JPH0521202A - Electronic circuit board - Google Patents

Abstract

PURPOSE:To provide an electronic circuit board which uses a thin line circuit pattern by selectively drawing out a resistance value from the thin line circuit pattern for the purpose of facilitating correction of the resistance value, even if valiability of resistance values which are inherent to a thin line circuit takes place when a electric resistance part is made by a thin line circuit pattern. CONSTITUTION:On a substrate 6, a thin line circuit pattern 11 which is continuously constituted while being bent many times constitutes resistors, thus an electronic circuit board configurated, and a plurality of terminal parts 12, 13, 14, 15 and 16 which are continuously formed starting from midway of the thin line circuit pattern 11 and a continuous terminal part 17 located at the position which allows connection with the terminal parts for setting a specified resistance value are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic circuit board, and more particularly, to an improvement of a feedback resistance section which constitutes a constant current drive circuit section.

[0002]

2. Description of the Related Art Conventionally, in a drive circuit for causing a driven body to perform constant current driving, it is known that an operational amplifier performs constant current driving by comparing with a reference voltage.
FIG. 4 shows an example of a constant current circuit for driving a plunger of a driven body. In this figure, a power supply 1 is mainly an externally mounted plunger 2, a control transistor 3 and a feedback resistor as shown by a broken line. 4 is connected. Further, the output side of the operational amplifier 5 is connected to the base side of the control transistor 3, and the branch portion of the feed back resistor 4 is connected to the negative side of the operational amplifier 5, forming a well-known constant current drive circuit. The driving of the plunger 2 is possible while keeping the current loop I constant.

FIG. 5 is an actual view of the feed back resistor 4 mounted on the circuit board of FIG. 4, which is 3.2 × 1.6 mm.
The chip resistance R (1Ω) having the outer dimensions of 2 is provided on the terminal (land) formed on the substrate 6 by soldering two pieces in parallel to obtain 0.5Ω. here,
If there is a resistance of 0.5Ω, one resistor is enough. In the drive circuit configured as described above, when the plunger or the like of the driven body is driven with a constant current, it is usually 300 to 4
It is necessary to pass a current of 00 mmA, but if the resistance value of the feedback resistor is high, the voltage effect in that part will increase and the loss will increase. A feedback resistor with a small value is used. Further, when such a constant current drive circuit is used in a small device such as a camera, the above-mentioned reflow type chip resistor is used in order to secure a built-in space.

[0004]

However, the production amount of the chip resistor used as described above having a resistance value of 1 Ω or less is extremely small, which may hinder the supply. Is priced about twice as much as the previous resistors. Therefore, it is conceivable to make an electric resistance part corresponding to the feed back resistance by a fine line circuit pattern on the substrate, but the fine line circuit pattern is likely to cause over-etching or under-etching due to variations in the etching process during pattern creation. However, there is a problem that it cannot be put into practical use because the resistance components differ by 20 to 30%.

Therefore, the present invention has been made in view of the above problems, and an object thereof is to make an electric resistance portion by a fine wire circuit pattern instead of using a chip resistor having the above problems. Even if there is a variation in the resistance value peculiar to the thin wire circuit pattern, the resistance value can be selectively extracted from the thin wire circuit pattern to facilitate the correction of the resistance value and to use the electronic circuit board using the thin wire circuit pattern. To enable.

[0006]

[Means for Solving the Problems] and

In order to achieve the above-mentioned object and achieve the purpose,
The electronic circuit board of the present invention is an electronic circuit board that constitutes a resistor by a thin wire circuit pattern that is continuously formed by bending a number of times on the board, and a plurality of continuously formed thin wire circuit patterns are formed in the middle thereof. And a continuous terminal portion arranged at a position connectable to the terminal portion so as to set a predetermined resistance value. Works as if set to a resistance value.

Further, preferably, the thin line circuit pattern is a resistor for a feedback resistor connected to an operational amplifier forming a constant current drive circuit, and works so as to form a constant current drive circuit. Also preferably, the connection works as if by soldering. Further, preferably, the terminal portion is provided on both sides of the thin wire circuit pattern, and the resistance value of the other terminal has a substantially intermediate value with respect to the resistance value of the terminal portion on one side. It works by connecting to a continuous terminal and setting a predetermined resistance value. Further, preferably, a part of the thin wire circuit pattern is formed to have a narrow width, and the mounting component works so as to be mounted so as to extend over the narrow portion.

[0008]

Embodiments of the electronic circuit board of the present invention will be described below in detail with reference to the drawings. An embodiment of the present invention is shown in FIG. Now, consider the case where the resistance value of the feedback resistor 4 is set to 1.5Ω. It is known that the pattern on the circuit board 6 has different resistance values depending on its thickness, width dimension, and length dimension. Therefore, considering a case where a copper foil having a thickness of 18 μm which has been commonly used has a pattern width dimension of 0.15 mm,
The resistance value per unit centimeter is about 0.06Ω. Therefore, to obtain a resistance value of 0.5Ω,
A length of 5 ÷ 0.06 = 8.33 cm is needed.

Further, the copper foil is subjected to an etching treatment in order to form a fine line circuit pattern. However, depending on the etching state, a predetermined pattern resistance may not be obtained due to overetching or underetching. is there. This variation is about 30% at maximum, and this variation is very inconvenient for those requiring constant current accuracy. Therefore, a means for correcting such variations is needed.

