JPH0592585A - Impact head drive circuit - Google Patents

Abstract

PURPOSE:To control driving current to the optimum state with an easy circuit structure by means of driving solenoids dependent on an energizing time which is a stored energizing time corrected by driving voltage of the solenoids when a current value of the solenoids is not detected. CONSTITUTION:An initial value of energizing time for solenoid; S1-SN for driving a plurality of wires is set by a means 3. Current values and drive voltages of the solenoids S1-SN are detected and measured by means 4 and 20, respectively. The measured drive voltage is stored in a means 21 and the stored drive voltage and the measured drive voltage are calculated at a means 22. Further, based on the detected current value, the energizing time for the solenoid is measured at a means 1 and the energizing time is stored in a means 2. Dependent on the detected current value, the energizing time is controlled at the means 22. On the other hand, when the current value is not detected, the solenoid is driven by a means 60 dependent on the energizing time whose stored value is corrected with a calculation value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impact head drive circuit.

[0002]

2. Description of the Related Art A conventional impact head drive circuit does not detect a drive current but simply controls the energization time of all solenoids according to a drive voltage value according to a preset energization time, or JP-B-59-. As shown in FIG. 45209 (shown in FIG. 10), all the wire driving solenoids are provided with the drive current value detection circuit 90, and the drive currents of the solenoids are individually controlled according to the output signal of the drive current value detection circuit 90.

[0003]

However, when the drive current is not detected, the drive current waveform fluctuates due to fluctuations in voltage, environmental temperature, or fluctuations in the resistance value of the solenoid due to heat generated by energizing the solenoid. As a result, variations in print quality and the response capability of the wire when the solenoid is driven are unavoidable. It goes without saying that individual solenoids can always be driven in an optimal state by detecting and controlling the drive currents of all solenoids, but the adjustment work of the circuit that determines the current detection value must be performed for all solenoids. Since it is necessary, it has a drawback that the adjustment becomes complicated.

The present invention solves such a problem. An object of the present invention is to optimize the drive current to the solenoid with a circuit configuration that facilitates the adjustment work of the circuit that determines the current detection value. It is to provide a driving circuit for controlling.

[0005]

SUMMARY OF THE INVENTION An impact head drive circuit according to the present invention is an impact head drive circuit having a plurality of wire drive solenoids, wherein initial value setting means for setting an initial value of energization time to the solenoids. Drive means for temporarily storing the drive voltage measured by the drive voltage measuring means when energizing the current value detecting means provided only for the solenoid of the unit, the drive voltage measuring means for the solenoid, and the solenoid having the current value detecting means Energization time to the solenoid by the voltage storage means, the drive voltage calculation means for calculating the drive voltage stored in the drive voltage storage means and the drive voltage measured by the drive voltage measuring means, and the output signal output from the current value detection means. Energization time measuring means for measuring the current, energization time storage means for temporarily storing the energization time obtained by the energization time measuring means, current value detection An energization time control means for controlling an energization time to a solenoid being driven at the time of detecting a current value by an output signal from the stage, and an energization time stored in the energization time storage means when the current value is not detected. The present invention is characterized by having an energization time applying means for driving the solenoid with the energization time corrected by the above result.

[0006]

The current value is detected by the current value detecting means provided in a part of the solenoids, the drive voltage measuring means measures the drive voltage of the solenoid when the current value is detected, and the measured drive voltage is the drive voltage storing means. Is temporarily stored by. When the current value is detected, the output signal of the current value detection means
The energization time control means controls the energization time of the solenoid being driven, the energization time measurement means measures the energization time to the solenoid, and the measured energization time is temporarily stored by the energization time storage means. When the current value is not detected, the solenoid is driven by the energization time stored in the energization time storage means by the energization time application means, the energization time being corrected by the result of the drive voltage calculation means.

[0007]

1 is a circuit block diagram showing an embodiment of the present invention.

In the figure, S1 to SN are wire-driving solenoids provided in the head (subscript N is the total number of solenoids, and the same applies hereinafter).

The current i flowing through each solenoid is expressed by the following equation.

