JPH0513066B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to print heads for wire dot printers.

(Prior Art) Conventionally, the control method for serial printers uses a space motor to move the carriage in which the print head is mounted, a line feed motor to feed paper, and a microprocessor to control the print head for printing. A control unit was composed of a control circuit for controlling the spacer, etc., and a drive circuit for driving the print head, and the control unit was connected to the space motor, line feed motor, and print head via connection cords. This conventional method will be explained based on the drawings.

FIG. 4 is a diagram showing the configuration of a conventional control unit and a carriage section. In the same figure, 31
1 is a control unit consisting of a control section 32, a drive circuit 33, and a connection connector 34. 32 is a control unit;
It consists of a microprocessor, etc. 33 is a drive circuit for supplying a drive voltage to the print head 37. Reference numerals 34 and 36 denote connection connectors, which function as connection portions for connection cords that connect the control unit 31 and the carriage portion 38. 35
is a connection cord for supplying the print head drive voltage from the drive circuit 33 to the print head 37. 37 is a print head for printing. Reference numeral 38 denotes a carriage portion, which is movable and includes a connector 36 and a print head 37.

FIG. 5 is a specific circuit diagram of FIG. 4. In the figure, 32 is a control unit, 35 is a connection cord, and 3
7 is a print head; 91 and 92 are transistors that are turned on and off by drive power trigger signals 101 and 102; 101 and 102 are drive power trigger signals corresponding to each of the two dot rows of the print head 37; 1101 to 1124; 1201 is a drive signal corresponding to each of the 24 pins built into the print head 37.
-1224 are print head drive transistors 1 that are turned on/off by drive signals 1101-1124;
401 to 1424 are pin driving coils for each of the 24 pins in the print head 37.

Next, to explain the operation, the drive voltage from the drive power supply is passed from the control unit 32 to the pin drive coil through the connection cord 35 via transistors 91 and 92 that are turned on and off by the drive power supply trigger signals 101 and 102. 1401-1412, 1413
~1424. Further, drive signals 1101 to 1124 from the control unit 32 are transmitted to the transistors 1
It is supplied to the pin drive coils 1401 to 1424 through the connection cord 35 via the pin drive coils 201 to 1224. Along with this, the print head 37 is driven.

(Problem to be Solved by the Invention) Here, the number of connection signals for the number N of printing pins built into the print head is (N+1) when the dot configuration is in one vertical row, and in the case of a stagger head with the dot configuration in two vertical rows. (N+2) books. That is, when a multi-pin head for printing Chinese characters or high-quality printing is used, there is a drawback that the number of connection cords increases. Therefore, the connecting cord 35 and the connecting connectors 34, 36 have become larger and the cost has increased, resulting in an increase in the price of the entire device. Further, since the carriage portion 38 is movable, the connection cord 35 having a large number of signals is not desirable in terms of appearance. Furthermore, since the print head drive circuit 33 is provided on the control unit 31 (generally on a board), the heat generated by switching the large amount of power supplied to the print head 37 is transferred to other logic components on the control unit 31. Because of the negative effects, it was necessary to mount a heat sink, etc.

(Means for Solving the Problems) To achieve the above object, the wire dot head of the present invention selectively drives a plurality of driving elements mounted on a carriage portion that moves in the printing direction to perform corresponding printing. Each printing head is provided with a coil for driving a pin for printing, and a first driving power source for driving each driving element; and a first driving power source for driving each driving element; a second drive power supply electrically independent from the power supply; a data signal for data to be printed by the print head; a clock signal for controlling serial-to-parallel conversion of the data signal; and drive control for the print head. a control unit disposed independently from the carriage, the control unit including a plurality of enable signals for enabling the drive control, and a control section for generating and transmitting a timing signal for controlling the timing of the drive control to the carriage section; a shift register mounted in the carriage section and converting a serial data signal from the control unit into a parallel data signal according to the clock signal; a plurality of latch circuits each latching and outputting a corresponding data signal, and a logic circuit section driven by the second drive power source, the logic circuit section being mounted on the carriage section and connected to the first drive power source. a drive circuit driven by electric power, which receives the data signals output in parallel from the plurality of latch circuits, and outputs a drive signal for driving the coil corresponding to the data signal. The drive circuit includes a plurality of drive elements, and an enable signal line for guiding the plurality of enable signals and a data signal line for transmitting the data between the carriage section and the control unit; A clock signal line for guiding the timing signal, first and second power supply lines for guiding the power of the first and second driving power sources, respectively, and a reverse current generated when switching the coil. It is characterized in that it includes a power supply line for regenerating to the first drive power supply.

