JPH068080B2 - Pen controller - Google Patents

Description

The present invention relates to a control device for driving a pen such as an XY plotter or a drafting machine.

[Conventional technology]

In order to bring a pen such as an XY plotter into contact with the writing surface in a state with little impact, mechanical braking may be performed using an air damper. However, if this method is adopted,
I cannot get a fast response. In order to solve this kind of problem, the applicant of the present application has proposed a method of electrically controlling the current of the pen drive coil in Japanese Patent Laid-Open No. 60-83134.

[Problems to be solved by the invention]

The pen control device disclosed in the above publication has a pen speed detector and is configured to reduce the pen drive current by negative feedback when the pen descending speed becomes large. Therefore, the pen impact load can be significantly reduced as compared with the case where the pen is lowered at a constant speed. However, it is required to obtain a better soft landing characteristic while securing a high-speed response characteristic. In order to meet this demand, it can be considered that the pen pressure setting signal is softly changed according to a predetermined program.
However, since this method is an open loop control, it has a drawback that the optimum control state cannot be obtained when the height of the pen with respect to the recording surface varies or other characteristics vary.

Then, the objective of this invention is providing the pen control apparatus which can obtain an ideal braking state easily.

[Means for solving problems]

The present invention for achieving the above object includes a writing pen, a pen driving device that includes a driving coil and drives the pen to selectively contact the recording surface by electromagnetic action, the pen and the pen. A pen position detector that detects the distance to the recording surface, a pen speed detector that detects the moving speed of the pen,
A pen pressure setting signal supply circuit that supplies a pen pressure setting signal corresponding to the desired pressure of the pen on the recording surface, a pen position detection signal obtained from the pen position detector, and the pen pressure setting signal supply circuit A selection circuit for selecting a larger one of the pen pressure setting signals generated, and a pen for generating a pen contact / separation control signal for separating the pen from the recording surface and for bringing the pen into contact with the recording surface. The pen is recorded in response to a contact / separation control signal generation circuit, at least an output of the selection circuit, an output of the pen contact / separation control signal generation circuit, and a negative feedback signal corresponding to the output of the pen speed detector. A drive current for contacting the surface is supplied to the drive coil, and when the drive current starts to be supplied, the drive current having the first polarity is supplied.
A pen drive current control supply circuit configured to supply a drive current having a second polarity opposite to the first polarity when the output of the pen speed detector becomes large; And a signal control circuit for controlling the level of the pen pressure setting signal to decrease during the period in which the drive current is flowing with the second polarity. It is related.

[Work]

In the pen control device of the above invention, when the pen is started to move toward the recording surface, the pen is sufficiently separated from the recording surface, so that a large position detection signal is generated and this is selected by the selection circuit. A relatively large current flows through the drive coil in response to the signal, and the response speed of the movement of the pen is increased. After that, when the pen approaches the recording surface, the position detection signal becomes smaller than the pen pressure setting signal, the pen pressure setting signal is selected, and the drive current is supplied based on this. On the other hand, when the speed detection signal increases as the movement of the pen progresses, the drive current decreases conversely, and as the decrease continues, a reverse current flows and the braking state occurs. In the present invention, the level of the pen pressure setting signal is lowered in response to this reverse current. As a result, strong braking is applied to the drive coil, and the impact load of the pen is reduced. According to the present invention, since the signal control circuit does not substantially participate in the supply of the drive current at the start of movement of the pen, the pen rapidly approaches the recording surface. The braking based on the reverse drive current is only for a short time at the position where the pen is close to the recording surface, and therefore the response speed is not significantly reduced. The method of controlling the pen pressure setting signal according to a program to flow an optimum drive current is open loop control, while the method of the present invention is closed loop control, so that an ideal braking state can be easily obtained. You can

〔Example〕

Next, a pen control device according to an embodiment of the present invention will be described with reference to the drawings.