FIG. 1A is a plan view of a first embodiment of a fine line circuit pattern, and FIG. 1B is an equivalent circuit diagram of the circuit of FIG. In both figures, a resistance pattern portion 11 in which a thin wire circuit pattern is formed by repeating U-turns several times as illustrated is formed on the substrate 6. A check land 12 is integrally formed at the position of the starting point of the resistance pattern portion 11. Connection lands 13, 14 provided by pulling out a pattern from the middle of the resistance pattern portion 11,
15, 16 are further provided as shown. Of these connection lands, the connection land 16 is the resistance pattern 1
It represents the end point portion of 1.

On the other hand, as shown in the drawing, a vertically long continuous pattern 17 is provided right next to this connection pattern, and a check land corresponding to the above-mentioned check land 12 and connection lands 13 to 16 is provided thereon. 18 and solder connection lands 19, 20, 21, 22 are provided. Connection lands 1 corresponding to the above configurations
3, 14, 15, 16 and the continuous pattern 17 are short-circuited, and then the resistance value between the check lands 12 and 18 is measured,
Select the closest resistance value and make solder connection, for example. In this way, an appropriate feedback resistance can be obtained regardless of the etching state (excluding the broken state).

Next, FIG. 2A is a plan view of a second embodiment of the fine line circuit pattern, and FIG. 2B is an equivalent circuit diagram of the circuit of FIG. In this figure, the difference from the first embodiment is that the number of adjustment points is increased in order to further improve the accuracy of the resistance value. That is, the above-mentioned first
The connection lands 31, 32, 33, 34 for extracting resistance values intermediate between the resistance values shown in the embodiment are the connection lands 13, 14,
A pattern 30 is formed at a position facing between 15 and 16 and integrally connected to the right pattern 17 so as to correspond to these connection lands 31, 32, 33 and 34.

With the above construction, when all the connection lands are provided on only one side of the resistance pattern as in the first embodiment, the resistance values are checked in order.
Although the number of checks becomes large, the second embodiment selects the intermediate resistance value provided on the left side when it is necessary to further check the resistance value on the right side land and then shift the resistance value to either small or large. By doing so, work efficiency can be improved.

FIG. 3 is a plan view showing a third embodiment of the fine line circuit pattern. In the figure, a part of the resistance pattern 11 in the first embodiment has a narrow portion 11a in which the width is narrowed and the direction is changed in the central portion as shown in the drawing.
Is formed. On both sides of the narrow portion 11a, land patterns 42, 43 for mounting a component element 41 such as a resistor are arranged. Usually, there is often a gap between the land patterns of the element 41 as described above.
When a certain area is required like the resistance pattern 11, the narrow portion 11a can be provided as described above to improve the space efficiency. Check lands 51 and 52 for measuring a resistance value are provided on the resistance pattern 11 having the above-described structure, and a connection land 5 is drawn out from the middle of the resistance pattern 11.
3, 54, 55 and connection lands 56, 57, 58 formed in the same pattern as the check land 52 are formed as shown.

Using the thin wire circuit pattern described above,
Since the portion corresponding to the feed back resistor 4 in FIG. 4 can be replaced, it is not necessary to use expensive chip parts. Moreover, the resistance value can be selected by forming solder connection lands at several places in the middle of the fine wire circuit pattern and selectively soldering them. The feedback resistance of the current circuit can be formed and it can selectively respond to the case where the constant current value is suddenly changed due to the entanglement of the actuator 2, so that not only a great cost advantage can be obtained but also the flexibility can be obtained. It is also very rich in terms of richness. The thin line circuit pattern is not limited to the feedback resistance of the constant current circuit, and can be applied to any electronic circuit as long as its resistance value is 1Ω or less.

[0016]

As described above, according to the present invention, when the electric resistance portion is formed by the fine line circuit pattern, even if there is a variation in the resistance value peculiar to the fine line circuit pattern,
By selectively extracting the resistance value from the thin wire circuit pattern, the resistance value can be easily corrected and the electronic circuit board using the thin wire circuit pattern can be used.

[Brief description of drawings]

1A is a pattern diagram showing a first embodiment, and FIG. 1B is an equivalent circuit diagram of FIG. 1A.

2A is a pattern diagram showing a second embodiment, and FIG. 2B is an equivalent circuit diagram of FIG. 2A.

FIG. 3 is a pattern diagram showing a third embodiment.

FIG. 4 is a constant current drive circuit diagram.

FIG. 5 is a plan view showing conventional electronic component mounting.

[Explanation of symbols] 1 power supply, 2 Plunger, 3 control transistors, 4 feedback resistance, 5 operational amplifier, 11 fine wire circuit pattern part, 12,18 Resistance value Checkland, 13, 14, 15, 16 connection land, 17 consecutive lands 19, 20, 21, 22 Connection lands.

Claims (5)

[Claims] 1. An electronic circuit board in which a resistor is constituted by a thin wire circuit pattern which is continuously formed by bending a large number of times on a board, wherein a plurality of terminal portions are continuously formed from the middle of the thin wire circuit pattern. And a continuous terminal portion arranged at a position connectable to the terminal portion for setting a predetermined resistance value. 2. The electronic circuit board according to claim 1, wherein the thin wire circuit pattern is a resistor for a feedback resistor connected to an operational amplifier forming a constant current drive circuit. 3. The electronic circuit board according to claim 1, wherein the connection is made by soldering. 4. The terminal is provided on both sides of the thin wire circuit pattern, and the resistance value of the other terminal portion is substantially intermediate with respect to the resistance value of the one terminal portion. The electronic circuit board according to any one of claims 1 to 3. 5. The electronic circuit board according to claim 1, wherein a part of the thin wire circuit pattern is formed to be narrow, and the mounted component is mounted so as to straddle over the narrow portion.