JPS623840Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reverse input safety device for a sound clock or clock device.

2. Description of the Related Art Conventionally, in electronic alarm clocks and the like, it is common to provide a sound output generated by an alarm circuit or the like to an electroacoustic transducer to make a time signal or the like. However, recently, when a small watch, especially a wrist watch, is subjected to a strong impact due to being dropped or hitting something, the electro-acoustic transducer is stimulated and generates a high voltage, which travels backwards through the acoustic drive circuit and into the watch circuit. It was found that the virus could infiltrate the computer and cause undesirable phenomena such as resetting and latch-up of the clock circuit, and destroying data in memory and registers. This tendency is particularly noticeable in the case of piezoelectric transducers, especially when a piezoelectric element is attached to a windshield to form a transducer.
As a countermeasure to this drawback, the present invention allows the two poles of the electroacoustic transducer to be short-circuited at all times, and when necessary, the short-circuit is broken using a signal in the alarm circuit that instructs the output of the time signal sound. This provides a configuration for Embodiments of the present invention will be described below with reference to the drawings.

In Fig. 1, 1 is the main timekeeping circuit section of an electronic clock with an alarm, and the reference signal generation circuit 2 (consisting of a memory in which the alarm time is set, a coincidence detection circuit, etc.) uses its internal logic to generate a signal. When the time has arrived, the sound generation instruction signal is output for, for example, several tens of seconds. Further, the acoustic signal generation circuit 3 extracts an acoustic output that actually controls the acoustic transducer drive element 4 . The AND gate of the acoustic transducer drive element 4 is opened by the sound generation instruction signal, and the acoustic output passes through and is boosted and amplified by an acoustic drive circuit consisting of a transistor 5, a current limiting resistor 6, and a coil 7, such as a piezoelectric buzzer. Sound the electroacoustic transducer 8. However, the poles of the speaker of the electroacoustic transducer 8 are usually short-circuited by a switching electronic element 9, such as a transmission gate.
This prevents malfunctions due to noise generated by the electroacoustic transducer, as stated in the purpose of the present invention. When the reference signal is output from the reference signal generation circuit 2, the signal passes through the OR gate 10, and cooperates with the inverter 11 to open the switching electronic element 9, so that the drive voltage generated at both ends of the coil 7 suffers a loss. It is designed so that it is not applied to the acoustic transducer 8. Next, the switch 12 is a correction switch 12 that is turned on when the input electroacoustic transducer 8 (in this embodiment, it is also used as a transducer for acoustic output) inputs data for correction of time and data. This is a switch, and by operating it, V _DD is applied to the OR gate 10 and the switching electronic element 9 is opened at any time. Furthermore, when the switch 12 is turned on, the AND gate 13 is opened. The corrective input is thus prepared, and the corrective output generated by the stimulation of the acoustic transducer 8 by the user is opened via a safety device to prevent overvoltage, such as a limiter 14 consisting of a Zener diode, for example. Pass through AND Gate 13,
The signal enters the input circuit 15 and is converted into an output signal suitable for correcting the time of the clock circuit 1 or correcting the memory data of the reference signal generating circuit 2. Note that during the period when the acoustic output is occurring, the reference signal closes the AND gate 13 to prevent the possibility that the acoustic drive voltage becomes a correction input. The inside of the broken line 16 is converted into an IC.

In extremely rare cases, high-voltage noise generated by a very large impact may exceed the threshold level and enter the IC 16 even if it is weakened by the switching electronic element 9, which acts as a short circuit element. 14. Always closed AND gate 1
The third class is an additional safety barrier.

As is clear from the above, the present invention is a sounding clock characterized by having an electronic element that short-circuits the electroacoustic transducer when there is no sounding instruction signal from the clock circuit. This has the effect of reliably preventing noise, which is sometimes generated when the electroacoustic transducer receives mechanical shock, from affecting the circuitry within the watch.

[Brief explanation of the drawing]

FIG. 1 is a circuit system diagram of a main part of an embodiment of the present invention. 1... Clock circuit, 2... Sound generation instruction signal generation circuit, 8... Electroacoustic transducer, 9... Switching electronic element.

Claims (1)

[Scope of utility model registration request] In a sounding clock that includes a clock circuit, a reference circuit that receives a signal from the clock circuit, an acoustic circuit, and an electroacoustic transducer that operates in response to a sound generation instruction signal from the reference circuit, when the sound generation instruction signal is not present, electroacoustic conversion is performed. A sounding clock characterized by being equipped with an electronic element that short-circuits the device.