JPH0252633B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a printing device that can set printing pressure to an optimum value.

[Technical background of the invention and its problems]

Some printing devices built into electronic typewriters, etc., have a age wheel with type formed on its tip placed close to the platen on which the paper to be printed is set, and a printing ribbon interposed between the paper and the type. There are some printers that are configured to print by hitting the above-mentioned type characters on paper via a printing ribbon with a hammer driven by a hammer magnet.

In a printing device having such a configuration, the density of the characters printed on the paper approximately corresponds to the magnitude of the impact force when the hammer strikes the type on the paper.
The magnitude of this impact force depends on the amount of energy of the current that is pulsed through the excitation coil of the hammer magnet when a print command signal is input from the keyboard, storage section, or the like. Therefore, in conventional printing devices, the amount of current energy is fixedly set to a predetermined constant value that is considered to give the optimum character density.

However, in an actual printing device, the magnitude of the impact force when the hammer hits the type against the paper is determined not only by the amount of current energy flowing through the excitation coil of the hammer magnet, but also by changes in the rigidity of the hammer, dage wheel, etc., and dimensional accuracy. , it also varies greatly depending on mechanical factors such as installation accuracy. Therefore, in order to achieve the best density of printed characters for each printing device at the time of product shipment or use, the current applied to the excitation coil of the hammer magnet should be adjusted while taking into account the mechanical factors mentioned above. The amount of energy, that is, the printing pressure converted into the amount of current energy must be set.

However, until now, no criteria or method for determining whether the density of printed characters is the best has been established, so each adjuster or printing device has to determine the density of the printed characters that has been adjusted as the best density. There was a problem that caused a difference. Therefore, there is a problem in that the print quality varies depending on the printing device, and the overall quality and reliability deteriorate.

[Purpose of the invention]

The present invention has been made based on these circumstances, and its purpose is to achieve uniform print density across each device by printing test characters that can easily determine the reference density. The object of the present invention is to provide a printing device that can obtain uniform printing quality and maintain uniform printing quality.

[Summary of the invention]

In the printing device of the present invention, a plurality of test printing pressures are set in the range from a printing pressure state of almost zero to a printing pressure state that sufficiently exceeds the normal printing pressure, and each set printing pressure designation data is temporarily stored. Print a reference character indicating the starting position on the paper. Next, a test printing means is provided for printing a plurality of identical test characters by sequentially increasing the printing pressure from the lowest to the lowest, starting from the adjacent character area of the printed reference character and corresponding to the aforementioned printing pressure designation data. ing. Further, a printing pressure setting means is provided which can arbitrarily set the printing pressure of type against the paper during normal printing.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block configuration diagram showing a printing device, and numeral 1 in the figure is a CPU (central processing unit) containing various arithmetic circuits, command registers, etc. this
CPU1 has data bus 2 and address bus 3.
A ROM 4 in which program data for the CPU 1 to control various parts is stored, and
Each RAM 5, which stores various print command data from a keyboard (not shown), etc., is controlled. The CPU 1 also includes a wheel control circuit 8 that controls a wheel drive motor 7, which is a pulse motor or the like to which a dage wheel 6 is attached, and a printing pressure setting means that adjusts the current value flowing to the excitation coil of the hammer magnet 9. A hammer drive circuit 11 sends an excitation signal a to the printing pressure adjustment circuit 10 of the printer, a ribbon feed control circuit 13 controls the ribbon feed device 12, a carriage control circuit 15 controls the movement of the carriage 14, and a feeder (paper feed) 16
an input port 19 to which a test start signal from a control switch 18 to start test printing is input, and a timer circuit 2 to set the pulse width of the excitation signal a.
0, etc. are connected via the data bus 2.

