JPS618609A - Bore diameter measuring instrument of printed circuit board - Google Patents

Abstract

PURPOSE:To measure correctly a bore diameter with a simple instrument by detecting the surrounding light irradiating to a photoelectric conversion element by a light receiving element for correction. CONSTITUTION:The current value of an ammeter 25 is made to change according to the bore of the hole 7 to be measured due to the electrical resistance value or optical current of a photoelectric conversion element 20 being varied in accordance with the incident light quantity thereof, when the luminous flux emitted from a light source 8 is made incident on the element 20 through the hole 7 to be measured with switches 23, 26 ON. In this case, a correcting circuit 22 is made to flow the circuit current correcting the surrounding light made incident on the element 20, since the surrounding light of the element 20 is detected by a photodetector 21 for sensibility correction, changing automatically the bias voltage of a transistor with the change of the electric resistance value thereof.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a non-contact analog type printed circuit board hole diameter measuring device that can easily measure the diameter of a through hole formed in a printed circuit board in the manufacturing process of the printed circuit board. .

[Technical background of the invention] Printed circuit board v! When constructing an A structure, it is necessary to confirm that the through-holes for mounting circuit elements are of appropriate dimensions.

In such cases, a printed circuit board pore size measuring device shown in FIGS. 2 and 3 has conventionally been used.

FIG. 2 shows an example of a contact type hole gauge, in which a measuring gauge 2 tapered toward the lower end is attached to a hole gauge main body 1 so as to be vertically movable. A gauge rod 3 is attached to the upper end of this measuring gauge 2.
Further, this gauge rod is always pushed upward by a spring (not shown). The hole gauge main body 1 is provided with a window 4 and a reference line symbol 5 for reading the scale engraved on the gauge rod 3.

When measuring the through-hole diameter of a printed circuit board using the hole gauge configured as described above, position the hole gauge over the hole to be measured 7 of the printed circuit board 6,
Press gauge rod 3. Thereby, the tapered measuring gauge 2 is inserted to a position commensurate with the diameter of the hole 7 to be measured.

As a result, a scale corresponding to the hole diameter is displayed at the reference line symbol 5 position of the window 4, and by visually reading this, the hole diameter of the hole 7 to be measured can be measured.

FIG. 3 shows an example of a non-contact digital pore diameter measuring device, in which a light source 8 and an image sensor 9 are arranged facing each other with a printed circuit board 6 in between, and between the printed circuit board 6 and the image sensor 9. A diaphragm 10 is inserted. This diaphragm 10 is provided to prevent the scanning range of the image sensor 9 from becoming excessively large, and is arranged with its center aligned with the center of the hole 7 to be measured. It is set to have a large diameter.

A sensitivity correction photometer 12 is installed near the periphery of the image sensor 9 to cancel the influence of ambient light on the image sensor 9.

The output of the image sensor 9 and the photometer 12 for sensitivity correction is 8b.
It is input to the IT microcomputer 13. The image sensor 9 optically captures the surroundings of the hole 7 to be measured, scans the distance D1 between two opposing points as shown in FIG. The results are displayed on the digital display 14.

[Problems with Background Art] However, the conventional printed circuit board hole diameter measuring device described above has the following drawbacks.

That is, with the hole gauge shown in FIG. 2, it is necessary to insert the measuring gauge 2 into the hole 7 to be measured and read the scale every time a measurement is made, which is a cumbersome task and also makes it impossible to record the measurement results as they are. Further, since it is a contact type, there is a drawback that the printed circuit board 6 is easily scratched or dusted.

In addition, the non-contact digital pore diameter measuring instrument shown in Figure 3 cannot automatically correct sensitivity based on ambient light intensity, so sensitivity correction must be performed each time pore diameter measurements are performed under different environments. It is rather inconvenient. Furthermore, since this method scans between opposing points around the hole to be measured, errors are likely to occur when applied to punched through-hole substrates where the through-holes have different cross-sectional diameters. Moreover,
Since it requires complex and high-grade equipment such as an image sensor and an 8-bit microcomputer, the cost of the measuring instrument is high, and the second
It cannot be easily installed like the hole gauge shown in the figure, and since it is equipped with a microcomputer, it requires a 100 AC power source, which has the drawback of being restricted in the location where it can be used.

[Object of the Invention] The present invention has been made to eliminate the above-mentioned disadvantages in the background art, and it is an object of the present invention to provide a printed circuit board pore size measuring device that has a simple structure and can be constructed at low cost.

[Summary of the Invention] The printed circuit board hole diameter measuring device of the present invention includes a light source that irradiates light near the hole to be measured on the printed circuit board, and an analog type that generates an electrical output according to the amount of light transmitted through the hole to be measured. A photoelectric conversion element, a measurement power supply and an ammeter connected to the photoelectric conversion element, a correction light receiving element that detects ambient light incident on the photoelectric conversion element, and corrects a current value flowing through the ammeter, and correction. It is characterized by being equipped with a circuit.

[Embodiments of the Invention] Next, the present invention will be described in detail with reference to FIGS. 1 and 5.

In FIG. 1, a light source 8 and an analog photoelectric conversion element 20 are disposed opposite to each other above and below a printed circuit board 6 so as to sandwich the printed circuit board 6 therebetween.

