DE102006028480A1 - Sensor device for contamination endangered areas in printing machines, has cleaning unit assigned to sensor and develops contamination removing ultrasonic vibrations at sending and receiving surfaces of sensor - Google Patents

Abstract

The device has a sensor (2), whose measuring signals exits and enters from the device into sending and receiving surfaces (3). A cleaning unit is assigned to the sensor and develops contamination removing ultrasonic vibrations at sending and receiving surfaces of sensor. An ultrasonic transducer (4) is integrated in the device and vibrations with ultrasonic frequency are fed into the sending and receiving surfaces. The ultrasonic transducer is arranged as separate cleaning unit at each sending and receiving surfaces and ultrasonic vibrations are carried on the sending and receiving surfaces.

Description

The The invention relates to a sensor device for polluting areas in printing presses.

In Printing presses become substrate throughput control and function monitoring of printing presses a variety of optical, magnetic, inductive or capacitive sensors used, their reliability or measurement accuracy due to external contamination, such as For example, paper dust or paint aerosols is impaired.

It It is known to clean optical sensors of adhering dusts blast air cleaning equipment to provide the sensors, however, even the risk of Pollution of the sensors in itself, because of the blown air pulses Dust from the environment of the sensor can be whirled up or Dirt particles are first directed through the glass device onto the sensor and settle on the sensor.

From the DE 103 57 439 A1 It is known to arrange ultrasound transmitters on guide surfaces of substrates in order to generate alternating pressure stresses on the guide surface, which compensate for the contact forces between guide surface and paint / lacquer particles and thus reduce the deposition of printing ink or lacquer.

Of the Invention is based on the object, the cleaning of sensors in polluting Areas to improve.

According to the invention Task by a sensor device with the features of the first Claim solved.

The The invention has the advantage that the deposition of measured values falsifies Dirt on the sensitive signal input and output surfaces of a Sensor compared to blown air purification equipment essential is reduced. Due to the intensive alternating pressure stresses In the ultrasonic vibration field, the deposit-forming adhesion adhesion forces of the Effectively overcome dirt particles. Another advantage is that with permanent activation the ultrasonic cleaning already the deposition of dirt particles to the sensor surface is prevented.

• – der Bedruckstoffvereinzelung,
• – der Bedruckstoffausrichtung vor dem Druck oder
• – des zeit- und lagerichtigen Bedruckstofftransportes zu und zwischen den Druckwerken

angeordnet. Aufgrund des oberflächlich auf dem Bedruckstoff anhaftenden Staubes, der sich während des Transportes vom Bedruckstoff löst und sich längs des Bedruckstoffweges in der Druckmaschine verteilt und niederschlägt, sind die Sensoren entlang des Bedruckstofftransportweges besonders verschmutzungsgefährdet. Für die vorgeschlagene Lösung ist die konkrete Ausgestaltung und Anordnung der vor Verschmutzung zu schützenden Sensoren unerheblich, so dass eine detaillierte Beschreibung der Sensoren und ihrer Anordnungspunkte nicht erforderlich ist.Sensors are in printing machines, for example, along the Bedruckstoffweges to control

• - the printing material separation,
• - the printing material orientation before printing or
• - the time and position of the substrate transport to and between the printing units

arranged. Due to the superficially adhering to the substrate dust that dissolves during transport from the substrate and distributed along the Bedruckstoffweges in the printing press and reflected, the sensors along the Bedruckstofftransportweges are particularly vulnerable to contamination. For the proposed solution, the specific design and arrangement of the sensors to be protected against contamination is irrelevant, so that a detailed description of the sensors and their arrangement points is not required.

The Invention will be explained in more detail using the example of an optical sensor. The associated Drawings have the following meaning:

1 schematic representation of an optical sensor with integrated ultrasonic cleaning device

2 schematic representation of an optical sensor with arranged thereon ultrasonic cleaning device

3 schematic representation of a combination of an optical sensor with an ultrasonic sensor

Like from the 1 As can be seen, there is an optical sensor 2 at least from a light transmitter (light source) and a light receiver detecting the intensity of the incoming measuring signal, wherein in the exemplary embodiment both parts are in a sensor housing 8th are arranged (light scanner, reflection light barrier). For protection against mechanical effects, the light transmitter and light receiver are equipped with a common, optically transparent cover, which must pass through the emitted measuring beam and the incoming measuring signal. Housing surfaces exposed to ambient conditions in the propagation path of the transmitted and received radiation are referred to below as transmitting and / or receiving surfaces 3 be designated. In the exemplary embodiment, the common transparent cover of light transmitter and light receiver forms the transmitting and / or receiving surface 3 the sensor device 1 ,

In a first constructive variant, at least one ultrasonic transducer 4 in a common sensor housing 8th with the sensor 2 arranged, being between the ultrasonic transducer 4 and the transmitting and / or receiving area 3 a known per se, ultrasonic frequencies transmitting mechanical or adhesive coupling (for example, adhesive connection) for transmitting the ultrasound there is vibration. The ultrasound transducer 4 can be directly on the inside of the transmitting and / or receiving surface 3 be fixed over the entire surface outside the beam path of the transmit and receive beams and is, for example, as piezzo-electric ultrasonic transducer 4 carried out at frequencies of 20 kHz to 1 GHz, which is to cancel the surface adhesive forces between the exposed transmitting and / or receiving surface 3 and the dirt particles which deposit thereon advantageously have an oscillation plane perpendicular to the transmitting and / or receiving surface to be cleaned 3 having.

