JPS6264226A - Electric device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an electrical device that issues an alarm in response to a decrease in the output of a power source battery.

[Technical Background of the Invention and Problems thereof] Conventionally, in electrical equipment using batteries as a power source, such as portable printers and word processors, voltage monitoring means for monitoring the output voltage of the battery has been provided. Some devices are configured to notify that it is time to replace the battery by, for example, turning off a monitor lamp when the voltage falls below a predetermined lower limit voltage. However, printers, word processors, etc. include inductance loads that frequently turn on and off, such as solenoids for driving the print head and motors for driving the carriage, so each time these loads are driven, the output voltage of the battery decreases. It is unavoidable that the value will drop instantaneously. For this reason, in the conventional configuration described above, there is a problem in that the monitor lamp goes out due to an instantaneous voltage drop in response to load driving even when the battery life is still sufficient. Since the period of time when the lights are turned off becomes gradually longer, the reality is that users only use the monitor lamps as a guide, and the problem is that the original purpose of the monitor lamps is not fully utilized. There was one point.

In order to deal with such problems, it is possible to provide a structure that latches the state when the battery voltage detected by the voltage monitoring stage falls below a predetermined lower limit voltage and the monitor lamp goes out. It is possible, but with this configuration, the monitor lamp remains off even when the output voltage of a battery that can be used continuously drops below the lower limit voltage instantaneously in response to load drive. In reality, even if such a configuration is adopted, it is difficult to accurately notify when it is time to replace the battery, as this may cause malfunctions and the characteristics such as internal resistance may differ depending on the battery. Met.

[Object of the Invention] The present invention has been made in view of the above circumstances, and its purpose is to provide an electrical device that has effects such as being able to accurately notify when it is time to replace the battery that makes up the power source. It is in.

[Summary of the Invention] In order to achieve the above object, the present invention provides a voltage monitoring means for outputting a voltage shortage detection signal when the output voltage of a battery serving as a power supply becomes below a predetermined lower limit level; a delay circuit that delays the voltage for a predetermined time and outputs the delayed signal as a delayed signal, a latch unit that is set to generate an alarm signal when both the voltage shortage detection signal and the delay signal are output, and the latch unit that responds to power-on. The configuration is such that an initialization means for resetting is provided for each,
This prevents an alarm signal from being generated when the output voltage of the battery momentarily drops.

[Embodiment of the Invention] An embodiment in which the present invention is applied to a printer will be described below with reference to the drawings.

In FIG. 1, a battery 1 serves as a power source, and its output voltage is applied to a power line Vd via a power switch 2. Reference numeral 3 denotes a voltage monitoring means provided to detect the level of the output voltage of the power supply line Vd and, in turn, the output voltage of the battery 1.
When the voltage is below u, a voltage shortage detection signal S3 consisting of a high level signal is output. 4 is a delay circuit that delays the voltage shortage detection signal S3 by a predetermined time T and outputs this as a delayed signal S4. 5 is a latch means, which includes an AND circuit 6 which receives the voltage shortage detection signal @S3 and delay signal No. 8 at its re-input terminal, and an R-S flip-flop 7 which receives the output from this AND circuit 6 at its set input terminal S.
Consists of. Therefore, in this latch means 5, when both the voltage shortage detection signal $3 and the delay signal S4 are input, the R-S flip-flop 7 is set, and a high level signal is output from the set output terminal Q. An alarm signal Sa is output. When the above-mentioned alarm signal Sa is output, for example, a monitor lamp (not shown) is lit to indicate that the battery 1 is due for replacement.A8 is a pulse generation circuit serving as initialization means; This generates a reset pulse P8 every time the voltage of the power supply line Vd rises and applies it to the reset input terminal R of the R-8 flip-flop 7. Although not shown, loads such as a solenoid for driving a print head and a motor for driving a carriage are connected to the power supply line Vd.

