JPH0542392Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an automobile watch installed in a car and a technology for preventing over-discharge of an automobile battery, and particularly relates to an automobile watch having an over-discharge prevention function of an automobile battery. be.

[Conventional technology]

Due to recent dramatic advances in electronics technology, various equipment installed in automobiles have become increasingly computerized, and automobiles have come to be equipped with a large number of electrical components with various functions.

[Problem that the invention attempts to solve]

Some of these electrical components include memory, etc. that require battery backup even when the car's key switch is turned off, so the amount of power consumed by the battery required for backup increases as the number of these electrical components increases. It is increasing. Therefore, if the automobile is left unused for a long period of time, the battery may become over-discharged, and there is a risk that the starter motor may not rotate when the automobile engine is started.

The present invention has been made in view of the above points, and an object of the present invention is to provide an automobile timepiece having a function of preventing battery over-discharge when the automobile is left unattended for a long period of time.

[Means for solving problems]

In order to solve the above problems, the present invention includes a power supply circuit that supplies power from the battery as backup power even after the key switch is turned off, a reset circuit that detects when the key switch is turned off, and a reset circuit that detects when the key switch is turned off. A timer signal is generated to accurately measure a certain period of time after the key switch is turned off using a pulse signal from a clock circuit that forms a clock drive signal, and to cut off the supply of backup power to each electrical component in the power supply circuit after this certain period of time has elapsed. A counter circuit for output is provided.

[Effect]

In the present invention, a long-time timer is constituted by a counter circuit that counts pulses using the signal output of a clock circuit. This results in
After a certain period of time has passed after the key switch of the automobile is turned off, the backup power supply from the battery to each electrical component is cut off.

〔Example〕

Next, an embodiment of the present invention will be described with reference to the drawings. The figure is a block diagram showing an embodiment of the automobile watch according to the present invention.

In the figure, 1 is a stabilized power supply circuit, which has a positive terminal (hereinafter referred to as the (+) terminal) 1a connected to the battery, a negative terminal (hereinafter referred to as the (-) terminal) 1b, and an accessory switch of the key switch. accessory terminal (hereinafter referred to as ACC terminal) 1c, and an illumination terminal (hereinafter referred to as ILL terminal) 1d that indicates the closing of the tail lamp circuit.
It supplies power to each circuit from the output terminal 1A and the output terminal 1B, and outputs an illumination control signal from the ILL terminal 1d via the output terminal 1C. Further, 2 is an oscillation circuit that has a crystal oscillator and generates a reference time signal, and 3 is an oscillation circuit that divides the frequency of the reference pulse from the oscillation circuit 2 and outputs a time signal as a clock drive signal. A clock IC as a clock circuit that outputs a pulse signal of a predetermined period; 4 a display element as a display device to which a time signal from the clock IC 3 is input and thereby display the time; 5 a display element to which a pulse signal is input from the clock IC 3; The level conversion circuit 6 counts the level-converted pulse signal from the level conversion circuit 5 when it is input to the clock input terminal 6a, and when the count reaches a preset count, the timer is output from the output terminal 6c. Counter IC as a counter circuit that outputs a signal, 7
detects the presence or absence of voltage at the ACC terminal 1c of the stabilized power supply circuit 1, and if the voltage is present, the counter IC6
This is a reset circuit that outputs a reset signal to the reset terminal 6b. The display element 4 is operated by the ACC terminal voltage stabilized by the stabilized power supply circuit 1, so when the key switch is turned off, this voltage disappears and the display disappears, reducing power consumption. Become. 8 is a power supply circuit to which a timer signal is inputted from the Qn output terminal 6c of the counter IC 6, and power is inputted from the (+) 1a and ACC terminal 1c of the stabilized power supply circuit 1; 8a is its power supply terminal; Electrical components including memory and the like that require backup are connected to this power supply terminal 8a. The power supply circuit 8 is composed of three transistors Tr1, Tr2, and Tr3. The transistor Tr1 has a base connected to the Qn output terminal 6c of the counter IC6 via the resistor R1, a collector grounded, and an emitter connected to one end of the resistor R3. A resistor R2 is connected between the base and collector of this transistor Tr1.
The base of the transistor Tr2 is connected to the other end of the resistor R3, the emitter is connected to the base of the transistor Tr3, and the collector is connected to the collector of the transistor Tr3. There is a resistance between the base of this transistor Tr2 and the emitter of transistor Tr3.
R4 is connected. The emitter of the transistor Tr3 is connected to the (+) terminal 1a of the stabilized power supply circuit 1, and the collector is connected to the cathode of the diode D and connected to the power supply terminal 8a via the resistor R5.
It is connected to the. The anode side of the diode D is connected to the ACC terminal 1c of the stabilized power supply circuit 1. Next, its operation will be explained.

