JPS5916935B2 - Line printer print misalignment correction circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a circuit for correcting printing misalignment caused by variations in hammer flight time and type moving speed of a line printer.

Conventionally, line printers have been widely used in which printing is performed by moving the type carrier to the printing position of the printer device and energizing the hammer magnet with a drive power supply, thereby aligning the timing of the impact of the hammer with the printing position. .

In this case, the time from the start of excitation until the hammer hits the type, that is, the hammer flight time, changes due to fluctuations in the drive power supply voltage and ambient temperature of the hammer magnet that drives the hammer.

Therefore, the hammer flight time varies by Tv seconds/V due to the driving power supply voltage and by Tth seconds/° C. due to the ambient temperature. Furthermore, if a motor such as a synchronous motor or an induction motor whose rotational speed depends on the power supply frequency is used as a drive source for the type carrier, the moving speed of the type will change due to fluctuations in the power supply frequency.

In addition, in the case of an induction motor, the moving speed of the type changes due to changes in printing and load around the conveyor. Furthermore, when a DC motor is used as a drive source, the moving speed of the type changes due to power supply voltage fluctuations and load fluctuations around the carrier. Therefore, if the hammer flight time is TF and the type moving speed is (1+α) higher than the normal speed, then if the hammer magnet is excited at the same timing, the hammer will hit the type at this time and at normal times. The position is shifted by α·TF-. As described above, the three main causes of printing misalignment are drive voltage related to hammer flight time, fluctuations in ambient temperature, and fluctuations in type moving speed.

SUMMARY OF THE INVENTION An object of the present invention is to provide a print misalignment correction circuit for a line printer that corrects the main causes of print misalignment to ensure normal hammer impact timing. In order to achieve the above object, the print misalignment correction circuit of the line printer of the present invention drives the type conveyor to sequentially pass the type to a printing position having a print hammer, and also includes means for detecting the timing of passage of the type. , a line printer comprising means for collating and selecting printed characters, and means for driving the printing hammer, and printing by exciting a hammer driving magnet with a drive current in accordance with the passing timing, the output cycle of the detection means; a conversion circuit that converts the moving speed of the type carrier calculated from the above into an analog voltage value; a circuit that is configured by an element whose output changes depending on the temperature and creates a voltage for the detected ambient temperature;
a circuit that creates a voltage with a waveform corresponding to the drive voltage by charging and discharging a voltage proportional to the voltage of a drive power source that drives the magnet at a predetermined time constant with the signal interval of the detection means as a period; It has means for weighting the output voltages from the three circuits to a predetermined ratio and mutually comparing the combined output of the two circuits with the output of the other circuits,
The present invention is characterized in that it includes a synthesis circuit that creates the delay time for the passage timing compensation from comparison matching points.

Hereinafter, the present invention will be explained in detail with reference to examples.

Generally, in line printer equipment, the type carrier or its first
A signal PSE emitter is obtained from the drive section, and as shown in FIG. Send to.

The print control section uses this signal PSE to know which characters the hammers of each digit are facing, and determines whether the hammer magnets of the digits facing the characters to be printed are excited all at once after a predetermined delay time τd. As shown in FIG. 2B, sequential excitation is performed at clock scanning timings, that is, one skew time, so that all digits (for example, 136 digits) are included between PSE pulses. However, this method is usually carried out by setting a reference value, and is subject to fluctuations in the magnet's drive power supply voltage,
Since fluctuations in ambient temperature and fluctuations in the moving speed of the type carrier are not particularly taken into consideration, deterioration in print quality is inevitable.

FIG. 2a is a schematic explanatory diagram showing the configuration of an embodiment of the present invention.