XY of the embodiment of the present invention shown in FIGS.
A pen controller for a plotter includes first, second, third, and fourth plate-shaped permanent magnets (1) to form a magnetic circuit.
Includes 1) (12) (13) (14). These four magnets (11) (12) (13) (1
4) are flat rare-earth cobalt magnets, each of which is formed in a quadrangle. The first and third permanent magnets (1
In 1) and (13), one of the main surfaces, that is, the left surface, is an N pole, and the other main surface, that is, the right surface is an S pole, which are magnetized substantially uniformly. Also, the second and fourth permanent magnets (12)
(14) is magnetized substantially uniformly so that one of its main surfaces, that is, the left surface becomes the S pole, and the other main surface, that is, the right surface becomes the N pole. As is apparent from FIGS. 2 to 5, the first permanent magnet (11) is fixed to one support member (15) so as to extend in the vertical direction, that is, the Y-axis direction. The second permanent magnet (12) is disposed adjacent to and below the first permanent magnet (11) and is fixed to one support member (15). Third permanent magnet (13)
Is fixed to the other support member (16) and the first permanent magnet (1
It is placed face-to-face with 1). The fourth permanent magnet (14) is fixed to the support member (16) below the third permanent magnet (13) and is arranged to face the second permanent magnet (12). As a result, the first space (17) is created between the first permanent magnet (11) and the third permanent magnet (13), and the second permanent magnet (12) and the fourth permanent magnet (14). ) And a second space (18) has been created.

Since the one and the other support members (15) and (16) shown in FIG. 2 are magnetic plates that do not magnetically saturate, four permanent magnets (1
1) to (14) form a magnetic closed circuit as shown by the dotted line in FIG. A plurality of arrows drawn from the center line of the first space (17) and the second space (18) below this in FIG. 3 indicate the direction and strength of the magnetic field on this center line. Indicates. That is, the length of the arrow indicates the strength of the magnetic field,
The direction of the arrow indicates the direction of the magnetic field. As is apparent from FIG. 3, a magnetic field in the first direction from the right to the left is generated in the first space (17), and the magnetic field in the second space (18) is opposite to the first direction. The magnetic field in the second direction is generated. The first permanent magnet (11) and the second permanent magnet (12) are vertically adjacent to each other with different polarities, and the third permanent magnet (13) and the fourth permanent magnet (14) are provided. Are adjacent to each other in the vertical direction with different polarities, the distribution of the magnetic field, that is, the lines of magnetic force in the first and second spaces (17) and (18) is four permanent magnets (11) to (14). Is determined by the interaction of. As a result, the strength of the magnetic field at the boundary P ₀ between the first space (17) and the second space (18) shown in FIG. 3 depends on the two permanent magnets (11) and (13). It is substantially zero due to the cancellation of the action and the action of the two permanent magnets (12), (14) below. Further, in the region near the boundary P ₀ , the magnetic field strength gradually increases almost linearly. To describe the strength of the magnetic field in the first and second spaces (17) and (18) in more detail, in the first space (17), the strength of the magnetic field gradually increases from the boundary P ₀ to the position P _1. And then gradually becomes smaller. On the other hand, the second boundary P ₀ in the space (18) to the P ₂ position 2
The strength of the magnetic field in the direction of increases gradually and then gradually decreases. Therefore, the magnetic flux distribution, that is, the strength of the magnetic field is substantially S-shaped as a whole.

The rectangularly wound drive coil (19) shown in FIGS. 1 and 2 is movably disposed in the first and second spaces (17) and (18) and is substantially It has a first portion (19a) that displaces in the first space (17) and a second portion (19b) that displaces substantially in the second space (18). When a direct current is passed through this drive coil (19) to bring down the pen, the first portion (19a) has a direction from right to left as shown by the arrow as shown in FIG. Current flows, the second
In the portion (19b), a current flows in a direction from left to right as indicated by the arrow. However, since the direction of the magnetic field acting on the first part (19a) is opposite to the direction of the magnetic field acting on the second part (19b), the first part (19a) and the second part (19a)
Both the part (19b) of and move downward. Drive coil
When (19) moves from the position of FIG. 4 to the position of FIG. 5, the strength of the magnetic field acting on the coil (19) changes according to the change of the position of the coil (19). If the torque for lowering the coil (19) from the position of FIG. 4 to the position of FIG. 5 is applied while keeping the current of the coil (19) constant, the position P ₁ to the position P _{2 of} FIG. When the coil (19) moves in the range of, the strength of the magnetic field acting on the first portion (19a) decreases, while the strength of the magnetic field acting on the second portion (19b) increases. . Therefore, the torque of the drive coil (19) varies little.

