JPH01232078A - Printer with detecting function for paper jamming - Google Patents

Abstract

PURPOSE:To prevent troubles from occurring due to paper jamming, by detecting as a paper jamming the condition where it is judged by a timer runout discriminating means that a current flowing to a driving motor has exceeded a reference value for at least a prescribed time. CONSTITUTION:A current flowing to a driving motor 12 is detected by a motor current detecting circuit 52. When an overcurrent detecting circuit 54 detects that the current is an overcurrent greater than a normal current, an overcurrent detection signal discriminating means 66 causes a timer 68 to measure the period of time for which the presence of an overcurrent detection signal continues, and a timer runout discriminating means 70 judges whether the period of time thus measured has reached a prescribed time indicating a paper jamming. When the prescribed time is reached, a timer runout signal generating means 72 turns OFF the motor 12 through the discriminating means 70, and displays the paper jamming on a paper jamming display device 56. When the output of the overcurrent detection signal from the discriminating means 66 ceases, a timer-resetting means 74 resets the timer 68. Thus, it is possible to detect a paper jamming securely end early, and to prevent troubles from occurring due to the paper jamming.

Description

[Detailed description of the invention] Industrial applications The present invention relates to paper jam detection in printers.

2. Description of the Related Art Recently, with the spread of computers, printers, which are their output devices, are being used in various places. These printers can be divided into impact type and non-impact type based on their principles. Furthermore, there are various impact types due to differences in printing methods, and various non-impact types due to differences in recording methods. All of these printers convert information sent from a computer from electrical signals into characters, etc., and print them on recording paper. At this time, a motor is used as a driving source for printing operations, moving the recording paper, and the like. For example, in a serial printer, the driving force is obtained from the motor, and the head prints one line on recording paper while moving one character at a time from the left, and then moves in the opposite direction and returns to the home position, printing one line. Paper is being fed. There are two types of serial printers: impact type and non-impact type.

Problems to be Solved by the Invention However, in such printers, the recording paper may not move smoothly for some reason, resulting in a paper jam. In particular, serial printers have a mechanism in which the head moves from left to right when printing and moves in the opposite direction when feeding paper, so if the recording paper gets caught in the head, it is likely to get caught and cause a paper jam. When a paper jam occurs, even if the motor is in operation (on state), the motor does not rotate smoothly and even stops rotating. Therefore, the time required for the head to return to the home position is prolonged, or the head does not return to the home position. Note that the motor will not turn off unless the head returns to the home position because the home switch will not be operated. At this time, a large mechanical load is applied to the motor, causing an overcurrent to flow. If left as is, a mechanical load will be applied and overcurrent will flow, causing the temperature of the motor to rise excessively. Therefore, the operator needs to be careful about the paper jam, and if it is discovered, immediately turn off the power and remove it using tweezers or the like. However, if paper jams occur repeatedly, it is not always possible to detect them early, which may shorten the lifespan of the printer, and furthermore, there is a risk that the printer may be destroyed due to the delay in detection.

The present invention has been made by focusing on these conventional problems, and includes a paper jam detection function that can prevent paper jams from shortening their lifespan and destroying them by detecting paper jams early and taking appropriate action. The purpose is to provide printers.

Means for Solving the Problems Means for achieving the above object will be explained below with reference to FIG. 1 which clearly shows the present invention.

This printer with a paper jam detection function has a function between the drive motor 12 and a paper jam indicator 56 that indicates a paper jam, in order to determine that an overcurrent has flowed to the motor 12 at the previous stage.
a motor current detection circuit 52 that detects the current flowing through the motor 12 and outputs a motor current detection signal; an overcurrent detection circuit 54 that compares the motor current detection signal with a reference value and outputs an overcurrent detection signal; The overcurrent detection signal determining means 66 determines whether or not there is an overcurrent detection signal, and the subsequent stage includes an overcurrent detection signal determining means 66 that determines whether or not the overcurrent detection signal is present. A timer 68 measures the duration, a timer set-up determination means 70 determines from the time indicated by the timer 68 whether a specified time indicating a paper jam state has been reached, and when the timer 68 is set up, the motor 12 is turned off and the paper jam is cleared. and a timer set-up signal generating means 72 that generates a signal to display the overcurrent detection signal, and sends the timer set-up signal to the paper jam indicator 56, and a timer 68 in the middle stage is reset when the overcurrent detection signal disappears. A timer reset means 74 is provided.

Operation When configured as described above, first, the motor current detection circuit 52
After detecting the current flowing through the drive motor 12, the overcurrent detection circuit 54 detects that the current is an overcurrent exceeding the normal current and creates a signal. At 66, it may be determined whether there is an overcurrent detection signal.

Next, the timer 68 increments the duration of the overcurrent detection signal by hl, and the timer set-up determining means 70 determines whether the time indicated by the timer 68 has reached a specified time indicating a paper jam state. Note that an overcurrent always flows when the motor 12 is started, but since it disappears in a short time, it can be distinguished from the prescribed time indicating a paper jam state. When the timer 68 is set up, a timer set-up signal generation means 72 generates a signal to turn off the motor 12 and indicate a paper jam. This timer setup signal immediately stops the motor 12 in operation. Also, a paper jam indicator 56
A paper jam will be displayed.