[0010]

[Equation 1]

The value of the current flowing through the solenoid changes due to the fluctuations of the parameters E, R, L, P and T in the above equation. However, in one head, the magnetic circuit of each solenoid is mostly composed of a common member, and since the number of turns T is the same, the variation in the inductance L among the solenoids is very small. Further, since the number of turns of each solenoid is the same, the resistance R of the solenoid is almost equal under the same temperature. Therefore, most of the fluctuation of the current i flowing through the solenoid is due to the fluctuation of the resistance value R and the fluctuation of the drive voltage E due to the temperature change.

Normally, it can be considered that the temperature in the head is almost uniform, and since the drive voltage E is commonly applied to each solenoid, the current of only some of the solenoids present in one head is eventually determined. Even if the value is detected and the drive current is controlled, a large difference does not occur as compared with the case where the drive current is controlled individually.
The present invention pays attention to this point, and 4 in FIG. 1 is a current value detecting means provided only in a part of the solenoids which characterizes the present invention.

In this embodiment, the drive current is detected only by one S1. D1 to DN are diodes, ZD1 to ZDN
Is a Zener diode that constitutes a back electromotive force absorption circuit when the solenoid is off.

Reference numeral 20 is a drive voltage measuring means for measuring the drive voltage. Reference numeral 21 is a drive voltage storage means for storing the drive voltage measured by the drive voltage measuring means 20 when the solenoid S1 is energized. Reference numeral 22 is a drive voltage calculation means for calculating the drive voltage stored in the drive voltage storage means 21 when the solenoid S1 is energized and the drive voltage measured by the drive voltage measuring means 20.
Reference numeral 3 denotes an energization time initial value setting means, which is an energization time t0 of an initial value that is preset in a preset state such as when the power is turned on.
Is set in the energization time storage means 2. Reference numeral 4 denotes a current value detecting means, which outputs a FULL signal when the current value flowing through S1 reaches a predetermined value that produces a predetermined optimum drive. An energization time control means 5 terminates energization of the solenoid being driven when the FULL signal is output from the current value detection means 4, and the solenoid is operated so as to perform the optimum driving according to the temperature and the driving voltage at that time. Control the energization time. Reference numeral 60 denotes energization time applying means which energizes the solenoid S1 and drives the solenoid for the energization time controlled by the energization time control means 5 when detecting the current value, and when the solenoid S1 is not energized and the current value is not detected. The solenoid is driven with the energization time to which the energization time t0 set in the energization time storage means 2 is corrected by the calculation result of the drive voltage calculation means 22. Further, at the time of printing, a solenoid to be energized is selected by an energizing solenoid selection signal HDm (subscript m is an integer from 2 to N, which will be described below) from an external control circuit (not shown). When the solenoid S1 is energized, the energization time measuring means 1 measures the energization time t1 and the driving voltage which are the optimum driving in accordance with the temperature and the driving voltage at that time, and sets the energization time storage means 2 in place of the initial value t0. To be done. Until S1 is driven again, all the solenoids S1 to SN are driven by the energizing time applying means 60 for the energizing time in which the energizing time t1 is corrected by the result of the driving voltage calculating means 22. Next, when S1 is driven again, it is energized so that it becomes the optimal drive according to the temperature and driving voltage at that time, the energization time t2 and the driving voltage at that time are measured, and all solenoids S1 to SN are driven by S1 again. Until this is done, the energization time t2 is driven with the energization time corrected by the result of the driving voltage calculation means 22. After that, the energization time and the driving voltage at that time are measured and stored so that each solenoid S1 is driven optimally, and all the solenoids selected by the energization solenoid selection signal are driven.

The present invention has been described above with reference to block diagrams, but each constituent means will be described below in more detail with reference to the drawings.

FIG. 2 shows the current value detecting means 4, the energization time controlling means 5, the driving voltage measuring means 20, the driving voltage storing means 21, the driving voltage computing means 22, the energizing time applying means 60 and the energizing shown in FIG. It is an embodiment of a detailed circuit of time measuring means 1, energization time storage means 2, energization time initial setting means 3. In this embodiment, the current value detecting means 4 detects that the drive current value reaches a preset value.

