JPS61262162A - Wire dot head driving circuit of printer - Google Patents

Abstract

PURPOSE:To reduce the number of connection cords, by mounting a serial- parallel converter and a drive circuit to a carriage part. CONSTITUTION:A metal carriage part 8 is constituted of a printing head 13 and a drive circuit containing a logic part such as a parallel-serial converter. Because of this, for example, in the case of a 24-pin staggered head, the number of the signals of connection cords come to 10. Enable signal wires 161, 162 load the data of drive pins set to a 24-bit shift register 21 to 12-bit latch circuits 201, 202 and further output the same to a drive transistor side. A data wire 17 serially sends the data of pins driving the printing head 13 and a clock signal wire 18 sends a clock signal for setting the serial data of the data signal wire 17 to the 24-bit shift register 21.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a print head drive circuit for a wire dot printer.

(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 the paper, and a microprocessor to control the print head for printing. A control unit was configured including a control circuit for performing the printing 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 carriage section. In the figure, 31 is a control unit, and a control section 32. It consists of a drive circuit 33 and a connection connector 34. Reference numeral 32 denotes a control unit, which is composed of a microprocessor and the like. Reference numeral 33 denotes a drive circuit for supplying a drive voltage to the print head 37. Reference numerals 34 and 38 denote connection connectors, which serve as a connection portion for a connection cord that connects the control unit 31 and the carriage portion 38. Reference numeral 35 denotes 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 38 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, 37 is a print head, 91 and 92 are transistors that are turned on and off by drive power trigger signals 101 and 102, and 102 is a dot consisting of two rows of the print head 37. Drive power trigger signals corresponding to each column; 1101 to 1124 are drive signals corresponding to each of the 24 pins built into the print head 37; 12;
01 to 1224 are print head drive transistors that are turned on and off by drive signals 1101 to 1124, 1401
-1424 are pin drive coils for each of the 24 pins in the printing pad 3.

Next, to explain the operation, the drive voltage from the drive power supply is sent to the drive power supply trigger signal 101, 102 from the control unit 32.
The pin drive coil 1401 is connected to the pin drive coil 1401 through the connection cord 35 through the transistors 91 and 92 that are turned on and off by
~1412, 1413~1424. Further, drive signals 1101 to 1124 from the control unit 32 are supplied to the bin drive coils 1401 to 1424 through transistors 1201 to 1224 and connection cords 35. 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 bins built into the print head is (N+1) when the dot configuration is in a single vertical row, and when the dot configuration is in a single vertical row, the number of connection signals is case (N
+2) Become a book. That is, when a multi-bin heft is used for printing Chinese characters or high-quality printing, there is a drawback that the number of connection cords increases. therefore,
The connecting cord 35 and the connecting connectors 34 and 38 have become larger and the cost has increased, resulting in an increase in the price of the entire device. Furthermore, since the carriage section 38 is movable,
The connection cord 35 with 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 switching of the large amount of power supplied to the print head 37 is Since the heat generated by the control unit 31 has an adverse effect on other logic components on the control unit 31, it was necessary to mount a heat sink or the like.

(Means for Solving the Problems) The features of the present invention for achieving the above object include a carriage part that moves in the printing direction, and printing by selectively driving a plurality of drive elements mounted on the carriage part. a print head, a control unit that controls the drive of the print head, a serial-to-parallel converter that converts serial drive information from the control unit into a parallel signal, and a drive element of the print head based on the output thereof. In the wire dot head drive circuit for a printer, the serial-to-parallel converter and the drive circuit are mounted on the carriage section.

(Function) According to the above configuration, since the serial-parallel converter is mounted on the carriage, the connection between the carriage and the fixed part is made by serial signals, and therefore the number of required lines is smaller than in the case of conventional parallel signals. This is a significant decrease in comparison. Serial-to-parallel conversion is performed on the carriage, and the ground for the power supply of the logic circuit for this purpose is wired separately from the ground for the power supply of the drive circuit, which requires a large current.

(Embodiment) FIG. 1 is a circuit diagram showing an embodiment of the present invention. In this embodiment, the print head is a 24-pin staggered head. In the figure, 1 is a control unit composed of a control section 2 and a drive power supply circuit, 2 is a control section composed of a microprocessor, etc.; 13 is a movable metal carriage part, which is composed of a drive circuit including a print head 13 and a logic section such as a parallel-to-serial converter; 13 is a print head that performs printing; and 15 is a print circuit mounted on the metal carriage part 8. Logic power supply lines 161 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 on the pins driven by the position head 13; 18 is a clock signal line for setting the serial data on the data signal line 17 to the 24-bit shift register 21; 18 is a metal carriage section 8. Ground wire of logic circuit implemented in 2
01 and 202 are set to 2 by enable signals 181 and 182.
1 which turns on and off the transistors 1201 to 1224 based on drive data from the 4-bit shift register 21;
2-bit latch circuit, 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 28 is a signal generated from the carriage section 8 to the print head. A power line for returning the generated back electromotive force to the power supply side, 22
91 and 92 are transistors that are turned on and off by the drive power trigger signals 101 and 102, and 101 and 102 are the drives corresponding to each of the two dot rows of the printing pad 13. Power trigger signal.

