JPH08182710A - Control circuit for drive motor for electrically operating bed - Google Patents

Abstract

PURPOSE: To ease an impact force off at the starting/stopping of a motor by installing a control means by which a motor is driven with the current speed shifted to a level target speed and then, done again toward the subsequent level target speed after the current speed coincides with the lever target speed. CONSTITUTION: A CPU 4 inputs a pulse signal from a pulse sensor PS as speed detection means connected integrally to a motor 2 into an input port 13 through a waveform processing means 5 or outputs a signal from an output port O3 to perform the on-off operation of a pair of transistors Q3 and Q4 for driving and FET to control the duty of the motor 2. A target speed table is used as target speed setting means into which a plurality of level target speeds in multiple stages from the stoppage of the motor 2 to a rated speed are written. The CPU 4 drives the motor 2 change the speed from the current speed to the next level target speed and does the motor 2 again to the subsequent level target speed after the current speed reaches the level target speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control circuit for a drive motor for an electric bed, and more particularly to a drive circuit for an electric bed for preventing a steep speed change at the time of starting and stopping a motor for operating a main part of the electric bed. The present invention relates to a motor control circuit.

[0002]

2. Description of the Related Art Conventionally, there is a bed in which each of these parts can be displaced by a motor actuator.
In such a motor actuator, if the power is turned on / off directly with a switch,
The motor suddenly starts / stops when it is turned off, and when a person is in bed, there is a risk of receiving an impact force when the switch is turned on / off.

To alleviate the impact force, it is possible to provide a shock absorber, for example, between the displacement portion and the actuator, but there is a problem that the structure becomes complicated and the device becomes large. Further, it is preferable to make the displacement speed relatively slow so that a large impact force is not generated, but in this case, there is a disadvantage that the operation time until the displacement is completed is long.

[0004]

SUMMARY OF THE INVENTION In view of the above problems of the prior art, the main object of the present invention is to reduce the impact force at the time of starting / stopping the motor with a simple circuit. It is to provide the control circuit of.

[0005]

According to the present invention, such an object is to start a motor for operating a main part of the bed by a switch operation, drive the motor at a predetermined constant speed, and stop the motor. And a target speed setting means for setting a step target speed of a plurality of stages between a stopped state of the motor and the constant speed, and a current speed. And a speed detecting means for detecting the current speed from the speed detecting means to drive the motor toward the step target speed, and the next step target speed after the current speed and the step target speed match. It is achieved by providing a control circuit for a drive motor for an electric bed, which has a control means for driving the motor. In particular, it is preferable that the step target speeds of the plurality of stages have a deviation between the step target speeds in the vicinity of the stopped state of the motor and the constant speed smaller than that in the intermediate portion.

[0006]

In this way, the stepped target speeds of a plurality of steps are set between the stopped state of the motor and the constant speed, and the motor is started / stopped according to the stepped target speeds. It is possible to moderate the change in speed during the period. Further, by relatively reducing the deviation between the stationary state side and the constant speed side between the target speeds of the respective stages, for example, if the target speeds of the respective stages are set at predetermined time intervals, the start of the start and the constant speed are Since the change in the target speed at each stage becomes gradual in each case immediately before reaching the speed limit, and before deceleration and immediately before the stop state, the speed in the vicinity of each of the stop state and the constant speed state is Changes will be gradual.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

FIG. 1 is a diagram showing a simplified essential part of a control circuit of an electric bed drive motor to which the present invention is applied. The control circuit 1 is used to start a motor 2 for displacing each main part of the bed, and when it reaches a predetermined speed (rated value of the motor), it is driven at a constant speed for a predetermined amount and stopped. Although only one motor is disclosed in the figure,
In the electric bed, three motors are used for the vertical movement of the whole and for the vertical movement of the head / foot. However, since each motor has the same drive circuit structure, 1 Two motors are shown as representatives.

In FIG. 1, switch signals from an ascending switch SW1 and a descending switch SW2 provided on an operation panel (not shown) are transmitted through a signal processing stage 3 to respective input ports of a CPU 4 as a control means. Input to I1 and I2. Output ports O1 for outputting forward and reverse signals to the CPU 4 in response to the switch signals.
O2 is provided, and drive transistors Q1 and Q2 for forward rotation and reverse rotation, which are on / off controlled by respective output signals, are connected to the output ports O1 and O2. The drive transistors Q1 and Q2 are connected to the coils of the forward and reverse rotation relays RL1 and RL2, respectively, and the coils are excited when the drive transistors Q1 and Q2 are turned on.

The common contacts of the relays RL1 and RL2 are connected to both terminals of the motor 2, and the terminals of the motor 2 are connected to the FETs in the de-energized state of the coil via the selection contacts of the relays RL1 and RL2. The power supply voltage + B is applied in the excited state of the coil.

The CPU 4 is provided with an input port I3 for inputting a pulse signal from a pulse sensor PS, which is integrally connected to the motor 2 and serves as a speed detecting means for generating a rotation pulse, through the waveform processing stage 5. Has been. Also,
The CPU 4 uses the FE to control the duty of the motor 2.
An output port O3 for outputting a signal for on / off controlling a pair of transistors Q3 and Q4 for driving T is provided. When both the transistors Q3 and Q4 are turned on by the output signal from the output port O3, the FET is turned on.

The transistor Q3 has a power supply voltage + when one of the switches SW1 and SW2 is turned on.
It is designed to be connected to B, and each switch SW1
The duty control can be performed when any of the SW2s is turned on. In addition, a timer circuit 6 including a capacitor and a resistor connected in parallel with each other and grounded is provided on a connection line between each of the switches SW1 and SW2 and the transistor Q3, and after each switch SW1 and SW2 is turned off. The transistor Q3 can be connected to the power supply for a predetermined time.

