JPS5812726B2 - Magnet Tokudohoshiki - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnet drive system that corrects printing timing in accordance with temperature changes in a magnet drive circuit.

Recent line printers have high-speed printing capabilities of about 1,500 to 2,000 lines per minute.

A line printer has a large number of printed characters, a number of digits equal to the number of digits in one line for printing the printed characters, and a magnet for driving the printed characters, and the magnet drive circuit is energized at an appropriate timing. This allows one line to be printed almost simultaneously.

FIG. 1 is an explanatory diagram showing a general configuration of a hammer magnet section.

That is, a hammer 3 and a hammer magnet 4 for impact printing are driven by a magnet drive circuit 5, facing the type drum 1 having a large number of type characters 2 arranged on its outer circumferential surface, and 6 is the printing paper. It is.

In order to ensure high speed, line printers use a mechanism that prints while moving the paper and type together, so the hammer collides with the type after the hammer magnet operates, that is, after the magnet coil is energized. If the time taken to print is slightly off, the printed characters will be misaligned, causing deterioration in print quality.

Therefore, the problem of the deviation in the operating time of the magnet is a major factor limiting the increase in the printing speed of line printers.

Naturally, if the deviation of the magnet operation time is the same, the deviation in character alignment will be larger in high-speed line printers with faster type running speed.Therefore, with the recent increase in speed of line printers, There is a need to more tightly control the operating time of magnets than before.

When considering variations in the operating time of a magnet, it is necessary to take into account timing shifts caused by fluctuations in power supply voltage and timing shifts mainly caused by changes in coil resistance due to increases in magnet temperature.

Since the operating time of the magnet depends on the current applied to the magnet coil, it is only necessary to control this coil current so that it is not affected by fluctuations in the power supply voltage, coil resistance, etc.

An im method of a magnet drive circuit based on such a concept has already been proposed by the present applicant.

(Japanese Patent Application No. 47-71577 [Refer to Japanese Patent Publication No. 53-3073]) FIG. 2 is an explanatory diagram showing an outline of the configuration of this proposed example.

In the figure, the collector of a transistor 13 is connected to the power supply voltage (+E) 1 through a parallel circuit of a diode and a magnet 10 consisting of a resistance component (γo) 11 and an inductance component 12 of a coil, and its emitter is connected to a resistor (Ro) 1.
Ground via 4.

The emitter output of a control pulse amplifying transistor 15 is connected to the base of the transistor 13, and the transistor 13 is opened and closed to perform normal control of the magnet drive circuit.

On the other hand, in the proposed example, a differential amplifier 16 and a diode 17 connected in the opposite direction to its output direction are connected in series to the feedback circuit from the emitter output of the transistor 13 to the base, and one input of the differential amplifier 16 is connected in series. The emitter output of the transistor 13 is input as the input, and the output of the reference waveform generation circuit 21 is input as the other input.

The reference waveform generation circuit 21 connects the collector of a reference waveform generation transistor 18 whose emitter is grounded to which the control pulse is inputted from a constant voltage source through a resistor 19 and a capacitor 20 between the grounded resistor and the capacitor of a time constant circuit. be done.

In such a configuration, the control pulse 9 is connected to the transistor 1.
transistor 1 so that a current waveform similar to the rising waveform during charging flows through the magnet 10.
Operate 3.

That is, the resistance of the magnet 10 in its normal state is γ.

The coil current when closed is i.

Then, the emitter voltage becomes i0Ro, so this and the voltage of the reference waveform from the reference waveform generation circuit 21 are input into the differential amplifier 16, and the voltage is input through the emitter output diode 17 of the transistor 15 so that the difference voltage becomes zero. It is controlled by a differential amplifier 16.

Now the resistance γ of the coil due to fluctuations in voltage (10E) or due to temperature changes.

By changing to a larger value Bi', the coil current i.

When changes to i' smaller than this, the emitter voltage becomes i'
Ro(iR(), and the differential voltage of the differential amplifier 16 increases,
The drawdown of the emitter output of transistor 15 is reduced and acts to increase the output current of transistor 13, or vice versa, due to variations in voltage or resistance γ of the coil.