The moving member (21) shown in FIGS. 1 and 2 is a drive coil (19).
It has an arm (21a) fixed to the XY plotter and supporting a pen (22) for writing on an XY plotter. This moving member (21)
Slide bearings to move the
(23) is attached to the moving member (21), and a shaft (pin) (24) extending in the vertical direction is engaged with the bearing (23). Further, the right end of the moving member (21) is linearly guided in the vertical direction by the guide member (25). The pin (24) and the guide member (25) are arranged on the fixing member (27). (2
6) is a coil spring for returning the moving member (21), which is wound around the pin (24) and fixed to the moving member (21).
It is located between (27). Reference numeral (28) is a stopper provided on the guide member (25) for determining the upper limit of the moving member (21).

The Hall element (29) as a position detecting element is
It is arranged in the center of the hollow portion (30) of 9) and is fixed to the moving member (21) with a fixed positional relationship with the coil (19). The Hall element (29) moves in the first and second spaces (17) and (18) having the magnetic field shown in FIG. 3 and generates a voltage corresponding to the magnetic field. That is, the Hall element (29) is a drive coil (1
9) Generates an output voltage corresponding to the position of the pen (22).
And the Hall element (29) for this position detection is
Since it is arranged in the center of 9), the magnetic field strength moves linearly and gradually within the range of P _{1 to} P _{2 in} FIG. 3, and the voltage corresponding to that position relatively accurately is applied. Occur. Therefore, the current of the drive coil (19) can be controlled according to the change of the position of the drive coil (19). Further, since the hall element (29) for the position detector is arranged in the hollow portion (30) of the drive coil (19), a special space for providing the position detecting means can be reduced.

As is apparent from FIGS. 1 and 2, a speed detection coil (32) as a speed detector is coaxially wound around the outer periphery of the drive coil (19). Therefore, this speed detection coil (32)
Together with the drive coil (19) the first and second spaces (17) (18)
Move in the magnetic field of. As a result, the speed detection coil (32)
The voltage corresponding to the speed of
Obtained from 2). That is, the speed of the pliers (22) is changed to the coil (32).
Can be detected with. Similar to the drive coil (19), the speed detection coil (32) has an upper portion (32a) substantially located in the first space (17) and a lower portion (substantially located in the second space (18) ( 32b), when the velocity detecting coil (32) moves in the range from position P ₁ to position P _{2 in} FIG. 3, if the strength of the magnetic field acting on the upper part (32a) decreases, Bottom (32b)
The strength of the magnetic field acting on is increased. Therefore, the coil (3
The total induced voltage in 2) does not change much due to changes in the position of the coil 32, and an output voltage corresponding to the moving speed of the coil 32 is generated.

Circuits related to the drive coil (19), the hall element (29), and the speed detection coil (32) shown in FIGS. 1 to 5 are as shown in FIG. In FIG. 6, (33) is a pen drive current control supply circuit, (34) is a pen up-down (pen contact / separation) control signal generation circuit, (35) is a pen pressure setting signal supply circuit, (3)
6) is a signal control circuit for controlling the level of the pen pressure setting signal according to the present invention, (37) is a pen position detector, and (38) is either a pen position detection signal or a pen pressure setting signal. A selection circuit (39) for selection is a current detector composed of a resistor.

The pen drive current control supply circuit (33) includes a differential amplifier (40) and
It consists of resistors (41) and (42), a diode (43), and first and second phase compensation circuits (44) and (45). The output of the differential amplifier (40) is connected so that _a drive current I _a flows through the drive coil (19). One input terminal (inverting input terminal) of the differential amplifier (40) is connected to the pen-up down control signal generating circuit (34) via the resistor (41) and the diode (43), and at the same time, the resistor ( 42) and the first phase compensation circuit (44) are connected to the speed detection coil (32), and further the second phase compensation circuit (45)
Is connected to the current detector (39) via. Current detector
(39) is connected in series to the drive coil (19), and the current detection signal corresponding to the current obtained from this is a differential amplifier via the phase compensation circuit (45) consisting of a low-pass filter or a resistor.
Negative feedback is given to (40). The speed detection voltage V _C obtained from the speed detection coil (32) is also negatively fed back to the differential amplifier (40) via the phase compensation circuit (44) composed of a low pass filter or a resistor.

