DE8800796U1 - Device for registering irrigation irregularities - Google Patents

Description

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Device for registering irrigation irregularities

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Online registration of casting irregularities, preferably dropouts, in band-shaped recording media cast on transparent layer supports, preferably magnetic tapes, which move relative to the device, in transmitted light with optoelectronic means over the entire width of the recording media, whereby as a photoreceiver preferably a photodiode registers the light flowing through and an evaluation electronics evaluates the registered light.

When producing photographic materials or magnetic recording media, flexible films made of cellulose triacetate or polyethylene terephthalate are preferably used as the layer carrier. It is necessary to check the film webs after coating for coating irregularities and defects in their surface, as such defects are known to have a significant impact on both the recording and reproduction quality of the recording media. Such checks are normally carried out on a random basis, for example by measuring the layer thickness using mechanical methods or examining the surface using interference optical methods.

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Such devices are known, among others, from DE- OS 16 23 196, 24 919, 29 09 400, 29 SS 716, 31 49 709, 32 48 157, 31 36 887, 29 07 620, 23 33 326, 23 55 185, 22 54 910, 29 28 997, EP 0 211 654 and L)S 3 §56 630. A method is also known in which a laser beam scans the film web and the reflected

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However, most of the known measuring devices have some disadvantages:

- They are not suitable for high casting speeds

- They are unable to ensure the quality of the watering both in the

the entire length as well as up to the pouring edge without gaps ».

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- They require high equipment and cost expenditure

- They depend on the ambient light and fluctuations _in

j the light source used

- They fail when the film web changes, i.e. across

is moved back and forth in the casting direction &ldquor;

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- They only register irrigation disturbances with large dimensions.

The task was therefore to create a device of the type mentioned at the beginning which does not have the above-mentioned "disadvantages". According to the innovation, the task was solved "with a device of the generic type with the features listed in the characterizing part of claims 1 and 2. Further details of the invention can be found in

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from the subclaims, the description and the drawings.

The new feature is explained in more detail below using the drawing, which shows

Figure 1 is a schematic diagram of the device according to the invention

Figure 2 shows another representation of a device according to the innovation

Figure 3 a schematic diagram of the electronic evaluation

Figures the separation of long- and short-term 4a and b signal changes, which can be separated using the basic circuit diagram according to Figure 3.

A preferred embodiment of the device according to the invention is shown in Figure 1. An elongated light source (1) housed in a lamp housing (6), for example a festoon lamp, which extends perpendicular to the film web running direction and whose luminance is kept homogeneous up to the edge zones by suitable light scattering devices (for example a ground glass screen (12)).

can be irradiated through the foil web (2). This consists of a recording medium cast on a transparent layer carrier, for example a magnetic tape. The direction of travel is indicated by an arrow. Below the foil web there is a collecting lens (3) which concentrates the light passing through onto a photoreceptor (4), for example a diode. It is essential to the invention that the length of the light source (1) is greater than the width

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the foil web (2) _so that light still passes by on both sides of it and hits the photo receiver. This device has the advantage _that even with lateral fluctuations of the moving foil web, the so-called traversing, the amount of light hitting the photo receiver remains constant, as long as the traversing area is in the homogeneous part of the

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The amount of light only changes when there is a sudden

f 10 casting irregularity, such as a casting failure, occurs.

j! The registered light change is evaluated by an evaluation

tronik (5) (Figure 3).

In the present innovation, the principle diagram of the zero point control shown in Figure 3-15 compensates for the sudden signal change caused by pour-outs.

£ separated from a long-term signal change, for example

This can be achieved by changing the intensity of the light source or the ambient light or by changing the illumination area, when the illumination area is not homogeneous. The appropriate time constant can be achieved by dimensioning the electrical components, which is familiar to any expert. In this way, as shown in Figures 4 a and 4 b, the input signal with short- and long-term voltage fluctuations is converted into the output signal, which only contains the short-term voltage peaks with a constant background. In addition, this circuit suppresses the photoelectric rest signal. The error signal in the form of the voltage peak shown can now be evaluated as desired according to the known state of the art.

Another preferred embodiment of the innovation is shown in Figure 2. Here, the light from the light source 1,

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which can also be a festoon lamp, via a light scattering device, for example a ground glass screen (12). (The light scattering device is not absolutely necessary for both versions according to Figures 1 and 2. Interference signals that arise from band oscillations in connection with the lighting inhomogeneity are eliminated by the electronics.) The light that passes through falls on a trough-shaped receiver housing (9) arranged below the film web 2, the inner walls (8) of which are designed to be reflective, so that the light finally hits a rod-shaped photo receiver (7) arranged in the bottom of the trough parallel to the light source.

Such photoreceivers are sold commercially, for example under the name Siemens SFH 100. The length of the photoreceiver (7) does not necessarily have to correspond to the width of the film web (2). The middle (dashed) part of the photoreceiver will normally be dark, since the light coming from the light source is suppressed by the film web, while the right and left edges are illuminated by light passing through the sides of the web or reflected on the inner walls (8). Even with this arrangement, oscillation, i.e. transverse displacement of the film web, does not cause any measurement or registration errors. The electronic evaluation takes place as shown above.

The described innovative arrangements, of which only two possible preferred devices are described without all possible innovative solutions being described exhaustively, offer particular advantages (they are particularly useful for the automatic online registration of casting errors).

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for example, with film webs, for example with magnetic tapes separated into usable widths, for example for half-inch video tape. Such strips, which pass through high speeds both during casting and during separation, are in this way monitored for casting defects up to the edge using an inexpensive device, so that rejects can be localized and the cost-effectiveness of production is significantly increased.

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Claims (1)

I Protection claims: I 1. Device for automatic online registration of i casting irregularities on transparent layer ä 5 carrier cast tape-shaped recording media, I preferably magnetic tapes, which are relative to the pre- ! direction, in through-light measurement with optoelectronic ', nic means across the entire width of the recording : voltage carrier, whereby the photoreceiver is preferably a [ 10 Photodiode registers the transmitted light and a i Evaluation electronics evaluate the registered light, thereby characterized by - by a transversely extending to the recording medium &iacgr; 15 kendr light source (1) the recording medium (2) with I a light beam can be penetrated and where the I Expansion area of the light source larger than the width \ of the recording medium is ! 20 - all the light passing through a convex lens (3) can be bundled onto a photoemitter (4) - in an evaluation electronics (5) short-term pulses of long-term signals are generated from the signal registered by the photo receiver. 25 nal fluctuations are separable. I 2. Device according to the preamble of claim 1, \ characterized by I 30 - a crntrackcndn transverse to the recording medium ! Light source (1) the recording medium (2) preferably wise with diffuse light, whereby the ¹ extension of the light source is larger than the width of the recording medium A-G 5307 - all the light passing through hits a trough-shaped receiver housing (9) with reflective inner walls (0) arranged below the recording medium, in the lower part of which there is an elongated photoreceiver (7) arranged parallel to the light source - in an evaluation electronics (5) in the signal registered by the photo receiver (4) long-term fluctuations can be separated from short-term pulses. II III t # ·