JPH037792Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a power supply control circuit for an electronic scale.

In recent years, there has been an increase in the number of electronic scales such as platform scales or health meters that can be easily moved without being restricted by installation locations, and batteries are therefore increasingly being used as power sources. In electronic scales that use batteries as a power source, it is always necessary to replace the batteries.When replacing the batteries, in conventional electronic scales, the load detection circuit that detects the load and the microcomputer that calculates the load must be replaced. Power may be accidentally supplied to loads that do not require power except during measurement, such as processors, display circuits that display weight, unit price, etc. If left unattended without knowing this, the battery This may lead to inconveniences such as wasting energy and shortening battery life.

This invention was created in view of the above-mentioned drawbacks, and when a battery is inserted, it reliably cuts off the power supply to loads that consume a lot of power and do not necessarily require power supply all the time, thereby eliminating wasteful battery consumption. The purpose of this invention is to provide a power control circuit for an electronic scale that is designed to make effective use of the balance.

The gist of this invention to achieve the above purpose is as stated in the claims for utility model registration above.

Next, preferred embodiments of this invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of a power supply control circuit for an electronic balance according to this invention, and FIG. 2 is a timing chart of the main parts of FIG. 1.

In these figures, 1 is a battery that supplies power, 2 is a flip-flop that is set by power-on switch S1 and reset by power-off switch S2, and 3 is a control switch whose opening and closing are controlled by the output P of flip-flop 2. . 4 is a voltage stabilization circuit, and power from battery 1 is supplied to control switch 3.
This voltage is stabilized and supplied to the load detection circuit 7, microprocessor 5, and display circuit 6. The load detection circuit 7 includes a load cell, capacitance type, photoelectric type sensor unit, etc., and electrically detects the weight of the object to be weighed. The detection signal detected by the load detection circuit 7 is processed by a microprocessor 5 such as calculation and comparison, and a signal corresponding to a weight proportional to the detected weight of the object to be weighed, a unit price, etc. is sent to a display circuit 6. The weight, unit price, etc. are finally displayed on the display circuit 6. Reference numeral 8 indicates a load B that does not always require power supply, and 9 indicates a load A that always requires power supply. Reference numeral 10 denotes a first delay circuit consisting of a resistor R1 and a capacitor C1, and is connected to the front stage of the set input terminal S of the flip-flop 2. Reference numeral 11 denotes a second delay circuit consisting of a resistor R2 and a capacitor C2, which is connected to the front stage of the reset input terminal R of the flip-flop 2.

In the embodiment shown in FIGS. 1 and 2, the time constant t1 of the first delay circuit 10 is smaller than the time constant t2 of the second delay circuit 11, that is, t1<
t2, and considering flip-flop 2 as positive logic, control switch 3
is closed when the output Q of flip-flop 2 is “H”,
The explanation will be given assuming that the output Q is open at "L".

In this configuration, if battery 1 is replaced with a new battery, the time t1 until the voltage M at the set terminal S of flip-flop 2 becomes smaller than the threshold value Vth of flip-flop 2, as shown in FIG. The voltage N of terminal R is the threshold value Vth
Since the time it takes for the voltage to decrease is shorter than t2, after the voltage M at the set terminal S goes to the "L" level, the voltage N at the reset terminal R goes to the "L" level, and the flip-flop 2 is reliably reset and output. An output signal P of "L" level is outputted from Q to the control switch 3. When the flip-flop 2 outputs the "L" level output signal P to the control switch 3, the control switch 3 is opened and the power supply to the load B8 is cut off. Therefore, when replacing battery 1, the power supply to load B will always be cut off, and even if you just replace the battery and store the electronic scale in that state, the battery consumption in load B will be reduced. is completely eliminated, and the battery can be used effectively. Also,
The first and second delay circuits can also absorb chattering when switches 1 and 2 are turned on.

In the above embodiment, the relationship between the time constants t1 and t2 of the first and second delay circuits 10 and 11 is expressed as t.
1<t2, but it is also possible to set t1>t2. In this case, the output from flip-flop 2 should be taken from the flip-flop 2, or a switch in which the control switch 3 operates in the opposite direction should be used. Bye.

As explained in detail above, this invention uses a simple structure to reliably cut off the power supply to load B, which consumes a large amount of power, when replacing batteries in electronic scales, prevents unnecessary battery consumption, and enables the switching of electronic scales. It is also possible to prevent chattering during charging, which has an extremely large practical effect.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a power control circuit of an electronic scale according to the present invention, and FIG. 2 is a timing chart of a delay circuit in FIG. 1. 1...Battery, 2...Flip-flop, 3...
Control switch, 4...Voltage stabilization circuit, 5...Microprocessor, 6...Display circuit, 7...Load detection circuit, 8...Load B, 9...Load A, 10...
...first delay circuit, 11...second delay circuit.

Claims (1)

[Scope of utility model registration request] a battery; a load A including a flip-flop connected to the battery and requiring constant power supply;
It does not necessarily require power supply at all times, including a voltage stabilization circuit, a load detection circuit, and a microprocessor that receives a detection signal from the load detection circuit and outputs an output signal proportional to the load to a display circuit. An electronic scale comprising: a load B; and a control switch provided between the battery and the load B, the control switch being operated by the output signal of the flip-flop to control power supply to the load B. It's hot,
A power supply control circuit for an electronic scale, comprising a delay circuit with different time constants provided in front of the set and reset input terminals of the flip-flop.