JPH09190916A - Solenoid driving apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving apparatus, which can secure a stabilized driving force with a simple constitution. SOLUTION: A solenoid 14 is driven by a solenoid driver 13 by using a driving current immediately before the previous off held in a backup memory 15 at the time of initialization. The time required for driving is obtained from the change in single state of a position detecting sensor. The driving time and present specified time are compared. When a load becomes heavy and the time is too slow at this time, the driving current is sequentially made large by changing on-duty ratio. When the load is light and the time is too quick conversely, the driving current is sequentially made smaller by changing the on-duty ratio. Thus, the optimum driving current is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive device for a solenoid used as an electric drive source for an optical microscope.

[0002]

2. Description of the Related Art Conventionally, a solenoid is sometimes used as an electric drive source for an optical microscope. In such a solenoid, a plunger is linearly movable in a hollow portion of a coil wound in a tubular shape, and the plunger is operated by turning on / off a current flowing through the coil.

In this case, in the operation of the solenoid, when a current flows through the coil, the plunger moves in one direction to attract the fixed magnetic pole, and when the current to the coil is cut off, the force of a return spring or the like causes the solenoid to operate. There is a type that returns to the original position, and a key type that performs suction / return operation according to the direction of the current flowing in the coil and holds this state with some force even if the coil current is cut off in the suction state. is there.

As a method for driving such a solenoid, a preset current is supplied to the solenoid for a certain period of time, and a sensor or the like is used to confirm whether the driving portion by the plunger has normally operated or a mechanism. Some devices have a function (retry function) of performing the operation again when the load does not operate normally due to a load change due to the change over time.

Further, for performing complicated operation control, for example, as shown in FIG. 5, the drive current of the solenoid 2 driven by the solenoid driver 1 is detected by the solenoid current detecting section 3, and the detection output is solenoid driven. By feeding back to the current control unit 4, the solenoid drive current control unit 4 grasps the state of the load by this feedback signal or always obtains an appropriate drive force from the solenoid drive signal input from the outside,
There is also one in which the solenoid drive current for the solenoid driver 1 is controlled. For example, Japanese Patent Publication 7-50
Japanese Patent No. 655 discloses such control of a solenoid. By the way, a solenoid used as an electric drive source of an optical microscope needs to set a strong driving force of the solenoid in order to ensure reliability of operation.

[0006]

However, when the drive current to the solenoid is increased, a large collision noise may be generated when the plunger operates and collides with the fixed magnetic pole. Therefore, in order to avoid such a collision noise, the drive current is suppressed to a minimum value with a small operation margin. However, if the drive current is set to a current value with a small operation margin, the load may not be able to be driven because the drive force may be insufficient due to load fluctuations due to changes over time in the mechanical section and changes in the outside air temperature.
This means that even if the device has a retry function, the same operation will fail many times when driven under the same conditions.

[0007] Further, there is a drawback that the circuit configuration becomes complicated in the case of monitoring the current flowing through the solenoid in operation and controlling it to the optimum current. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a solenoid drive device that has a simple structure and can secure a stable driving force.

[0008]

According to the first aspect of the present invention,
A solenoid for driving the load, a drive means for supplying a drive current to the solenoid, a detecting means for detecting a drive time required for driving the load by the solenoid, and a drive means for detecting the drive time based on the drive time detected by the detecting means. The control means controls the drive current of the drive means to determine the optimum drive current.

According to a second aspect of the present invention, in the first aspect, the control means compares the drive time detected by the detection means with a preset specified time, and the control means compares the drive time with the predetermined time. The drive current by the drive means is varied to obtain the optimum drive current such that the drive time falls within the specified time range.

[0010] The third aspect of the present invention is the first or second aspect.
In the description, when the drive current is larger than a preset upper limit value, the abnormality occurrence is notified. As a result, claim 1
Alternatively, according to the invention described in 2, it is possible to check the influence of the change of the load on the operation of the solenoid and to change the drive current of the solenoid according to the result so as to match the load state. It is possible to reduce the effect when there is a problem, and always ensure stable operation.

According to the third aspect of the present invention, since an abnormality can be notified by a display or the like when there is an abnormality on the load side including the drive system, it is possible to prevent the abnormality from further spreading.
The safety can be further increased.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 shows a schematic structure of a solenoid drive device to which the present invention is applied. In the first embodiment, the control of the drive current of the solenoid is executed by the on-duty ratio for changing the average current value by the ratio of the on / off time of the conduction current.

In the figure, 11 is a CPU,
A solenoid 14 is connected to 11 via a position detection sensor section 12 and a solenoid driver 13, and a backup memory 15 and a ROM 16 are further connected.