The drive current of the solenoid S1 is detected by the resistor Rref connected in series to the drive element Q1. The microprocessor MPU which controls the driving operation of the head outputs the address decode signal CSO and selects the data bus 10 as the data to be output in the data selector 6, and the latch 7 which is the energization time storage means 2 has the solenoid energization time as the initial data. The data corresponding to is output in advance. At the timing when the initial data is not output to the latch 7, the data selector 6 selects and outputs the output signal of the counter 5 which is the energization time measuring means 1.

The operation of the circuit shown in FIG. 2 will be described below with reference to the timing signal diagram of FIG. Reference characters PTS and CLKO in the figure denote a print timing signal and a clock signal output from an external control circuit (not shown).

First, a solenoid having a current value detecting means
The energizing operation in the period A in which S1 is energized will be described. When the print timing signal PTS is input, the latch 31 which is the drive voltage storage means 21 inputs the drive voltage data V1 ′ output from the A / D converter 30 which is the drive voltage measurement means 20. When the print timing signal PTS is input while the HD1 signal is on, the output of the flip-flop 9 which is the energization time control means 5 is turned on, which is the base signal of the transistor Q1.
Since the H1 signal turns on, energization of the solenoid S1 is started. The voltage corresponding to the current detection value set by dividing the reference voltage V2 with resistors RA and RB is input to the-terminal of the comparator CMP, and the current value signal Crnt is input to the + terminal of CMP, and the drive current is detected. When the value is reached, the FULL signal turns on, and as a result, the output of the flip-flop 9 turns off and the H1 signal turns off. The counter 5 which is the energization time measuring means 1 has the clock signal counting operation enabled while the energization signal H1 is on, that is, the period during which the solenoid S1 is energized, and counts CLKO. Stores the count value of the counter 5 as the energization time data Ta when the H1 signal is turned off. When the HD1 signal turns on, the output of the inverter INV-A turns off, and as a result, the output of the AND-B signal turns off.
The energization selection signal HDm of the solenoid Sm is output as an Hm signal by the energization signal H1 at the AND gate ANDm.

Next, the energizing operation in the period B in which the solenoid S1 is not energized will be described. As shown in FIG. 4, Va>Vb>
When the solenoid is driven with a voltage of Vc, the current waveform is i
a, ib, ic, and drive voltage is V as shown in Fig. 5.
The time required to reach the predetermined detection current value at a, Vb, and Vc is ta, tb, and tc. Therefore, when the drive voltage in the non-energized period B changes from the drive voltage in the period A in which the solenoid S1 is energized, the manner of rising of the current changes, and the time until the current reaches the preset current value changes. In order to reduce this change and set the reaching current value to the set value, period A
The energization time stored in is corrected. Driving voltage calculation means 2
The arithmetic element ALU1 which is 2 subtracts the drive voltage data PV1 output from the latch 31 from the drive voltage data V1 ′ output from the A / D converter 30, and the arithmetic element MUL outputs the drive voltage value at the time of driving output from the ALU1 and the solenoid. When the value dV of the voltage difference from the drive voltage at the time of energizing S1 is calculated and converted so as to be the energization time data dT of the time difference to reach the preset drive current value, and the arithmetic element ALU2 is dV> 0 When Tb <Tp and dV <0
The energization time data dT and the energization time data Tp output from the latch 7 are calculated so that Tb> Tp. When the print timing signal PTS is turned on, the timer 8 inputs the energization time data Tb output from the ALU2, and turns on the gate signal HON2 until the clock signal CLKO is input for the energization time data. HD
Since the 1 signal is off, the output of the inverter INV-A is turned on, and as a result, the output of the AND-B signal becomes HON2, and the energization selection signal HDm of the solenoid Sm is the AND gate ANDm and the Hm signal is generated by the gate signal HON2 Is output.

As described above, when the solenoid S1 for detecting the current value is energized, the solenoid for driving is energized until it is detected that the driving current value of the solenoid S1 reaches a preset value, and the energizing time and the driving voltage at that time are applied. Is measured and stored, and when the solenoid S1 is not energized, the solenoid is driven with the energization time in which the stored energization time is corrected by the calculation result of the stored driving voltage and the driving voltage during driving.

