JPS6232541Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to sewing machines, and in particular to stitch formation whose operation can be controlled by supplying electric power and positioning each electromechanical actuator. The present invention relates to a sewing machine equipped with a device.

BACKGROUND OF THE INVENTION Conventionally known sewing machines include those in which the position coordinates of successive stitches are stored in a memory having addressable memory locations corresponding to a plurality of user-selectable patterns. especially,
In the system described in U.S. Pat. No. 4,016,821, issued April 12, 1977, logic circuitry is used to select and read stitch pattern information stored in memory in synchronization with sewing machine operations. . The digital information retrieved from memory is converted into an analog positional signal that directly controls the position of the sewing machine's normal stitch forming device to reproduce the stitch pattern corresponding to the selected stitch information. control a closed-loop servo system that includes a moving-coil linear actuator. Also, in the system described in US Pat. No. 3,847,100, issued November 12, 1974, a solenoid is used as an actuator of a skip stitch mechanism to stop the reciprocating movement of the needle. In all of these conventional systems, the actuator operates independently of the sewing machine's main drive motor. Therefore, if an abnormal operating condition occurs, the main drive motor may stop and unnecessary high power may be supplied to the actuator even though no sewing operation is being performed. In such a case, a fairly large continuous current flows through the actuator, causing the actuator to overheat and increasing the internal temperature of the arm bed assembly.

SUMMARY OF THE INVENTION Accordingly, the present invention aims to reduce the operating temperature and heat dissipation of the actuator of a sewing machine when the main drive motor of the sewing machine is stopped.

One possible method for achieving this objective is to turn off the power to the actuator when the main drive motor is stopped, but this is not a preferred method. This is because the actuator that controls the lateral position of the needle needs to maintain its current position, so that the needle does not move during needle changes or threading, for example.

Therefore, another object of the present invention is to reduce the operating temperature and heat dissipation of the actuator when the main drive motor of the sewing machine is stopped without completely cutting off the power to the actuator.

A further object of the present invention is to prevent the user from having to pay attention to such electrical constraints when the sewing machine is operating normally.

In accordance with the principles of the present invention, the above and other objects of the present invention provide for a sewing machine having a stitch forming device whose motion is controllable by supplying electrical power and positioning an electromechanical actuator. A detection device that detects the operation of the sewing machine and outputs a signal representing the operation, and a power limiter that limits the power supplied to the actuator to a certain upper limit when the signal does not appear within a predetermined time. It is achieved by doing so.

According to the present invention, the power limiting device is configured to operate only when power above a predetermined level is supplied to the actuator.

(Embodiments of the invention) The invention will now be described in detail with reference to the accompanying drawings.

As shown by imaginary lines in FIG. 1, the arm bed set 10 includes a bed 11, a support 12 extending upward from the bed 11, and a bracket arm 13 projecting above the bed 11. The drive mechanism of the sewing machine has an upper shaft 14 and a lower shaft 15, which are interconnected and temporally related to each other by a conventional drive mechanism (details not shown) including a drive motor 16. ing. And bracket arm 13
A needle 17 is supported by a needle bar 18 which is attached to make a lateral movement in a swinging member 19, so that the needle 17 makes a reciprocating movement up and down. To provide reciprocating movement to the needle, needle bar 18 is connected to upper shaft 14, this connection including a releasable connection point indicated by reference numeral 20. The separable connection point 20 is known in the prior art as a skip stitch mechanism, the details of which are described in the aforementioned U.S. Pat. No. 3,847,100. The skip stitch mechanism 20 is operatively connected to a needle bar release solenoid 21. The skip stitching operation is executed based on a plurality of conditions, the details of which will be described later.

To impart a lateral movement to the needle 17, a drive link 25 is pivotally connected to the rocker member 19 at position 26, the link 25 being described in U.S. Pat. No. 4,016,441 issued April 5, 1977. It is mechanically connected to a reversible linear actuator 27. Therefore, by controlling the linear actuator 27 it is possible to determine the lateral position of the sewing machine needle 17.

