JPS63103677A - Device for switching load - Google Patents

Abstract

PURPOSE:To simplify the composition of a circuit, by detecting an overload with the bridge circuit consisting of a motor and three resistors. CONSTITUTION:Resistors 3a, 3b and 4 and a motor M form a bridge circuit. When a high-level signal of a given width is supplied at a terminal 7a, transistors 2b and 2a conduct and the motor M is started. When the armature current is reduced, the voltage at a point A becomes lower than that at a point B, and so the output of an operator amplifier 5 is set to be of high level, and the transistors 2a and 2b are kept in conduction. When an overload condition stops the motor M, the two input signals of the operator amplifier 5 become at the same voltage level, and the operator amplifier 5 produces no output so that the motor M is de-energized.

Description

[Detailed Description of the Invention] [Industrial Application Fields] First, the present invention can be used in a device in which a DC motor is used to move the door lock bin of an automobile up and down, and in an opening/closing device that uses the up and down movement of a door window glass. can.

First, it is possible to make use of the vertical movement of the top cover of the copy machine which holds the document to be copied.

[Conventional technology]

Several techniques for the same purpose are already known.

For example, there is a means for stopping the forward and reverse movement of a load at a set position by using a position detection element (limit switch or semiconductor sensor).

[Problems to be Solved by the Invention] First, the above-mentioned conventional means requires a position detection device, which is complicated and expensive, and also has the problem of increasing the frequency of failures.

Second, since an electric circuit for rotating the motor in the forward and reverse directions is provided separately, there is a problem in that the circuit becomes complicated.

Third, it is necessary to automatically stop the load and motor due to overload. For example, when a child gets their head caught in a car window or a foreign object gets stuck in the car window, it is necessary to automatically stop or immediately turn the car upside down.

Also, in copy machines, since the thickness of the document differs, the stopping point of the top lid will correspondingly differ. Therefore, it is necessary to automatically stop due to overload. Although this is necessary, there is a problem in that no practical means have been provided.

[Means for solving problems]

The transistor bridge circuit rotates the motor forward and reverse,
In addition, a bridge circuit consisting of an electric motor and three resistors detects the overload back electromotive force, and detects the first. first. All of the third problems have been resolved.

Both bridge circuits are integrated without being separated, simplifying the circuit configuration.

[Effect]

Since an overload detection circuit with a resistor having a value equal to the armature resistance is adopted, when the motor rotates forward or reverse, the output of the detection circuit is changed to a different one. It can be set to the second voltage level, and the detection output can be made to disappear when stopped due to overload.

This detection output controls the transistor bridge circuit to control forward and reverse rotation, such as stopping the motor.

Therefore, the electrical circuit is simplified.

Since the command electric signal to start the forward and reverse rotation of the motor is performed by an electric signal having a set width, an effective technical means can be provided in the case of automation.

〔Example〕

Next, the present invention will be explained in detail with reference to FIGS. 1 and 2.

In FIG. 1, symbol M is a DC motor, which is used as a load, and transistors Φ, kob, koe, and 2cL constitute a transistor bridge circuit.

Symbol l is the positive electrode of the DC power supply.

The armature resistance of the motor M and the resistances II and 34.36 are made equal in resistance value, and the resistances 3rg, 3h, and u and the motor AI form a bridge circuit.

When the transistors C and C are conducting, the armature current flows to the right and rotates normally. When transistors C and C become conductive, the motor M rotates in reverse. , When the motor M stops due to a negative load overload while the motor M is rotating in the forward direction, the voltages of the two input signals of the operational amplifier 3 become equal, and the operational amplifier 3 becomes equal in voltage. output disappears.

Therefore, the pace input to the transistors α and 2b disappears, and the energization of the electric motor M is stopped.

Burnout is therefore prevented.

Next, when an electric signal of a set width and a noise level is inputted from the terminal 71, the transistor B becomes conductive, and the base input of the transistor 21 is obtained through the inverting circuit Aα, and the transistor B becomes conductive.

Therefore, electric motor M starts. When the armature current decreases, the voltage at point A becomes lower than that at point B, so the output of operational amplifier S is converted to a high level, and transistor α
, b are kept conductive and continued rotation takes place.

