US3697982A - Tone control signal circuit having tone pulses followed by continuous tone - Google Patents

Abstract

A control signal generator circuit for an annunciator such as an electric tone in the form of a buzzer or bell consisting of three principle circuits: a timer circuit; a multivibrator; and an amplifier circuit. These circuits are connected across a single power supply. The multivibrator provides the function of producing a series of pulses to the amplifier circuit for causing the annunciator to operate on an intermittent basis. The timer circuit provides the function of converting the operation of the annunciator from producing an intermittent audio signal to a continuous audio signal after a predetermined period of time.

Description

[ Oct. 10,1972

United States Patent Kawaki et al.

W mm CS ME m NT 8 m u m um ww aw L C rm A Nm mm U m? n TO T 0 N Ell mm TH m 3,284,796 11/1966 Borsattino..............340l384 E 3,504,364 3/1970 Abel..... ...340/384 E Primary Examiner-Harold T. Pitts BY CONTINUOUS TONE [72] inventors: Katsumi Kawaki; Mmshi Usui,

both of Kawasaki, Japan Assignec: Tokyo Tokei Selzo Kahlil, Ltd.,

Attorney-Carothers and Carothers Kawasaki-shi Kanagawa-ken, Japan Dec. 3, 1970 Appl. No.: 94,825

ABSTRACT [22] Filed:

A control signal generator circuit for an annunciator 1 such as an electric tone in the form of a buzzer or hell consisting of three principle circuits: a timer circuit; a

multivibrator; and an amplifier circuit. These circuits [30] Foreign Applic'fion mm! are connected across a single power supply. The mul- June 10, 1970 Japan 45 514 tivibrator provides the function of producing a series of pulses to the amplifier circuit for causing the annunciator to operate on an intermittent basis. The timer circuit provides the function of converting the operation of the annunciator from producing an inter mittent audio signal to a continuous audio signal after a predetermined period of time.

RmR m m Wma 36m wm 0 m 3 m I L 0 d S M Ul F HUN um 4 Claims, 2 Drawing Figures V V Tmse AsrA r/c M04 77 VIBRA r012 AMPLIFIER (1260 I T TONE CONTROL SIGNAL CIRCUIT HAVING TONE PULSES FOLLOWED BY CONTINUOUS TONE BACKGROUND OF THE INVENTION The present invention relates to a control signal circuit which may be conveniently employed as a ringing tone generator in an alarm clock.

The prior art tone generator generates a ringing tone continuously from the beginning of its ringing operation to the end of its ringing cycle. Recently, two-step type tone generators have been used which are adapted to generate, for a predetermined period of time from the time of initial ringing, a low frequency ringing tone, a low level ringing tone or an intermittent ringing tone and thereafter to generate a continuous ringing tone. I-Ieretofore, most of these two-step type ringing tone generators have been operated through the provision of mechanical means. Consequently, they have the disadvantages of being complex in structure, difficult in manufacture, and quite apt to become faulty after very little use.

In view of the fact that recently electric timepieces which make use of electric energy as a driving source for the timepieces have been widely used, it is preferable from the standpoint of compactness and simplification in manufacture of timepieces, as well as durability and lasting use, that the ringing tone for an alarm also be generated electrically.

SUMMARY OF INVENTION The principle object of the present invention is the provision of an electric tone generator driving circuit, which is adapted to operate an electric tone generator (for instance, a buzzer or an electric bell) intermittently for a predetermined initial period of time and then continuously for a subsequent period of time to provide a two-step type of electric tone signal generator. This also provides an alarm ringing tone generator for an electric alarm clock having an electric two-step system.

Another provision of the present invention is a twostep type control signal circuit characterized by an electric power supply circuit including an electric power source and a power source switch, a timer circuit including a charging circuit comprising a transistor having its base connected with a capacitor in the charging circuit, an astatic multivibrator, and an amplifier circuit for amplifying the output signal from the astatic multivibrator and applying it to an electric tone generator which forms the load in the amplifier circuit. The timer circuit, the astatic multivibrator and the amplifier circuit are connected in parallel to the electric power supply circuit. A load resistor provided in the timer circuit is also the biasing resistance of the astatic multivibrator.

According to the present invention, during the charging periods of the charging circuit the oscillatory pulses of the astatic multivibrator are amplified by the amplifier circuit and then applied to the electric tone generator forming the load in the circuit. Consequently, the electric tone generator is operated intermittently to generate an intennittent tone. However, when the charging of the capacitor in the charging circuit has been carried out to a predetermined voltage level, the transistor in the charging circuit is turned on so that a current flows through the load resistor. Since this load resistor is in common with the biasing resistor of the astatic multivibrator, the oscillatory action of the astatic multivibrator ceases; consequently, a current flows directly through the load of the amplifier to generate a continuous tone. Thus, tone signal generation is enabled to operate in a two-step manner, first intermittently and then continuously. It is also possible to generate the intermittent tone for a desired time interval and to regulate the period of generation of the intermittent tone by adjusting the time constants of the astatic multivibrator and the charging circuit, respectively.

