SEWING MACHINE DRIVE DEVICE

Abstract: A sewing machine drive device in which the output voltage of a DC/DC converter solenoid power source circuit (8) is used as a solenoid power source, the DC/DC converter solenoid power source circuit (8) receiving a direct current (7) which is obtained by directly rectifying and smoothing an alternating current (1), and the power source voltage is controlled by a voltage control signal from a sewing machine control circuit (6). Since the solenoid power source circuit (8) is constituted in the form of a DC/DC converter, the voltage control signal of the sewing machine control circuit (6) is freely controlled by an output voltage control circuit in the solenoid power source circuit, making it possible to eliminate noise during the control operation when the solenoid is being held and to freely set the voltage during the control operation to hold the solenoid.

Description: The present invention relates to a sewing machine drive apparatus having a power source circuit for driving a solenoid of a sewing machine for industrial use. BACKGROUND ART A conventional example is shown in FIG.4 and elucidated. Numeral 1 designates an AC power source, numeral 6 designates a sewing machine control circuit, numeral 7 designates a rectifying-smoothing circuit, numeral 9 designates a solenoid drive circuit, numeral 10 designates a solenoid, numeral 11 designates a transformer, and numeral 12 designates a chopping control circuit. With regard to the sewing machine drive apparatus constituted as mentioned above, its operation is described referring to FIG.5. The AC power source 1 is transformed to a rated input voltage of the solenoid 10 by the transformer11; its output is smoothed by the rectifying-smoothing circuit 7, thereby a solenoid power source is made. And, a solenoid drive signal of the sewing machine control circuit 6 is received by the solenoid drive circuit 9; the solenoid 10 is driven by taking said solenoid power source as an input; after elapse of a time period, chopping signal of a frequency from said sewing machine control circuit 6 is received by the chopping control circuit 12; and thereby, output voltage of the solenoid is controlled and output current of the solenoid is reduced. However, in such a constitution, after driving and holding the solenoid, since chopping control is executed on the output voltage which is for holding the solenoid by the chopping control circuit 12, an acoustic noise of chopping sound (frequency of the chopping signal) is generated during the control thereof, so that there is a disadvantage to give unpleasant feeling to a user. From US-A-3 904 890 a gated stop signal circuit is known, which purposes to the detection of the stop or the last cycle before stopping of a cyclically operating device and to the generation of an electrical signal according to the detected condition. DISCLOSURE OF THE INVENTION Purpose of the present invention is, to provide a sewing machine drive apparatus which eliminates the acoustic noise during the control under the holding of the solenoid and can freely set a voltage in the control for holding the solenoid during the control. To attain this purpose, a sewing machine drive apparatus in accordance with the present invention is constituted that an output voltage of a DC/DC converter solenoid power source circuit is used as a power source of a solenoid, which uses a DC power source direct rectification and smoothing of an AC power source as an input, and that the voltage of the power source by a voltage control signal from a sewing machine control circuit. The present invention can, by constituting the solenoid power source circuit by DC/DC type converter, control the voltage control signal of the sewing machine control circuit freely by an output voltage control circuit in said solenoid power source circuit. BRIEF DESCRIPTION OF THE DRAWINGS FIG.1 is a block diagram of a sewing machine drive apparatus in a first embodiment in accordance with the present invention; FIG.2 is a time chart showing drive characteristics of solenoid of the sewing machine drive apparatus in accordance with the present invention; FIG.3 is a block diagram of a sewing machine drive apparatus in a second embodiment in accordance with the present invention; FIG.4 is the block diagram of the conventional sewing machine drive apparatus; and FIG.5 is the time chart of deriving characteristics of the solenoid of the conventional sewing machine drive apparatus. BEST MODE FOR EMBODYING THE INVENTION Hereafter, a first embodiment in accordance with the present invention is described referring to the drawings. FIG.1 shows a sewing machine drive apparatus in the first embodiment in accordance with the present invention. In FIG.1, numeral 1 designates an AC power source, numeral 2 designates a first rectifying-smoothing circuit, numeral 3 designates a motor drive circuit, numeral 4 designates a synchronous motor, numeral 5 designates a sewing machine, numeral 6 designates a sewing machine control circuit, numeral 7 designates a second rectifying-smoothing circuit, numeral 8 designates a DC/DC converter/solenoid power source circuit, numeral 9 designates a solenoid drive circuit, and numeral 10 designates a solenoid. In respect of the sewing machine apparatus of the first embodiment which is constituted as mentioned above, its operation is described in the following referring to FIG.1 and FIG.2. A voltage agreeing with a rated voltage of the solenoid is output from the DC/DC converter/solenoid power source circuit 8 which takes output of a DC power source from the second rectifying-smoothing circuit 7 connected to the AC power source 1, as input. On the other hand, the solenoid drive signal is transmitted to the solenoid drive circuit 9 from the sewing machine control circuit 6; the solenoid 10 is driven by inputting voltage of said solenoid power source; voltage control signal is transmitted to said solenoid power source circuit 8 from said sewing machine control circuit 6 after elapse of a certain time period; and voltage of the power source of the solenoid drive circuit 9 can be controlled freely. As mentioned above, according to the present embodiment, by providing the DC/DC converter/solenoid power source circuit 8 which takes output of the DC power source (SIC) of the second rectifying-smoothing circuit 7 connected to the AC power source 1 as input, and by controlling the voltage of the solenoid power source and the voltage control signal from the sewing machine control circuit 6 freely by the voltage control circuit in said power source circuit, an acoustic noise (chopping sound) during the voltage control for reducing solenoid output current in holding of the solenoid can be eliminated. Also, since a voltage for holding the solenoid can be controlled freely, a control can be executed by outputting a voltage agreeing to a kind of the solenoid by which the solenoid can be held. For example, a kind of the solenoid is driven by 40 V and held by 20 V. And, as another kind of the solenoid can be controlled so as to be driven by 40 V and held by 10 V, very effective voltage control can be done. FIG.3 shows a sewing machine drive apparatus in a second embodiment in accordance with the present invention. In FIG.3, numeral 1 designates an AC power source, numeral 2 designates a rectifying-smoothing circuit for main power source, numeral 3 designates a motor drive circuit, numeral 4 designates a synchronous motor, numeral 5 designates a sewing machine, numeral 6 designates a sewing machine control circuit, numeral 8 designates a DC/DC converter/ solenoid drive circuit(SIC), and numeral 10 designates a load of a solenoid; the above-mentioned ones are similar to those of the constitution in FIG.1, and the different point from the constitution in FIG.1 is omission of the second rectifying-smoothing circuit 7. In respect of the sewing machine drive apparatus of the second embodiment which is constituted as mentioned above, the following operation is described with further referring to FIG.2. A voltage on a rated voltage of the solenoid is output from the DC/DC converter/solenoid power source circuit 8 which takes output of a DC power source from the rectifying-smoothing circuit 2 connected to the AC power source 1 as input. And, the solenoid drive signal is transmitted to the solenoid drive circuit 9 from the sewing machine control circuit; the solenoid 10 is driven by inputting a voltage of said solenoid power source; after elapse of a time period, voltage control signal from said sewing machine control circuit 6 is received by a voltage control circuit which is contained in said solenoid power source circuit 8, and thereby the voltage of the solenoid power source can freely be controlled. As mentioned above, according to the present embodiment, by providing the DC/DC converter/solenoid power source which takes an output voltage of the rectifying-smoothing circuit 2 for main electric power source connected to the AC power source as input, and by controlling the voltage of the solenoid power source and the voltage control signal from the sewing machine drive (SIC) circuit 6 freely by the voltage control circuit contained in said power source circuit 8 (SIC), the same effect as that of the first embodiment can be obtained. POSSIBLE UTILITY IN INDUSTRY As mentioned above, the present invention, provides the DC/DC converter solenoid power source which takes an output voltage of a rectifying-smoothing circuit connected to an AC power source as input, and can control an output voltage of solenoid by voltage control signal from a sewing machine control circuit, so that output current of the solenoid in holding of the solenoid is reduced and an acoustic noise in voltage control can be eliminated, and, since a voltage in the voltage control can freely be controlled, more effective solenoid holding current can be limited (SIC).