As shown in the figure, the output signal S of the same waveform shaping circuit 1 as in FIG. That is, it is inputted into the voltage compensation circuit 3 together with the driving voltage to obtain the output E, and then the outputs Ev and Eth are obtained by the type movement speed compensation circuit and the temperature compensation circuit 4,
These signals are combined by the combining circuit 5 to change the timing of generation of the signal PSE, and if necessary, sent to the print control unit via the delay circuit 6, thereby making it possible to reduce printing deviation. As shown in FIG. 2b, the hammer magnet control circuit of the printing control section is a series circuit in which a driving voltage V is applied to one terminal and grounded via a series resistor R, a hammer magnet L, and a switching element 10. An excitation signal after the PSE signal described above is added to drive the hammer.

FIGS. 3A and 3B show the operating characteristics of the output Ev of the voltage compensation circuit 3 shown in FIG. 2, and are diagrams for explaining the principle of the main part of the present invention.

The characteristic shown in the figure a is that the inverted signal of the signal S shown in the figure b is applied to the voltage compensation circuit 3, and the rise time is T with the time constant τ. The saturation value E1=KV, which is proportional to the driving voltage, is reached, and with the rise of the signal S, that is, the fall of the inverted signal, the characteristic changes to a falling characteristic with a time constant τ2. This falling characteristic is utilized for correction in the present invention. Now this output E is E. When , it is the standard output value when the type movement speed and ambient temperature indicate the standard values, and this E. It is assumed that the time T corresponding to , is the excitation start timing of the hammer magnet. Here, when the magnet drive voltage drops to 7, the characteristic falls to the saturation value ES=K7 shown by the broken line, and the reference output value E. The time to reach T changes from T1 to T(. The amount of variation in T, which corresponds to the change in the drive voltage, depends only on the time constant τ2. In other words, in the range where the variation in the drive voltage is not too large, the amount of variation in T1 is It is approximately proportional to the amount of variation in V. Therefore, a time constant τ2 is selected that matches the variation in T with respect to the drive voltage V, that is, the variation rate of the hammer flight time.On the other hand, the reference output value E.

When the voltage rises to E2, the time for the output to become E2 is T2, and conversely, when it decreases to E3, the time for the output to become E3 is T3. That is, when the moving speed of the type increases, the excitation timing of the hammer magnet must be accelerated, so the reference output value E. increases, and conversely, if the type movement speed decreases, the standard output value E. lower.
Similarly, if the hammer flight time becomes shorter as the ambient temperature rises, the reference output value E changes as the temperature rises. Conversely, if the hammer flight time becomes longer as the temperature rises, the reference output value E will increase as the temperature rises. lower. Therefore, in the present invention, the time T is determined by an inverted signal of the signal S.

On the other hand, the time Tr corresponding to the E value of the above-mentioned time constant τ2 falling characteristic is determined from the composite value of the correction output related to the fluctuation of the ambient temperature of the hammer magnet and the fluctuation of the type moving speed. Select this as the timing to start excitation of the hammer magnet. With this method, it is possible to correct printing deviations due to variations in type moving speed and ambient temperature, and to prevent deterioration in print quality.

FIG. 4 shows a specific circuit example of the voltage compensation circuit 3 shown in FIG.

In the figure, the inverted signal of the signal S is transferred to the switching element 1.
Voltage dividing resistors R,, R2 with driving voltage applied to one end through 1
A voltage dividing point is taken out, and a parallel circuit of a resistor R3 and a diode D1 is connected in series with this, and a capacitor C1 is connected in parallel to obtain an output Ev. In this case, the proportionality constant k in Fig. 3
is k=ClR,R2R,/R2, time constant τ1 during charging and discharging
, τ2 are obtained from τ,=R1+R2τ2=ClR3, and the required rise and fall characteristics can be set.

FIG. 5 shows a specific circuit example of the type movement speed compensation circuit section of the compensation circuit 4 of FIG. 3, and FIGS. 6A and 6B are diagrams for explaining its operation.