Next, the operation of the above structure will be explained with reference to FIG. 2, which shows waveforms of various parts in FIG. 1. Time 1 in Figure 2.
When the power switch 2 is turned on and the output of the battery 1 is applied to the power line Vd, the pulse generating circuit 8 outputs a reset pulse P8 in response to the rise of the output voltage of the power line Vd. R-8 flip 70
The knob 7 is reset. At this time, when the output voltage of the battery 1 exceeds the lower limit level ■u as shown in FIG.
is not output, so the R-S flip-flop 7 remains in the reset state. From this state, when the load is energized and the output voltage of the battery 1 temporarily drops below the lower limit level Vu, the voltage monitoring means 3 detecting this moment outputs a voltage shortage detection signal S3. However, if the output period of this voltage shortage detection signal S3 is shorter than the delay time T of the delay circuit 4 (in other words, if the battery 1 still has some life left), the voltage shortage detection signal S3 disappears. Since the delayed signal S4 is output after (
At time t3), both signals 83 and 84 are not output simultaneously, so the R-S flip-flop 7 is held in the reset state. After this, when the capacity of battery 1 decreases and its output voltage drops below the lower limit level Vu (
At time t4), the voltage shortage detection signal S3 is sent from the voltage monitoring means 3.
will be output continuously, so the subsequent time t
When the delayed signal S4 is output at step 5, a high level signal is output from the AND circuit 6, the R-S flip-flop 7 is set, and the R-8 flip-flop 7 outputs the alarm signal Sa.

As a result, a monitor lamp (not shown) is turned on in response to the alarm signal Sa to notify that it is time to replace the battery 1. In this case, according to the applicant's experimental results, good notification can be achieved if the lower limit voltage Vu is set to 60 to 80% of the nominal voltage of the battery 1 and the delay time T is set to about tens of milliseconds to several seconds. I understand.

According to the present embodiment described above, the alarm signal Sa is not output when the output voltage of the battery 1 temporarily drops below the lower limit level Vu in response to the drive of the load, and the battery 1
When the output voltage of the battery 1 continues to drop below the lower limit level vu for more than 11 J (delay time T) at a certain time, in other words, when the capacity of the battery 1 drops to a capacity that really requires replacement, an alarm signal Sa is sent. Since the configuration outputs
It is possible to accurately notify the time to replace the battery 1 based on the alarm signal Sa, regardless of variations in the characteristics of the battery 1.

In addition, in the above embodiment, within the delay time T, the battery 1
When the output voltage reaches the lower limit two or more times and falls below the bell VU, the undervoltage detection signal S3 and the delay signal S4 are output at the same time, even though the battery 1 has sufficient capacity, and the alarm signal Sa is output. However, in order to deal with such a problem, a delay circuit that includes an integral element or a delay circuit that is forcibly initialized in response to the disappearance of the input may be used. Further, in the above embodiment, the latch means was constructed using the R-S flip-flop 7, but instead of this,
Other latch means such as a flip-flop may be used, or the microprocessor for controlling the printer's operation may have the latch function. In this case, the output terminal of the AND circuit 6 may be connected to the interrupt terminal of the microprocessor. Connect to. Further, in the above embodiment, the time to replace the battery 1 is notified in response to the lighting of the monitor lamp, but the notification may be made in response to the turning off of the monitor lamp.

However, the present invention is not limited to the embodiments described above and shown in the drawings, but can be modified in various ways without departing from the gist, such as being widely applicable not only to printers but also to general electrical equipment using batteries as a power source. This can be implemented by

[Effects of the Invention] As is clear from the above description, the present invention has the practical effect of being able to accurately notify when it is time to replace a battery in an electrical device using a battery as a power source. .

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is an electric circuit diagram, and FIG. 2 is a timing chart for explaining the operation. In the figure, 1 is a battery, 2 is a power switch, 3 is a voltage monitoring means, 4 is a delay circuit, 5 is a latch means, 6 is an AND circuit, 7
8 represents an R-8 flip-flop, and 8 represents a pulse generation circuit (initialization means).

Claims (1)

[Claims] 1. In an electrical device using a battery as a power source, voltage monitoring means outputs an undervoltage detection signal when the output voltage of the battery falls below a predetermined lower limit level, and the voltage monitoring means delays the undervoltage detection signal for a predetermined time. a delay circuit that outputs a delay signal; a latch unit that is set to generate an alarm signal when both the voltage shortage detection signal and the delay signal are output; and an initialization unit that resets the latch unit when the power is turned on. An electrical device characterized by comprising means.