Infrared heating apparatus for heating web-like material

Claim 2

Apparatus for use in heating a web-like material during its passage through a processing machine, said apparatus comprising at least one heating panel which faces a path of travel taken by a web-like material when passing through a processing machine, said panel is equipped with at least one short-to-medium-wave infrared-radiation producing element, a controlling circuit having means for varying the heat emission of the heating panel as a function of the magnitude of a control signal, a control means providing an output to the controlling circuit of the control signal, said control means comprising a sensor generating a signal corresponding to the rate of passage thereby of web-like material which signal is supplied to a first input of a control circuit, and a second input of the control circuit to which a manually operable adjusting device is connected for adjusting the rate of change of the control signal as a function of the signal corresponding to the rate of passage of web-like material.

Claim 3

Apparatus for use in heating a web-like material during its passage through a processing machine, said apparatus comprising at least one heating panel which faces a path of travel taken by a web-like material when passing through a processing machine, said panel is equipped with at least one short-to-medium-wave infrared-radiation producing element connected to a power supply through semiconductor switching means, a controlling circuit for delivering ignition impulses to the semiconductor switching means, wherein the ignition time within each half period of the power supply voltage is determined by a control signal in such a manner that the heat emission of the heating panel varies as a function of the magnitude of the control signal, said control signal being provided to the controlling circuit by a control means which comprises a sensor generating a signal corresponding to the rate of passage thereby of web-like material, which signal is supplied to a first input of a control circuit an output of which delivers the control signal which increases as a function of increasing rate of passage of web-like material, wherein the control circuit has a second input to which a manually operable adjusting device is connected for adjusting the rate of increase of the control signal as a function of the increasing rate of passage of web-like material.

Claim 4

Apparatus for use in heating a web-like material during its passage through a processing machine, said apparatus comprising at least one heating panel which faces a path of travel taken by a web-like material when passing through a processing machine, said panel is equipped with at least one short-to-medium-wave infrared-radiation producing element connected to a power supply through semiconductor switching means, a controlling circuit for delivering ignition impulses to the semiconductor switching means, wherein the ignition time within each half period of the power supply voltage is determined by a control signal in such a manner that the heat emission of the heating panel varies as a function of the magnitude of the control signal, said control signal being provided to the controlling circuit by a control means which comprises a sensor generating a signal corresponding to the rate of passage thereby of web-like material, which signal is supplied to a first input of a control circuit an output of which delivers the control signal which increases as a function of increasing rate of passage of web-like material, wherein the control circuit has a second input to which a manually operable adjusting device is connected for adjusting the rate of increase of the control signal as a function of the increasing rate of passage of web-like material.

Claim 5

Apparatus according to claims 1 or 2, wherein the sensor generates a pulsed signal, the frequency of which is proportional to the rate of passage of web-like material, the control circuit comprising a converter which is provided with an impulse generator which, in response to the pulsed signal, delivers output impulses having a predetermined impulse duration which are supplied to a switch input of an analog switching means, an analog input of which receives a dc-voltage the value of which is determined by the adjusting device, while an analog output is connected to a low-pass filter an output of which controls an amplifier which provides the control signal.

Claim 6

Apparatus according to claims 1 or 2, wherein the control signal is also supplied to a monitoring circuit which disconnects the controlling circuit when the control signal is smaller than a reference value corresponding to a given rate of passage.

Claim 7

Apparatus according to claim 4, wherein said reference value is adjustable by means of an adjusting device.

Claim 8

Apparatus according to claim 4, wherein the monitoring circuit comprises a time-delay means which energizes the controlling circuit after a predetermined period of time during which the control signal has exceeded the reference value.