Also shown in FIG. 1 is a portion of the fabric feed mechanism having a feed dog 34 supported on a feed table 35. The mechanism for imparting fabric feeding motion to the feed dog 34 includes a feed drive shaft 36 driven from the lower shaft 15 via a gear 37, a cam 38 attached to the feed drive shaft 36, and a pit man including the cam 38. 39, and the pitman 39 is connected to reciprocate the sliding member 40 on the slotted feed adjustment guide 41. The pitman 39 is pivotally connected to the feed carriage 35 via a link 42 so that the distance and direction of the feed stroke of the feed dog 34 is determined according to the slope of the guide 41. The inclination of the guide 41 is determined by a reversible linear actuator 43 of the same type as the linear actuator 27.
can be controlled by A linear actuator 43 is pivotally connected at 47 to an arm 48 which is connected to a shaft 4 coupled to a guide 41.
It is fixed at 9.

FIG. 1 further includes a timing pulse generator 5.
0 is shown, which is disclosed in U.S. Pat. No. 3,939,372.
You can use the types listed in the issue. This pulse generator 50 pulses once every rotation of the upper shaft 14.
generates a series of individual timing pulses. The operation of this pulse will be described later.

The circuit configuration shown in FIG. 2 is an implementation of the present invention, which supplies power to the needle bar release solenoid 21, needle lateral movement linear actuator 27, and feeding linear actuator 43 when the sewing machine is not operating. Contains circuitry used to limit The arrangement of FIG. 2 further includes circuitry for controlling the needle oscillation linear actuator 27 and the feed linear actuator 43 during stitch formation in a selected pattern. The entire circuit of FIG. 2 can be incorporated into printed circuit board 52 (FIG. 1) in arm bed assembly 10. The control circuit for the needle lateral movement linear actuator 27 includes a needle lateral movement logic circuit 101.
A position signal is input from 01 to the addition connection point 102. In addition to the above-mentioned input terminal, the summing connection point 102 has another input terminal, into which a signal representing the actual position of the linear actuator 27 for needle oscillation is inputted. Therefore, the addition junction 10
The output of 2 represents the error signal, which signal is sent to the input of preamplifier 103. The output of the preamplifier 103 is then supplied to a power amplification stage including a preamplifier 104 and a power amplifier 105, where positioning control of the linear actuator 27 for needle traverse is performed. Similarly, the control circuit for controlling the linear feed actuator 43 has a feed logic circuit 107 from which a position signal is input to the summing connection 108 . In addition to the inputs mentioned above, the summing junction has another input, into which a signal representing the actual position of the linear feed actuator 43 is input. The output of summing junction 108 therefore represents an error signal, which signal is fed to the input of preamplifier 109. The output from preamplifier 109 is supplied to a power amplification stage including preamplifier 110 and power amplifier 111, where positioning control of feed linear actuator 43 is performed. Note that the needle lateral movement logic circuit 101 and the feeding logic circuit 107
The input signal for the is provided from the output of a read-only memory (ROM) storing stitch pattern coordinates for a plurality of user-selectable patterns, as described in the above-mentioned U.S. Pat. It is known in the prior art as described in No. 4016441. This ROM is a large-scale integrated circuit (LSI)
113. Also, LSI
113 includes a logic circuit, which allows the user to select a pattern and the timing pulse generator 50.
In response to a timing pulse from the logic circuit, a signal for reading stitch pattern coordinate information from the ROM is output from the logic circuit. Although this LSI has various control functions, only the functions related to the present invention will be explained here.

