JPS6052777A - Voltage monitor circuit - Google Patents

Abstract

PURPOSE:To set information concerning the number of cells from external to realize a voltage monitor circuit which can respond to a change of the number of cells, by arranging an external switch for changing a reference voltage or an input voltage of a comparator in the voltage monitor circuit. CONSTITUTION:Transistors TRs Q1 and Q2 constitute the comparator together with load resistances R5 and R6, and a constant voltage due to diodes D1 and D2 is supplied to the base of the TRQ2 independently of a battery voltage. A divided voltage, which is determined by resistances R1 and R2 and resistances R3 and R4, of the battery voltage is supplied to the base of the TRQ1. An upper trigger voltage is determined by the ratio of the resistance R3 to resistances R1 and R2, and a lower trigger voltage is determined by the ratio of resistances R3 and R4 to resistances R1 and R2. Terminals are provided at the connection point of resistances R1 and R2 and on a power supply line, and the circuit between these terminals is short-circuited or opened by an external switch 12 such as a DIP switch or the like adjusting a trigger voltage with the external switch 12.

Description

[Detailed Description of the Invention] [Technical Field] Guidance lighting equipment and emergency lighting equipment only perform their original functions when they operate effectively and reliably in emergencies such as disasters. At the same time, daily maintenance and management on the user side is extremely important.

In this sense, voltage monitor circuits that detect and display the lifespan of storage batteries built into guide lights and emergency lighting equipment facilitate inspection.
This is useful in promoting its maintenance and management. The present invention relates to a voltage monitoring circuit for a storage battery built into a guide light or an emergency lighting device.

[Background technology]

Guidance lights and emergency lighting equipment are usually powered by commercial power,
In the event of a power outage, it automatically switches to the built-in storage battery and lights up in an emergency using inverter oscillation.

The voltage monitor circuit detects and displays the battery life by detecting that the battery voltage has fallen below a specified value. That is, if the voltage of the battery decreases more than the specified value due to the emergency lighting of the appliance for a specified period of time, the voltage monitor circuit determines that the battery is at the end of its service life and issues a % warning. However, if the emergency lighting is then returned to normal lighting, the battery voltage will be restored by charging even if the battery has reached the end of its life.

For this reason, the negative voltage monitor circuit is provided with a memory function so that once the battery voltage falls below a specified value, it remembers that the battery life has expired.

FIG. 1 shows a block diagram of the voltage monitor circuit.

The circuit consists mainly of Schmitt circuit 4.

Powered by battery voltage. As a 4-person Schmitt circuit, the constant voltage output from constant voltage circuit 1 and the battery voltage are connected to resistance R.
The two voltages divided by R1 and R2 are input. When the battery voltage is normal, resistors R1 and R are set so that the voltage divided by resistors R1 and R2 is greater than the output voltage from constant voltage circuit 1.
2. If a constant voltage output value is set, the drive circuit 3 will not operate and the monitor light emitting diode LED will not light up.

Now, the battery voltage decreases, and a divided voltage of 2 is generated across resistor R1.
When the constant voltage output voltage drops below the bottom trigger voltage of the Schmitt circuit, the circuit reverses and the light emitting diode L
ED lights up.

If the upper trigger voltage of the Schmitt circuit is set sufficiently higher than the battery voltage, the light emitting diode LE once lit
Since D continues to light up even after the battery voltage is restored, it has a memory function.

Further, in order to turn off the lit light emitting diode LED, a reset circuit that applies a voltage pulse higher than the upper trigger voltage to the Schmitt circuit 4 is required, but this is omitted here for convenience.

Now, in this voltage monitor circuit, when the number of batteries (hereinafter referred to as the number of cells) changes, it is necessary to change the circuit constants and reset the operating point. Particularly when considering the use of ICs for voltage monitor circuits, preparing ICs according to the number of cells poses problems in terms of cost and development planning. In addition, mounting part of the circuit externally to the basic IC may cause mounting problems, and in equipment that requires a wide range of temperature characteristics, such as emergency lights, it is necessary to attach a part of the circuit externally to the basic IC. is also a problem.

The present invention has been made in view of this point, and an object of the present invention is to create a voltage monitor circuit that can respond to changes in the number of cells.

[Purpose of the invention]

An object of the present invention is to realize a voltage monitor circuit that can respond to changes in the number of cells by externally setting information regarding the number of cells.

[Disclosure of the invention]

The gist of this invention is to detect and store abnormalities in battery voltage by comparing the reference voltage and battery voltage with a comparator, and to change the reference voltage of the comparator in the voltage monitor circuit of An external voltage monitor circuit with a switch is used to change the voltage. The present invention will be explained below based on examples.

