JPH0430403A - Dc solenoid driving method - Google Patents

Abstract

PURPOSE:To reduce impact sound by a method wherein the input signal voltage to be applied to a DC solenoid is transformed into intermittent pulse waveform, and the duty ratio of an input pulse is increased stepwise. CONSTITUTION:A driving control circuit 50 consists of a CPU, which outputs a pulse-width modulation signal (g), and a MOSFET which drives a solenoid. Also, a surge-absorbing diode D is arranged in parallel with the above-mentioned solenoid. When a signal voltage (g), in which a duty ratio increases gradually with the passage of time, is added to the gate of the above-mentioned MOSFET, the driving current (i) of the solenoid is brought into a stepped form, and the plunger 16 of the solenoid becomes gentle like an operation curved line. The impact sound of the member driven by the DC solenoid is reduced or extinguished.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for driving a DC solenoid, and particularly to one installed in office equipment that requires quiet operation.

[Prior Art] Many DC solenoids are used as operating means in office equipment, such as copying machines and related equipment.

However, these conventional DC solenoids are driven by a step-like input signal without interruption at the time of input.

[Issue to be solved by the invention 111 However, in such a conventional drive method, as shown in FIG. As shown in diagram m, the operating speed of the solenoid is too fast.
Since the impact noise of moving parts is large and the impact damage the durability of the parts, there is a strong need to reduce the operating speed and eliminate impact noise in order to make office equipment quieter and more durable. Ta.

[Object of the Invention] The present invention has been made in view of the problems in the conventional driving method of a DC solenoid. The purpose of this study is to provide a method for driving a DC solenoid that aims to improve durability and eliminate impact noise.

[Means for Solving the Problems] The gist of the present invention to achieve the above object is as follows: In a method for driving a DC solenoid installed in office equipment, an input signal voltage to the DC solenoid is controlled to The present invention resides in a method of driving a DC solenoid in which the input pulse has an intermittent pulse waveform and the duty ratio of the input pulse is gradually increased.

[Function] When the solenoid is started, the input signal voltage to the DC solenoid is given in an intermittent pulse waveform, and the duty ratio of this input pulse is increased over time, so that the solenoid plunger responds to the conventional step input. It operates more slowly than the response, produces less impact noise, and can minimize component deterioration due to impact.

[Example 1] An example of a circuit configuration that realizes the method of the present invention will be described below with reference to the drawings.

As an example of office equipment equipped with a DC solenoid,
FIG. 3 shows an example of a document feeding device 10 that feeds a document onto a platen P of a copying machine C.

The document feeding device 10 includes a paper feed tray 11 on which a document is placed;
A paper feeding unit 20 for separating and feeding originals sheet by sheet; a transporting unit 30 for transporting the separated originals sheet by sheet onto the platen P and positioning them for exposure operation of the copying device; It consists of a discharge section 40 for discharging documents, a discharge tray 13 for receiving discharged documents, and the like.

In the document feeding device 10 having the above configuration, the pickup roller 2 slides into contact with the bottom sheet of the document on the paper feed tray 11 and feeds out the document.
1, a weight leaf spring 23 is provided which contacts the uppermost paper and presses it downward at appropriate times, and a solenoid SL1 for operating this weight leaf spring 23 is provided.

Further, a solenoid SL2 is provided for operating a stopper 22 that timely stops the front edge of the stacked documents.

Near the rear end of the conveying section 30, as shown in the figure, there is a solenoid SL3 for operating a positioning stopper 35 for locking and positioning the leading edge of the document on the platen P.

Furthermore, the exposed original is ejected as is from the ejecting section 40, or it is sent to the platen again along the reverse feed guide 44.
A solenoid SL4 is provided for operating a switching claw 43 that switches between sending the paper back up and copying the back side.

In the figure, 24 is a separation roller, 25 is a separation pad, 26.
27 is a registration roller, 31 is a conveyor belt, 32.33
is a belt roller, 34 is a press roller, 41 is a discharge guide, and 42 is a discharge roller.

As an example of the solenoids SL1 to SL4, the solenoid SLI for the weight plate spring 23 is used in the fourth Q? Shown in l.

The solenoid SLI has a main body 15 with a coil wound inside.
, an actuating plunger 16, an actuating pin 16a implanted in the actuating plunger 16, a swinging arm 17 supported by a shaft 18 and deflected to one side by a spring 19, etc. When the coil is energized, the plunger 16 moves as shown in the figure. is pulled downward, and the action pin 16a rotates the swing arm 17 counterclockwise, causing the weight plate spring 23 to perform a pressing operation toward the pickup roller 21.

FIG. 1 shows an embodiment of a drive control circuit that implements the solenoid drive method of the present invention.

As shown in the figure, the drive control circuit 50 is composed of a CPU that transmits a pulse modulation signal g, and a MOSFET that receives this signal g and generates a drain current to drive a solenoid. Further, a surge absorbing diode D is arranged in parallel with the solenoid. The modulation signal g during the pulse is the CPU
This is done by software.

As shown in FIG. 2, when the signal voltage g whose duty ratio increases over time is applied to the gate of the MOSFET, the drain current, that is, the solenoid SLI
The driving current i becomes stepwise as shown in FIG. 2, and the plunger 16 of solenoid SL1 operates at -111m
It becomes vertical like this.

The increase rate of the driving current i over time is much more rapid than that of the conventional one shown in section 5, and therefore the movement of the actuating plunger 16 of the solenoid SLI is also very rapid, as shown in m in the figure. It will be relaxed. In addition, pulse width modulation can be easily adjusted by changing the software, so depending on the nature of the office equipment and the location of each solenoid,
Alternatively, the optimum operation pattern can be selected depending on the required power, etc., and this can contribute to preventing impact noise and improving durability.

[Effects of the Invention] According to the method for driving a DC solenoid according to the present invention, the input to the DC solenoid is made into an intermittent pulse waveform, and the duty ratio of the input pulse is gradually increased. The operating speed of the solenoid is moderately reduced, the impact noise of the parts driven by the DC solenoid is reduced or eliminated, and the durability of the operating parts is improved, which greatly contributes to improving the quality of office equipment equipped with the solenoid. be.

[Brief explanation of drawings]

Fig. 1 is a drive control circuit diagram of an embodiment for realizing the method of the present invention, Fig. 2 is a diagram of the operation of a solenoid similarly driven by the above circuit, and Fig. 3 is an example of the installation of a solenoid in a document feeding device. FIG. 4 is an elliptical diagram of a solenoid installed in the weight leaf spring of the document feeding device, and FIG. 5 is an explanatory diagram of the operation in the conventional driving method. LL L2 L3 L4 Solenoid drive control circuit for solenoid switching claw for solenoid positioning stopper for solenoid stopper for document feeder weight plate spring

Claims (1)

[Claims] In a method for driving a DC solenoid installed in office equipment, the input signal voltage to the DC solenoid is made into an intermittent pulse waveform, and the duty ratio of the input pulse is gradually increased. A method for driving a DC solenoid characterized by the following.