1201 to 1224 are 12-bit latch circuits 201, 2
Print head drive transistors 1401-1424 are turned on and off by signals 02 and 24 in the print head 13.
Pin drive coil for each pin, 241, 242.250
Reference numerals 1 to 2524 indicate diodes for causing current to flow at the end of driving the print head 13.

FIG. 2 is a time chart of this embodiment.

FIG. 3 is a time chart showing in detail the data transfer portion in FIG.

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

First, the control unit 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 part 8 via the connection cord 22, and the 24-bit shift register 21 is
The four pieces of data are stored and output to the next stage 12-bit latches 201 and 202.

Next, when driving the print head, the control section 2.

For example, among the pins of the print head 13, the coils 1401 to 141 simultaneously send out drive power application timing signals 101, 102 and enable signals 181, 182 corresponding to one or both of the head pin rows to be driven.
When driving the pin corresponding to pin 2, the drive power trigger signal 101 and enable signal 181 are sent out at the same time.

The enable signal 161 or 182 is input to the 12-bit latch 201 or 202 via the connecting cord 22. The 12-bit latches 201 and 202 latch the data from the 24-bit shift register 21 by inputting the enable signal 11111.1θ2, and output it to the next stage drive transistors 1201-1224. At this time, the 12-bit latch circuits 201 and 202 latch the data in the shift register 21 at the falling edge of the enable signals 181 and 182, respectively.
At the low level of 2, the latched data is output to the next stage transistor side.

Drive power supply trigger signals 101 and 102 are provided by transistors 13
1, is input to i32, and controls the drive power applied to the pad 13 for each print.

When the transistors 91 and 92 become conductive, the drive current flows only to the coils connected to the transistors 1201 to 1224 that are in the conductive state by the enable signals tet and te2 among the coils 1401 to 1424 of the print head 13, and printing is started. will be held. Repeat this operation thereafter.

Here, data transfer for the next printing is performed using the enable signal 181 after the previous data is transferred to the shift register.
, 182 fall, the previous data is latched in the latch circuit and can be sent out at any time until the next printing operation begins.

(Effects of the Invention) As explained above, according to the present invention, the print head drive circuit is mounted on the metal carriage part, and the control unit/
For example, in the case of a 24-bin stagger head, the number of connection cord signals between the control unit and the movable metal carriage is reduced because the print data signals from the head are sent serially. The number is 26
The number of books decreases from 10 to 18. Therefore, the connector used for connection can also be made smaller. Furthermore, since the serial-parallel conversion circuit is mounted on the metal carriage and the number of I10 ports used in the control section for serially sending print data signals is reduced, the configuration of the control unit can be simplified. Furthermore, by providing a drive circuit that generates a large amount of heat on the 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 heat radiation means, eliminating the need for heat radiation devices such as heat radiation plates and cooling fans, which were required in the past, and reducing costs. On the other hand, driving a wire dot head requires a very large amount of energy to drive the bin, 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 implemented, a potential difference occurs between the control unit and the control unit, but by separating the ground wire as in this example, the logic voltage value and input logic signal level at the carriage section are guaranteed, so the stability is maintained. 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.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an embodiment of the present invention, Fig. 2 is an operation time chart of this embodiment, Fig. 3 is a detailed diagram of the data transfer timing of Fig. 2, and Fig. 4 is a conventional print head. FIG. 5 is a specific circuit diagram of FIG. 4, showing the configuration of the control unit and carriage section. l, 31... control unit, 2.32... control section,
8...Metal carriage part, 13.3? ...Print head, 15...Logic power supply line, 181.162...Enable signal line, 17...Data signal line, 18...Clock signal line. 18...Logic ground line, 2B...Drive power line,
23... Drive power supply ground wire, 201.202... 12-bit latch circuit, 21...
・24-bit shift register, 22.35...Connection code, 33...Drive circuit, 34.38...Connection connector, 91.92...Transistor, 101.1
02... Drive power supply trigger signal, 241.242.12
01-1224...Diode, 1201-1224
...Drive transistor. 1401-1424...Pin drive coils.

Claims (2)

[Claims] (1) A carriage unit that moves in the printing direction, a print head mounted on the carriage unit that selectively drives a plurality of drive elements to print, a control unit that controls the drive of the print head, and the control unit A wire dot head drive circuit for a printer comprising: a serial-to-parallel converter that converts serial drive information from a serial drive into a parallel signal; and a drive circuit that drives a drive element of the print head based on the output of the serial-parallel converter; A wire dot head drive circuit for a printer, characterized in that a parallel converter and a drive circuit are mounted on the carriage section. (2) Ground the power supply of the logic circuit of the carriage section,
2. The wire dot head drive circuit for a printer according to claim 1, wherein power is distributed through a line separate from the ground of the power source for driving the drive element.