Pen up-down control signal generator circuit (34) (40), power source E ₁
And a switch S ₁ for generating a zero volt down signal _VL when the switch S ₁ is off, that is, a signal for bringing the pen into contact (down), and a high level up signal corresponding to E ₁ when the switch S ₁ is on. V _{H, that} is, a signal for separating (up) the pen is generated. The level of the pen-up signal V _H is
It is set sufficiently higher than the levels of the position detection signal V _A and the pen pressure setting signal.

The pen pressure setting signal supply circuit (35) supplies the pen pressure setting signal V _B consisting of a voltage of a constant level corresponding to the pressure for making the pen (22) of FIG. 1 contact the writing paper (46) as shown in FIG. Occurs in.

The signal control circuit (36) is a part related to the present invention, and in this example, the output line (4) of the pen pressure setting signal supply circuit (35) is used.
7) consisting of a resistor (48) connected in series, a line (49) on the output side of this resistor (48) and a diode (50) connected between the output terminal of the differential amplifier (40), The diode (50) is turned on when the output voltage of the differential amplifier (40) becomes negative, and the potential of the line (49), that is, the pen pressure setting signal level is lowered.

The position detector (37) is a Hall element (29) for position detection,
It has a reference voltage circuit composed of a resistor _RA and a zener diode ZD, a variable resistor R _B for obtaining a bias voltage (offset adjustment voltage), a summing amplifier (51), and a pen (2
The position detection signal V _A shown in FIG. 8 is generated according to the position of 2). The summing amplifier (51) adds the voltage obtained from the Hall element (29) and the bias voltage. As a result, the Hall element (29) moves from the first space (17) to the second space (1
Even if the direction of the Hall voltage is reversed by shifting to 8), the one-direction position detection signal V _{A, that} is, the position detection voltage shown in FIG. 8 can be obtained. Output line (5) of amplifier (51)
Since 2) is connected to the other input terminal (non-inverting input terminal) of the differential amplifier (40) via the selection circuit (38), the position detection signal V _A is positively fed back and the drive corresponding thereto is performed. An electric current flows.

The selection circuit (38) is composed of a diode (53) and two resistors (54) and (55). When the position detection signal V _A is higher than the pen pressure setting signal V _B , the diode (53) conducts to detect the position. When the signal V _A is selected and the position detection signal V _A is lower than the pen setting signal V _B , the diode (53) becomes non-conductive and the pen setting voltage V _B is selected. In this embodiment, writing paper pen (22) from the upper limit position P _A of the pen (22) as shown in FIG. 8 (4
The position detection signal V _A gradually decreases as the contact position P _C to 6) is approached, and becomes smaller than the pen pressure setting signal V _B at the position P _B where the pen (22) approaches the writing paper (46). . Therefore,
The selection circuit (38) selects the position detection signal V _A corresponding to the positions P _A to P _B , and selects the pen pressure setting signal V _B corresponding to the positions P _B to P _C.

Next, the up-down operation of the pen will be described. Now, in the up state of the drive coil (19) as shown in FIG. 4, when the down signal _{VL of} zero volt is generated from the down control signal generation circuit (34) at the time point t _{1 in} FIG. The control by the up signal V _H is released, and the control state by the output of the selection circuit (38) is set. At the start of pen down, the pen (22) is at the upper limit position P _A , so the position detection signal V _A is relatively high.
Is occurring. At this time, the speed detection signal and the current detection signal are also zero. Therefore, a relatively large drive current I _a is supplied from the differential amplifier (40) to the drive coil (19) with the first polarity (positive direction). When the drive current increases, the current detection signal and the speed detection signal increase. However, since the phase compensation circuit (44) (45) composed of a low-pass filter is provided, sufficient current is supplied to the drive coil (19) at the time of start-up despite the increase in the current detection signal and the speed detection signal. You can For this reason, the pen (22)
It descends rapidly against 6). When the pen (22) passes the position P _B shown in FIG. 8, the position detection signal V _A becomes lower than the pen pressure setting signal V _B , and therefore the selection circuit (38) outputs the pen pressure setting voltage V _B. The setting signal V _B is input to the differential amplifier (40). When the pen (22) starts descending, the descending speed gradually increases, and the speed detection signal V _C shown in FIG. 7 (D) gradually increases. Since the speed detection signal V _C is negatively fed back, it becomes higher than the level of the pen pressure setting signal V _B , and the output voltage of the differential amplifier (40) is negative (second polarity).
become. Therefore, the driving current I _a is t ₃ to t _{4 in} FIG. 7 (E).
Flows in the opposite direction as shown in. When the output of the differential amplifier (40) becomes negative in this way, the diode (50) of the signal control circuit (36)
Is turned on, the level of the pen pressure setting signal V _B of the line (49) is lowered, the output voltage of the differential amplifier (40) is further lowered, and the drive coil (19) is driven in a driving state (braking). Action) becomes stronger. When the braking action becomes stronger, the pen (22)
Of the diode (50), the level of the speed detection signal V _C also decreases, and the direction of the drive current I _a becomes positive again.
Turns off. As a result, the pen pressure setting signal V _B is again supplied to the differential amplifier (40) as it is. Since the pen (22) continues to descend, the pen (22) finally hits the paper (46).