Other objects and advantages appear in the following description and claims.

The accompanying drawings show, for the purpose of exemplification without limiting the invention or the claims thereto, certain practical embodiments illustrating the principles of this invention wherein:

FIG. 1 is a circuit diagram of the tone signal generator circuit comprising this invention.

FIG. 2 is a graphic illustration of the current waveform flowing through load 2 in the amplifier circuit of Fig. 1.

Referring now to the figures, in Fig. I, the block encircled by a dotted line 1 represents the timer circuit utilizing a charging circuit. The dotted-line block 2 represents the astatic multivibrator, and the dotted-line block 3 represents the amplifier circuit containing an electric tone generator Z such as a bell or a buzzer which forms the load for the circuit. The switch means S is connected in series with the power supply E which is a d.c. source provided in any convenient manner well known in the prior art. The charging capacitor C l is connected in series with the charging resistor R1 both of which are connected across the power supply E by means of supply lines 4 and 5. An NPN or PNP transistor TRl is used in the charging circuit and is operative when the charging capacitor has reached a predetermined voltage level.

The astatic multivibrator 2 comprises the gating resistor R2 connected on one side to line 4 and on the other side to the emitters of both transistors TR2 and TR3. The transistors TR2 and TR3 may be of the PNP or NPN type to perform the oscillating function. The resistors R3 and R4 are the load resistors of the astatic multivibrator 2. The R-C circuits represented as C2 and R6 connected to the base of transistor TR3, and C3 and R7 connected to the base of transistor TR2 are the A-C time constant settings for the multivibrator circuit.

In the amplifier circuit 3, TR4, which may be a PNP or NPN transistor device, has its base connected to the collector of transistor TR3, while its emitter is connected through the biasing resistor R5 to one side of the power supply B through line 4 as in the case of bias ing resistor R2 and charging resistor R1. The collector of transistor TR4 is connected to the load Z of the amplifier circuit 3 which is an electric tone generator such as a bell or buzzer in an alarm clock or other such timepiece.

The timer circuit 1 and the astatic multivibrator 2 are connected in common by line 6 through the gating resistor R2, while the multivibrator circuit 2 and the amplifier circuit 3 containing the electric tone generator Z are directly connected through line 7. Each of these circuits 1, 2 and 3 are connected in parallel to the power supply by means of supply lines 4 and 5.

Assuming now that the switch S within the internal mechanism of the timepiece has been closed, power is supplied from the power source E through lines 4 and 5 simultaneously to the charging circuit in the timer circuit l the astatic multivibrator circuit 2, and the amplifier circuit 3. The gating resistor R2 serves both as a load resistor for the charging transistor TRl in the timer circuit 1 and as a series resistor in the emitter circuits of the transistors TR2 and TR3 in the astatic multivibrator circuit 2, and is connected commonly to each of these circuits to achieve a gating effect.

The multivibrator 2 is connected to the power supply E through the gating resistor R2 so that a square waveform voltage is generated across the resistor R4 depending upon the time constant determined by the capacitors C2 and C3, and the resistors R6 and R7. This square waveform voltage is amplified by transistor TR4 in the amplifier circuit 3, and, thus, an intermittent waveform of current flows through its output side, that is, through the tone generator Z. The period of this intermittent waveform can be selectively determined by appropriately selecting the capacitors C2 and C3 and the resistors R6 and R7 to choose the time constant.

With the switching on of switch means S, an electric charge is gradually stored in the capacitor C1 through the resistor R1, the potential difference between the base and the emitter of transistor TRl increasing in accordance with the time constant determined by the capacitor C1 and the resistor R1. When this potential difference reaches a predetermined value, the transistor TRl becomes conductive and current flows through line 6 to the gating resistor R2 in the load circuit of transistor TRl. As a result, there is an abrupt voltage drop across the gating resistor R2. Since gating resistor R2 serves also as a series resistor for the astatic multivibrator circuit 2, a biasing voltage is applied to the emitters of transistors TR2 and TR3 of the astatic multivibrator 2, and therefore, multivibrator 2 stops its oscillatory action.

Simultaneously with the ceasing of the oscillatory action of the astatic multivibrator 2, the load resistor R4 of the oscillator circuit serves as a biasing resistor for transistor TR4 in the amplifier circuit 3, so that the base potential applied at the transistor TR4 is lowered, resulting in a continuous current through the tone generator Z to provide for its constant operation.

Referring now to Fig. 2, the period Tl, which is the intermittent sounding tone, is determined by the time constant of the capacitors C2 and C3 and the resistors R6 and R7 in the astatic multivibrator 2. The selectable period T2 of the intermittent sounding tone which ends at the starting point of the continuous sounding tone is determined by the R-C time constant of the capacitor Cl and the resistor R1 in the timing circuit 1. The period T3 is the time when the continuous sounding tone is being generated, that is, a constant current I across the load Z, and continues until the switch means S is opened.

