JPS58103073A - Pattern reader - Google Patents

Abstract

PURPOSE:To read an input pattern in a high speed with a simple constitution, by measuring the length between an object pattern and an image pickup device and changing the quantity of deflection or the like of the image pickup device on a basis of this information to read always the input pattern with a certain magnification. CONSTITUTION:An object pattern 1 is moved to reach the position just under an image pickup device 2 and is detected. At this time, the height of an object having the pattern 1 is projected by the vertical scanning of a line image sensor 3, and a height signal value is measured by a height measuring circuit 4. This signal value is inputted to a deflection controlling circuit 5, and the deflection speed is changed in accordance with this height to make the magnification of an image picked-up pattern constant. That is, if the object is high, a length L between a magnifying lens 6 and the object is reduced, and the pattern 1 is picked up as a large pattern. In this case, the deflection speed is made high to read the pattern, and the pattern signal is always sampled at a constant time, and thus, the size of the object pattern is made constant apparently. The sampling frequency of the pattern may be changed instead of the deflection speed.

Description

Detailed Description of the Invention (1) Technical Field of the Invention The present invention relates to a pattern reading device that detects character patterns, etc., and particularly to a reading system that detects patterns regardless of the distance difference between an object and an image pickup device. Regarding equipment.

(2) Technical Background After electronic components such as C) and resistors are attached to circuit boards, they are inspected to see if they are of the same type (1) or different types.In addition, important communications The manufacturing date and manufacturing lot number of the installed parts are checked and saved in the equipment. However, in all cases, the detection is done visually by the operator, and even if equipment production is automated, Regardless, inspection is a task that requires a large number of man-hours.Therefore, it cannot be overstated that it is desirable to perform such a detection task automatically.

(3) Prior art and problems Conventionally, image patterns such as character patterns have been captured using an imager such as T.
V-Right Camera Various pattern reading devices are well known that scan optically and binarize the signal for detection, and some are used as terminals for electronic computers. Among these, in order to optically read regular patterns such as printed characters at high speed with a simple device configuration, the pattern reading device is designed to read at a constant magnification.
Haku-tsumano-Ak &'L, J + Reading + Coffin 9-fitting furnace is advantageous. However, since the electronic components mounted on the circuit board as described above differ in size, the distance between the detection surface and the imager changes and the magnification changes, causing the problem that accurate pattern matching cannot be achieved with the above method. There is. Therefore, in order to deal with such changes in distance, a method is adopted in which a special zoom lens is used to change the magnification so that it always remains at a constant magnification, or a method is adopted in which the image pickup device is moved up and down to always maintain a constant distance. However, since they all involve mechanical movement, there are problems with response speed and device durability.

(4) Purpose of the Invention The present invention eliminates the above-mentioned problems, and even if the distance between the target pattern and the image pickup device changes, the magnification of the read pattern is always constant, and the correction is automatically performed. We propose a reading device.

(5) Structure of the Invention The present invention is characterized by measuring the distance between the target pattern and the imager using, for example, an image sensor, and determining the amount of deflection of the imager based on the information in item 7 or (-J pattern sampling). The pattern reading device is equipped with a function of constantly reading the input cover pattern at a constant magnification by changing the frequency, and will be described in detail below with reference to the drawings.

(6) Embodiment of the Invention A block diagram of an embodiment of the present invention is shown in FIG. 1, and this is an example in which the magnification of an imaged pattern is made constant by changing the amount of deflection. In the figure, the target pattern 1 moves and reaches directly below the imager 2, and the pattern is detected.
Immediately before or at the same time, the height of the object having the target pattern l is captured by vertical scanning of the line image sensor 3, and the height signal value is measured by the height measurement circuit 4. The height signal value is input to the deflection control circuit 5, and the deflection speed is changed within the same circuit according to the height, so that the magnification of the imaged pattern is kept constant. That is, when the height of the object having the target pattern l is high, the distance between the magnifying lens 6 and the object becomes small, and the target pattern l is imaged as a thick Hiko pattern. At that time, if the deflection speed is increased, the pattern is read by the imager 2, and the pattern signal is sampled at a constant time, the size of the target pattern will appear to be constant. Then, patterns with the same pattern magnification will be input to the pattern signal storage circuit. In FIG. 1, 7 is a binarization circuit for the imaging pattern, 8 is a sampling clock oscillation circuit, and 9 is a pattern signal storage circuit, in which the pattern signal output from the pattern signal storage circuit 9 and an electronic computer (not shown) are connected.
The pattern is recognized by matching it with a pattern stored in advance.

FIG. 2 shows an outline of a deflection control circuit that changes the height signal value from the height measurement circuit 4. The measured height signal value is converted into an analog voltage by the DA conversion circuit 10.
The current is input to a constant current power supply circuit 11 as shown in the figure, and a constant current value corresponding thereto is stored in a capacitor C. Then, the voltage from the capacitor C passes through the amplifier 12 to the deflection coil generating circuit of the imager, and then through the transistor TR to synchronize the constant current power supply circuit 11, and also synchronize the sampling clock oscillation circuit as shown in FIG. In addition, the constant current power supply circuit 11
acts so that the voltage generated across the current detection resistor R becomes constant, and the load current becomes constant.

FIG. 8 is a block diagram showing another embodiment according to the present invention, which is an example in which the pattern sampling frequency is changed to obtain a constant pattern magnification. As in FIG. 1, the target pattern l moves, the pattern is detected directly below the imager 2, the height captured by the line image sensor 8 is measured by the height measurement circuit 4, and the height signal value is A sampling clock frequency oscillator 18 whose frequency can be made variable is inputted. The sampling clock frequency oscillator 18 is composed of a DA converter circuit 20 and a voltage controlled oscillator 21, for example, as shown in FIG. 4, and the sampling clock frequency changes according to the changed voltage.

If the magnifying lens 6 and the target pattern l on the object are taken, the sampling clock frequency will be slow and the pattern will not be small, and the pattern with a constant magnification can be input into the pattern signal storage circuit 9. be. In this example, unlike the previous embodiments, the deflection speed of the deflection control circuit 15 is constant and the amount of deflection does not change, so the device has the advantage of being simpler than the previous example.

In either case, it is assumed that the lens 6 has a sufficient depth of focus against changes in the height of the object having the target pattern l.

(7) Effects of the Invention As can be seen from the explanation of the embodiments above, the present invention is a method of optically detecting a varying distance and adding a correction circuit, so it has a high-speed response and a reading device. It is also simpler and cheaper to manufacture than mechanical correction methods.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of the reading device according to the present invention, FIG. 2 is a partial circuit diagram thereof, FIG. 7 is a block diagram of another embodiment, and FIG. 4 is a partial diagram thereof. be. In the figure, 1 is the target pattern, 2 is the imager, 8 is the line image sensor, 4 is the height measurement circuit, 5 and 15 are the deflection control circuits, 6 is the magnifying lens, 7 is the binarization circuit, and 8.18 is the a sampling clock oscillation circuit, 9 a pattern signal storage circuit, 10.20 a DA conversion circuit, 11 a constant current power supply circuit,
12 is an amplifier, 18 is a deflection coil, and 14 is a synchronizing signal generating circuit. 11 Figure 2 shadow 3 Figure 4 2 fi4 (.

Claims (1)

[Claims] Reading the general pattern signal with an imager that performs deflection scanning;
A pattern reading device that detects the pattern by converting it into a value measures the distance between the target pattern and the imager, and changes the amount of deflection of the imager or the sampling frequency of the pattern based on this information to constantly detect the input pattern. A pattern reading device characterized by being provided with a function of reading at a constant magnification.