By changing γ′ smaller than this, the coil voltage i.

When changes to i/ larger than this, the emitter voltage becomes i'
R0>iRO and the differential voltage of the differential amplifier 16 decreases,
The drawdown of the emitter output of transistor 15 increases, operating to reduce the output current of transistor 13.

In this way, the coil current i is generated by the current waveform regulated by the reference waveform from the reference waveform generation circuit 21.

Since this is controlled, it is possible to keep the operating time of the hammer magnet, that is, the printing timing, constant without being affected by voltage fluctuations or coil temperature changes.

FIG. 3 compares the current value of the magnet coil with respect to the time axis using a curve 31 when no current waveform control is performed and a curve 32 when current waveform control is performed.

Curve 31 changes due to voltage fluctuations or coil temperature changes, as shown by solid lines and broken lines, whereas curve 32 is not affected by these at all.

The above is a correction of printing timing only with respect to voltage fluctuations and coil temperature changes.WaterIf a temperature change actually occurs, in addition to the above-mentioned coil resistance change, the hammer and mechanisms such as hammer magnets etc. The relative spacing generally changes in the direction of decreasing as the temperature rises, accompanied by changes in the shape and dimensions of the parts, etc., resulting in an earlier printing timing.

Therefore, in the case where current waveform control is performed as in the proposed example, the operating time Ft of the magnet exhibits a decreasing characteristic as the temperature rises, as shown by the curve 42 in FIG.

On the other hand, when the current waveform is not controlled, that is, when the switching type is used, the influence of the resistance of the magnet coil is much greater than the influence of the temperature rise of the mechanical part, so the overall result is as shown by curve 41 in the figure. Shows rising characteristics.

The present invention focuses on these two curves 41 and 42, and considers the possibility of ensuring almost constant printing timing overall by providing a non-protruding switching operation region in a part of the current control system. .

An object of the present invention is to provide a method for correcting printing timing deviations caused not only by changes in coil resistance due to temperature changes in a magnet drive circuit but also by changes in shape of a magnet.

The purpose is to provide a magnet drive circuit that is composed of a circuit that detects the current flowing through the magnet coil and a circuit that controls the current given to the magnet coil to a predetermined value by a signal from the detection circuit. The magnet drive circuit operates at a rate such that the change in the magnet operation time and the change in the magnet operation time due to temperature changes in the magnet mechanism etc. are offset, and the change in the magnet operation time due to temperature changes is minimized. This is achieved by providing a region where no current is applied for a part of the time.

The present invention will be described in detail below with reference to examples.

As mentioned above, the principle of the present invention is to provide a conventional uncontrolled switching operation region in the current control system.

As an example of the current control method, the method of the present invention will be explained below with respect to the current waveform control method described above.1 In FIG. Follow the characteristic 310 curve Oa and set the initial value i at this point.

The curve ab of the current waveform-controlled characteristic 33 is moved to the curve ab, and the characteristic Oab shown by the arrow is obtained as a whole.

That is, the ratio of the combination of these two curves is set appropriately so that the delay element of the operation time due to the uncontrolled switching operation characteristic 31 and the advance element of the operation time due to the current waveform controlled characteristic 33 are canceled out to almost zero.

Therefore, in the characteristics showing the change in print timing Ft with respect to the time change in temperature rise shown in FIG. 4, there is a characteristic curve 41 without current waveform control which shows a rising characteristic, and a characteristic curve 42 with current waveform control which shows a falling characteristic. The fifth characteristic, which is obtained by synthesizing at an appropriate ratio, obtains a nearly flat characteristic 43.
The figure is an explanatory diagram showing the configuration of an embodiment of the present invention according to the above principle.

In the figure, the difference from the proposed example in FIG. 2 is that a resistor 22 is newly inserted in series with the capacitor 20 of the time constant circuit in the reference waveform generating circuit 21.

The initial value is biased by this resistor 22 and input to the differential amplifier 16, and the initial value i of the current waveform controlled characteristic 33 in FIG.

is set.

Therefore, the differential amplifier 16 is configured so that the feedback circuit is not inserted up to the intersection a of the characteristics 31 and 33, so that the uncontrolled characteristic 31 is switched to the control characteristic 33 at the intersection a.

Other embodiments of the present invention are shown in FIGS. 6 and 7.

FIG. 6 shows the coil current waveform of the constant current type magnet drive circuit, and FIG. 7 shows an example of the constant current type magnet drive circuit.

In the waveform of FIG. 6, 34 indicates the current flowing through the coil, which is the current i.

A current waveform 35 shows a case where the current is not controlled, and a coil current determined by the power supply voltage and the coil constant flows.

Assume now that in the case of no current control, the waveform 36 appears when the coil constant changes due to temperature rise.

As shown by a waveform 34 in such a magnet system, when current is controlled, an uncontrolled current is applied to the coil between ob and b, and the current is controlled after point b.

Furthermore, when the resistance component of the coil increases due to the temperature rise of the coil and changes from waveform 35 to waveform 36, the part where the current is not applied becomes 0-b', and the time of 0-b and o
-b' time is longer than ob' time.

Here, we pay attention to the following relationship.

(1) Magic level increase → coil resistance γ.

When the number of dogs increases, i decreases between 0 and b', and a delay (increase) in the magnet operation time occurs between 0 and b'.

(2) Temperature rise → Change in shape and dimensions of mechanical parts → Magnet operation time becomes faster (reduced).

Therefore, i is adjusted so that the increase in (1) and the decrease in (2) are canceled out.

A waveform 35 can be set. The circuit diagram of the embodiment shown in FIG. 7 is configured to apply a constant level voltage to the reference voltage input terminal 18 of the differential amplifier 16, and is the same as the embodiment shown in FIG. 5 except that the waveform of this reference voltage is different. .

That is, it is considered that the resistor 22 in FIG. 5 is opened and a constant voltage is applied.

Therefore, the operating principle is exactly the same for both.

i in FIG.

In FIG. 7, the waveform 35 is set such that the voltage applied to the reference voltage input terminal and the power supply voltage 1E are matched to the characteristics of the magnet 10 so that the change in operating time is minimized.

As explained above, according to the present invention, the current waveform controlled characteristic and the uncontrolled characteristic are combined to compensate for the influence of resistance and shape change due to temperature change as a whole, and the operating time of the hammer magnet, that is, the printing It becomes possible to hold the timing almost constant.

Of course, since uncontrolled characteristics are included in one part, some influence of voltage fluctuations in this part remains, but the degree of influence is small and it is possible to sufficiently reduce printing deviation.

In the above embodiments, the method according to the proposed example was used as the current waveform control method, but it goes without saying that the present invention is not limited to this and can be applied to other current waveform control methods.

[Brief explanation of the drawings] Fig. 1 is a general explanatory diagram of the hammer/magnet section of a line printer, Fig. 2 is an explanatory diagram showing the configuration of a conventional proposed example, and Fig. 3 is an explanatory diagram showing the configuration of a conventional proposed example.
4 and 4 are principle explanatory diagrams based on the characteristics of the conventionally proposed example and the characteristics of the present invention compared thereto, FIG. 5 is an explanatory diagram showing the configuration of the embodiment of the present invention, and FIGS. 6 and 7 are It is an explanatory diagram of another embodiment of the invention, in which 10 is a magnet.
Coil, 11 is the same resistance, 12 is the same inductance, 13
are switching transistors, 14, 19, and 22 are resistors, 15 is a control pulse amplification transistor, 16 is a differential amplifier, 17 is a diode, 18 is a reference waveform generation transistor, 20 is a capacitor, and 21 is a reference waveform generation circuit. show.

Claims (1)

[Claims] 1. In a magnet drive circuit consisting of a circuit that detects the current flowing through the magnet coil and a circuit that controls the current given to the magnet coil to a predetermined value using a signal from the detection circuit, the magnet operating time due to temperature changes in the magnet coil The change in the magnet drive circuit's operating time is adjusted at such a rate that the change in the magnet operating time due to temperature changes in the magnet mechanism portion etc. is canceled out, and the change in the magnet operating time due to temperature changes is minimized. A magnetic drive system characterized by having a region in which the current is not controlled.