JPH0410706Y2 - - Google Patents

Description

[Detailed explanation of the idea] (b) Industrial application fields The present invention relates to printed circuit boards.

(b) Prior Art In recent years, various electrical appliances such as microwave ovens and washing machines have been equipped with control circuits consisting of microcomputers, and electrical appliances have become electronically controlled. Such a product can be found in, for example, Japanese Patent Application Laid-Open No. 175589/1989 for microwave ovens. In this case, the control circuit receives a signal having the same frequency as the commercial power supply frequency, forms a time signal based on the signal, and performs various time controls.

In Japan, there are areas where the commercial power frequency is 50Hz and areas where it is 60Hz, so the control circuit for forming the time signal depends on which area the electrical product is used in. The control form must be changed.

That is, when an electrical product is used in an area with a commercial power supply frequency of 50 Hz, the control circuit has a control mode for forming a one-second time signal by inputting a signal having the same frequency as the commercial power supply frequency 50 times. Take. Accurate time control is achieved by such a time signal. However, if such electrical products are directly used in areas with a commercial power supply frequency of 60Hz, they will receive signals with the same frequency as the commercial power supply frequency.
When inputted 50 times, a 1 second time signal is generated every 5/6 seconds, and accurate time control is no longer possible. Therefore, when using the above electrical appliance in a 60Hz area, the control form of the above control circuit is to form a 1 second time signal by inputting a signal having the same frequency as the commercial power supply frequency 60 times. It has to be changed so that it does.

Now, FIG. 4 shows a printed circuit board 10 incorporated in the above-mentioned electric product, on which a microcomputer 11 constituting the above-mentioned control circuit is mounted, and a changing unit 12 for making the above-mentioned changes is mounted. Implemented. The changed part is common terminal 1
3, 50 and 60 Hz switching terminals 14a and 14b, and a lead wire 15 for switchingly connecting the common terminal 13 to the switching terminals 14a and 14b. In this case, when the common terminal 13 is switched and connected to the 50Hz switching terminal 14a, the microcomputer 11 operates in a control mode (50Hz area ), and when the common terminal 13 is switched and connected to the 60Hz switching terminal 14b, the microcomputer 11 performs control to form a one-second time signal by inputting a signal having the same frequency as the commercial power supply frequency 60 times. format (compatible with 60Hz region). Referring to the circuit shown in FIG. 5, when the former switching is performed, a high level signal is input to the switching terminal P of the microcomputer 11.
1 takes the former control form. When the latter switching is performed, a low level signal is input to the terminal P, and the microcomputer 11 thereby takes the latter control mode.

However, in such a configuration, each time the commercial power supply frequency changes, switching and connection must be performed one by one, resulting in poor workability and high costs. In addition, for products that handle water, such as washing machines, printed circuit boards are required to be moisture resistant, so it is necessary to apply a moisture resistant coating with all components mounted. 14a,
Care must be taken not to insulate the terminals 14b to which the lead wires 15 are not connected, and workability is also poor in this respect.

Additionally, FIG. 6 shows another printed circuit board 16. As shown in FIG. In the board, the changing section 12 is composed of two connecting terminals 17a, 17b, and lead wires 18a, 18b extending from these terminals to the outside of the printed circuit board 16 and being connected to and disconnected from each other. In this case, when both lead wires 18a and 18b are connected, the microcomputer 11 takes a control mode compatible with the 50Hz region, while both lead wires 18a and 18b are connected.
When 8a and 18b are separated, the microcomputer 11 takes a control mode compatible with the 60Hz region. still,
FIG. 7 shows a circuit corresponding to such a configuration.

In such a configuration, the moisture-resistant coating is performed with the lead wires 18a and 18b connected, and in this case, the mutual contact portions 19 are not coated, so there is no need to take the above-mentioned precautions when coating. This improves workability. However, disconnecting and disconnecting each time the commercial radio wave frequency differs still results in poor workability and high costs. Moreover, the lead wires 18a, 1
Since the lead wires 8b extend to the outside of the board, if the lead wires 18a and 18b are placed near a high voltage part outside the board 16, induced noise will be carried on the lead wires 18a and 18b, and this noise will be transferred to the board. This leads to the microcomputer 11 above, causing the microcomputer 11 to malfunction.