The position detection sensor unit 12 is composed of a combination of a photo interrupter and a light shielding plate, a Hall IC and a magnet, and detects whether a load (not shown) driven by the solenoid 14 is at a predetermined position. The state is transmitted as an output signal. The solenoid driver 13 is composed of a driver IC, a transistor, and the like, and controls on / off of voltage application for driving the solenoid 14. The backup memory 15 is composed of EEPROM, NVRAM, etc.
Even if the power is turned off, the conditions such as the drive current when the solenoid 14 is driven when the power was last turned on and necessary data are stored. The ROM 16 stores a control program for the CPU 11. The CPU 11 then outputs the output signal from the position detection sensor unit 12 and the backup memory 1
Control based on the on-duty ratio that takes in information from 5 to calculate the drive time required to drive the load, and changes the average current value of the drive current of the solenoid 14 to the solenoid driver 13 by the ratio of the on / off time of energization. I'm trying to tell you.

Next, the operation of the embodiment thus constructed will be described with reference to the flow chart shown in FIG. First,
When the power is turned on and initialization is performed, in step 201,
The solenoid drive current immediately before being turned off, which is held in the backup memory 15, is taken into the CPU 11.

Next, at step 202, the solenoid 14 is driven by the solenoid driver 13 by the drive current thus fetched. Then, based on the output signal from the position detection sensor unit 12, the CPU 11 checks the completion of movement of a load (not shown) driven by the solenoid 14 and calculates the driving time required for driving. And step 2
In step 03, the drive time at this time is compared with a preset specified time. The specified time here is the driving time in the optimum driving state obtained in advance by experiments or the like.

Then, if the drive time at this time is within the specified time, the routine proceeds to step 204, where it is further judged whether or not the drive current at this time is smaller than the previously set value.
If YES, the drive current is set as the optimum drive current, the drive current by the solenoid driver 13 is determined in step 205, and the solenoid 14 is driven in the normal operating state. If NO, in step 206,
A margin is added to the drive current, and in step 205,
The drive current by the solenoid driver 13 is fixed, and the solenoid 14 is normally operated.

On the other hand, in step 203, if the load is light and the driving time is earlier than the specified time, the driving current value is reduced in step 207, and if the load is heavy and the driving time is later than the specified time, in step 208. , The drive current value is increased. That is, the reason why the driving time is too early or too late as described above is that the driving current is not an appropriate value for the current load state. In this case, the on-duty ratio from the CPU 11 should be changed. As a result, the drive current is increased or decreased.

Here, the control of the on-duty ratio by the CPU 11 is as shown in FIG. 3, in which the voltage is always applied during the period from the start of driving the solenoid 14 to the end of the driving. While,
This period is divided into a plurality of steps, and the on / off time ratio of voltage application in each step is controlled.

Specifically, a control line is connected from the CPU 11 to the solenoid driver 13, and the control line is turned on / off based on the on-duty ratio.
The voltage applied from the solenoid driver 13 to the solenoid 14 is made variable.

Then, in step 209, it is judged whether or not the drive current is within the specified range, and if YES here, the process returns to step 202, and this time the solenoid driver 13 drives the solenoid 14 with this drive current. In step 203, the same operation as described above is repeated until the drive time falls within the specified time range, and the optimum drive current is obtained.

If NO in step 209, it is determined in step 210 that the drive unit has failed, and error processing is performed. Therefore, by doing so, the solenoid 14 is driven by the solenoid driver 13 using the drive current immediately before the power-off that is held in the backup memory 15, and the drive is started from the change in the signal state of the position detection sensor unit 12. Calculate the required drive time, compare this drive time with a preset specified time, and if the load becomes heavy and the time is too slow, increase the drive current sequentially by changing the on-duty ratio, and vice versa. Even when the load is light and the time is too early, the drive current is gradually reduced by changing the on-duty ratio so that the drive current is within the specified range and the optimum drive current within the specified time range is obtained. That is, that is, the influence of the change with time of the load on the operation of the solenoid 14 is checked, and the solenoid 14 is given according to the result. Since the dynamic current is changed to match the load condition, the effect of load fluctuation can be reduced.In addition, such an operation is performed at initialization to optimize the current load condition. Since the drive current is determined, malfunctions due to the influence of loads during use can be reliably prevented, and a stable drive force can always be secured. (Second Embodiment) FIG. 4 shows a schematic configuration of a second embodiment, and the same parts as those in FIG. 1 are denoted by the same reference numerals.