In FIG. 5, the timer 12 is activated by the signal S for a certain period of time T.
If the duration of the signal S is constant, the signal S itself may be used as is. This timer output is input to the base of the switching transistor 13, taken out from the collector to which a predetermined voltage +E4 is applied via a resistor R4, and passed through an integrating circuit consisting of a series resistor R5 and a parallel capacitor C2 to obtain an output Ev. That is, for the timer output shown in FIG. 6b which is applied intermittently, as shown by the waveform of the output Ev in FIG. is obtained. The time constants τ3 and τ4 during charging and discharging of this circuit are τ3
=(R4+R,)C2, τ4=R5C2.
If the time constants τ3 and τ4 are set sufficiently large with respect to the interval between the signals S, the output Ev is smoothed to a certain value, and at the same time, small speed fluctuations of the type carrier called jitter can be absorbed.
This output Ev decreases as the interval between the signals S increases because Tb becomes longer, and conversely increases as the interval between the signals S decreases, thus increasing and decreasing in accordance with the moving speed of the printed characters. Note that a temperature sensing element is used in the temperature compensation circuit section in the compensation circuit 4, and the temperature fluctuation output Eth is taken out and handled in the same manner as the above-described type movement speed Ev.

FIG. 7 shows a specific example of the synthesis circuit shown in FIG.

In the same figure, the temperature fluctuation output Eth of the temperature sensing element 14 to which voltage +E is applied and the fluctuation output E of the printing speed are adjusted to the correction factor through separate amplifiers 15 and 16 and resistors R6 and R7. The comparison value E is synthesized after being adjusted as follows. shall be. This value is compared with the output Ev from the voltage compensation circuit 3 shown in FIG. 2 by a comparator 17, and when they match, the excitation start timing for the hammer magnet is generated. Furthermore, instead of the temperature sensing element, a constant voltage diode such as a Zener diode can be used, and the characteristic of temperature fluctuations having different signs above and below a predetermined voltage can be utilized.

Furthermore, by providing a constant voltage diode to which such a predetermined voltage +E5 is applied in place of the power supply voltage +E4 in Figure 5, the circuit in Figure 5 alone can act as a compensation circuit for variations in type movement speed and ambient temperature. can do.

As explained above, according to the present invention, each compensation circuit compensates for the voltage fluctuation of one drive power source of the hammer magnet, the ambient temperature fluctuation, and the movement speed fluctuation of the type carrier, and each compensation circuit. It is equipped with a circuit that changes the excitation start timing of the magnet using an output that combines the outputs of
As a result, predetermined characters on the type carrier can be moved to the printing position in accordance with the impact timing of the hammer and printed, and printing quality can be significantly improved.

[Brief explanation of the drawing]

Figures 1A and b are explanatory diagrams of the conventional example, Figures 2A and b are schematic diagrams showing the configuration of the embodiment of the present invention, and Figures 3A and b are the
4, 5, and 7 are specific circuit examples of the main parts of the embodiment shown in FIG. 2a, and FIG. 6A
, b are explanatory diagrams of the operation of the circuit of FIG. 5, in which 1 is a waveform shaping circuit, 3 is a voltage compensation circuit, 4 is a type movement speed compensation circuit and a temperature compensation circuit, and 5 is a synthesis circuit.

Claims (1)

[Claims] 1. means for driving a type conveyor to sequentially pass the type to a printing position having a printing hammer, detecting the timing of passage of the type, and means for collating and selecting the type;
In a line printer that has a drive means for the printing hammer and performs printing by exciting a hammer drive magnet with a drive current in response to the passage timing, the speed of the type conveyor calculated from the output cycle of the detection means is A conversion circuit that converts the moving speed into an analog voltage value, a circuit that is composed of elements whose output changes depending on the temperature and creates a voltage corresponding to the detected ambient temperature, and a voltage of the drive power source that drives the magnet. a circuit that creates a voltage with a waveform corresponding to the drive voltage by charging and discharging a proportional voltage at a predetermined time constant with the signal interval of the detection means as a period; and a circuit that creates a voltage with a waveform corresponding to the drive voltage, and a predetermined ratio of the output voltages from the three circuits. and means for mutually comparing the outputs of the two circuits by weighting the outputs of the two circuits with the outputs of the other circuits, and a combining circuit for creating the delay time for the passage timing compensation from the comparison matching point. Features a printing misalignment correction circuit for line printers.