(Example 1) FIG. 2 shows Example 1 of the present invention. A storage battery BT is connected as a power source for the circuit. Resistors Ri and R2 from the power supply line
, R,, R4 are connected in series, and the end of R4 is connected to the ground line. The connection point between resistor R2 and resistor RB is connected to the base of transistor Ql, the emitters of transistor Q1 and transistor Q2 are short-circuited and connected to resistor R7, and the opposite side of resistor R7 is connected to ground. Also, transistors. The collectors of 1°Q2 are connected to the power supply line via resistors R5 and R6, respectively. On the other hand, the base of transistor Q2 is connected to the connection point between resistor R8 and diode D1. The opposite side of the resistor R8 is connected to the power supply line, and the opposite side of the diode D1 is connected to the ground via the diode D2. The connection point between the collector of transistor Q2 and resistor R is connected to the base of transistor q3, the emitter of transistor i is connected to the power supply line, and the collector of transistor Q6 is connected to resistor R.
Connect to ground through a series connection consisting of 9 and RID. The connection point between resistor R9 and R,10 is transistor Q4. !
=Q517) Connect to the base. The emitter of the transistor Q4 is connected to ground, and the collector of the transistor Q4 is connected to the power supply line through a series connection consisting of a resistor R11 and a light emitting diode LED.

Further, the collector of transistor q5 is connected to the connection point between resistors R5 and R4, and the emitter is grounded.

Therefore, transistors Ql and Q2 are connected to load resistors 5 and R6.
It forms a comparator together with transistor q2.
Regardless of the battery voltage, diodes DI and D2 are installed at the base of
A constant voltage consisting of: The battery voltage is connected to the base of transistor Q1 by resistors (R1+R2) and (R3+R4).
A voltage determined by is supplied. Now, when the battery voltage is normal, the base of transistor Q1 is connected to transistor Q.
The ratio of resistors (R1+R2) and (R5+R4) is determined so that a voltage higher than the constant voltage applied to the base of 2 is applied. Then transistor Q1 turns on and transistor Q
2I: tOFF, so transistor Q3. Q41
Q5 is all OF, FL, and light emitting diode LED is off. However, the battery voltage drops and transistor Q
When the base voltage of transistor Q1 becomes lower than the base voltage of transistor Q2, the comparator is inverted and vice versa.
is turned off and transistor Q2 is turned on, so that transistor Q5. Q4. Q5 turns on and the light emitting diode LED lights up. At this time, the transistor Q5 is turned on, so the resistor R4 is short-circuited, and the circuitry causes the voltage to have hysteresis. As described above, the upper trigger voltage is determined by the ratio of the resistors R5 and (R1+R2), and the lower trigger voltage is determined by the ratio of the resistors (R5+R4) and (R1+R2). Therefore, as shown in Figure 2, if a terminal is provided between the connection point of resistors R1 and R2 and the power supply line, and an external switch 12 such as a DIP switch is used to short-circuit or open the terminals, the external It can be seen that the trigger voltage can be set by increasing or decreasing it with the switch 12. In this way, even if the number of cells changes, it is possible to respond to changes in the voltage to be detected by setting the external switch.

In the first embodiment, the constant voltage circuit is composed of a resistor and a diode, but this is the same even if other constant voltage circuits are used.

The above effect can be obtained by replacing the resistor Ri, [2 with a number of resistors so that the resistance used between the storage battery and the base of the transistor Q1 can be selected as appropriate, or by fixing the resistors R1 and R2 and changing the resistor R4. Similar effects can be expected even if

(Example 2) FIG. 6 shows Example 2 of the present invention. circuit configuration, connections,
The operation etc. are the same as in the first embodiment.

In the second embodiment, the terminal of the switch is provided at the ground and the connection point between the diodes D1 and D2, and an external switch 16 is provided between them.

Therefore, by short-circuiting and opening the two terminals using the external switch 12, the reference constant voltage changes, so that the detected voltage can be changed.

Example 2 differs from Example 10 in that the reference voltage is changed.
It is different from the method of changing the input voltage.

Furthermore, the same effect can be obtained by using other circuits as the reference voltage as long as the voltage can be set externally.

[Effects of the Invention] As detailed above, the present invention allows the same circuit to respond to changes in the number of cells by setting information on the number of cells from outside.

In the present invention, when this circuit is integrated into an IC, the only increase in the number of parts is an external switch for setting the number of cells, which is very advantageous in terms of implementation.
This has great advantages in terms of cost and product development. And since no semiconductor elements are used in the external circuit,
There is no need to consider the difference in temperature characteristics between the IC and the external circuit.

[Brief explanation of the drawing]

FIG. 1 is an explanation of a conventional example using a block diagram, and FIG. 2 is an explanation of a conventional example using a block diagram. FIG. 6 is a circuit diagram of the second embodiment. ■In the figure, R is a resistor, BT is a storage battery, Q is a transistor, and D is a diode. Patent applicant Matsushita Electric Works Co., Ltd. Patent attorney Toshimaru Takemoto (and 2 others) Figure 2-47R- Figure 3

Claims (1)

[Claims] (11. By comparing the reference voltage and the battery voltage with a comparator, an abnormality in the battery voltage is detected and stored. According to the supplementary voltage monitor circuit that displays and warns about the abnormality,
A voltage monitor circuit with an external switch for changing the reference voltage of the comparator or for changing the input voltage.