DD148823A1 - CCD ARRANGEMENT FOR LENGTH MEASUREMENT - Google Patents

Abstract

The invention is used for long Maszstaebe or Meszlatten. The task is to overcome the limit of the mesa range due to the manufacturing technology of a CCD line. This is done by at least two CCD rows are at least offset by their width against each other, where d. Limiting their elements lie in the measuring direction on a straight line. The CCD lines can be arranged in two tracks on a common carrier. They are interconnected, whereby they are supplied with a common clock, illuminated CCD lines are detected and the video signal is evaluated.

Description

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Title; CCD arrangement for length measurement

Field of application of the invention:

The invention relates to a CCD array for length measurement in which the information about the length to be measured is given by the different position of a light beam to a CCD array.

Characteristic of the known technical solutions:

It is known to use linear arrays of photodetectors for length measurement. In DD 108 147, a linear photoreceptor array is illuminated by a light source via a movable scan mark. The length information is obtained in an incremental way. In DE-OS 2756364 a leveling staff is given, which also works with a linear array of photoreceptors. Such arrangements are not designed for a large measuring range due to the high cost. The resolution of the measuring system is linked to the size of the receiver. To achieve greater resolutions, several staggered rows of receivers are used, which in turn require an additional complicated evaluation and thus further increase the cost of such an arrangement. It is also known to use CCD lines for length measurement. In DE-OS 2703563 a CCD array is illuminated by a light source. By hiding a part of a linear light source with a movable mask or moving the light source by a movable component, the transmission of the length information in the CCD array. 3562

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With such arrangements, it is not possible to measure longer lengths, since the length of a CCD line is limited for technological reasons to a few centimeters, and a linear string of CCD lines is not technically useful. Due to the technological process of producing such lines, it is not possible for the boundary of the photosensitive receivers to coincide with the chip boundary.

Aim of the invention;

By the invention, a CCD array for length measurement is to be created, which allows to overcome the conditional by the manufacturing technology of a CCD line limit of the measuring range.

Explanation of the essence of the invention;

The object of the invention is to provide a CCD array for length measurement, in which any number of CCD lines can be arranged one behind the other and the detection of any measuring range with a simple electronics is possible. This object is achieved in that at least two CCD rows are arranged successively, that both CCD rows are offset from each other at least by their width against each other, that the end of a CCD line with the end or an element boundary of the other CCD line is on a straight line and that the lines are connected in a suitable manner electronically with each other. A favorable arrangement results when the CCD lines are arranged alternately in two tracks. Thus, any number of lines can be arranged one behind the other, without resulting in a large lateral distance.

According to another embodiment, each CCD line can be mounted in a housing. This results in a particularly simple embodiment, since the CCD components can be soldered in commercial form. It is expedient that the CCD lines are arranged on a common carrier, the arrangement of the necessary stability

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and consistency of length gives. It makes sense to provide the CCD lines with a common clock to recognize illuminated CCD lines by electronic Schwellwertbildner and bring the video signals of these lines to the Aus-Rating. This results in the possibility to keep the electronic effort relatively low by a part of the electronics for all lines used together.

The invention can be used particularly favorably for long scales or geodetic measuring slats.

Embodiment;

The invention will be explained in more detail below with reference to the schematic drawing in which:

Pig. 1 shows a first embodiment of the CCD arrangement in view,

Pig. 2 a section through the arrangement according to Pig. 1 along the line A-A,

3 shows a second embodiment of the CCD arrangement in view,

Pig · 4 a section through the arrangement of Pig. 3 along the line B-B,

Pig. 5 an enlarged section of Pig. 3 along the line B-B, Pig. 6 shows an enlarged detail of FIG. 3 along the line B-B in a second embodiment, and FIG. 7 shows an electronic circuit for operating the CCD arrangement.

Fig. 1 shows a detail of a CCD array, are attached to the CCD lines 11-17 in housings 1-7.

The CCD lines 11; 13; 15; 17 are in a track, the CCD lines 12; 14; 16 arranged in a second track. Their lateral distance C is given by the width of the housing 1-7. The recognizable in Figure 2 housing 5; 6 are soldered to a printed circuit board 22, which includes a portion of the wiring and at the same time a common

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Represent carrier for all CCD lines. The printed circuit board 22 is expediently applied to a main body 21, in whose channel 23 further printed circuit boards can be accommodated. These are not shown for the sake of simplicity. Such an arrangement is relatively easy to produce, but disadvantageous is still the large distance C between the two tracks. This disadvantage is caused by an arrangement according to Pig. 3 and Pig. 4 avoided. The CCD lines 11; 13; 15 are again arranged in a track, the lines 12; 14; 16 in a second lane, but in each Pail without housing. The recognizable in Figure 4 CCD lines 13; H are applied to a common carrier 24. This can for example be a circuit board. The CCD lines can be cemented to the carrier 24, the wiring can be done in a known manner by bonding, optionally on one or more separate circuit boards, which may also be mounted on the carrier 24. These are not necessary for understanding the invention and therefore not shown. The carrier 24 is mounted in a channel 23 of the main body 21. To protect the CCD lines is a cover 25, which may be, for example, an optically flat and anti-glare glass. Such a cover is also in a version of Pig. 2 possible. Advantageous to the arrangement according to Pig. 3 and. 4 is the small distance D between the tracks, which is limited only by the width of the CCD lines (chip width). To achieve a gap-free measuring range, it is necessary that the end of a line and the beginning of the next line is on a straight line, so in lines 13 and 14 in Pig. 3 on the straight B-B. In Pig. 5 is an enlarged detail of Pig. 3, wherein it can be seen how the photosensitive elements 20 of both lines 13; 14 seamlessly connect to each other. Since full sensitivity is not guaranteed for the last elements of a line, there is also an overlap