FIG. 2 shows a schematic diagram of the print head section, which is comprised of the age wheel 6, hammer magnet 9, ribbon feeding device 12, etc. That is,
A platen 22 that is connected to a feeder 16 (not shown) and sets paper 21, and a ribbon feeding device 12.
A print ribbon 23 set in the print head, a type 24 attached to the tip of the dage wheel 6, and a hammer 25 are arranged in a straight line. The hammer 25 is attached to one end of a support rod 27 that is pivotally supported by a support shaft 26, and a hammer magnet 9 is disposed adjacent to an iron plate 28 attached to the other end of the support rod 27. Therefore, when a current is applied to the excitation coil of the hammer magnet 9, a magnetic attraction force acts on the iron plate 28, the support rod 27 rotates, and the hammer 25 moves the type 24 onto the paper 21 set on the platen 22. It is configured such that characters are printed on the paper 21 by typing.

The printing pressure adjustment circuit 10 is configured as shown in FIG. 3, for example. That is, a print command signal input from the CPU 1 to the hammer drive circuit 11 via the data bus 2 is converted into a pulse-like excitation signal a shown in FIG. 4 within the hammer drive circuit 11, and is output from the output terminal. Ru. The excitation signal a sent from the hammer drive circuit 11 is sent to the buffer 3.
1, is input to the positive input terminal of the differential amplifier 33 via the resistor 32. The output signal of this differential amplifier 33 is inputted to the base terminal of a transistor 35 via a resistor 34. Furthermore, the collector output terminal of this transistor 35 is connected via a resistor 36 to the transistor 3 for controlling the current of the hammer magnet 9.
It is input to the base terminal of 7. The emitter terminal of this transistor 37 is connected to a DC power supply ( _Vpp ) for supplying current energy to the excitation coil 38 of the hammer magnet 9, and the collector output terminal is connected to one end of the excitation coil 38. . The excitation current output from the collector output terminal is discharged to the ground via the excitation coil 38 and the characteristic improvement resistor 39, but a part of the current flows through the voltage detection circuit 40 connected in parallel to the characteristic improvement resistor 39.
flows. As shown in the figure, this voltage detection circuit 40 is composed of two voltage dividing resistors 41a and 41b and one variable resistor 42, and the detected voltage obtained from the movable terminal of this variable resistor 42 is transmitted through a resistor 43. It is input to the negative side input terminal of the differential amplifier 33. Note that a series circuit including a resistor 44 and a capacitor 45 is inserted between the positive input terminal and the output terminal of the differential amplifier 33. This series circuit lowers the oscillation frequency of the chopper included in the excitation current b of the excitation coil 38 shown in FIG. 4 due to the differential amplifier 33 to an appropriate value. Further, a diode 46 for preventing backflow is inserted between the collector output terminal of the transistor 37 and the ground.

The CPU 1 is configured to control each section as follows according to a program stored in the ROM 4 when a key input signal is input from, for example, a keyboard (not shown). That is,
The CPU 1 sends control signals to the carriage control circuit 15, feeder control circuit 17, and ribbon feed control circuit 13 to drive the carriage 14, feeder 16, and ribbon feed device 12, respectively. Also,
The CPU 1 sends a command signal to the wheel control circuit 8, and controls the dage wheel 6 so that the type 24 corresponding to the key input signal is positioned in front of the platen 22.
controls the rotation of the wheel drive motor 7 to which the wheel drive motor 7 is attached. Furthermore, a print command signal is sent to the hammer drive circuit 11, and a pulsed excitation signal a as shown in FIG. 4 is outputted to the output end of the hammer drive circuit 11. Therefore, the output signal of the differential amplifier 33 has a waveform obtained by amplifying the excitation signal a when no voltage is applied to the negative input terminal. As a result, the transistor 37 turns on and off in response to the excitation signal a, and an excitation current b shown in FIG. 4 flows through the excitation coil 38, so that characters are printed on the paper 21 as described above. A part of this excitation current b flows to the voltage detection circuit 40. Therefore, a voltage is detected at the movable terminal of the variable resistor 42, and this voltage is input to the negative input terminal of the differential amplifier 33. As a result, this detected voltage becomes approximately the same voltage level as the excitation signal a output from the hammer drive circuit 11, so the output voltage of the differential amplifier 33 decreases. Therefore, the transistor 37 is turned off, and the excitation current b decreases to zero. Then,
Current no longer flows through the voltage detection circuit 40, the potential difference between the positive input terminal and the negative input terminal of the differential amplifier 33 increases again, and the output voltage of the differential amplifier 33 increases. As a result, the exciting current b increases again. By repeating these actions continuously,
As shown in FIG. 4, it is possible to maintain the level of excitation current b within a certain range when excitation signal a is applied. The current level of this excitation current b can be changed from state A to state B and state where no detection voltage is input to the negative input terminal of differential amplifier 33 by changing the position of the movable terminal of variable resistor 42 of voltage detection circuit 40. It is possible to change the state. Therefore, by adjusting the resistance value of the variable resistor 42, the current value of the excitation current b, that is, the printing pressure, can be freely set within a certain range.

