activated to read out the transponders. The transponder returns the respective signal for the measured temperature to the receiver unit 8. There are wireless connections 9 between the transmitter/receiver unit 8 and the transponders.

Claims

1. A configuration for detecting a physical parameter at a stack of sheets resting on top of each other, the configuration comprising:

at least one sensor inserted between two sheets in the stack for responding to changes in the parameter;

a stationary evaluation unit; and

a wireless connection between said at least one sensor and said evaluation unit.

2. The configuration according to claim 1, wherein said wireless connection is a radio link between said at least one sensor and said evaluation unit.

3. The configuration according to claim 2, wherein said at least one sensor includes a transponder.

4. The configuration according to claim 3, wherein said at least one sensor is strip-shaped, and said transponder includes an antenna projecting from the stack.

5. The configuration according to claim 1, wherein the physical parameter is temperature, and said at least one sensor responds to temperature changes in the stack.

6. The configuration according to claim 1, wherein the physical parameter is humidity, and said at least one sensor responds to humidity changes in the stack.

7. The configuration according to claim 1, wherein the physical parameter is pressure, and said at least one sensor responds to pressure changes in the stack.

8. The configuration according to claim 1, wherein the stack is disposed in a delivery of a sheet-fed printing press having a conveying path for the sheets, a drier disposed in the conveying path, and a control unit for the drier, and said evaluation unit is connected to the control unit.

9. The configuration according to claim 8, which further comprises a device associated with the stack for inserting said at least one sensor.

10. The configuration according to claim 1, wherein said at least one sensor is a microsensor.

11. The configuration according to claim 10, wherein said at least one sensor has outer dimensions of less than 1 mm.