In the second embodiment, the drive current of the solenoid is varied by changing the voltage applied to the solenoid. In this case, in FIG.
A display unit 17 is connected to 11, and a voltage variable unit 18 is connected between the solenoid driver 13 and the CPU 11. Here, the display unit 17 is composed of a display member such as an LED, and when an abnormality occurs on the solenoid driver 13 side, the C
When the PU 11 makes a decision, the LED 11 is turned on or off by a signal from the CPU 11 to indicate the occurrence of an abnormality. The voltage varying unit 18 is composed of a D / A converter or the like, and is for converting the digital data from the CPU 11 into an analog value and setting the output voltage of the solenoid driver 13.

In this case, however, at the time of initialization when the power is turned on, the solenoid drive current immediately before being turned off last time is fetched into the CPU 11, and the solenoid driver 13 is driven by this drive current as in the first embodiment. Drives the solenoid 14.

From this state, the completion of movement of a load (not shown) is checked and the drive time is confirmed by an output signal from the position detection sensor section 12, and the drive time at this time is compared with a preset specified time. Then, if the drive time is within the specified time, the drive current is determined as the optimum drive current, and the drive time is too early or too late due to a malfunction on the load side. If the drive current is not an appropriate value, the CPU 11 outputs a voltage change signal to the voltage variable unit 18.

In this case, when the load is light and the driving time is too early, the voltage varying section 18 controls to lower the voltage so as to reduce the driving current of the solenoid driver 13, and
When the load becomes heavy and the driving time is too slow, the voltage is controlled to increase so as to increase the driving current of the solenoid driver 13. Then, while the drive current for the solenoid 14 is being changed by the voltage control by the voltage varying unit 18 as described above, the drive state is checked and finally the optimum drive current is determined.

Further, when the optimum drive current is obtained, an upper limit value is set in advance, and if the drive current exceeds the upper limit value, an abnormal situation occurs and C
The display unit 17 is turned on or blinks according to a signal from the PU 11 to display the occurrence of an abnormality, thereby notifying the user of the abnormality and preventing further expansion of the abnormality.

Therefore, even in this case, the same effect as that of the first embodiment can be obtained, and when the drive current is set, the upper limit value is set, and when the drive current exceeds the upper limit value, an abnormal situation occurs. The occurrence can be displayed on the display unit 17 and the abnormality can be reported when there is an abnormality on the load side including the drive system. Therefore, further abnormality can be prevented and safety is further enhanced. You can also

In the above-described embodiment, the case where the optimum drive current is obtained at the time of initialization has been described, but the drive current can be optimized as described above even when the solenoid is driven arbitrarily. .

The above description is based on the embodiment.
The present invention also includes the following inventions. (1) In the solenoid drive device according to claim 1,
Further, it has a storage means for storing the solenoid drive current immediately before the last power-off, and the first solenoid drive is performed by the solenoid drive current immediately before the last power-off by this storage means. By doing so, it is possible to prevent a malfunction due to the influence of the load during use, and always secure a stable driving force.

[0031]

As described above, according to the present invention, it is possible to secure a stable operation at all times by using a simple structure to suppress the influence of the load over time. Further, since it is possible to notify the abnormality when there is an abnormality on the load side including the drive system by a display or the like, it is possible to prevent the abnormality from further spreading and further enhance the safety.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a first embodiment of the present invention.

FIG. 2 is a flowchart illustrating the operation of the first embodiment.

FIG. 3 is a diagram for explaining control based on an on-duty ratio according to the first embodiment.

FIG. 4 is a diagram showing a schematic configuration of a second embodiment of the present invention.

FIG. 5 is a diagram showing a schematic configuration of a conventional solenoid drive device.

[Explanation of symbols]

 11 ... CPU, 12 ... Position detection sensor section, 13 ... Solenoid driver, 14 ... Solenoid, 15 ... Backup memory, 16 ... ROM, 17 ... Display section, 18 ... Voltage varying section.

Claims (3)

[Claims] 1. A solenoid for driving a load, a drive means for supplying a drive current to the solenoid, a detecting means for detecting a drive time required for driving the load by the solenoid, and a drive detected by the detecting means. A drive device for a solenoid, comprising: a control means for controlling a drive current by the drive means based on time to determine an optimum drive current. 2. The control means compares the drive time detected by the detection means with a preset prescribed time, and changes the drive current by the drive means according to the comparison result to change the drive time. 2. The solenoid drive device according to claim 1, wherein an optimum drive current is determined so as to fall within the specified time range. 3. The solenoid drive device according to claim 1, wherein when the drive current is larger than a preset upper limit value, an abnormality is notified.