From the foregoing, it can be seen that a two-step type alarm tone generator is provided by means of a simple electric circuit, simplifying the structure of an alarm clock or other such timepiece. Accordingly, this makes it possible to provide for an alarm clock with a two-step electric type alarm tone generator which is simple to manufacture and virtually incapable of wearing out when comparing such alarm devices to those of the mechanical type.

Although what has been described above has been directed to a control signal circuit as applied to an electric alarm clock, it is a matter of course that the present invention need not be limited to such a particular application, but instead it can be generally applied to any type of annunciator.

We claim:

I. A control signal circuit for controlling the current flow through an annunciator to cause intermittent operation followed by continuous operation of said annunciator comprising a timer circuit having a charging capacitor and resistor connected in series and a transistor having its base connected between said charging capacitor and resistor, a multivibrator having its input connected to said timer circuit, an amplifier circuit having said annunciator as a load, said timer circuit, said multivibrator and said amplifier circuit being connected in parallel and across a power supply, the output of said multivibrator circuit being coupled to the input of said amplifier circuit so that said annunciator may be intermittently activated by the repetitive output frequency signal of said multivibrator, said timer circuit including a gating resistor as a load thereof which is connected to said multivibrator for biasing and to cease the operation of said multivibrator when said charging capacitor is charged to a predetermined potential value causing said annunciator to be continuously activated.

2. The control signal circuit of claim 1 characterized in that said amplifier circuit includes a transistor having its base connected across said power supply through biasing resistors.

3. The control signal circuit of claim 1 characterized by switch means connected in series with said power supply to place said circuit in operative condition.

4. A control signal circuit for operating a mechanical annunciator first by providing an intermittent signal to said annunciator for its operation followed by a continuous operation comprising a timer circuit, a multivibrator, and an amplifier circuit all connected in parallel and across a power supply,

I. said amplifier circuit comprising an annunciator connected in series with an amplifier transistor, the base of which is connected across said power supply through biasing resistors ll. said multivibrator comprising two transistors with companion RC networks and accompanying load resistors, the output of said multivibrator connected to the base of said amplifier transistor between said biasing resistors ll]. said timer circuit comprising a charging capacitor and charging resistor connected across said power supply with a timer transistor connected across said power supply in series with a gating resistor, said timer transistor and gating resistor also connected to the emitters of said multivibrator transistors, the base of said timer transistor connected between said charging capacitor and said charging resistor and 6 IV. switch means connected in series with said power annunciator when said charging capacitor has supply to place said circuit in operative condition reached a predetermined potential causing concausing duction of said timer transistor and a voltage a. said multivibrator to produce an intermittent P acfoss gatmg to signal on said annunciator to cause intermittent 5 cease the y action of Sam mumvlbl'a' operation of the latter; and b thereafter causing continuous operation of said

Claims (4)

1. A control signal circuit for controlling the current flow through an annunciator to cause intermittent operation followed by continuous operation of said annunciator comprising a timer circuit having a charging capacitor and resIstor connected in series and a transistor having its base connected between said charging capacitor and resistor, a multivibrator having its input connected to said timer circuit, an amplifier circuit having said annunciator as a load, said timer circuit, said multivibrator and said amplifier circuit being connected in parallel and across a power supply, the output of said multivibrator circuit being coupled to the input of said amplifier circuit so that said annunciator may be intermittently activated by the repetitive output frequency signal of said multivibrator, said timer circuit including a gating resistor as a load thereof which is connected to said multivibrator for biasing and to cease the operation of said multivibrator when said charging capacitor is charged to a predetermined potential value causing said annunciator to be continuously activated.

2. The control signal circuit of claim 1 characterized in that said amplifier circuit includes a transistor having its base connected across said power supply through biasing resistors.

3. The control signal circuit of claim 1 characterized by switch means connected in series with said power supply to place said circuit in operative condition.

4. A control signal circuit for operating a mechanical annunciator first by providing an intermittent signal to said annunciator for its operation followed by a continuous operation comprising a timer circuit, a multivibrator, and an amplifier circuit all connected in parallel and across a power supply, I. said amplifier circuit comprising an annunciator connected in series with an amplifier transistor, the base of which is connected across said power supply through biasing resistors II. said multivibrator comprising two transistors with companion RC networks and accompanying load resistors, the output of said multivibrator connected to the base of said amplifier transistor between said biasing resistors III. said timer circuit comprising a charging capacitor and charging resistor connected across said power supply with a timer transistor connected across said power supply in series with a gating resistor, said timer transistor and gating resistor also connected to the emitters of said multivibrator transistors, the base of said timer transistor connected between said charging capacitor and said charging resistor and IV. switch means connected in series with said power supply to place said circuit in operative condition causing a. said multivibrator to produce an intermittent signal on said annunciator to cause intermittent operation of the latter; and b. thereafter causing continuous operation of said annunciator when said charging capacitor has reached a predetermined potential causing conduction of said timer transistor and a voltage drop across said gating resistor sufficient to cease the oscillatory action of said multivibrator.

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