Further, the timer reset means 74 resets the timer 68 when the overcurrent detection signal disappears, and prepares for timing the next overcurrent detection signal.

Example Hereinafter, the present invention will be described in detail based on the accompanying drawings.

FIG. 2 is a perspective view showing the internal structure of a thermal dot printer to which the present invention is applied, and FIG. 3 is a block diagram showing its driving circuit, etc. In the figure, 10 is a thermal dot printer, 12 is a head and recording paper drive motor installed on a mounting stand 14, and 16 is a head main body. The head main body 16 consists of a head unit 18 and support plates 20 for FPC (flexible printed wiring board) connected to each head included therein, and is horizontally mounted on left and right support frames 22 and 24 fixed to the installation stand 14, respectively. It is supported by a guide pin 26 and a head feed screw 28. Moreover, the head body 16
The claw provided in the head feed screw 28 is inserted into the helical groove 30 cut on the outer periphery of the head feed screw 28. Further, these guide pins 26, head feed screws 28, etc. are arranged parallel to the surface of the platen 32. Therefore, when the motor 12 is driven, the head feed screw 28 receives the driving force and rotates, thereby moving the head main body 16 in the direction of the arrow X along the surface of the platen 32. At this time, when a thermal head drive signal is applied, each head sequentially moves from left to right one character at a time while moving toward the platen.
One line is printed on the recording paper attached to the second side. When one line of printing is finished, the direction of rotation of the motor 12 is always the same, but since the claws of the head body 16 break, the head body 1
6 returns in the opposite direction and simultaneously feeds the paper by one line.

When the head main body 16 contacts the home switch 34 upon reaching the home position XO, the motor 12 is turned off and its rotation stops. Each of these operation signals is applied from an external drive circuit 38 via an FPC 36 or the like. In addition, 4
0 is a terminal circuit board for operating the printer 10.

This drive circuit 38 is centered around a CPtJ (central processing unit) 42, and includes an amplifier circuit 44 consisting of a transistor array.
, a motor drive circuit 46, a tacho generator waveform shaping circuit 48, a print pulse width control circuit 50, and the like. Moreover, the CPU 42 includes ROM (read-only memory), RAM (n-output writable memory), 1.0 (input/output board), and the like. This CPLJ 42 corresponds to the brain, and executes overall control according to program instructions, performs arithmetic and logical operations, and temporarily stores the results. It also controls peripheral devices. The ROM stores a control program for overall control, a paper jam removal program, print data, etc. Further, the RAM stores measurement data calculated by the CPU 42, print data converted from the measurement data, and the like. Furthermore, 1. O indicates these CPU 42, memory, etc. and other circuits 44, 46.
Connect with 48.50 etc.

A thermal head drive signal and a motor drive output signal are sent from the drive circuit 38 configured in this manner to the printer 10.
Conversely, a home switch signal and a tacho generator signal are sent from the printer 10 to the drive circuit 38. That is, CPU4
For example, if one word (one data) has an 8-bit configuration, the print data signal output from the transistor array 44
After that, it is converted into 7 thermal head drive signals, and 8
The above-mentioned FPC3 including two signal lines (one is a ground line)
6 to each of the seven heads each having an array of heating diodes in the printer 10.

Note that a +5V common power line is connected to each head. Further, the motor control signal output from the CPU 42 is converted into a motor drive signal by a motor drive circuit 46, and is input to the motor 12 in the printer 10. Note that a +5V power line is connected to the motor 12. Conversely, from the printer 10, the head body 1
6 presses the home switch 34, a home switch signal that turns off the motor 12 is input to the CPU 42. Then,
A motor stop signal of 25m5 is output as a motor control signal, and the drive signal is turned off. Also, printer 10
The tachogenerator signal (TG multiplied signal is shaped by the tachogenerator waveform shaping circuit 48, becomes a timing signal, and enters the CPU 42. Based on this timing signal, the timing for displaying the print data as dots on the recording paper is determined, A pulse current flows through each head in accordance with the head drive signal.Incidentally, the tachogenerator is
Since the motor is directly connected to the shaft of the motor, the rotational speed of the motor after starting, that is, the position of the head main body 16 can be determined from the tachogenerator signal. Note that a ground wire is connected to the home switch 34 and the tachogenerator. Furthermore, since the print pulse width control circuit 5O is connected to the CPU 42, it is possible to adjust the pulse width according to the external temperature and change the heat generation time of each head. Therefore, from the start of the motor,
After printing 22...2 characters for the line and feeding the paper, the motor stops and starts the next cycle.
The relationship between the above-mentioned signals is shown in FIG. 4 by the timing chip p-1-.