It is expedient for the vibrational decoupling of the sensor 2 the transmitting and / or receiving surface 3 for example in an elastic seal 6 in the sensor housing 8th to store. To increase the mechanical strength, it is advantageous to the transmitting and / or receiving surface 3 , which is usually made of a glass, in a swinging or elastic on the sensor housing 8th stored frame 7 and this at a frame broadening or extension to the ultrasonic transducer 4 coupled, with constructive or optically required distances between sensor 2 and ultrasonic transducers 4 can be advantageously realized. If transmitting and / or receiving surfaces 3 exist as separate surfaces, is at least one ultrasonic transducer 4 assigned to each surface.

In an in 2 shown second structural variant is the ultrasonic transducer 4 as a separate cleaning device outside of the sensor 2 receiving sensor housing 8th on an outside of the sensor device 1 arranged and transmits the ultrasonic vibrations to the transmitting and / or receiving surface 3 by vibration coupling to the transmitting and / or receiving surface 3 or one the transmitting and / or receiving surface 3 enclosing framework 7 analogous to the first variant.

In a variety of practical applications, it is necessary due to the increasing width of the properties of the substrates to be processed to use multiple sensors with complementary measuring ranges, such as an optical sensor 2 with an ultrasonic sensor 5 to combine for multiple sheet control. The optical sensor 2 It is used for determining the thickness of thin and medium paper stocks, the ultrasonic sensor 5 is intended for higher paper or board thicknesses (> 350g / m ² ).

With a fixed coupling of the ultrasonic transducer 4 / of the ultrasonic sensor 5 to the transmitting and / or receiving surface 3 of the optical sensor 2 ( 3 ) or an orientation of the ultrasonic sensor 5 on the transmitting and / or receiving surface 3 is it possible to use the ultrasonic sensor 5 to be used as a cleaning device. During operation of the ultrasonic sensor 5 becomes the transmitting and / or receiving area 3 by the effect of the sound emissions of the active ultrasonic transducer 4 cleansed of dirt. The ultrasonic sensor 5 fulfills a double function. With active ultrasound substrate control the ultrasonic transducer works 4 as an ultrasonic sensor 5 and at the same time as a cleaning device. The ultrasonic sensor 5 can also be activated in the operating phases of the printing press, in which it is not required for printing material control, for continuous cleaning of the transmitting and / or receiving surface advantageous 3 of the optical sensor 2 ,

This variant requires a greater effort to set and calibrate the ultrasonic sensor 5 , as with resonant transmitting and / or receiving surface 3 the vibration parameters of the ultrasonic transducer 4 from the sensor 2 to be influenced.

For the operation of the device according to the invention:

Through stray dust or paint particles that settle on the transmitting and / or receiving surfaces 3 the sensor device 1 precipitate, their transparency is reduced and the intensity of the measuring beams or measuring signals in undefined manner reduced, so there is a Messwertverfälschung and incorrect control of the printing press. By transmitting vibrations with ultrasonic frequency to the transmitting and / or receiving surface (s) 3 These are excited to vibrate, initiate the alternating pressure forces in the boundary layer area, which overcome the adhesive forces of the dirt particles and thus lead to detachment of the particles.

The example of an optical sensor 2 described sensor device 1 is analogous to all other sensors with contamination-induced Messsignaldrift, for example, capacitive sensors applicable.

1

sensor device

2

sensor

3

Send- and / or receiving surface

4

Ultrasound transducer

5

Ultrasonic Sensor

6

elastic poetry

7

frame

8th

sensor housing

Claims (4)

Sensor device ( 1 ) for polluting areas in printing presses, wherein the sensor device ( 1 ) at least one sensor ( 2 ) whose measuring signals at transmitting and / or receiving surfaces ( 3 ) from the sensor device ( 1 ) and / or enter, characterized by a cleaning device which the sensor ( 2 ) and pollution-removing ultrasonic vibrations at the transmitting and / or receiving surfaces ( 3 ) of the sensor ( 2 ) trains. Sensor device ( 1 ) according to claim 1, characterized in that at least one ultrasonic transducer ( 4 ) in the sensor device ( 1 ) and vibrations with ultrasonic frequency in the transmitting and / or receiving surfaces ( 3 ). Sensor device ( 1 ) according to claim 1, characterized in that at least one ultrasonic transducer ( 4 ) as a separate cleaning device at each transmitting and / or receiving surface ( 3 ) is arranged and ultrasonic vibrations on the transmitting and / or receiving surfaces ( 3 ) transmits. Sensor device ( 1 ) according to one of the preceding claims, characterized in that the sensor ( 2 ) an ultrasonic sensor ( 5 ), which ultrasonic vibrations also on the transmitting and / or receiving surfaces ( 3 ) transmits.