Skip stitches may be performed at various times, such as at the beginning of a pattern, after a single pattern has been sewn, or during operations such as basting or double-feeding. During such an operation, the needle bar release solenoid 21 is energized by applying a low level signal to the lead wire 115. The lead wire 115 connects a pair of collector release circuits 117A, 117 connected in parallel.
It is connected to the output terminal of B. This parallel circuit acts as a buffer between the solenoid 21 and the rest of the logic circuit. Logic inputs to amplifiers 117A and 117B are provided by inverter 119 connected to NAND gate 121. NAND gate 12
A normally low level signal is input to the input terminal 123 of 1, and the input signal normally causes the output to be at a high level. Another input terminal 1 of NAND gate 121
As will be described in detail later, a high-level signal is usually input to 25. Therefore, under this input condition, the lead wire 115 is in a circuit state, and the needle bar release solenoid 21 is kept in a de-energized state.
When energizing the needle bar release solenoid 21 to perform skip stitching, a high level needle bar release signal (NBR signal) is supplied from the LSI 113 to the lead wire 123. Thereby, NAND gate 1
21 output becomes low level, inverter 11
9 goes high, resulting in a low level signal appearing on lead 115 and energizing the needle bar release solenoid 21.

According to the principles of the invention, a circuit is provided to detect when the main drive motor 16 of the sewing machine has stopped for a predetermined period of time, for example 6 seconds. When such a condition is detected, if the needle bar release solenoid 21 is energized, the detection circuit will activate the solenoid 21.
limit power to. Further, even when the sewing machine is in an abnormal operating state, as will be explained in detail later, the power to the needle lateral movement linear actuator 27 and the feeding linear actuator 43 is limited. However, when the sewing machine is operating normally, the power to the needle traverse linear actuator 27 and the feed linear actuator 43 is not restricted, and these actuators are maintained at their respective positions.

As will be explained in detail later, 6 of the main drive motor 16
When a second stop is detected, a high level signal appears on lead 127. The other input terminal of the NAND gate 129 receives a high frequency signal with a frequency of 25 KHz and a duty cycle of 50%, for example.
It is supplied from the LSI 113 via the lead wire 131. Thus, when lead 127 is high and lead 125 is high for 50% of the time, the signal state of lead 125 is high for 50% of the time. When the NBR signal of lead wire 123 is at a high level, it is the needle bar release solenoid 2.
1 is energized, and the signal state of the lead wire 125 is high level and low level at a rate of 50%, and the signal state of the lead wire 115 is 50%.
Low level for % period. This signal frequency is high enough to keep the needle bar release solenoid 21 energized without chattering. By reducing the average supply voltage to the needle bar release solenoid 21 by 50%, the power consumption of the needle bar release solenoid 21 is reduced to 25% of the power when continuously energized.

The high level signal that appears on lead 127 when the main drive motor 16 is detected to have stopped for 6 seconds is also provided to the base of transistor 133. Transistor 133 and transistor 135 constitute a Darlington circuit. When a high level signal appears on lead 127, transistors 133,1
35 is conductive, and the relay coil 13 is connected from the power supply 137.
A current path to 9 is formed. Relay 139 includes two normally open contacts 141 and 143. Preamplifier 104 is connected to power amplifier 10 via resistor 145.
5. Similarly, preamplifier 110
is connected to the power amplifier 111 via a resistor 147. Relay contact 141 is connected to a line including resistor 149, and this line is for grounding the connection point between resistor 145 and the input end of power amplifier 105. Similarly, relay contact 143 is connected to a line that includes a resistor 151, and this line is for grounding the connection point between resistor 147 and the input end of power amplifier 111. When relay 139 is energized by a high level signal appearing on lead 127, relay contacts 141 and 143 are closed, forming respective ground tracks including respective resistors 149 and 151. These ground lines connect the respective preamplifiers 104, 110 and power amplifiers 105, 1
It has the effect of a voltage divider between 11 and 11. In this example, the value of resistors 145 and 147 is 430 ohm.
The value of resistors 149 and 151 is 160 ohms. Therefore, when relay contacts 141, 143 are closed, the input voltage to power amplifiers 105, 111 is approximately 27.2 of the output voltage of preamplifiers 104, 110.
%. When the sewing machine is operating normally, the actuators 27, 43 are in the proper position and an error signal of substantially zero value is present at the preamplifier 10.
4,110. In times like this,
The effect of inserting resistors 149, 151 is negligible and the power and heat dissipation are not reduced. And the user of the sewing machine does not notice any change at all. However, when certain abnormalities occur in the operating conditions, a large error signal may be generated and the actuator may become stuck. For example, if power is applied to the sewing machine when the needle is in a far horizontal position and is penetrating the fabric, the circuitry may attempt to return the needle to the center, or when the feed dog is located above the throat plate. This is the case when the circuit tries to move the feed dog if power is supplied to the sewing machine when the fabric presser foot is down to the feed dog position. In such a situation, a relatively large error signal is generated. power amplifier 10
5, 111 and preamplifiers 104, 11
The feedback path formed between each input terminal of 0 includes gain setting resistors 153 and 155 of the power amplification stage. Therefore, the resistors 149 and 151 are
It has a function of setting the upper limit of the maximum voltage supplied to the actuators 27 and 43. This upper limit is about 27.2% of the supply voltage, and the maximum heat dissipation is reduced accordingly.