Further, the CPU 1 is configured to perform test printing operations based on the flowchart of FIG. 6 when a test start signal for starting test printing is inputted from the control switch 18 through the input port 19. That is, when the control switch 18 is turned on, as shown in FIG.
Set to the printing device shown in the figure. Next, a printing pressure parameter PP indicating the density of characters printed at P1 is set to a value higher than the normal printing pressure.

The printing pressure parameter PP as printing pressure designation data is set as follows. In other words, the density of the characters printed on the paper corresponds to the amount of current energy flowing to the excitation coil of the hammer magnet 9, so if the pulse width T and peak value H of the excitation signal a shown in FIG. Concentration varies. In the printing pressure parameter PP of this embodiment, the peak value H is constant, and the pulse width T is set by the timer circuit 20.
With the signal from T=0, that is, pulse widths from zero printing pressure to a printing pressure that sufficiently exceeds normal printing density are set at equal intervals as shown in FIG. Therefore, each time the printing pressure parameter PP is increased by one step, the pulse width T increases and the density increases.

After setting the printing pressure parameter PP to the normal printing pressure or higher in P1, print the above reference character "".
When printing is completed, a control signal is sent to the carriage control circuit 15 to increase the carriage position CARI by one character. Then, a character counter (text CNT) indicating the number of prints of the test character "A" is cleared to zero, and the above-mentioned printing pressure parameter PP is also cleared to zero. Next, at P2, check the character counter (sentence
After confirming that CNT) has not reached the set number N (N=11 in the embodiment) of the printing pressure parameter PP, the test character "A" is set at the printing position shown in FIG. Then, the printing pressure parameter PP is initially set to zero, and this printing pressure parameter PP
Print with the printing pressure set in (initially zero printing pressure). After printing, the carriage position CARI and character counter (text CNT) of the carriage 14 are counted up, and the printing pressure parameter PP is increased by one step. After increasing the printing pressure parameter PP, the process returns to P2, and it is determined whether the character counter (sentence CNT) has reached the set number N. If it has not reached the set number N, the test character "A" is printed again. In this way, the test character "A" is continuously printed in the test printing area 51 as shown in FIG. 7 while increasing the printing pressure parameter PP one step at a time. Then, at P2, the character counter (sentence CNT) is set to N
When it reaches this point, a control signal is sent to the feeder control circuit 17 to drive the feeder 16 and feed the paper. Furthermore, after the carriage 14 is returned to its original position, the test printing operation is completed.

When the test printing operation is completed, the test printing area 51 of the paper 21 has a test character "A" whose density increases sequentially from the adjacent character area to the right side of the reference character I, as shown in the first column of FIG. " is printed continuously.