In the system of this embodiment, the level of the pen pressure setting signal V _B is lowered according to the present invention immediately before the pen (22) hits the paper (46), and a large amount of braking is applied, so that the pen is moved at a relatively low speed. (22) collides with the recording surface of the paper (46), and this impact load becomes smaller. FIG. 9 schematically shows the speed (time-positional relationship) of the pen (22), the characteristic line (56) shows the case of conventional constant speed control, and the characteristic line (57) follows the present invention. The control result is shown, and the characteristic line (58) does not include the signal control circuit (36). If the signal control circuit (36) shown by the characteristic line (58) is not provided, sufficient braking characteristics cannot be obtained, and it takes time to gradually decelerate, and the pen speed is controlled from the high pen height. Must. On the other hand, the characteristic line (5
When the signal control circuit (36) according to the present invention shown in 7) is provided, the pen position signal gain for the pen pressure setting signal is increased in order to improve the braking characteristic, and the pen speed from the low position to the pen speed is increased. Can be controlled to shorten the descent time.

Next, the difference between this embodiment and the conventional example will be described in more detail. When constant speed control is performed during pen down operation, if the descending speed is increased to improve the pen down response characteristic, the impact load at the time of down becomes large, and if the descending speed is reduced, the response characteristic deteriorates.

When controlling the pen down speed according to the change in the pen height, in order to reduce the impact force, a large deceleration force or a time for gradually decelerating is required. If there is a limit in the braking characteristics and there are variations in pen height and braking characteristics, sufficient braking cannot be obtained unless the pen down speed is controlled from the height of the pen at a high position, or a large impact force is generated. Small impact force but long response time.

In order to obtain a small impact force and quick response characteristics when the pen is down, it is necessary to detect the accurate pen height signal, sufficient braking force, and detect that the tip of the pen has come into contact with the recording surface, and set the specified pen pressure. I need.

The pen control circuit of the present embodiment detects the reverse polarity current supplied to the drive coil when the pen is down, and reduces the pen pressure setting signal until sufficient braking is obtained. it can. Therefore, the pen-down speed can be controlled from the height of the pen which is lower than that of the conventional method, and the change in the impact force due to the variation in the pen height is small.

When the pen (22) contacts the paper (46) at time t _{5 in} FIG. 7,
The speed detection signal becomes zero. Therefore, a constant current corresponding to the pen pressure setting signal V _B is supplied to the drive coil, and t ₂
After a short time, the contact pressure of the pen (22) becomes almost constant.

7 at t ₆ the point of view in order to up-pen (22), Atsupudaun control signal supply circuit (34) outputs a down signal V _L of
From the up signal V _H to the position detection signal V _A
The up signal V _H set to be larger than the maximum value of is input to the differential amplifier (40). As a result, the output of the differential amplifier (40) becomes a negative voltage, a reverse drive current flows, and both the action and the return spring (26) raise the drive coil (19) and the pen (22).

[Modification]

The present invention is not limited to the above-mentioned embodiments, and for example, the following modifications are possible.

(1) Instead of the diode (50) of the signal control circuit (47) of FIG. 6, a transistor (60) is connected between the line (49) and the ground as shown in FIG. ) Through a resistor (61) and an inverting amplifier (62)
May be connected to (39). Also in this case, when a reverse current is detected by the current detector (39), the negative voltage corresponding thereto is inverted by the inverting amplifier (62) and the transistor (60)
Becomes a conductive state corresponding to the drive current I _a . As a result,
Pen pressure level setting signal V _B levels are down, the braking is intensified.

