JPH0334805Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a switch circuit that transmits a signal from a manual switch to an electronic switch (analog switch, etc.) via a switch drive circuit to open/close the switch. It relates to a switch circuit that has a function to set the state.

The main part of the switch circuit of this invention is ^I2L .
(Integrated Injection Logic) circuit,
It also includes an auxiliary current source circuit that injects an injector current when the main power is cut off. Further, the auxiliary current source circuit is configured to inject the injector current only into the memory circuit that stores the setting conditions of the switch when the main power supply is cut off.

Even if the injector current is injected from the auxiliary current source circuit to only some of the memory circuits as described above, if the main power is cut off for a long time, the capacity of the auxiliary current source circuit will be insufficient and the memory circuit will be damaged. This has the disadvantage that the memory may be erased and the setting conditions become unstable when the main power is restored.

The present invention is intended to solve the above-mentioned drawbacks, and its main purpose is to turn on a predetermined switch in the switch circuit to set the initial state when the ability of the auxiliary current source circuit is insufficient when the main power is turned on. The purpose is to provide a switch circuit with functions.

Another object of the present invention is to provide a switch circuit which determines whether the switch is turned on or off depending on the setting conditions of the memory circuit when the charging potential of the charging circuit included in the auxiliary current source circuit is high.

Such a switch circuit includes an auxiliary current source circuit, the main part of which is formed by an I ² L circuit. Then, when the main power is turned on, a preset switch is activated, and when the main power is restored, if the setting conditions for the switch are stored in the memory circuit, the switch is set based on the memory.

Below, the first part of the switch circuit according to the present invention will be explained.
This will be explained based on FIGS. 4 to 4.

FIG. 1 is a block diagram of a switch circuit. The signal input stage is a switch 1 with a self-returning contact.
and an indicator light 2. The detection circuit 3, memory circuit 4, and drive circuit 9 are a switch drive circuit section. The detection circuit 3 converts the signal from the switch 1 into a pulse, which is transmitted to the storage circuit 4 and stored therein.
Furthermore, the signal is transmitted to open and close the analog switch 5, and also transmits the signal to the drive circuit 9 to keep one of the indicator lights 2 lit. Further, a part of the detection circuit 3 and the memory circuit 4 are formed of I ² L elements, and an injector current is injected into these I ² L elements from the current source circuit 6 via the resistor 11, the diode 12, and the resistor 13. ing. When the main current source is turned on, a charging current flows into the auxiliary current source circuit 7 through the resistor 15 and into the capacitor 16.

Now, when the main power supply is cut off, an injector current is injected from the auxiliary current source circuit 7 into the I ² L circuit forming the memory circuit 4 to maintain the memory. On the other hand, the potential of the charging circuit of the auxiliary current source circuit 7 is
When the voltage between the terminals of the auxiliary current source circuit 7 falls below a predetermined level, a charging current is supplied to the auxiliary current source circuit 7 via the level shift circuit 8 and the diode 14, and the voltage of the switch 1 is One switch is put into a pseudo on state, and the other switches are put into a reset state. Further, the diode 14 prevents current from flowing from the auxiliary current source circuit 7.

In the switch circuit of the present invention, the initial state of the switch 1 is controlled by the potential of the voltage between the terminals of the auxiliary current source circuit 7. When the main power is turned on, the auxiliary current source circuit 7
The capacitor 16 forming the charging circuit is in a discharged state, and the voltage across the terminals of the capacitor 16 is zero potential. However, the potential of the voltage across the terminals of the capacitor 16 increases as a charging current flows through the predetermined indicator light 2, level shift circuit 8, diode 14, and resistor 15. Therefore, when the main power is turned on, the potential at one connection point 17 of the switch 1 is at a low level, and the other connections are set at a high level since the switch is in an open state. In this way, a charging current is supplied to the capacitor 16 of the auxiliary current source circuit 7 to short-circuit the contacts of a predetermined switch, thereby generating a pseudo signal and setting an initial state. When the switch 1 of the signal input stage is arbitrarily set and the setting conditions are stored in the memory circuit 4, and the main power supply is cut off, an injector current is injected from the auxiliary current source 7 into the memory circuit 4, and the memory is stored. Hold.
Then, when the main power is restored, the switch is set based on the memory in the memory circuit 4. In addition, if the main power supply is cut off for a long time, the auxiliary current source circuit 7
When the capacity of the memory circuit 4 is consumed and it becomes difficult to hold the memory circuit 4, the setting conditions of the switch are lost. In this case, when the main power is restored, the initial state of the switch 1 is set by setting the preset potential between the contacts of the switch to a low level.

