METHOD OF ADJUSTING ELECTRONIC CIRCUITS

Abstract: A method of adjusting electronic circuits in a process for manufacturing and adjusting television receivers and the like. Connection lines (17), (18) are connected in advance, in series or in parallel with adjusting elements (12), (13), which are inserted in predetermined current paths in an electronic circuit (10), the connection lines (17), (18) having the property of being melt-served when current is supplied from an external source. Condition of the electronic circuit (10) is detected by a circuit (5), which determines whether the connection lines (17), (18) are to be severed. Current is supplied to the connection lines (17), (18) from the external source to sever them. This makes it possible to eliminate semi-fixed resistors, to increase reliability after adjustment, to simplify adjustment, and to reduce the time required for adjustment.

Description: This invention relates to a method for adjusting an electronic circuit used for a television receiver or the like when it is adjusted upon being manufactured. In an electronic circuit for use in a television receiver and so on, the characteristic thereof is normally changed and adjusted by finely adjusting the magnitude of a current flowing through such circuit. This is generally carried out by setting the electronic circuit in the driving (operating) mode and, in this state, rotating a semi-fixed resistor inserted into the circuit, the voltage and the like at a necessary operation point are adjusted so as to fall within a standardised value. According to this method, since the scattering of the characteristics of the semi-fixed resistor itself is large, even if the adjusting angle of the semi-fixed resistor is determined, the characteristics of all the electronic circuits cannot always fall within the standardised values. For this reason, the rotational adjustment must be carried out in each electronic circuit, requiring a relatively long time of about 20 seconds for one adjustment. Further, since the semi-fixed resistor is of a so-called moveable type, after the adjustment, the rotational angle may be changed due to the vibration, contact and so on. Accordingly, upon transportation and the like thereof, care has to be taken that this semi-fixed resistor is not disturbed, etc. US-A-3656115 and 4201970 disclose methods of trimming currents using fusible matrices corresponding to the precharacterising part of claim 1. This invention seeks to use fusible links to enable the semi-fixed resistor to be omitted to thereby improve the reliability of the electronic circuit after it was adjusted and also is to simplify the adjustment itself to thereby reduce the adjusting time. According to the present invention, there is provided a method for adjusting an electronic circuit wherein the circuit includes at least one connection wire, connected in series or in parallel to an element inserted at a predetermined point of said electronic circuit and which can be melt-cut by flowing a current therethrough; characterised in that the electronic circuit is compensated for tolerances therein to set an operation state to a standardized value by detecting the operation state of said electronic circuit by a detector circuit and, on the basis of the detected result, it is judged whether said at least one connection wire is to be melt-cut or not and, if so, said detection circuit command at least one of said at least one connection wire to be melt-cut by automatic supply from adjustment means of said current through at least one of said connection wire thereby to adjust said electronic circuit. The invention will be further described by way of non-limitative example with reference to the accompanying drawings, in which:- Figure 1 is a block diagram useful for explaining an embodiment of a method for adjusting an electronic circuit according to the present invention, figure 2 is a cross-sectional view illustrating an example of an element used in the present invention, and figures 3, 4, 5 and 6 are cross-sectional views illustrating main parts of other embodiments of the present invention, respectively. An embodiment of a method for adjusting an electronic circuit according to the present invention will hereinafter be described with reference to the drawings. In Fig. 1, reference numeral 1 designates a signal input terminal, 2 a preceding stage circuit, 3 a succeeding stage circuit and 4 a signal output terminal. To a DC power source such as a drive power supply source and the like in the preceding stage circuit 2, four resistors 11, 12, 13 and 14 are connected in series. The connection point between the resistors 12 and 13 is connected to a predetermined point of the preceding stage circuit 2. In that case, the resistors 12 and 13 become adjusting elements and the resistance values thereof