(Function) The wired dot head of the present invention converts a serial data signal from the control unit into a parallel data signal by the shift register as described above, thereby providing a connection between the control unit and the carriage section. minimize the number of data signal lines connecting the first and second
By operating the drive power supplies independently of each other and by separately providing the first and second power supply lines that connect the control unit and the carriage section, By reducing the adverse effects such as malfunction of the logic circuit section due to noise generated on the power supply drive line 1, and by shifting the timing of successive activation of each of the enable signals, the timing of the activation is shifted. It enables reduction of maximum power required and fine adjustment of printing control.

(Embodiment) FIG. 1 is a circuit diagram showing an embodiment of the present invention. In this embodiment, the print head is a 24-pin stagger head. In the figure, 1 is a control unit composed of a control section 2 and a drive power supply circuit;
8 is a control section composed of a microprocessor, etc.;
is composed of a print head 13 and a drive circuit including a logic section such as a parallel-to-serial converter, and is connected to a movable metal carriage section, 13 is a print head that performs printing, and 15 is a logic circuit mounted on the metal carriage section 8. logic power supply line, 16
1 and 162 are enable signal lines for loading the drive pin data set in the 24-bit shift register 21 into the 12-bit latch circuits 201 and 202, respectively, and further outputting it to the drive transistor side;
17 is a data line that serially sends data from the pins driven by the print head 13, and 18 is a data signal line 1.
7 serial data to 24-bit shift register 2
1, a clock signal line 19 is a ground line for the logic circuit mounted on the metal carriage part 8, and 201 and 202 are enable signal lines 16.
1,162, the transistor 1201 is activated based on the drive data from the 24-bit shift register 21.
21 is a 24-bit shift register that temporarily stores drive data for the print head 13, 23 is a ground wire for the drive transistor mounted on the metal carriage section 8, and 26 is the carriage section 8. 22 is a power line for returning the back electromotive force generated in the print head to the power supply side; 22 is a connection cord that bundles each signal line; 9
1 and 92 are transistors that are turned on and off by drive power supply trigger signals 101 and 102;
2 is a driving power supply trigger signal corresponding to each of the two dot rows of the print head 13; 1201 to 2;
1224 is a print head drive transistor that is turned on and off by signals from the 12-bit latch circuits 201 and 202; 1401 to 1424 are pin drive coils for each of the 24 pins in the print head 13;
2, 2501 to 2524 are diodes for allowing the current to flow freely when the printing head 13 is finished being driven.

FIG. 2 is a time chart of this embodiment.
FIG. 3 is a time chart showing details of the data transfer portion in FIG.

The operation of this embodiment will be explained using FIGS. 2 and 3.

First, the control section 2 serially sends data indicating whether or not the 24 pins in the print head 13 are driven to the data signal line 17, and at the same time sends a clock synchronized with the data on the data signal line to the clock signal line 18. do. The signal is input to the 24-bit shift register 21 mounted on the metal carriage section 8 via the connection cord 22, and the 24 pieces of data are stored and transferred to the next stage 12-bit latch 20.
1,202.

Next, when driving the print head, the control section 2
A drive power supply timing signal 101 corresponding to one or both of the head pin rows to be driven;
102 and enable signals 161 and 162 are sent simultaneously. For example, when driving the pins of the print head 13 that correspond to the coils 1401 to 1412, the drive power trigger signal 101 and the enable signal 161 are sent out at the same time.

Enable signal 161 or 162 is input to 12-bit latch 201 or 202 via connection cord 22. 12 bit latch 201,
202 latches the data from the 24-bit shift register 21 by inputting the enable signals 161 and 162, and latches the data from the 24-bit shift register 21 to drive transistors 1201 to 1 of the next stage.
224 side. At this time, the 12-bit latch circuits 201 and 202 each receive the enable signal 16.
At the falling edge of 1,162, the data in the shift register 21 is latched, and the enable signals 161, 162 are
The latched data is output to the next stage transistor at the low level.

Drive power trigger signals 101 and 102 are input to transistors 91 and 92 to control the drive power applied to each print head 13.

When the transistors 91 and 92 become conductive, among the coils 1401 to 1424 of the print head 13, the transistors 1201 to 1224 which are rendered conductive by the enable signals 161 and 162 are turned on.
The drive current flows only to the coil connected to the
Printing is performed. Repeat this operation thereafter.

Here, the data transfer for the next printing is as follows:
After the previous data is transferred to the shift register and after both enable signals 161 and 162 fall, the previous data is latched in the latch circuit, so the period until the next printing operation starts. It can be sent at any time.