The CPU 42 of this drive circuit 38 additionally has 1. An overcurrent detection circuit 54 connected to a motor current detection circuit 52 interposed in the +5V power line of the motor 12 is connected via O to a paper jam indicator 56 consisting of an LED (light emitting diode) or the like. A specific example of the motor current detection circuit 52 and overcurrent detection circuit 54 is shown in FIG. This motor current detection circuit 52 detects a current (2) flowing through the motor 12 from a voltage drop across a resistor 58 interposed in a +5V power line, amplifies it with an operational amplifier 60, and outputs it as a motor current detection signal S1.

In addition, the overcurrent detection circuit 54 receives the motor current detection signal @S1.
and a reference value SO using an operational amplifier 62, and when the motor current exceeds the normal current and becomes an overcurrent, an overcurrent detection signal S is generated.
Outputs 2. Note that the reference value SO is obtained by the reference voltage circuit 64 by dividing the constant voltage of the Zener diode using resistors.

Next, the paper jam handling operation will be explained.

FIG. 6 is a flowchart of a paper jam removal program consisting of steps P1 to P9. After the recording paper is installed in a predetermined position of the printer 10, first, the motor drive signal is turned on at Pl, the head and recording paper drive motor 12 are started, and the printer 10 starts printing. Next, at P2, it is determined whether the overcurrent detection signal @S2 is present (on). YE
In the case of S, go to P3 and there is an overcurrent detection signal S2 (
Starts a timer that determines the duration of on). Then P
4, and it is determined from the time indicated by the timer whether a specified time indicating a paper jam condition has been reached. Note that when the motor 12 starts, as shown in FIGS. 4 and 7, an overcurrent always flows and the overcurrent detection signal S2 is present (on), but this is constant due to the motor 12 and does not change to 10 for a short time. , can be distinguished from the specified time t1 indicating a longer paper jam state. If NO, the process goes to P5, where the timer is reset when the overcurrent detection signal S2 disappears, and prepares for timing the next overcurrent detection signal. Next, the process goes to P6, and it is determined whether printing of one line on the recording paper and feeding of the paper has been completed.

In the case of NO, the process returns to P2 and prints one line and feeds the paper while repeating steps P2 to P6. Normally, after one line of printing and paper feeding is performed after the motor 12 is started, the head body 16 reaches the home position XO, the home switch 34 is activated, and the motor 12 is turned off and stopped. If YES, go to Pl and determine whether to start printing and paper feeding for the next line valve. If YES, Pl
The process returns to step 1 and repeats steps P1 to P7, changing the line one by one and printing on the recording paper, and feeding the paper. However, when a paper jam occurs, the motor 12 does not rotate smoothly and even stops rotating. Therefore, an overcurrent continues to flow through the motor 12 for more than the specified time t1, and the timer is set in the previous P4. It will go up, so go to P8. At P8, the motor stop signal is turned on for 25 ms in order to turn off the motor 12 and stop it. Next, the process goes to P9, where a signal indicating a paper jam is given to the paper jam indicator 56 to display the paper jam. Therefore, paper jams are reliably detected early and the operating motor 12 is immediately turned off even if the home switch 34 does not work. At the same time, the paper jam indication alerts the operator. It can be removed quickly.

Detailed Description of the Invention According to the present invention, a paper jam is reliably detected at an early stage, the operating drive motor is immediately turned off and stopped, and the paper jam is displayed. Short life and destruction can be prevented, and work efficiency is improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a printer with a paper jam detection function according to the present invention. FIG. 2 is a perspective view showing the internal structure of a thermal dot printer to which the present invention is applied, and FIG. 3 is a block diagram showing its driving circuit, etc. FIG. 4 is a timing chart showing the relationship between each operation signal in one cycle necessary for printing one line and feeding paper in the same printer. FIG. 5 is a diagram showing a specific example of the motor current detection circuit and overcurrent detection circuit shown in FIG. 3. FIG. 6 is a flowchart of the paper jam removal program stored in the ROM included in the drive circuit. FIG. 7 is a diagram showing an overcurrent detection signal. 10...Printer]2...Drive motor 32...
・Platen 34...Home switch 38...Drive circuit 42...CPU 52...Motor current detection circuit 54...Overcurrent detection circuit 56...Paper jam indicator 66...Overcurrent detection Signal determination means 68...
・Timer 70...Timer set-up determination means 7
2...Timer set-up signal generation means 74...
Timer reset means 4 Dormitory Figure 4 Figure 5 Q Figure 7

Claims (1)

[Claims] A motor current detection circuit that detects the current flowing through the drive motor and outputs a motor current detection signal; an overcurrent detection circuit that compares the motor current detection signal with a reference value and outputs an overcurrent detection signal; An overcurrent detection signal determining means for determining whether a detection signal is present, a timer for measuring the duration of presence of an overcurrent detection signal, and a timer setup determining means for determining from the time indicated by the timer whether a predetermined time indicating a paper jam condition has been reached. a timer setup signal generation means that turns off the motor and generates a signal to indicate a paper jam when the timer is set up; a paper jam indicator that receives the timer setup signal and displays a paper jam; and a timer that detects an overcurrent. A printer with a paper jam detection function, characterized by comprising a timer reset means that resets when the signal disappears.