A timer is provided to detect that the sewing machine main drive motor 16 has stopped for 6 seconds. This timer is a toggle type flip-flop 161, 163, 1
It consists of a 6-stage counter with 65, 167, 169, and 171 counters. Flip Flop 161-1
71 counts the pulses of the 8 Hz clock signal supplied from the LSI 113 via the lead wire 173. The pulse on lead wire 173 is the NAND gate 17
5 is supplied to one input end of 5.

The output of the inverter 179 is supplied to the other input terminal of the NAND gate 175 via a lead wire 177. Note that the input terminal of the inverter 179 is
It is connected to the output terminal of the NAND gate 181.
The NAND gate 181 has lead wires 183, 185,
It has three input terminals connected to 187.
A power-on signal is output from the LSI 113 to the lead wire 183. This power-on signal is normally high and goes low when power is first applied to the sewing machine. The signal appearing on lead 185 is
This is a pattern selection signal from the LSI 113. The pattern selection signal is normally high and goes low when a new pattern is selected. Lead wire 1
A signal 87 is an output signal of the inverter 191 which receives an input signal from the LSI 113 via the lead wire 193. The signal on lead 193 is the upper axis timing pulse from pulse generator 50 (FIG. 1). The pulse of the lead wire 193 is a signal that becomes high level every time the upper shaft 14 rotates once according to the operation of the sewing machine main drive motor 16. Lead wire 19
When this signal of 3 appears on lead 187, it is inverted. Therefore, the signal on lead wire 177 is normally high level, but becomes low level in the following three cases.

1 When the sewing machine is first powered on and a low level pulse appears on lead 177 2 When a new pattern is selected and lead 17
If a low-level pulse appears on lead wire 177 while the sewing machine main drive motor 16 is operating, the low-level pulse on lead wire 177 has the function of clearing flip-flops 161 to 171.
This resets the timer for 6 seconds. When the signal on lead wire 177 becomes high level, NAND
Gate 175 becomes conductive, and the 8Hz clock on lead 173 is connected to NAND gate 1 via lead 195.
97 is supplied to one input terminal. From the output end of NAND gate 197, counting pulses are supplied to flip-flops 161-171 via lead wire 199. The other input terminal of the NAND gate 197 is connected to the NAND gate 20 via a lead wire 203.
1 output is provided. When the signal on lead 203 is high, 8 Hz clock pulses are counted. The signal state of lead 203 goes high when any of the four inputs of NAND gate 201 goes low. Two of these four inputs are connected to the aforementioned leads 177,1.
99, and the remaining two are flip-flop 1
Lead wires 205 from each output end of 69, 171,
It is 207. When the signals on leads 205 and 207 both go high, it indicates that the six stage flip-flop counter has reached 48 counts. Since 8 Hz clock pulses are being counted, 48 counts corresponds to 6 seconds of time. Therefore, when six seconds elapse without a low level signal appearing on lead 177, the signal on lead 203 becomes low. In this state, the NAND gate 197
is cut off, so the counting operation ends. At this time, a high level signal appears on lead wire 127 due to the switching operation of depletion type FET devices 209 and 211. The high level signal on the lead wire 127 limits the power supply to the needle bar release solenoid 21 and the actuators 27, 43 as described above.