(2) The signal control circuit (47) may be moved to the output stage of the selection circuit (38).

(3) Add the output of the speed detection coil (32) and the output of the current detector (39) and let them pass through a common phase compensation circuit, and set one of the phase compensation circuits (44) and (45). You may omit it.

(4) The differential amplifier (40) has two stages, and the output of the pen-up control signal generation circuit (34) and the output of the selection circuit (38) are input to the differential amplifier of the previous stage, and the differential amplifier of the latter stage is input. The output of the differential amplifier in the previous stage and the output of the phase compensation circuits (44) and (45) may be input to. Further, a drive circuit may be independently provided at the output stage of the differential amplifier (40).

(5) A phase compensation circuit may be connected to the output stage of the amplifier (51).

(6) Instead of the Hall element (29), another position detecting element such as a magnetoresistive element may be used.

(7) Permanent magnet in pen drive device (11) (12) (13) (14)
The structure of the electromagnetic actuator composed of the drive coil (19) and the drive coil (19) may be variously modified as disclosed in JP-A-60-83134.

〔The invention's effect〕

As is clear from the above, according to the present invention, the braking force is increased by changing the level of the pen pressure setting signal based on the change in the direction of the drive current. Therefore, when the pen approaches the recording surface, braking is effectively performed. Can be easily achieved. Further, as compared with the open loop control method in which the pen pressure setting signal supply circuit changes the pen pressure setting signal by software, since the method of the present invention is closed loop control, variations in the distance from the tip of the pen to the recording surface, etc. You can apply ideal braking without being affected much.

[Brief description of drawings]

FIG. 1 is a front view showing a pen control device according to the present invention by cutting a part thereof. FIG. 2 is a sectional view showing a portion corresponding to line 2-2 of the apparatus shown in FIG. FIG. 3 is a sectional view showing the directions and strengths of magnetic fields based on the first to fourth permanent magnets in the apparatus of FIG. FIG. 4 is a sectional view showing a state in which the drive coil has moved upward in the apparatus of FIG. FIG. 5 is a sectional view showing a state where the drive coil is moved downward in the apparatus shown in FIG. FIG. 6 is a circuit diagram showing a drive coil, a position detector, a speed detection coil, and an electric circuit connected to these of the device of FIG. FIG. 7 is a waveform diagram showing the state of each part in FIG. FIG. 8 is a diagram showing the relationship between the pen position detection signal and the pen pressure setting signal in the circuit of FIG. FIG. 9 is a diagram showing changes in the pen position with time. FIG. 10 is a circuit diagram showing a modified pen control device. (11) to (14) ... Permanent magnet, (19) ... Drive coil, (22) ... Pen, (32) ... Speed detection coil, (35) ... Pen pressure setting signal supply circuit, (36) ... Signal control circuit , (37) ... Phase detector.

Claims (1)

[Claims] 1. A writing pen, a pen drive device including a drive coil for driving the pen to selectively contact the recording surface by electromagnetic action, and a gap between the pen and the recording surface. A pen position detector for detecting, a pen speed detector for detecting a moving speed of the pen, a pen pressure setting signal supply circuit for supplying a pen pressure setting signal corresponding to a desired pressure of the pen with respect to the recording surface, A selection circuit that selects a larger signal of the pen position detection signal obtained from the pen position detector and the pen pressure setting signal set by the pen pressure setting signal supply circuit; A pen contact / separation control signal generation circuit for generating a pen contact / separation control signal for separating the pen from the surface and for bringing the pen into contact with the recording surface, and at least the output of the selection circuit and the pen contact / separation control signal generation circuit. And a negative feedback signal corresponding to the output of the pen speed detector, respectively, to supply a drive current to the drive coil for bringing the pen into contact with the recording surface. A drive current of a first polarity is supplied at the start of supply, and a drive current of a second polarity opposite to the first polarity is supplied when the output of the pen speed detector increases. A pen drive current control supply circuit, and in response to the drive current or a signal corresponding thereto, during a period in which the drive current flows with the second polarity,
A pen control device comprising: a signal control circuit for controlling to lower the level of the pen pressure setting signal.