Claims: Sewing machine drive apparatus comprising a motor drive circuit (3) for driving a motor and a solenoid drive circuit (9) for driving a solenoid, characterized by : a first rectifying-smoothing circuit (2) which is connected to an AC power source (1), a second rectifying-smoothing circuit (7) which is connected to the AC power source (1) and a DC/DC converter solenoid power source circuit (8) which takes an output voltage of the second rectifying-smoothing circuit (7) as input, wherein the motor drive circuit (3) takes an output voltage of the first rectifying-smoothing circuit (2) as an input and the solenoid drive circuit (9) takes the output voltage of the power source circuit (8) as input and receives solenoid drive signals from a sewing machine control circuit (6) for controlling the sewing machine. Sewing machine drive apparatus comprising a motor drive circuit (3) for driving a motor and a solenoid drive circuit (9) for driving a solenoid, characterized by : a rectifying-smoothing circuit (2) which is connected to an AC power source (1), and a DC/DC converter solenoid power source circuit (8) which takes an output voltage of the rectifying-smoothing circuit (2) as input, wherein the motor drive circuit (3) takes an output voltage of the rectifying-smoothing circuit (2) as an input and the solenoid drive circuit (9) takes the output voltage of the power source circuit (8) as input and receives solenoid drive signals from a sewing machine control circuit (6), whereto output voltage for driving the DC/DC-converter (8) of solenoid (SIC) is inputted, for controlling the sewing machine. Sewing machine drive apparatus according to claim 1 or claim 2, characterized in that the output voltage of the DC/DC converter solenoid power source circuit (8) can freely be voltage-controlled by receiving control signal of output voltage of the solenoid (10) from the sewing machine control circuit (6) by an output voltage control circuit contained in the DC/DC converter solenoid power source circuit (8).

Inventors: NODA, HIROMITSU
Applicants: MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD
Application year: 1989
Main classification: D05B69
IPC codes: D05B69