(c) Problems to be solved by the invention In a printed circuit board on which a control circuit and a modification part for changing the control form of the control circuit are both mounted, the invention facilitates modification work at the modification part. Another object of the present invention is to suppress high costs, facilitate the work of applying moisture-resistant coating to a substrate, and suppress malfunctions of the control circuit.

(d) Means for Solving the Problems The present invention provides a printed circuit board on which a control circuit and a changing part for changing the control form of the control circuit are mounted, in which the changing parts follow a predetermined order. The control circuit has a terminal for repeatedly inputting a signal corresponding to the sequential cutting of the plurality of cutting locations, and the control circuit is based on the signal input through the terminal. It is characterized in that the control form is sequentially and repeatedly changed.

(e) Effects With the above means, the control form of the control circuit can be easily changed and the cost increase can be suppressed, furthermore, the work at the time of moisture-resistant coating of the substrate can be facilitated, and malfunctions of the control circuit can be suppressed.

(F) Embodiment A printed circuit board according to an embodiment of the present invention will be described below.

In FIG. 1, a printed circuit board 1 incorporated in an electrical appliance such as a microwave oven or a washing machine includes a microcomputer 2 that constitutes a control circuit for temporally driving and controlling a controlled load such as a motor; A changing unit 3 for changing the control form of the microcomputer is also installed. The changing section 3 is composed of one jumper wire 4 and two resistors 5 and 6. In this case, the jumper wire 4 and the resistor 5 are connected to the left terminal with the front protrusion 4a,
5a is formed, and these protrusions 4a, 5a serve as cutting points. The cutting order of the cutting locations is indicated by the numbers written on the substrate 1.

FIG. 2 shows the back side of the board 1 before components such as the microcomputer 2 are mounted. A large number of through holes 7, 7, etc. are formed at appropriate locations on the board 1, through which the terminals of the components are inserted when the components are mounted, and conductive holes 7, 7, etc. are formed on the back surface of the board 1. Patterns 8, 8, . . . are formed. The back surface of the substrate 1 including the patterns 8, 8, . . . except for the areas near the through holes 7, 7, . . . is covered with a solder resist film (hatched portions). In this case, the area near the through holes 7, 7, . . . consists of circular parts 9a, 9a, . . ., surrounding the holes 7, 7, . Such a protruding piece 9
b, 9b... exist in the opposite direction from the circular parts 9a, 9a... with respect to the adjacent through holes 7, 7....

In such a configuration, when a component is mounted, the terminal of the component is inserted into each through hole 7, 7..., and when the back side of the board 1 is dipped in a solder bath, the component terminal and the through hole 7, 7... Solder adheres to the area,
The parts are soldered. In this case, the solder attached to the circular parts 9a, 9a... corresponding to the adjacent through holes 7, 7... is pulled in opposite directions by the projecting pieces 9b, 9b..., and the component terminals inserted into the adjacent through holes are This can significantly prevent short circuits caused by soldering.

FIG. 3 shows the circuit on the substrate 1, in which the jumper wire 4 and the resistor 5 are connected in series, and the other resistor 6 is connected in parallel to the jumper wire 4 in the modified portion. The connection point W between the jumper wire 4 and the resistors 5 and 6 is connected to the microcomputer 2.
It is connected to the switching terminal P of.

With the above configuration as it is, the microcomputer 2 receives a high level signal at the switching terminal P, and takes a control mode compatible with the 50 Hz region. That is, a one second time signal is formed by inputting a signal having the same frequency as the commercial power supply frequency 50 times.

Next, the number 1 written on the board 1 is nearby.
When the protrusion 4a of the jumper wire 4 is cut, the microcomputer 2 receives a low level signal at the switching terminal P (the resistance values of the resistors 5 and 6 are determined in advance so that such a low level signal is input). ), the control form is compatible with the 60Hz region. That is,
A one-second time signal is formed by inputting a signal having the same frequency as the commercial power supply frequency 60 times.

