JPH0119101Y2 - - Google Patents

Description

[Detailed Description of the Invention] In this invention, the recording pen is galvanometer-driven by the electromagnetic force generated by supplying a recording signal to a drive coil placed in a magnetic field, and the drive coil and reel are commonly used. The present invention relates to a pen writing recording device in which negative speed feedback is applied to a drive circuit by a feedback coil.

Figure 1 shows an example of the conventional circuit configuration of this type of drive unit, where 1 is a recording pen drive coil, 2 is a speed detection coil that shares the winding frame with this drive coil, and 3 is a high-frequency compensation This is a drive circuit including a circuit 4 and a negative feedback amplifier 5. Further, R1 is a resistor for detecting the drive current, and RV1 is a variable resistor for adjusting the level of the speed signal. Together with the speed detection coil 2, this constitutes a feedback circuit, and a normal output corresponding to the drive current generated in the resistor R1. A feedback voltage and a speed signal superimposed on the feedback voltage and corresponding to the speed of the recording pen adjusted by a variable resistor RV1 for adjusting the amount of feedback are fed back to the drive circuit 3 in a negative manner. The drive coil 1 and the speed detection coil 2 can be attached to the recording pen side like a movable wire type galvanometer, or conversely, they can be attached to a movable iron type galvanometer.
It is conceivable that these coils 1 and 2 may be fixed as in the case of a movable magnet type galvanometer. With this kind of circuit configuration, when performing high-frequency compensation and improving the frequency response to about 100Hz, the frequency response characteristics at frequencies above the resonance point of the galvanometer will be
Since the attenuation is 12dB/oct, the response characteristics of the recording pen are brought closer to the 6dB/oct characteristics by speed negative feedback.
Furthermore, the high frequency compensation circuit 4
The response range has been expanded to about 3 times. However, although such a circuit configuration widens the frequency band, there is a problem in that ringing occurs in the recording waveform for rectangular wave input recording signals.

It is therefore an object of the present invention to provide a pen recording device of the type mentioned at the outset, which not only has a wider frequency band but also exhibits a flatter frequency response characteristic.

The above-mentioned ringing occurs because the frequency response characteristic of the recording pen shown in Fig. 1 produces a peak in the high range as shown in Fig. 2, a. The peak is drive coil 1
The above objective is achieved based on the confirmation that this is due to the transformer coupling effect between the speed detecting coil 2 and the speed detecting coil 2. In other words, the speed signal induced in the speed detection coil 2 increases at 6 dB/octave as the speed increases (Fig. 2, b) when the amplitude of the galvanometer, that is, the pen swing width is constant with respect to the frequency. The phase changes from a lead of 90° with respect to the input signal of the drive coil 1 to a phase shift of 0° at the resonance point of the recording pen and a lag of 90° as the frequency further increases.
On the other hand, the transformer coupling component between the drive coil 1 and the speed detection coil 2 has a drive input characteristic (second
Due to the differential transformer action of both coils 1 and 2, the amplitude is 6 dB/oct up to the resonance point, and at frequencies above the resonance point, as shown in Fig. 2, c.
Increases by 18dB/octave, and the phase is always constant due to differential action.
It will move only 90 degrees. Therefore, the phase difference between the pure speed signal (Fig. 2, b) and the transformer-coupled component superimposed thereon (Fig. 2, c) approaches 180° in the high frequency range (for example, around 100 Hz), The speed feedback signal is supplied to the drive coil 1 with a valley-like decrease in this frequency region (dotted line in Figure 2, b), and the drive signal correspondingly increases in a peak-like manner, resulting in ringing. become. Therefore, according to the present invention, by providing a transformer-coupled component canceling circuit in the feedback circuit, a flat frequency response characteristic without ringing can be realized.

Next, the present invention will be explained based on the illustrated embodiments.

FIG. 3 shows the canceling circuit part of this embodiment. The canceling circuit 10 of the transformer coupling component added to the circuit shown in FIG. The detection signal of the drive current detection resistor R1 connected in common is input, and the differential circuit consists of a capacitor C10 and a resistor R10, an inverter consists of an operational amplifier A10 and its feedback resistor R11, a resistor R12 and It is composed of an adder circuit consisting of R13. Differential circuits C10 and R10 correspond to differential characteristics between the drive coil 1 and the speed detection coil 2,
The current waveform of the drive current flowing through the drive coil 1 at the resistor R1 is differentiated. This differential signal is inverted by inverters A10 and R11 and added to the speed signal from the speed detection coil 2, and at this time, the transformer coupling component generated in the speed detection coil 2 is canceled. As a result, in addition to the normal output feedback signal, a speed signal without valley-like amplitude changes is negatively fed back.
As shown by the dotted line in FIG. 2, a flat frequency response characteristic can be obtained.

As is clear from the above description, according to the present invention, by providing the feedback circuit with a circuit for eliminating the transformer-coupled component generated in the speed detection coil, it is possible to draw a waveform without ringing for a rectangular wave input. Furthermore, a significant advantage arises in that deterioration of response characteristics can be avoided when the transformer-coupled component of the speed detection coil increases in response to the need for large drive inputs due to the use of low magnetic flux density or heavy recording pens. It will be done. In addition, since the erase circuit is implemented using a CR circuit, power loss can be reduced compared to the coil method, space can be saved, and it can also be formed on a printed circuit board. Furthermore, the transmission characteristics can be easily adjusted with high precision by selecting parts.

[Brief explanation of the drawing]

FIG. 1 shows an example of the circuit configuration of a conventional drive section of a pen-writing recording device, FIG. 2 shows its operating characteristics, and FIG. 3 shows a circuit configuration according to an embodiment of the present invention. 1: Drive coil, 2: Speed detection coil, 3: Drive circuit, 4: High frequency compensation circuit, 10: Eraser circuit.

Claims (1)

[Claims for Utility Model Registration] A pen in which the drive circuit that drives the recording pen by supplying a recording symbol to a drive coil in a magnetic field has a negative feedback circuit using a speed detection coil that shares the drive coil and the winding frame. In the writing/recording device, a negative feedback circuit includes a drive current detection resistor commonly connected between both of the coils and a reference potential, and a drive current detection resistor that serves as a circuit for erasing a transformer coupling component from the drive coil to the speed detection coil. A differentiation circuit consisting of a resistor and a capacitor receives the detection signal of , and its differential output is supplied to the - input terminal, the + input terminal is connected to the reference potential, and the output signal from the output terminal is connected to the speed detection coil. A pen-writing recording device comprising: an operational amplifier for adding the speed signal to the speed signal of the pen-writing recording device.