The light from the light source 8 is placed on the printed circuit board 6 through the hole 7 to be measured.
A diaphragm 10 is provided to prevent the light from entering through other pinholes 7'.

The opening degree of this diaphragm is adjusted by the diaphragm drive mechanism 11 so that its opening area is slightly larger in diameter than the hole to be measured.

A sensitivity correction light-receiving element 21 is arranged above the diaphragm 10 slightly outside the inner circumferential surface of the diaphragm 10 and detects ambient light of the photoelectric conversion element 20 .

The above-described charging conversion element 20 and sensitivity correction light receiving element 21 are connected to a switch 23 and a battery power source 24 via a correction circuit 22.
and an ammeter 25 , and the light source 8 is also connected to a battery power source 27 via a switch 26 .

FIG. 5 shows a specific example of the circuit configuration shown in FIG. 1, in which a photoelectric conversion element 20 and a resistor 31 are connected between the collector base of the transistor 30, and a sensitivity correction light receiving element 21 is connected between the pace emitters. A variable resistor 32 is connected.

Further, a switch 23, a power supply 24, and an ammeter 25 are connected in series between the collector and emitter of the transistor 30.

In the pore size measuring device of the present invention configured as described above, when the switches 23 and 26 are turned on and the light beam from the light source 8 is made to enter the photoelectric conversion element 20 through the hole 7 to be measured, the photoelectric conversion element 20 receives the human light. Since the electric resistance value or photocurrent of C changes depending on the distance between the holes 7 and 7, the current value of the ammeter 25 changes depending on the diameter of the hole 7 to be measured. In this case, the ambient light of the photoelectric conversion element 20 is transmitted to the light receiving element 2 for sensitivity correction.
1 and its electrical resistance value changes to automatically change the bias voltage of the transistor 30, so that the correction circuit 22 flows a circuit current that corrects the ambient light incident on the photoelectric conversion element 20. .

The analog photoelectric conversion element 20 and correction light receiving element 21 mentioned above may be CdS or other photoconductive elements whose electrical resistance value changes depending on the amount of received light, as well as photoconductive elements whose photocurrent changes depending on the amount of received light. Analog elements such as transistors and photovoltaic cells can be used.

Further, the correction circuit 22 is not limited to the above example, but as shown in FIG.
b may be constructed from a differential amplifier circuit that is symmetrically combined. In FIG. 6, the same parts as in FIG. 5 are given the same reference numerals.

If an AD converter is added as an option in these embodiments, the measurement results can be outputted to an external circuit as a digital signal, and can also be automatically recorded as necessary.

[Effects of the Invention] As described above, in the present invention, the photoelectric conversion element and the correction light receiving element can be configured with inexpensive analog elements such as photoconductive elements and photovoltaic cells, and an inexpensive pore size measuring instrument with a simple circuit configuration can be obtained. be able to.

In addition, the ambient light incident on the photoelectric conversion element is detected by the correction light receiving element and automatically corrected by the correction circuit, so it can be used in environments where the ambient light fluctuates significantly or when moving to a different location. It is also possible to accurately measure the diameter of pinholes. In addition, the structure is simple and lightweight, and since it can be powered by a battery, it is convenient to carry and can be used even in places where AC power is not available.

In addition, since it is a transmission type, it is possible to accurately measure punched through holes, and it can be applied to a wide range (e.g. 0.2 to 10 mm) regardless of the thickness of the printed circuit board, and it is a non-contact type. , it is possible to obtain the effect that scratches, dust, etc. are less likely to adhere to the printed circuit board.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing an embodiment of the present invention, Fig. 2 is an explanatory diagram showing how a conventional contact type hole gauge is used, and Fig. 3 is an example of a conventional non-contact type digital hole diameter measuring device. The explanatory diagram, FIG. 4, is a cross-sectional view of the hole to be measured for explaining the measurement method, and FIGS. 5 and 6 are circuit diagrams showing embodiments of the present invention, respectively. 1... Hall gauge body 2...
・・・・・・・・・Measuring gauge 3・・・・・・・・・・・・
・・Gauge rod 6・・・・・・・・・・Printed circuit board 7・・・・・
・・・・・・Measurement hole 8・・・・・・・・・・・・
・Light source 9... Image sensor 10...
......Aperture drive mechanism 11...Aperture drive mechanism 12...
......Photometer 20 for sensitivity correction...
...Photoelectric conversion element 21....
・Correction light-receiving element 22...Correction circuit patent attorney Sa Suyama - Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (3)

[Claims] (1) A light source that irradiates light near the hole to be measured on a printed circuit board, an analog photoelectric conversion element that generates an electrical output according to the amount of light transmitted through the hole to be measured, and a measurement device connected to this photoelectric conversion element. A hole diameter of a printed circuit board, characterized in that the printed circuit board is equipped with a power source and an ammeter, and a correction light-receiving element and a correction circuit that detect ambient light incident on the photoelectric conversion element and correct a current value flowing through the ammeter. Measuring instrument. (2) The printed circuit board pore diameter measuring device according to claim 1, wherein the analog photoelectric conversion element and the correction light receiving element are photoconductive elements whose electrical resistance value changes depending on the amount of received light. (3) The printed circuit board pore size measuring device according to claim 1 or 2, wherein the power source for the light source and for measurement is a battery.