FIG. 4 shows an embodiment of the switch circuit of the present invention. The symbol of the I ² L element is shown in FIG. 2, and its equivalent circuit is shown in FIG. I is an injector terminal. In FIG. 4, the signal input stage includes switches 1 ₁ -1 _o having a plurality of self-resetting contacts and light emitting diodes 2 ₁ -2 _o connected in series. The detection circuit ₃₁ is formed of transistors _T1 to _T3 , ^I2L element _A1, etc., and the detection circuit 3n has a similar configuration. The memory circuit 4 ₁ is formed from a flip-flop (hereinafter abbreviated as F/F) consisting of I ² L elements A ₂ and A ₃ , and the F/F 4 _o has a similar structure.
18 is a signal transmission circuit, one of the output terminals of ^I2L element _A4 goes to electronic switch ₅₁ , and the other output terminals
Transistor T ₇ of drive circuit 9 ₁ via I ² L element A ₅
connected to the base of. I ² L element A ₉ is also connected in a similar manner. Electronic switches 5 ₁ to 5 _o are analog switches, etc., and a and n are signal sources.

The I ² L element forming the switch circuit is supplied with an injector current from the current source circuit 6. Its configuration includes a voltage source circuit 10, an injector resistor 11, a diode 12, and an injector resistor 13. The other end of the injector resistor 11 is connected to I ² L elements A ₂ , A ₃ ...A ₇ , which form the memory circuit 4.
A ₈ is connected to the injector terminal and also to the auxiliary current source circuit 7. And diode 1
4 and a level shift circuit 8 to the connection point between the switch 1 ₁ and the light emitting diode 2 ₁ . The auxiliary current source circuit 7 is formed from a resistor 15 and a capacitor 16.

Now, turn on the main power to this switch circuit.
Since the capacitor 16 of the auxiliary current source circuit 7 is in a discharged state, the potential of the voltage between the terminals of the auxiliary current source circuit 7 is at a low potential. Therefore, the connection point 17 between the switch ₁₁ and the light emitting diode ₂₁ has approximately zero potential, so the switch ₁₁ is equivalent to a short-circuited state, and a switch-on signal is transmitted, turning off the transistors _T1 to _T3 of the detection circuit ₃₁ . becomes. Also, since the potential of the input terminal of I ² L element _A1 becomes a high potential (H level), the output terminal becomes L level and at the same time the F/
Reset F4 _o . Also, sequentially I ² L elements A ₄ ,
A ₅ is activated, transistor T ₇ is turned on, drive circuit 9 ₁ is activated, and light emitting diode 2 ₁ remains lit. Further, based on the operation of the drive circuit 9 ₁ , the output terminal of the I ² L element A ₁ of the detection circuit 3 ₁ is inverted from the L level to the H level. Further, since the capacitor 16 of the auxiliary current source circuit 7 is charged, the potential of the voltage between its terminals and the potential of the connection point 17 become H level.

When the switch 1 _o is pressed, the switch drive circuit is activated and the light emitting diode 2 _o is kept lit. At the same time, a reset signal is transmitted from the I ² L circuit A ₆ to the F/F 4 ₁ to release the memory of the F/F 4 ₁ . When the switch 1 of the signal input stage is set in this way, it is stored in the memory circuit 4. If the main power supply is cut off in such a state, the injector current from the auxiliary current source circuit 7 will be I ² L of F/F4 ₁ to 4 _o.
It is supplied to the element and the memory is retained. However, if the main power supply is cut off for a long period of time, the capacitor 16 will naturally have insufficient capacity and the memory of the storage circuit 4 will be erased. Then, when the main power is restored, if the charge in the capacitor 16 of the auxiliary current source circuit 7 is completely discharged when the main power is turned on, the voltage is transferred from the power supply voltage V _CC through the indicator light 2 ₁ and the level shift circuit 8. Since the charging current flows to the capacitor 16, the switch 1 ₁
The contacts of the switch 11 are brought into a substantially short-circuited state, and the contacts of the switch ₁₁ are pseudo-on, and the switch at the signal input stage is set to its initial state based on predetermined conditions.

The level shift circuit 8 has a function of level shifting the potential at the connection point 17 between the indicator lamp 2 ₁ and the switch 1 ₁ , and changes the potential at the connection point 17 to the level at which the capacitor 16 of the auxiliary current circuit 7 is charged. The function is to apply the power supply voltage V _CC to the capacitor 16 through the indicator light 2 ₁ etc. when the charging potential of the capacitor 16 decreases, and it is similar to the potential of the voltage between the terminals of the capacitor 16. It can be formed by

Of course, the present invention is not limited to the embodiment shown in FIG. 4, and if it is desired to obtain a predetermined current amplification degree, various known methods such as connecting I ² L elements in several stages may be used.

As mentioned above, the switch circuit of the present invention has a circuit system that monitors the potential of the charging circuit section of the auxiliary current source circuit 7, and when the capacitor 16 is in a discharged state,
A predetermined switch is set to a pseudo-on state. Alternatively, when the memory circuit is operating, the switch is reset based on the memory. Therefore, there is no possibility of unstable operation when the main power is turned on or restored, and there is an advantage that a stable switch circuit can be provided by a simple circuit.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a switch circuit according to the present invention, Fig. 2 is a diagram showing the symbol of an I ² L element, Fig. 3 is an equivalent circuit diagram thereof, and Fig. 4 is a diagram of a switch circuit according to the present invention. FIG. 2 is a circuit diagram showing an example. 1, _{1 1} ~ 1 _o : Switch, 2, _{2 1} ~ 2 _o : Indicator light, 3, _{3 1} ~ 3 _o : Detection circuit, 4: Memory circuit, 4
₁ to 4 _o : flip-flop, 5, _{5 1} to 5 _o : electronic switch, 6: current source circuit, 7: auxiliary current source circuit, 8: level shift circuit, 9, 9 ₁ to 9 _o : drive circuit, 10: Voltage source, 11, 13: Injector resistance, 12, 14: Diode, 15: Resistor, 1
6: Capacitor, 18: Signal transmission circuit, A ₁ ~
_A10 : ^I2L element, _T1 to _T9 : transistor.

Claims (1)

[Scope of utility model registration request] a signal input stage in which a plurality of switches each having a self-resetting contact paired with an indicator lamp are arranged; a detection circuit including an I ² L element that converts a signal from the signal input stage into a pulse; It is composed of a flip-flop consisting of I ² L elements corresponding to the number of contacts, and includes a memory circuit that stores the pulse signal from the detection circuit, and a memory circuit that stores one of the plurality of signals based on the signal from the memory circuit. a drive circuit that operates an electronic switch that selects one signal and lights one of the indicator lights; a current source circuit that injects an injector current into each I ² L element included in the detection circuit and storage circuit; A charging current is supplied from the current source circuit, and an auxiliary current source circuit includes a resistor and a capacitor that injects an injector current into the storage circuit configured with a flip-flop when the main power supply is cut off; The cathode of a diode is connected to the connection point with the current source circuit, and the level shift circuit is connected between the anode of the diode and the connection point between a predetermined contact point of the switch and the indicator light, and when the main power is cut off, , the injector current is supplied from the auxiliary current source circuit to the flip-flop of the memory circuit to maintain the latch state, and when the main power is restored, the memory circuit is returned to the state before the cut-off according to the latch state of the memory circuit. When the capacitor of the auxiliary current source circuit is in a discharged state, a charging current is supplied to the capacitor of the auxiliary current source circuit via the level shift circuit, thereby shorting the contact terminals of the predetermined switch. A switch circuit characterized by a state.