Next, an operation procedure based on the present invention by the motor drive circuit thus constructed will be described below with reference to the flow chart of FIG. For example, when the raising switch SW1 is turned on, a normal rotation signal is output from the output port O1 to excite the relay RL1, and a drive current in the normal rotation direction flows to the motor 2. And step ST
At 1, the current rotation speed of the motor 2 is detected by inputting the rotation pulse from the pulse sensor PS.

In the device of the present invention, as shown by an imaginary line in FIG. 3, a target as a target speed setting means in which a plurality of step target speeds Vn, which are set in multiple steps between the stopped state V0 and the rated speed Vr, are written in advance. A speed table is provided. Therefore, when the rotation speed is generated and the rotation speed is detected in step ST1, in step ST2, the step target speed immediately above (at the time of rising) closest to the current speed Vs detected in step ST1 is calculated from the target speed table. To get
The target speed Vo at that time is set.

Then, in step ST3, the current speed Vs
The difference ΔV between the target speed Vo and the target speed Vo is calculated, and the next step ST
In step 4, if there is a speed difference ΔV, the process proceeds to step ST5, and if there is no speed difference ΔV (when the current speed Vs reaches the target speed Vo), the process returns to step ST1.

When the process proceeds to step ST5, it is determined which of the current speed Vs and the target speed Vo is larger.
If the target speed Vo is higher than the current speed Vs, the process proceeds to step ST6, and control is performed to increase the output in order to increase the rotation speed of the motor 2. On the contrary, the target speed Vo
If the current speed Vs is larger than the current speed, step S
In step T7, control is performed to increase the output that reduces the rotation speed of the motor 2. Step ST6 or step ST7
If it has passed, the process returns to step ST1.

When the process returns to step ST1, the current speed Vs is newly detected. At this time, if the newly detected current speed Vs is larger than the previous target speed Vo, the next new speed Vs is detected. The target speed Vo is acquired from the table and reset. The above steps are repeated in the same manner, and if the current speed Vs has reached the rated speed Vr, the rated speed Vs is reached.
The r is set to the target speed Vo, and the constant speed operation control of the device is performed. This constant speed operation control is continued until the raising switch SW1 is turned off.

In this way, at the time of starting, the speed is increased by sequentially replacing each step target speed Vo until the rated speed is reached, so it is possible to prevent a rapid speed change from the start to the constant speed. Further, in this embodiment, as shown in FIG. 3, the time between each step target speed Vo is set to a constant value in advance, and in each vicinity of the stopped state and the rated speed Vr, the next step target speed Vo is set. The deviation is set to be relatively small, and the deviation between the next step target speed Vo and the next one is set to be relatively large. Then, the target speed V for each stage
By controlling the speed between o by proportional control, the speed can be gradually increased at the beginning of starting and immediately before the rated speed is reached. Therefore, it is possible to prevent a rapid speed change at the start of activation and when the rated speed is reached, and no impact force is applied to a person sleeping on the electric bed during displacement.

When the raising switch SW1 is turned off to stop the motor 2 at an arbitrary position, the raising switch S
Although the power supply voltage + B via W1 is not applied to the transistor Q3, the voltage necessary for driving the transistor Q3 is applied for a predetermined time by the timer circuit 6 as described above, and the FET can be controlled during that time. Then, although the steps are the same as those at the time of starting, control is performed to set the next target speed Vo lower than the current speed Vs.

As shown in the imaginary line in FIG. 3, the target speed table to be referred to at the time of stop also has a step target speed Vo at the start of deceleration from the rated speed and immediately before the stop state, as in the case of starting. The deviation from the next one is set to be relatively small, and the deviation between them is set to be relatively large. Therefore, it is possible to perform the gradual deceleration control without a sudden speed change as in the start-up. Further, in the present embodiment, the target speed table at the time of deceleration is set separately from that at the time of starting, but the same table may be used.

[0021]

As described above, according to the present invention, a plurality of stepped target speeds are set between the stopped state of the motor and the constant speed, and the motor is started and stopped according to the stepped target speeds. The change in speed between the stopped state and the constant speed state can be moderated. In addition, by making the changes in speed near the stopped state and the constant speed state slower than in the middle part, the start of starting or just before stopping when displacing the main part of the electric bed by the motor actuator It is possible to realize speed control that gently changes the displacement speed with a simple circuit configuration, improve the cost of the device, and reduce discomfort caused by a rapid speed change when displacing the main part of the electric bed. And so on, the effect is great.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a main part of a motor drive circuit to which the present invention is applied.

FIG. 2 is a flow chart of control according to the present invention.

FIG. 3 is a diagram showing an operating state.

[Explanation of symbols]

 1 Control Circuit 2 Motor 3 Signal Processing Stage 4 CPU 5 Waveform Processing Stage 6 Timer Circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Soda 1268-1, Hirosawa-cho, Kiryu-shi, Gunma Mitsuba Electric Manufacturing Co., Ltd.

Claims (2)

[Claims] 1. A control circuit for an electric bed drive motor for controlling a motor for activating a main part of a bed by a switch operation to drive the motor at a predetermined constant speed and stop the motor. A target speed setting means for setting a step target speed in a plurality of stages between the stopped state of the motor and the constant speed, a speed detecting means for detecting a current speed, and a current speed from the speed detecting means. And driving the motor toward the step target speed, and controlling the motor toward the next step target speed after the current speed and the step target speed match. Control circuit for electric drive motor for electric bed. 2. The step target speeds of the plurality of stages are set such that a deviation between the step target speeds in the vicinity of the stopped state of the motor and the constant speed is set to be smaller than an intermediate portion. The control circuit for the drive motor for an electric bed according to claim 1.