When the key switch of the automobile is set to on, the engine is running, and the automobile is running, the stabilized power supply circuit 1 receives power supplied from the battery from the (+) terminal 1a and the (-) terminal 1b. After stabilization, the oscillation circuit 2, clock IC 3, level conversion circuit 5, and counter IC are output from the output terminal 1A.
6, the power supplied from the ACC terminal 1c is stabilized, and the stabilized power is supplied to the display element 4 from the output terminal 1B. The oscillation circuit 2 generates a reference pulse of a constant period and outputs it to the clock IC 3. The clock IC 3 divides the frequency of the reference pulse and outputs the pulse signal in the middle of the frequency division to the level conversion circuit 5, and also outputs the frequency-divided time signal to the display element 4.
The display element 4 is composed of a fluorescent display tube, a light emitting diode, a liquid crystal, etc., and digitally displays the time upon receiving the time signal. The illumination control signal input from the ILL terminal 1d to the clock IC3 from the output terminal IC via the internal protection circuit of the stabilized power supply circuit 1 changes the duty ratio of the pulse of the time signal generated by the clock IC3. By this, the brightness of this display element 4 is adjusted. on the other hand,
The level conversion circuit 5 that receives the pulse signal converts the level of this signal to a counter IC 6 connected to the next stage.
The level is converted to match the signal level of the counter IC6, and this level-converted signal is output to the clock input terminal 6a of the counter IC6. The reset circuit 7 outputs a reset signal to the reset terminal 6b of the counter IC6 since the car is in a running state and voltage is supplied to the ACC terminal 1c, so the counter IC6 outputs a reset signal to the clock input terminal 6a. It does not accept the frequency signal, and the state of the timer signal output from the Qn output terminal 6c is set to the "L" level. Therefore, the base potential of the transistor Tr1 of the power supply circuit 8 decreases, so a base current flows through its base and the transistor Tr1 is in the on state. Current is flowing through the circuit. Due to the voltage drop caused by this current, the base potential of the transistor Tr2 also decreases, and the base current also flows to the bases of the Darlington-connected transistors Tr2 and Tr3, and each transistor is in an on state. Therefore, each electrical component connected to the power supply terminal 8a of the power supply circuit 8 has two Darlington-connected transistors Tr2 connected from the (+) terminal 1a of the stabilized power supply circuit 1 to the power supply circuit 8. , the power supply path via Tr3 and the protective resistor R5, and the protective diode D of the power supply circuit 8 from the ACC terminal 1c of the stabilized power supply circuit 1.
The power is supplied from two systems: and a power supply path via the protection resistor R5.

Now, if the key switch of the car is turned off, the engine is stopped, and the car is not running, the voltage supplied to the ACC terminal 1c of the stabilized power supply circuit 1 disappears, so the time is displayed on the display element 4. disappears, and power is supplied from the power supply terminal 8a to each electrical component from the (+) terminal 1a of the stabilized power supply circuit 1 to the two Darlington-connected transistors Tr2 and Tr3 of the power supply circuit 8 and the protective resistor R.
This is done only by the route via 5. Furthermore, since there is no voltage at the ACC terminal 1c of the stabilized power supply circuit 1, the reset circuit 7 connected to the ACC terminal 1c detects that the key switch has been turned off, and outputs it to the reset terminal 6b of the counter IC 6. The reset signal is stopped and the counter IC6
Cancels the reset state. From this point on, the pulse signal that has been input to the clock input terminal 6a is input, and counting of the number of pulses of the pulse signal is started. When the count number of these pulses reaches a predetermined constant number, that is, when a predetermined constant time has elapsed since the key switch of the car was turned off, the counter IC6
An "H" level timer signal is output from the Qn output terminal 6c. As a result, the base potential of the transistor Tr1 of the power supply circuit 8 rises, no base current flows, and the transistor Tr1 is turned off. Therefore, resistor R4, resistor R3 and transistor Tr1
No current flows through the series circuit consisting of the emitter and collector of the transistor Tr2, and the base potential of the transistor Tr2 rises. Therefore, no base current flows to the bases of the Darlington-connected transistors Tr2 and Tr3, and each transistor is turned off. Become. Therefore, the power supply path from the (+) terminal 1a of the stabilized power supply circuit 1 to the Darlington-connected transistors Tr2 and Tr3 of the power supply circuit 8 and the protective resistor R5 is cut off, and the power supply path from the power supply terminal 8a to each The power supply to electrical components is completely cut off after a certain period of time, for example, one week, after the key switch of the automobile is turned off.

[Effect of idea]

As described above, the automobile clock according to the present invention includes a power supply circuit that supplies power from the battery as backup power even after the key switch is turned off, a reset circuit that detects when the key switch is turned off, and a reset circuit that detects when the key switch is turned off. A counter circuit is provided that counts pulse signals from the clock circuit after it is turned off and outputs a timer signal after a certain period of time has passed, and when the timer signal is input, the supply of backup power to each electrical component in the power supply circuit is cut off. With this configuration, the supply of backup power from the battery to each electrical component is accurately cut off after a predetermined period of time has passed after the car's key switch is turned off, making it easier to leave the car unused for long periods of time. This makes it possible to prevent the situation in which the vehicle cannot be started due to over-discharge of the battery that occurs when the battery is over-discharged. Therefore, there is no need to worry about removing the battery terminal when leaving the car for a long time or parking it.

In addition, since the signal from the clock circuit in the existing clock circuit is used, it is possible to accurately count without being affected by the environment such as temperature even when counting with a counter circuit for a long time, and the circuit is small and inexpensive. can be configured.

[Brief explanation of the drawing]

The figure is a block diagram showing an embodiment of the automobile watch according to the present invention. 2...Oscillation circuit, 3...Clock IC, 4...
Display element, 6... Counter IC, 7... Reset circuit, 8... Power supply circuit.

Claims (1)

[Claims for Utility Model Registration] Consists of an oscillation circuit that generates a reference time signal, a clock circuit that divides the output from the oscillation circuit to form a clock drive signal, and a display device that displays time using the clock drive signal. In an automobile clock, there is a reset circuit that detects that the key switch of the automobile is turned off and releases the reset signal, and a preset count that counts the pulse signal from the clock circuit from the time when the reset signal is released. a counter circuit that outputs a timer signal when the number reaches the specified number; a counter circuit that supplies power from the battery to each electrical component of the automobile as a backup power supply even after the key switch is turned off; and inputs the timer signal from the counter circuit. a power supply circuit that cuts off the supply of backup power to each of the electrical components based on the above, and a set count number of the counter circuit is set to prevent over-discharge of the battery. clock.