are selected to be extremely low as compared with other resistors 11 and 14. By way of example, respective resistance values R₁, R₂, R₃ and R₄ of the resistors 11, 12, 13 and 14 are 200KΩ, 200Ω , 300Ω and 300KΩ , respectively. An electronic circuit 10 is constructed as described above. The connection points among the respective resistors are denoted by P, Q and R, respectively. Connection wires 17 and 18 are previously connected in parallel to the resistors 12 and 13 which become the adjusting elements, respectively. Fig. 2 illustrates an element 19 which incorporates therein the connection wires 17 and 18. The connection wires 17 and 18 are connected between one ends of three terminals 7, 8 and 9 made of conductive material and this portion is molded by a mold material 20 such as resin and so on. As the connection wires 17 and 18, there can be used such one which can easliy be melt-cut by the current flowed thereto. In practice, such a connection wire is suitable which can easily be melt-cut by a current of 2A (about 0.6V) for a time period of 2m sec. In this case, as the connection wires 17 and 18, it is desirable to use such a connection wire having a resistance value of, for example, about 0.22 Ω . Turning back to Fig. 1, the terminals 7, 8 and 9 of the above mentioned element 19 are previously connected (soldered) to the aforesaid points P, Q and R of the electronic circuit 10, respectively. After the adjustment which will be described later, they are not removed. Accordingly, on a printed circuit board, this element 19 is mounted together with other electronic parts, too. Next, the adjusting method will be described. As shown in Fig. 1, there are prepared a detector circuit 5 and an adjusting circuit 6. A measuring terminal (electrode) of the detector circuit 5 is connected to a necessary point to be measured (the connection point between the preceding stage circuit 2 and the succeeding stage circuit 3, in this embodiment) of the electronic circuit 10 and lead wires from the adjusting circuit 6 are respectively connected to the aforesaid points P, Q and R. Then, the electronic circuit 10 is set in the driving (operating) state and the operating state (characteristic and the like) of the electronic circuit 10 is checked by the detector circuit 5. If the electronic circuit is in its normal operating state, the connection wires 17 and 18 are not melt-cut but are left as they are. Therefore, at that time, the resistors 12 and 13 are in the short-circuited state, respectively. If under this operation state such a result is obtained by making the resistance value at the ground side from the point Q be slightly larger, a current is supplied to the connection wire 18 from the adjusting circuit 6 to thereby melt-cut this connection wire. In the case reverse to the above, it is enough that the connection wire 17 is melt-cut. Alternatively, if such a result that both the resistors 12 and 13 are used is better, it is enough to melt-cut both the connection wires 17 and 18. While the supply of the current from the adjusting circuit 6 may be manually carried out on the basis of the detected result by the detector circuit 5, it may be possible that the supply of the current is automatically carried out by controlling the adjusting circuit 6 on the basis of a command signal issued from the detector circuit 5. Even when the prior art semi-fixed resistor is used, since the practical variable range of the resistance value is very small as compared with the whole resistance value (the resistance value between the point Q and the ground in Fig. 1), if the resistance values of the respective resistors are set to be satisfactory values, the satisfactory adjustment can be brought about by either of the connection and disconnection of the connection wires as seen in the above mentioned example. According to the present invention as set forth above, since under the operation state of the electronic circuit 10 the necessary connection wire 17 or 18 or both of them are only melt-cut on the basis of the detected result by the detector circuit 5, it is possible to carry out the adjustment of the so-called electronic circuit very easily and for an extremely short time of period (several milli seconds). Accordingly, even when the adjusting operation is carried out in each electronic circuit 10, it hardly takes a long time of period for such adjustment. Further, although the semi-fixed resistor tends to easily vary its resistance value due to the invasion of dusts, water and so on or because it has a movable portion, according to the method of the present invention, since such semi-fixed resistor is not required, even after it was adjusted, the resistance value thereof is not changed, thus increasing the reliability by that much. Fig. 3 illustrates other embodiment of the present invention. In