JPS59230494A - Dc motor control circuit of watch - Google Patents

Abstract

PURPOSE:To maintain the voltage applied to a motor substantially constant even if a power source voltage varies by connecting a control transistor which inputs at the base the output of a voltage divider for dividing a battery voltage in parallel with the base circuit of a drive transistor. CONSTITUTION:When an alarm switch S becomes ON at the set time and an alarm output is generated from a terminal (a), a transistor FT is turned ON, a base current is flowed to a transistor T1, which is turned ON, thereby driving a DC motor M. When a battery E is new and a voltage of 1.2V or higher is applied to the motor M, this voltage is applied between a diode D and the base, the emitter of a transistor T2. Thus, the transistor T2 becomes ON, the source voltage of the transistor FT decreases, and the base current of the transistor T2 decreases. Since negative feedback is thus applied, the applied voltage of the motor M is held at the voltage 1.2V.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a DC motor control circuit for a watch.

For example, in a clock that uses a bell to generate an alarm sound,
A drive transistor is connected in series to a DC motor for driving the bell, and an alarm output from a clock circuit is supplied to its base input to drive the DC motor. Therefore, as the battery voltage decreases, the rotation of the DC mole decreases, and the volume of the bell gradually decreases. [Also, if you set the volume so that the appropriate volume is obtained when the battery is new, the DC motor may not be driven even when there is still enough battery power left.] On the other hand, set the DC motor so that it will continue to drive even if the battery voltage drops considerably (and
When the battery is new, the problem is that the volume is too loud.

In addition, cuckoo clocks have the disadvantage that the movement of the pigeons changes depending on changes in battery voltage. In other words, when the pond is new, the DC motor rotates quickly and the pigeons move quickly, but as the heavy oil is used up, the pigeons move slowly.

Therefore, the present invention eliminates the above-mentioned drawbacks by preventing the voltage applied to the DC motor from changing even if the lightning voltage fluctuates L2 within a certain range.

An embodiment of the present invention will be described below based on the drawings. Ar
In the clock circuit, when the set time alarm switch S is closed, a drive output is generated from the output terminal α and turns on the first control transistor FT. The source of transistor FT is connected to battery F8 via resistor R2. Diode D and resistor R1 constitute a voltage divider circuit,
The diode Did has a forward voltage of, for example, 0.6 V and operates as a constant voltage element. T2 (6M2 control transistor, for example, base-emick voltage is 0.6
V is used, and the sum of this voltage and the forward voltage of the diode D, which is a voltage 1, 2, is always applied to the DC motor M. The DC motor 4M is for driving a bell (not shown). The DC motor MVc is connected in series with the T and Lri drive transistors.

In the above configuration, when the alarm switch S is turned on at the set time and an alarm output is generated from the terminal α, the transistor FT is turned on, and the transistor T1Vc is turned on by flowing the hess current, thereby driving the M-flow motor M. If the battery E is new and a voltage of 1.2 V or more is applied to the DC motor MK, this voltage will be applied to the diode D.
and is applied between the emitters of transistors T2'7) and T2'7). Therefore, the transistor 4T2 is turned on, the current flowing through the resistor R2 increases, and the collector potential of the transistor T2, that is, the source potential of the transistor 41FT decreases.

Therefore, isometrically, the mutual conductance of transistor FT decreases, and the base current of transistor T1 decreases. Since negative feedback is applied in this manner, the voltage applied to the DC motor M is maintained at 1.2VK, which is the sum of the voltages between the diode D and the base-emitter of the transistor T2.

Because of this configuration, even if the voltage of the battery E fluctuates, the DC motor MK
A constant voltage determined by the base-emitter voltage of 2 is applied, and a constant and comfortable bell sound can be generated at all times.

In the above example, the voltage applied to the DC motor is applied to the diode D and the base-emitter T11 of the transistor T2.
Although the voltage is set to 1.2v based on the pressure vc, the voltage is not limited to this.

By the way, it is possible to intermittently rotate a constant angle by driving with a DC motor 'jM+d' pulse. And by this one drive, Shimoku (not shown)
It is possible to generate a single bell sound by rotating the ring by a certain angle. Therefore, by utilizing this, the bell can achieve the function of gradually waking people up by gradually shortening the interval between single bell sounds as time passes, or by increasing the number of bell sounds that are rung at one time. be able to. To achieve this, it is sufficient to generate pulses from the terminal α of the clock circuit A, and control the generation interval and the like.

In such cases, the present invention exhibits particularly great effects. For example, if you try to achieve the above function with a conventional device, the volume of the bell that rings with one pulse will change sharply due to fluctuations in battery voltage, and the number of times each pulse will hit the bell will change.

In the present invention, the number and volume of bell sounds produced by one pulse do not change, and a pleasant bell sound can always be generated.

Note that the present invention is applicable not only to a bell but also to a case where a chime mechanism, a pigeon mechanism, etc. are driven as a load.

Further, in the example of e above, a diode and a resistor are used as the voltage dividing circuit, but a resistor may be used instead of the diode. However, in this case, the voltage applied to the DC motor varies slightly due to variations in battery voltage. In other words, this is because the divided voltage ′ fluctuates due to fluctuations in battery voltage.
This variation is equal to the battery voltage variation multiplied by the voltage division ratio, so it can be suppressed to a slight variation.

Furthermore, the first control transistor FT is not limited to a MOS transistor, but may also be a bipolar transistor.As described above, according to the present invention, even if the battery voltage fluctuates, the voltage applied to the DC motor can be kept almost constant. 2. Therefore, if a bell is used as a load, it can be sounded at a constant volume, and if a pigeon mechanism or the like is used, it can be driven at a constant volume.

[Brief explanation of the drawing]

The drawing is an electrical circuit diagram showing an embodiment of the present invention. A...Clock circuit D...Diode R1, R2
...Resistor FT...First control transistor T1...Drive transistor T2...Second control transistor M...DC motor E...Battery and more Applicant Seikosha Co., Ltd. Agent Patent Attorney Tsutomu Mogami 4

Claims (1)

[Claims] A DC motor that drives the load, a drive transistor connected in series to the DC motor, a clock circuit that generates a drive output at a preset time, and a battery that is connected via a resistor to operate based on the drive output. a first control transistor that supplies a base current to the drive transistor; a voltage divider circuit that divides the voltage of the battery; a voltage output of the voltage divider circuit is used as a base input, and a collector that connects the resistor and the first control transistor; The emitter connected between the transistors is composed of an upper P DC motor and a second control transistor connected between the drive transistors. A DC motor control circuit for a timepiece, wherein negative feedback is applied to a base current supplied from a first control transistor to the drive transistor.