With a printing device configured in this way, the printing pressure, that is, the density, can be increased by a predetermined number of characters (5 in the embodiment) from the readable start character 52 when viewed from the reference character "I" side of the printed test character. Characters located in the increasing direction are defined as standard printing pressure characters 53 in this printing device, and this standard printing pressure character 5
The printing pressure in step 3 is set as the standard printing pressure, that is, the standard density. Then, when setting the actual printing pressure, the pulse width T of the excitation signal a is adjusted so as to match the printing density of the reference printing pressure character 53, or the excitation signal a is used in the printing pressure adjustment circuit 10 described above. Adjust the peak value H (current value) of

Generally, when the printing pressure parameter PP is set to a certain number or more at equal intervals, the number of characters from the legible start character 52 to the standard printing pressure character 53 (standard density character) is almost constant. For example, if a test character "A" is printed in a printing device in which the printing density appears higher than usual due to the adjustment value of the printing pressure adjustment circuit 10 or mechanical factors, the second
As shown in the column, the legible starting character 52 is the first
Move to the left of that column. However, the number of characters up to the standard printing pressure character 53 (standard density character) is the same value as that in the first column.

With such a printing device, when the control switch 18 is turned on at the time of shipment or use, a test character "A" as shown in FIG. 7 is automatically printed out on the paper 21. Then, a character located in a direction in which the density increases by a predetermined number of characters (5 in the embodiment) from the readable start character 52 may be set as the reference printing pressure character 53. Therefore, as a means of determining the standard printing pressure character 53 (standard density character), there is no need to visually determine the density difference, so that differences in the determination result may occur due to mechanical factors of the adjuster or the printing device. There isn't.

As a result, uniform print density can be achieved across each device.
Pulse width T of excitation signal a or printing pressure adjustment circuit 1
This can be obtained by adjusting the peak value H at 0.

〔Effect of the invention〕

As described above, according to the present invention, a plurality of test characters whose print densities sequentially change are automatically printed out on a sheet of paper. Therefore, a character having a standard density can be easily selected from among the plurality of printed characters. Then, a printing pressure corresponding to the reference density can be set using a printing pressure adjustment circuit (printing pressure setting means). Therefore, uniform print density can be obtained across each printing device, and uniform print quality can be maintained.

[Brief explanation of the drawing]

The figures show a printing device according to an embodiment of the present invention, in which Fig. 1 is a block configuration diagram, Fig. 2 is a schematic sectional view showing the main parts, and Fig. 3 is a circuit diagram showing the main parts. , FIG. 4 and FIG. 5 are waveform diagrams showing the operation, FIG. 6 is a flowchart showing the test printing operation, and FIG. 7 is a diagram showing the test printing results. DESCRIPTION OF SYMBOLS 1...CPU, 6...Dage wheel, 9...Hammer magnet, 10...Print pressure adjustment circuit, 11...Hammer drive circuit, 12...Ribbon feeding device, 14...
Carriage, 16...Feeder, 18...Control switch, 20...Timer circuit, 21...Paper, 2
3... Printing ribbon, 24... Type, 25... Hammer,
33... Differential amplifier, 35, 37... Transistor,
38... Excitation coil, 40... Voltage detection circuit, 42...
Variable resistance, 52...Readable start character, 53...Reference printing pressure character.

Claims (1)

[Claims] 1. In a printing device that prints characters on paper by energizing a hammer magnet that drives a hammer that strikes type for a predetermined period of time, the printing pressure of the type on the paper ranges from a state of approximately zero to a state that sufficiently exceeds the normal printing pressure. A printing pressure specification data storage means for setting multiple stages in the range up to and storing each set printing pressure specification data, printing a preset reference character at the printing start position of the paper, and printing the printed reference character. a test printing means for sequentially printing predetermined identical test characters in descending order of printing pressure according to each printing pressure designation data stored in the printing pressure designation data storage means, starting from an adjacent character printing area; 1. A printing device comprising: printing pressure setting means for arbitrarily setting the printing pressure of type on paper during normal printing.