Furthermore, the number 2 written on the board 1 is nearby,
When the protruding portion 5a of the resistor 5 is cut off, the microcomputer 2 receives a high level signal again at the switching terminal P, and takes a control mode corresponding to the 50 Hz region.

In such a configuration, the operation for changing the control form of the microcomputer 2 every time the commercial radio wave frequency differs is simply by cutting the cutting portion of the changing section 3, and the workability is extremely high. Also, the jumper wire 4 and the resistors 5 and 6 that constitute the changing section 3
The lead wires are cheaper than conventional lead wires for switching, connecting, and disconnecting, and the cost increase of the board 1 can be suppressed. Furthermore, when applying a moisture-resistant coating to the fundamental wave 1, there is no place to perform the above-mentioned switching, that is, there is no place where care must be taken not to insulate, so workability is good in this respect as well. Furthermore, since there are no lead wires extending outside the board 1, the microcomputer 2 may be affected by the above-mentioned induced noise.
There is no possibility that it will malfunction. Furthermore, change part 3
Since the cutting portions have protrusions 4a and 5a that are easy to cut, the substrate 1 can be cut without damaging it. If a moisture-resistant coating is applied here, it goes without saying that such coating will not be damaged, and the moisture resistance of the substrate 1 will not deteriorate.

In this embodiment, as shown in FIG. 3, by adding resistors R1 and R2 and making it possible to sequentially disconnect resistors 6 and R1, the number of switching circuits corresponding to 50 and 60 Hz regions can be increased accordingly.

Furthermore, in this embodiment, the microcomputer 2
The change in the control form is for changing the frequency, but it may also be for changing the time display, for example, for switching to 12-hour display or 24-hour display.

(g) Effects of the invention According to the invention, in a printed circuit board on which a control circuit and a changing part for changing the control form of the control circuit are both mounted, the control form can be changed by a simple cutting operation at the changing part. can be done,
Therefore, the workability of changing the control form can be significantly improved.

Furthermore, since the changing section has a plurality of cutting points that are sequentially cut in a predetermined order, and the control form is repeatedly changed in sequence according to such cutting, the control form once changed is Returning to its original form as necessary requires only a simple cutting operation, and workability can be significantly improved in this respect as well.

Furthermore, the configuration associated with the above-mentioned cutting can be made cheaper than conventional lead wires for switching, connecting, and disconnecting, and the cost increase of the printed circuit board can be suppressed.

Furthermore, the configuration that performs the cutting as described above has no structural switching points compared to the conventional case where lead wires are used, and therefore, when applying a moisture-resistant coating to a printed circuit board, it is difficult to avoid insulation. Moisture-resistant coating work is improved because there are no areas that require careful attention.

Furthermore, since it is not necessary to provide a lead wire extending outside the printed circuit board in order to change the control form, there is no situation where induced noise is transmitted to the control circuit through such a lead wire, and therefore the above-mentioned problem is avoided. The control circuit will not malfunction due to noise.

[Brief explanation of drawings]

Fig. 1 is a perspective view of a printed circuit board according to an embodiment of the present invention, Fig. 2 is a rear view of the same, Fig. 3 is a circuit diagram of the same, Fig. 4 is a perspective view of a conventional printed circuit board, and Fig. 5 is a perspective view of the same. FIG. 6 is a perspective view of another conventional printed circuit board, and FIG. 7 is a circuit diagram of the same. 2...Microcomputer, 3...Change section,
4a, 5a...Protrusion parts.

Claims (1)

[Scope of utility model registration request] In a printed circuit board on which a control circuit and a changing section for changing the control form of the control circuit are both mounted, the changing section has a plurality of cutting points that are sequentially cut in a predetermined order, The circuit has a terminal for repeatedly inputting a signal corresponding to the sequential cutting of the plurality of cutting points, and the control form is sequentially and repeatedly changed based on the signal inputted through the terminal. circuit board.