When the load becomes overload and motor M stops,
As described above, the energization is automatically stopped.

Next, when an electric signal of the set width is inputted from the terminal 7b, the transistor d becomes conductive, and the signal is passed through the inverting circuit 6b to the transistor 27? is conductive.

Therefore, the electric motor M reverses.

At this time, the voltage at point A changes as the armature current decreases.
Since the voltage rises from point B, the output of operational amplifier 5 becomes low level, and inverting circuit 1. The high level output through e makes transistors d and 1 conductive, and the subsequent rotation is sustained.

When the load becomes overloaded, the motor M stops and the back electromotive force disappears, so the voltages at points A and B become equal,
The output of operational amplifier 3 disappears. Therefore, 1. The electric motor M automatically stops.

As can be understood from the above explanation, the electric motor M is driven in the forward and reverse directions by the input signals at the terminals 74.about.7h, and has the ability to automatically stop due to overload.

Furthermore, the electric circuit for this purpose is simplified and can be integrated into an integrated circuit, making it compact and inexpensive.

Capacitor/2 is for smoothing back electromotive force, armature current, and pull voltage.

Dotted line/4! If a monostable circuit with an output of a set width shown as 4, /Q b is inserted, the input signal at the terminals 71.76 may be an electrical signal of a small width.

In FIG. 2, an electric motor M is fixed to the main body and has the same symbol as that in FIG. When there is an input signal from terminal 7, the motor M starts rotating in the normal direction.

When the rotation axis io* rotates in the direction of the arrow, the gear 10 fixed thereto also rotates. The gear 9 meshing with the gear 10 rotates clockwise, and the gear 9b also rotates synchronously.

The rotating shaft 9a, gears 9h, 9 are fixed to 7 bodies, and the rotating shaft q
α is supported by a bearing fixed to the main body (not shown).

Gear g meshes with gear 9h and rotates in the direction of the arrow.

The rotating shaft 4 is supported by a shaft bearing fixed to the main body (not shown) and is fixed to a gear wheel.

The protrusion th of the gear wheel h also rotates in the counterclockwise direction of the arrow, and when it comes into contact with the restraining pin 13b set on the main body, an overload occurs, and the electric motor M automatically stops.

Next, when an input signal for starting is received from the terminal b in Fig. 1, the electric motor M starts to rotate in reverse, so the protrusion gb rotates clockwise and the restraining pin /J mounted on the main body is rotated clockwise. It comes into contact with I and overloads, so it automatically stops.

What is indicated by the symbol // is a load, which can be rotated left and right by the above-mentioned angle by the rotation axis t1.

If the load is, for example, a top lid of a copy machine that presses and holds a document to be copied, the following operation can be performed.

It is assumed that the rotation support shaft of the top cover is configured to rotate in synchronization with the rotation axis α, and in the illustrated state K, the top cover is holding a document and a copying operation is in progress.

The electrical signal when copying is completed is sent to terminal 71 in Figure 1.
When inputted to , the electric motor M rotates in the normal direction, and the rotating shaft gΦ rotates in the counterclockwise direction to lift up the top cover. Projecting part gh
When it comes into contact with the restraining pin 13b, the lift-up operation is automatically stopped. . The user knows when the copying is finished,
The next copy is ready.

Place the document on top of the copy machine and connect terminal 7b in Figure 1.
When an electric signal is input by pressing the push button switch, the electric motor M starts to rotate in reverse, the top lid descends, presses the document, applies pressure, and automatically stops when overload occurs.

In order to maintain the above-mentioned pressing force on the top cover, part of the reduction gear shown in FIG. 2 may be replaced by a worm gear.Next, copying is started by pressing the copy start button. As can be seen from the above explanation, there is a feature that the copying operation is automated.

In this case, the restraining pin 13g is on the load/l side, that is, due to the overload due to the pressing and clamping of the document,
This becomes unnecessary as the motor will stop.

An eccentric cam plate is provided that rotates in synchronization with the gear wheel, and a lever device that comes into sliding contact with this cam plate rotates the top cover in the direction of pressing and holding documents, and a spring installed on the top cover allows the top cover to slide on the cam surface. The purpose is also achieved as a means of lifting up.

