Transport apparatus for tape-type media and method for regulating the transport speed

1. A transport apparatus for a medium taking the form of a strip having perforation hales, the apparatus including a device for determining the transport speed of the medium, the device including a linear ray sensor extending along the transport direction and having. a combined length at least as long as one perforation hole and the distance between two perforation holes in the medium transport direction for imaging a selected portion of the medium encompassing at least a pair of spaced perforation holes along the transport direction and a region between said pair of perforation holes, comprising:

means for illuminating at least the selected portion of the medium; and

a signal processing circuit connected to the linear array sensor for determining the transport speed of the medium from the output signals from the linear ray sensor, wherein the signal processing circuit identifies characteristic intensity patterns associated with at least the pair perforation holes and the region between perforation holes and calculates the transport speed of the medium from the displacement of the intensity pattern between a first read-out instant of the linear ray sensor and a subsequent read-out instant and a read-out clock rate.

2. The transport apparatus as claimed in claim 1 , wherein the signal processing circuit has a line memory, for storing the image data of the linear array sensor.

3. The transport apparatus as claimed in claim 1 wherein a read-out device reads the linear array sensor at a predetermined clock rate.

4. The transport apparatus as claimed in claim 1 , wherein the signal processing circuit evaluates a plurality of intensity patterns and forms a mean value from the associated transport speeds.

5. The transport apparatus as claimed in claim 1 , wherein the signal processing circuit outputs a speed signal representing the transport speed.

6. The transport apparatus as claimed in claim 1 , further comprising a servo circuit which regulates the transport speed as a function of the speed signal of the signal processing circuit.

7. A film scanner with a transport apparatus as claimed in claim 1 .

8. A film recorder with a transport apparatus as claimed in clam 1 .

9. A method for regulating the transport speed of a medium taking the form of a strip, comprising the steps of:

a) reading a linear array sensor for imaging a selected portion of the medium encompassing at least a pair of spaced perforation holes spaced along the transport direction and a region between said pair of perforation holes;

b) storing the output data of the sensor liner array in an image memory;

c) determining intensity patterns from the output data of the linear ray sensor associated with at least the pair of the perforation holes and the region between perforation holes;

d) ascertaining the displacement of an intensity pattern between a first read-out instant and a subsequent read-out instant and calculating the transport speed, and

e) generating a speed signal representing the transport speed of the medium,

f) regulating the low-frequency portion of fluctuations of the speed signal supplied to a servo unit in order to regulate the transport speed of the medium, and

g) regulating the high-frequency portion of fluctuations of the speed signal supplied to an image data processing circuit in order to effect image stability corrections.