FIG. 6 shows the current value detecting means 4, the energizing time controlling means 5, the driving voltage measuring means 20, the driving voltage storing means 21, the driving voltage calculating means 22, the energizing time applying means 60 and the energizing shown in FIG. It is an embodiment of a detailed circuit of time measuring means 1, energization time storage means 2, energization time initial setting means 3. In this embodiment, the current value detecting means 4 detects that the integrated value of the solenoid drive current reaches a preset value.

The drive current of the solenoid S1 is detected by the resistor Rref connected in series with the drive element Q1. The microprocessor MPU which controls the driving operation of the head outputs the address decode signal CSO and selects the data bus 10 as the data to be output in the data selector 6, and the latch 7 which is the energization time storage means 2 has the solenoid energization time as the initial data. The data corresponding to is output in advance. At the timing when the initial data is not output to the latch 7, the data selector 6 selects and outputs the output signal of the counter 5 which is the energization time measuring means 1.

The operation of the circuit shown in FIG. 6 will be described below with reference to the timing signal diagram of FIG. Reference characters PTS and CLKO in the figure denote a print timing signal and a clock signal output from an external control circuit (not shown).

First, a solenoid equipped with a current value detecting means.
The energizing operation in the period A in which S1 is energized will be described. When the print timing signal PTS is input, the drive voltage storage means 21
The latch 31 is the A / D which is the drive voltage measuring means 20.
The drive voltage data V1 ′ output from the converter 30 is input. When the print timing signal PTS is input while the HD1 signal is on, the output of the flip-flop 9 which is the energization time control means 5 is turned on, which is the base signal of the transistor Q1.
Since the H1 signal turns on, energization of the solenoid S1 is started. When the H1 signal turns on and the switching element F1 turns off, the operational amplifier OP, the resistor R1, the resistor R2, and the capacitor C operate as an integrating circuit of the Crnt signal. Reference voltage-Vr is resistor RC, R
The voltage corresponding to the integrated value of the current divided by D is input to the + terminal of the comparator CMP, the current value integration signal SUM is input to the-terminal of CMP, and the integrated value of the drive current to the solenoid S1 is When the set detection value is reached, the FULL signal turns on, and as a result, the flip-flop 9 turns off and the H1 signal turns off. When the H1 signal turns off, the switching element F1 turns on and the operational amplifier
The output value of the Crnt signal integrator circuit including OP, resistor R1, resistor R2, and capacitor C is reset to zero. The counter 5 which is the energization time measuring means 1 has the clock signal counting operation enabled while the energization signal H1 is on, that is, the period during which the solenoid S1 is energized, and counts CLKO. Stores the count value of the counter 5 as the energization time data Ta when the H1 signal is turned off. When the HD1 signal turns on, the output of the inverter INV-A turns off, and the energization selection signal HDm of the solenoid Sm changes to AND gate A.
It is output as an Hm signal by the energization signal H1 at NDm.

Next, the energizing operation in the period B in which the solenoid S1 is not energized will be described. As shown in FIG. 8, Vd>Ve>
When the solenoid is driven by the voltage Vf, the current integral waveform becomes like sumd, sume, and sumf. As shown in FIG. 9, when the drive voltage is Vd, Ve, and Vf, the time to reach the predetermined detected current integral value is Like td, te, tf.
Therefore, when the drive voltage in the non-energized period B changes from the drive voltage in the period A in which the solenoid S1 is energized, the way the current rises changes, and the time until the integrated value of the current reaches the preset integrated value changes. To do. The energization time stored in the period A is corrected in order to reduce this change and set the reaching current integral value to the set value. The arithmetic element ALU1 is the A / D converter 3
The drive voltage data PV1 output from the latch 31 is subtracted from the drive voltage data V1 ′ output from 0, and the arithmetic element MUL outputs a voltage difference between the drive voltage value output by the ALU1 and the drive voltage value when the solenoid S1 is energized. Value dV is calculated and converted so as to become energization time data dT of the difference in time to reach the preset integral value of the driving current, and when the calculation element ALU2 is dV> 0, Tb> T
When p and dV <0, the energization time data dT is set so that Tb> Tp.
The energization time data Tp output from the ALU2 is calculated. When the print timing signal PTS is turned on, the timer 8 inputs the energization time data Tb output from the latch 7 and outputs the clock signal CLKO.
Gate signal HON2 for the period until the power-on time data is input
Turn on. Since the HD1 signal is off, inverter I
NV-A output is turned on, and as a result, AND-B signal output is HON2
The energization selection signal HDm of the solenoid Sm is output as an Hm signal by the gate signal HON2 at the AND gate ANDm.

