JP2872235B2 - Printer device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to processing when a printer cover of a printer such as an electronic typewriter is opened. [Prior Art] Conventionally, printer devices such as electronic typewriters, especially type printers using a type wheel or the like, have a cover switch or the like to identify the open / close state of the printer cover. When the operator opens the printer cover for the purpose of replacing the cassette, etc., or replacing the thermal head, replacing the ribbon cassette, or taking out the ribbon cassette when printing on thermal paper in the thermal transfer printer, almost It is designed so that the printing operation is interrupted at the same time and the printing is resumed almost at the same time when the printing operation is closed again, so that the operator can exchange various parts on the stationary carrier. On the other hand, various conductive metal components such as a support member of a ribbon cassette and mechanical and electrical components typified by a motor paper presser are mounted on a carrier mounted in the printer, especially with a print head and the like. , Many of which have the potential to be directly touched by the operator. Therefore, the event that should be noted at this time is the effect of the instantaneous discharge of the static electricity charged on the human body.For example, in a dry room, the value may reach several kilovolts or more. At present, the device is devised everywhere in order to ensure the safety of the device and prevent erroneous operation of the electronic circuit. For example, electrically floating metals on a carrier are forcibly set to the ground potential, and are further connected to a chassis of the printer body with a flexible metal plate, or a metal-to-metal connection using a braided wire, a logical connection. High-frequency removal to a circuit, addition of a filter, and the like can be mentioned. Since these are essentially unnecessary for performing the basic functions of the device, the cost of the device is substantially increased, and the reliability is eventually reduced. [Problems to be Solved by the Invention] In view of the above, the present invention has been made, and the instantaneous discharge to the carrier, which is originally considered to be most susceptible to static electricity, particularly in a low-humidity environment, a 10-hour environment. In the case of a room with a stiff floor, plus the clothes worn by the operator, and the discharge phenomena that are most likely to occur when these conditions overlap, the present invention performs appropriate static electricity treatment to correct the electronic circuit. The operation is to be prevented beforehand. Embodiment An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is an electrical block diagram embodying the present invention. Here, 1 is a CPU, for example, HD6 manufactured by Hitachi, Ltd.
It is 303Y and performs a 1 MHz synchronization operation by a 4 MHz crystal oscillator 2. A terminal MPO1 is an input for setting an operation mode of the CPU. In this case, an external ROM (Read Only Memory) is used and an internal RAM (Random Access Memory) is used. Reference numeral 3 denotes a ROM in which various programs for executing the operation commands of the CPU 1 are stored. Reference numeral 4 denotes a work RAM for executing the programs. Therefore, the power supply of the RAM 4 is designed to be backed up by the battery 9. Reference numeral 5 denotes an LSI which incorporates an address decoder in a gate array, an I / O port for printer control, a logic circuit for printer servo motor control, and a thermal head drive control logic circuit in addition to the logic circuit. The output of the gate array circuit 5 is amplified by the printer driver 6, and the printer's carrier drive motor, paper feed motor, head-down motor, ribbon feed motor,
The printer 7 including other solenoids is driven. 8
Is the printer cover switch and CPU1 interrupt pin ▲
Connected to ▼. The printer cover switch 8 replaces the ribbon cassette,
The printer head responds to the behavior of the printer cover when the printer cover is opened and closed when performing maintenance or replacement of the thermal head, etc. When the printer cover is open, it is “High” and closed. Keep “Low” level. Next, the related operation between the CPU 1 and the printer cover switch 8 according to the present invention will be described. The CPUI interrupt terminal used in this embodiment
Is also the data input terminal, and the interrupt terminal ▲
By masking the interrupt bit of ▼, it functions as a data input terminal. First, after resetting after power-on, the CPU 1 masks the interrupt bit of the interrupt terminal ▲ ▼ by the initial setting program, and simply sets the printer cover switch 8
Set so that the output of is input as data. Thereafter, an operation routine for normal printer control is executed. Next, when the printer cover switch 8 is opened by the operator, the output of the printer cover switch 8 becomes low level, and the CPU 1 performs the cover open processing operation shown in FIG. First, the print command being processed is executed (S1, S2), the printer is set to the non-operation state (S3), and then the write inhibit signal INH output is set to high to hold the contents of the RAM4 (S4).
Set the interrupt input terminals ▲ ▼ for interrupt input, and at the same time, set the interrupt to Enable and then enter the “stop” mode (S
Five). Therefore, since the address bus, data bus, etc. of the CPU 1 all enter a state of being fixed to a non-transfer state (a state in which the bus line is cut off), except for the interrupt terminal ▲ ▼ terminal, any other pulse nozzle is received. However, it is impossible to imagine getting into the wrong operation. [Effects of the Invention] As described above, according to the present invention, it is possible to prevent the CPU from malfunctioning. Furthermore, when the printer cover is opened, the CPU, ROM,
Since it is possible to prevent noise pulses from entering the address bus and data bus connecting the RAM and undesirably rewriting the contents of the RAM, protection of the contents of the stored RAM can be prevented. It is reasonably feasible.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a printer according to an embodiment of the present invention, and FIG. 2 is a flowchart showing a cover open process of the present invention. 1 ... CPU 2 ... Crystal oscillator 3 ... ROM 4 ... RAM 5 ... Gate array circuit 6 ... Driver 7 ... Printer 8 ... Printer cover switch

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B41J 29/12 B41J 29/00 B41J 29/38

Claims (1)

(57) [Claims] A CPU for controlling a printing operation, a ROM in which a program executed by the CPU is stored, and a RAM used in executing the program by the CPU
An address bus and a data bus for connecting the CPU to the ROM and the RAM; and a detecting means for detecting that a printer cover has been opened. The CPU has a printer cover opened by the detecting means. A printer device that operates in a mode that does not use the address bus and the data bus when it is detected that the printer has been touched. 2. A CPU for controlling a printing operation, a ROM in which a program executed by the CPU is stored, and a RAM used in executing the program by the CPU
An address bus and a data bus for connecting the CPU to the ROM and the RAM; and a detecting means for detecting that a printer cover has been opened. The RAM has a printer cover opened by the detecting means. A printer device which is set to a write-protected state when it is detected that the touch has been made.