If a small gear is fixed to the rotating shaft gα and a rack gear meshed with this gear is used to move the pin of a car door lock up and down by a predetermined stroke, only an electric signal will cause
You can lock and unlock the door.

Compared to conventional means using electromagnetic lenoid, this method uses less electric power and has the effect of significantly reducing mechanical noise.

Also, in the event of an overload due to an accident, burnout of the electric motor can be prevented. Deterrent bin /3a, /J h in Figure 2
, by removing the protruding part b, and by the driving force of the rotating shaft t4,
It is also possible to raise and lower the glass of a motor vehicle door by known means. If a foreign object, especially a child's neck, etc. gets caught when the window glass is raised, an electric circuit is installed to immediately input the electric signal to terminal 7bK in Figure 1.
This has the effect of preventing burnout of the electric motor M and injury to human life. In this case, it is necessary to install the following electric circuit.

Provide an electric switch/leaf that opens only when the window glass is raised and closed. Symbol /7 is a monostable circuit, which outputs a high-level signal with a set width when the high-level signal from the operational amplifier S disappears.

If a foreign object gets caught in the window glass and the operation stops midway, the high level output of operational amplifier j disappears due to overload, and the output of monostable circuit 17 is transferred to transistors 2e, 2e,
, 2d to reverse the electric motor M, so that the window glass automatically lowers and the objective is achieved.

When the window glass rises and closes without any obstruction, the electric switch /A is open and the input of the above-mentioned electric signal is cut off. Therefore, the electric motor M can be automatically stopped due to overload.

Even if the window glass falls, it can automatically stop due to overload.

〔effect〕

As can be understood from the above explanation, there are the following effects.

1st. The first input signal allows the load to move forward or backward, and the load can be automatically stopped due to overload. Furthermore, the control circuit for the DC motor serving as the drive source is simplified and can be formed into an integrated circuit, so it can be manufactured in a small size and at low cost.

It has a function to stop due to load overload, so
It is economical as there is no need to separately install a device to prevent burnout.

Therefore, it is possible to automate the vertical movement of the top cover of a copying machine, and it is also possible to provide an effective means as a driving device for opening and closing the window glass of a car door.

In addition, it can also be used as a reciprocating device for general loads.

[Brief explanation of the drawing]

FIG. 1 is an electric circuit diagram of the device of the present invention, and FIG. 1 is an explanatory diagram of the same load driving device. l...Power supply positive terminal, Ko signal, Ko b λC, Co d...
・Transistor, M...DC motor, S...operational amplifier, /qa, tuh, tri...
・Monostable circuit, /A...electric switch, io
, 'y, qb, f...gear, ion, qa, ga
...rotating shaft, gb...protrusion, /3 Is,
/,? b...Suppression bin, l/...Load, ?
4, 7b... Input terminal for electric signal of forward/reverse command of electric motor M.

Claims (1)

[Claims] A bridge circuit consisting of the first, second, third, and fourth transistors that uses a DC motor as a load and energizes the motor in the forward and reverse directions for forward and reverse rotation, and an armature resistance inserted in series with the motor. a series connection body of a first resistor having a resistance value, a second and third resistor having the same resistance value, a parallel circuit of the series connection body and the series connection body of the above-mentioned motor and the first resistor; , an operational amplifier that compares the voltage at the connection point of the third resistor with the voltage at the connection point of the motor and the first resistor, and converts its output to the first and second voltage levels in response to forward and reverse rotation of the motor. , the output at the first voltage level conducts the first and third transistors located diagonally in the bridge circuit to energize the motor in the positive direction, and the output at the second voltage level causes the second and third transistors to conduct in the positive direction. an energization control circuit that conducts the transistor No. 4 to energize the motor in the reverse direction to control forward/reverse operation of the motor; and a first input that inputs the base input to the first and third transistors for a set time. a control circuit; a second input control circuit for inputting a base input to the second and fourth transistors for a set time; a deceleration device for decelerating the rotation of the motor; and a load driven by the output of the device. , a means for mechanically blocking the movement of the load when it moves a predetermined distance in the forward direction, and a means for mechanically blocking the same movement when the load moves in the opposite direction. Device.