As described above, when the solenoid S1 for detecting the current value is energized, the solenoid for driving is energized until it is detected that the integrated value of the driving current value of the solenoid S1 reaches a preset value, and the energization time at that time is determined. Also, the drive voltage is measured and stored, and when the solenoid S1 is not energized, the solenoid is driven with the energization time corrected by the calculation result of the stored drive voltage and the drive voltage at the time of energization stored.

[0028]

As described above, according to the present invention, the characteristic of the fluctuation of the current value flowing in the solenoid in the same head is utilized, and the current value is detected by only some of the solenoids.
When energizing the solenoid provided with the current value detecting means, the energizing time of the solenoid to be driven is controlled by the output signal of the current value detecting means, and the energizing time to the solenoid and the driving voltage are measured and temporarily stored to obtain the current value. When the solenoid provided with the detection means is not energized, the solenoid is driven with the energization time corrected by the calculation result of the driving voltage storing the energization time stored in the energization time storage means and the driving voltage at the time of driving. In addition, it is possible to always drive the head coil under optimum conditions against temperature changes and voltage fluctuations, even though the circuit is easy to adjust the current detection value, ensuring high print quality and stable head response. You can gain the ability.

[Brief description of drawings]

FIG. 1 is a block diagram of a circuit according to an embodiment of the present invention.

FIG. 2 is a detailed circuit diagram of one of the block diagrams shown in FIG.

FIG. 3 is a timing signal diagram of the embodiment shown in FIG. 2 of the present invention.

FIG. 4 is a relational diagram of a drive current value and energization time.

FIG. 5 is a diagram showing a relationship between an energization time and a driving voltage until a certain current value is reached.

6 is another detailed circuit diagram of the block diagram shown in FIG. 1. FIG.

FIG. 7 is a timing signal diagram of the embodiment shown in FIG. 6 of the present invention.

FIG. 8 is a relationship diagram between a drive current integral value and a conduction time.

FIG. 9 is a diagram showing the relationship between the drive time and the energization time until a certain integrated current value is reached.

FIG. 10 is a conventional drive circuit diagram.

[Explanation of symbols]

 1 energizing time measuring means 2 energizing time storing means 3 energizing time initial value setting means 4 current value detecting means 5 energizing time controlling means 20 driving voltage measuring means 21 driving voltage storing means 22 driving voltage calculating means 60 energizing time applying means 90 current value Detection circuit Ta Measurement energization time data signal Tb Memory energization time data signal HD1 to HDN Energization solenoid selection signal H1 to HN Solenoid energization signal i1 to iN Solenoid drive current

Claims (1)

[Claims] 1. A drive circuit for an impact head having a plurality of wire driving solenoids, initial value setting means for setting an initial value of energization time to the solenoids, current value detecting means provided only for some solenoids, and solenoids. Driving voltage measuring means, driving voltage storage means for temporarily storing the driving voltage measured by the driving voltage measuring means when energizing the solenoid provided with the current value detecting means, and stored in the driving voltage storage means Drive voltage calculating means for calculating the drive voltage thus measured and the drive voltage measured by the drive voltage measuring means, energizing time measuring means for measuring the energizing time to the solenoid by the output signal output from the current value detecting means, An energization time storage means for temporarily storing the energization time obtained by the energization time measurement means, and an output signal from the current value detection means When the current value is detected, the energization time control means for controlling the energization time of the solenoid being driven, the energization time stored in the energization time storage means when the current value is not detected is determined by the result of the drive voltage calculation means. An impact head drive circuit, comprising: an energization time applying unit that drives a solenoid with a corrected energization time.