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the CCD lines around one or more elements possible, as they Pig. 6 shows. The last two elements 20 of the line 13 and the first two elements 20 of the line 14 cover the same length range. The signal of the respective first and last element of each line can be electronically suppressed in a known manner. Fig. 7 shows the evaluation electronics based on an arrangement with seven CCD lines, the example in Pig. 1 are shown. Lines 3 to 6 with their immediate downstream electronic components are omitted for simplicity. They are the same as shown in lines 1, 2 and 7. A clock generator 71 is connected to a clock generating logic 72. This generates in a known manner the necessary for the operation of the CCD lines 11-17 multi-phase clock signals which are supplied via drivers 73 to the CCD lines 11-17. The CCD lines are connected in parallel to the common driver 73. Each output 91-97 of a CCD line is connected to a differential amplifier 31-37, the differential amplifiers amplifying the video signal in a known manner and separating it from the impressed Rücksitztakt. Each of the differential amplifiers 31-37 is connected to a threshold generator (comparator) 41-47 which, in the presence of a signal exceeding the threshold, turns on the respective hold circuit (Plip-Plop) 51-57 connected to it. The latch circuits 51-57 are connected to a control logic. The control logic 74 is connected to the gates 61-67 which it can open. The gates 61-67 are further connected to the differential amplifiers 31-37. The gates 61-67 are connected to the A / D converter 75. This is connected via a buffer memory 76 to the microcomputer 77. Furthermore, the control logic 74 via the start pulse line 81 with the logic for clock generation 72 and the computer 77 is connected. The calculator 77 is over the

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Reset line 82 connected to all holding members 51-57. The computer is still connected via line 83 to the control logic 74. The circuit works in the following way. The CCD lines 11-17 are supplied via the clock generation logic 72 and the driver 73 with a common clock, so that the reading is common in all CCD lines. The CCD line 12 is illuminated, for example. Via its output 92, it outputs its video signal to the differential amplifier 32. Since the line 12 is illuminated, the video signal exceeds the threshold of the threshold generator 42 which switches the latch 52. The logic 74 opens with the next start pulse on the start pulse line 81 the gate 62, through which the video signal from the differential amplifier 32 can get directly into the A / D converter 75. There, it is converted into digital information and forwarded to the buffer memory 76, which stores it in the microcomputer 77 until it is accepted. Another start pulse on the start pulse line 81 causes the logic 74 to close the gate 61 again, since the transmission of the video signal is completed. The logic 74 is also on the line 83 to the computer 77, the number of the switched holding member and thus the number of the illuminated CCD line 12. Are multiple CCD lines illuminated, for example, when a light beam along the axis B-B in Pig. 3, these are read one at a time by the logic 74 opening, with each start pulse on the line 82, one of the gates 61-67 whose holding circuit 51-57 indicates an illuminated line, in the example of illumination of the axis B-B after Pig. 3 successively the gates 63 and 64. It must then be submitted successively both line numbers on the line to the computer 77. The logic 74 has a counter or even a computer structure for this Pail. If the reading is completed, which the computer 77 through the line 83 or the absence of a signal in the memory

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Rather, 76 is displayed after several start pulses 81, it returns via the line 82, the holding circuits 51-57. The computer 77 performs in a known manner a center of gravity detection in the video signal of the illuminated lines. In the read-only memory 78 of the computer 77, data such as length, element size and distance of the CCD lines and optionally the overlapping of elements 20 according to FIG. 6 must be stored for the further evaluation. With this data, the computer 77 can then calculate the measurement result and provide or display it for further processing. A particular advantage of the circuit of Fig. 7 is that only relatively small logic units such as the amplifiers 31-37, the threshold formers 41-47, the holding members 51-57 and the gates 61-67 are the same number as the CCD rows must be present. The invention is not limited to the embodiment. Thus, with appropriate geometry of the CCD array, it is possible to extend the application of the invention to multi-coordinate and angle measurement and other measurements where measurement with a CCD array over a wide range of measurement is required. The overlap of elements need not necessarily be an integer multiple of the element size if the size of the overlap is stored in read-only memory 78. Furthermore, it is not absolutely necessary to switch the CCD lines in parallel from the clock. It is also possible to assign a separate driver to each CCD line. To suppress the noise level, the video signal can be transmitted several times. The threshold value of the Koraparatoren can be designed depending on external conditions, such as Urafeidlicht, distance and strength of the light source, adjustable. Finally, the invention is not limited to the number of CCD lines shown.

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Claims (5)

-8- 218 9Ü8 Invention claim: 1. CCD array for length measurement, characterized in that at least two CCD rows are arranged successively, that both CCD rows are offset from each other at least by their width against each other, that the end of a CCD line with the beginning or an element limit of other CCD line is on a straight line and that the lines are connected together in a suitable manner 2. CCD arrangement according to item 1, characterized in that at least four CCD rows are arranged, which are arranged alternately in two tracks · 3 * CCD arrangement according to item 2, characterized in that each CCD line is mounted in a housing. 4. CCD arrangement according to point 2, characterized in that all the CCD lines are arranged on a common carrier · 5. CCD array according to item 1, characterized in that the CCD lines are supplied with a common clock that electronic Schv / ellwertbildner are provided to detect illuminated CCD lines and that the video signals of these lines reach the evaluation. DazujL pages drawings 3562