The above condition is maintained until a new pattern is selected and a low level pulse appears on lead 185, or until machine main drive motor 16 is activated and an upper axis timing pulse appears on lead 193. When any of the above pulses appears, a low level pulse appears on lead wire 177, so a high level signal appears on lead wire 203, and as a result, the operation of the six-stage counter is resumed.
Needle bar release solenoid 21 and actuator 2
On July 7, 43, 100% power was supplied again.

The above has described a configuration for restricting the power supply to the electromechanical actuator of the sewing machine while the sewing machine is stopped. It should be noted that the above configuration is merely a means of explaining the application of the principles of the present invention, and many different configurations may be devised within the scope of the "claims for registration of a utility model."

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a sewing machine to which a configuration based on the principles of the present invention can be applied, and FIG. 2 is a block diagram of an example of a circuit constructed based on the principles of the present invention. Explanation of reference numbers, 113...LSI, 161,1
63,165,167,169,171...Flip-flop (counter), 149,151...
Resistance of voltage divider, 139...Relay, 141,1
43... Relay contact (switch), 21... Needle bar release solenoid, 27... Linear actuator for needle lateral swing, 43... Linear actuator for feeding,
181...NAND gate (detection device).

Claims (1)

[Claims for Utility Model Registration] (1) In a sewing machine equipped with a stitch forming device and a main drive motor whose operation can be controlled by supplying electric power to determine the position of an electromechanical actuator, Detects the operation of the main drive motor,
a detection device that outputs an operation signal representative of the operation; and when the operation signal does not appear for a predetermined period of time;
a power limiting device for limiting power that can be supplied to the actuator to a value substantially lower than that that can be supplied during operation of the main drive motor. (2) Utility model registration Claim 1, characterized in that the detection device has a device that detects the rotation of the main drive motor of the sewing machine and supplies the operation signal in synchronization with the motor rotation. sewing machine. (3) Scope of Utility Model Registration Claims Paragraph 1 provides for a sewing machine that is capable of sewing a plurality of patterns according to the user's selection, and the detection device is configured to sew a plurality of patterns according to the user's selection. The sewing machine characterized in that it has a device for responsively providing the operating signal. (4) The sewing machine according to claim 1, wherein the detection device includes a device that outputs the operation signal in response to electric power being supplied to the main drive motor of the sewing machine. . (5) Claims 2, 3, or 4 of the utility model registration claim, wherein the power limiting device comprises: a clock device that supplies clock pulses of a constant frequency; a counting device that counts the clock pulses; and the counting device. A sewing machine comprising: a device for reducing the power in response to the count reaching a predetermined count; and a device for resetting the counting device in response to the operation signal. (6) Utility Model Registration The sewing machine according to claim 1, wherein the power limiting device includes a device that changes the duty cycle of the voltage supplied to the actuator. (7) Utility Model Registration The sewing machine according to claim 1, wherein the power limiting device includes a voltage dividing device that can be selectively connected in a power supply path to the actuator. (8) In claim 7 of the utility model registration claim, the voltage dividing device comprises: a first resistor connected in series to the power supply path; a second resistor connected between one end of the second resistor and a reference voltage; a normally open switch device connected in series with the second resistor; and a normally open switch device connected in series with the second resistor; A sewing machine comprising: a device for closing a switch device.