this embodiment, except for the fact that the resistor 13 as the adjusting element is connected in series to the connection wire 18, other circuit elements are connected in the same way as those of Fig. 1. The respective resistance values R₁, R₂, R₃ and R₄ of the resistors 11, 12, 13 and 14 are selected to be 50KΩ ,270Ω , 33KΩ and 4.7KΩ , respectively. In this embodiment, under the illustrated state, the resistor 12 is short-circuited and the resistors 14 and 13 are connected in parallel to each other, so that the resistance value between the points P and Q is zero and that the resistance value between the points Q and R is 4114Ω which is slightly lower than 4700Ω. If under such state either the connection wire 17 or 18 or both of them are melt-cut the respective resistance values to the ground side and to the opposite side from the point Q can be adjusted finely. Fig. 4 shows a further embodiment of the present invention. In this embodiment, two routes are provided for the P-Q-R path and the above mentioned connection wires 17 and 18 are interposed in the routes, in which the two routes are both used or either of them is used, selectively. Fig. 5 shows a further embodiment in which capacitors 22 and 23 as the adjusting elements are connected in parallel to a capacitor 21 via the connection wires 17 and 18. In this case, the capacity value can be adjusted by melt-cutting the connection wires 17 and 18 in the manner similar to the above. Fig. 6 shows a further embodiment in which coils 25 and 26 as the adjusting elements are connected in parallel to a coil 24 via the connection wires 17 and 18. Also in Fig. 6, the inductance value can be adjusted by melt-cutting the connection wires 17 and 18 similarly as described above. While in the above mentioned embodiments the adjusting elements and the connection wires therefor are independently provided, such a version may be possible that a bonding wire used for the interconnection of a semiconductor is used as the connection wire, the adjusting element is provided in parallel to this bonding wire, they are molded integrally and terminals are led out from one and another ends of the molded member. While the above mentioned connecting wires 17 and 18 are molded by the mold material, of course, they may be connected discretely. EXPLANATION FOR REFERENCE NUMERALS Reference numeral 5 represents the detector circuit, 6 the adjusting circuit, 10 the electronic circuit, 12 and 13 the adjusting elements, respectively, 17 and 18 the connection wires, respectively and 19 the element.

Claims: A method for adjusting an electronic circuit (10) wherein the circuit includes at least one connection wire (17, 18), connected in series or in parallel to an element inserted at a predetermined point (P, Q, R) of said electronic circuit and which can be melt-cut by flowing a current therethrough; characterised in that the electronic circuit (10) is compensated for tolerances therein to set an operation state to a standardized value by detecting the operation state of said electronic circuit by a detector circuit (5) and, on the basis of the detected result, it is judged whether said at least one connection wire (17, 18) is to be melt-cut or not and, if so, said detection circuit (5) command at least one of said at least one connection wire to be melt-cut by automatic supply from adjustment means (6) of said current through at least one of said connection wire thereby to adjust said electronic circuit. A method of producing a plurality of electronic circuits having a standardized operation state, characterized by applying to each circuit the method of claim 1. A method for compensating an electronic circuit according to claim 1 or 2, characterised in that said adjusting element comprises at least one resistor element (R1-R4). A method for compensating an electronic circuit according to claim 1 or 2, characterised in that said adjusting element comprises at least one capacitor element (21, 22, 23). A method for compensating an electronic circuit according to claim 1 or 2, characterised in that said adjusting element comprises at least one inductor element (24, 25, 26). A method for compensating an electronic circuit according to any preceding claim, wherein the circuit includes a housing element (19) which houses said at least one connection wire (17, 18) to be melt-cut by flowing a current therethrough. A method for compensating an electronic circuit according to claim 6, characterised in that said housing element includes three terminals (7, 8, 9).

Inventors: MITSUHASHI TAKAMICHI, UENO TAKEHIKO, UJIHARA TSUNENOBU, MITSUHASHI, TAKAMICHI SONY CORPORATION, UENO, TAKEHIKO SONY CORPORATION, UJIHARA, TSUNENOBU SONY CORPORATION
Applicants: SONY CORP, SONY CORPORATION
Application year: 1985
Main classification: H03H1
IPC codes: H04N17, H04N5, H03H1, H03H5