(Effects of the Invention) As explained above, according to the present invention, the print head drive circuit is mounted on the metal carriage part,
Since the print data signals from the control unit are sent serially, there is an advantage that the number of signals in the connection cord between the control unit and the movable metal carriage is reduced. For example, in the case of a 24-pin staggered head, the number of connection cord signals will be reduced from 26 to 10.
The number of books will decrease by 16. Therefore, the connector used for connection can also be made smaller. Furthermore, since the serial-parallel conversion circuit is mounted on the metal carriage section and the number of I/O ports used in the control section is reduced in order to send print data signals in serial, the configuration of the control unit can be simplified. Furthermore, by providing a drive circuit that generates a large amount of heat on a metal carriage, it is possible to prevent the adverse effects of heat on other logic components, and the metal carriage itself can be used as a heat sink. Since the part itself is movable, the airflow generated during its movement can be used as a heat radiating means, which eliminates the need for heat radiating devices such as heat radiating plates and cooling fans, which were required in the past, resulting in cost reduction. On the other hand, driving a wire dot head requires a very large amount of energy to drive its pins, so there is a large voltage drop in the drive power ground wire of the connection cable, and a logic circuit to drive the print head is installed in the carriage. When it is mounted, a potential difference occurs between it and the control unit, but by separating the ground wire as in this example, the logic voltage value and input logic signal level in the carriage section are guaranteed, so it is stable. Can print.

In the present invention, a drive circuit is provided on the drive target side, heat generated by the drive circuit is radiated using a metal base, etc. on the drive target side, and the method of transferring drive data to the drive circuit is serial transfer, so the number of signals is Since it can reduce the amount of noise, it can also be used in space motor drive circuits, line feed motor drive circuits, etc. of printers.

Furthermore, the present invention provides, by shifting the timing of each of the enable signals of each of the latch circuits,
This has the effect of reducing the maximum power required in the carriage section and easily achieving high quality printing by finely adjusting the printing position.

[Brief explanation of drawings]

Figure 1 is a circuit diagram showing one embodiment of the present invention, Figure 2 is a circuit diagram showing one embodiment of the present invention.
3 is a detailed diagram of the data transfer timing of FIG. 2, FIG. 4 is a diagram showing the configuration of the conventional print head control unit and carriage section, and FIG. 4 is a specific circuit diagram of FIG. 1, 31... control unit, 2, 32... control section,
8... Metal carriage part, 13, 37... Print head, 15... Logic power supply line, 161, 162
...Enable signal line, 17...Data signal line, 18
...Clock signal line, 19...Logic ground line, 2
6... Drive power supply line, 23... Drive power supply ground line, 20
1,202...12-bit latch circuit, 21...24-bit shift register, 22,35...connection code, 3
3... Drive circuit, 34, 36... Connection connector, 9
1,92...Transistor, 101,102...Drive power supply trigger signal, 241,242,1201-1
224...Diode, 1201-1224... Drive transistor, 1401-1424... Pin drive coil.

Claims (1)

[Scope of Claims] 1. A plurality of drive elements mounted on a carriage part that moves in the printing direction are selectively driven to operate the corresponding print heads, and each print head has a pin for printing. A wire dot head equipped with a coil for driving, a first driving power source for driving each of the driving elements, a second driving power source electrically independent from the first driving power source, and a second driving power source for driving the printing element. a data signal of data to be printed by the head, a clock signal that controls serial-to-parallel conversion of the data signal, and a plurality of enable signals that enable drive control of the print head and control the timing of the drive control. and a control unit disposed independently of the carriage, the control unit being mounted on the carriage and transmitting the serial data signal from the control unit to the carriage. a shift register that converts into parallel data signals in accordance with a clock signal; and a plurality of latch circuits that respectively latch and output parallel corresponding data signals from the shift register in accordance with the plurality of enable signals. and a logic circuit section driven by the second drive power source, the drive circuit being mounted on the carriage section and driven by the power from the first drive power source, the drive circuit comprising: a logic circuit section driven by the second drive power source; The drive circuit includes a plurality of drive elements each receiving the data signals output in parallel and outputting a drive signal for driving the coil corresponding to the data signal, the carriage unit and the control unit An enable signal line for guiding the plurality of enable signals, a data signal line for transmitting the data, a clock signal line for guiding the timing signal, and the first and second and a power supply line for regenerating a reverse current generated when switching the coil to the first drive power source. A wire dot head featuring: