JPH0647930A - Impact printer - Google Patents

Abstract

PURPOSE:To separately detect an abnormality of a printing coil or a drive transistor by a simple construction by a method wherein the presence/absence of an occurrence of an abnormal state is judged in accordance with detection outputs of first and second detection circuits. CONSTITUTION:An impact printer comprises a plurality of printing coils 60 commonly connected to a power source 64, a plurality of transistors 68 provided correspondingly to the printing coils 60, and a first detection circuit 54 for detecting a voltage change between the power source 64 and the printing coils 60. The printer is provided with a second detection circuit 56 for detecting a voltage change between the printing coils 60 and the transistors 68 and a judging means 50 judging the presence/absence of an occurrence of an abnormal state in accordance with detection outputs of the first and second detection circuits 54, 56.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention uses a coil for printing,
The present invention relates to an impact printer that prints on recording paper. The impact printer includes a type printer that prints by printing a type using a printing hammer and a wire dot printer that prints on a recording paper by driving a print pin (wire pin).

In such an impact printer, in order to drive a printing hammer and a wire pin, a printing coil and a transistor for supplying a current to the printing coil are provided. If a disconnection or short circuit occurs in the printing coil or transistor, printing will not be performed. Therefore, the impact printer executes the abnormality detection process immediately after turning on the power of the apparatus or immediately before starting the printing operation.

[0003]

2. Description of the Related Art Conventionally, JP-A-57-108974, JP-A-51-78932, and JP-A-52-85 are known.
No. 422, Japanese Unexamined Patent Publication No. 52-85421, and Japanese Utility Model Laid-Open No. 54-84026, a drive pulse for detection is applied to a drive transistor, and the detection output causes disconnection of a coil for printing An impact printer is disclosed which detects an abnormality of a drive transistor.

[0004]

However, the conventional impact printer is configured to detect an abnormality in only one of the printing coil and the drive transistor. An object of the present invention is to provide an impact printer that can detect abnormalities in a printing coil or a driving transistor by separating them with a simple configuration.

[0005]

As shown in FIG. 1, an impact printer according to the present invention includes a power source 64 and a plurality of printing coils 60 commonly connected to the power source 64.
And a plurality of transistors 68 provided corresponding to each of the printing coils 60 for driving each of the printing coils 60, and detecting a voltage change between the power supply 64 and the printing coil 60. A first detection circuit 54 for
Based on the detection output of the second detection circuit 56 for detecting the voltage change between the printing coil 60 and the transistor 68 and the detection outputs of the first and second detection circuits 54, 56, the occurrence of an abnormal state is detected. The impact printer is characterized by comprising a determination unit 50 for determining the presence or absence of the impact printer.

[0006]

According to the impact printer of the present invention, the abnormal state of the printing coil 60 and the driving transistor 68 can be detected by the combination of the first and second detection circuits 54 and 56, and the circuit configuration is simplified. be able to.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 is an explanatory view of the configuration of an embodiment of an impact printer to which the present invention is applied. In the figure, the continuous folding paper 2 is conveyed by a tractor 4 having a tractor pin 4a that engages with its feed hole 2a. The paper feed motor 6 rotates the tractor 4 via the pulley 8, the belt 10 and the pulley 12 to convey the paper 2. The paper feed motor 6 has a drive circuit 40.
Drive control is performed by the paper feed control unit 42 via. The paper feed control unit 42 executes a line feed operation of the paper 2 in response to a drive instruction from the print control unit 50.

The platen 14 is arranged so as to face the print head 22, and is driven to rotate via a pulley 16, a belt 18 and a pulley 20 to guide the paper 2. The print head 22 is composed of a plurality of print blocks 22 a (12) each of which carries a plurality of print pins (24), and is mounted on a shuttle 26 that reciprocates along a guide rod 24. Therefore, a total of 288 printing pins are mounted on the shuttle 26.

The printing blocks 22a are mounted on the shuttles 26 by fastening means such as screws (not shown) that can be attached / removed, and can be replaced individually. Each print pin of the print head 22 has a drive circuit 5
It is driven in accordance with a drive instruction from the print control unit 50 via 2.

The shuttle 26 is reciprocally driven by a drive motor composed of a plurality of magnets 28 mounted on the lower surface of the shuttle 26 and a plurality of coils 30 mounted on the frame side of the impact printer. Drive motor coil 30
Is controlled by the print control unit 50 via the drive circuit 54, and the reverse drive operation, constant speed operation, stop operation, etc. of the shuttle 26 are controlled.

The first and second detection circuits 54 and 56 are driving circuits 52 for driving the respective print pins of the print head 22.
It is provided for detecting an abnormal state of.
The timing of the line feed operation of the sheet 2 performed by the print control unit 50 via the sheet feed control unit 42, the reversal of the shuttle 26, the constant speed, and the stop control are described in detail in US Pat.
Since it is described in the specification of No. 819,556, its detailed description will be omitted.

FIG. 1 is an explanatory diagram of a detailed configuration of the drive circuit 52 shown in FIG. In the figure, 288 printing coils 60 _{-1 to} 60 _-288 provided corresponding to each print pin of the print head 22 are commonly connected to 40 V via a resistor 62.
Is connected to the power source 64. The relay 66 has a resistor 62
And is capable of being turned on / off in response to a command signal from the print control unit 50, and is forced to be turned off by an output signal of the second detection circuit 56 as described later. Can be

Each printing coil 60_-1~ 60_-288Respectively
Driving transistor 68_-1~ 68 _-288Is connected
It Transistor 68 for each drive_-1~ 68_-288Prints
The drive signal from the control unit (Fig. 2) 50 to 150 μs is selective.
Is turned on / off.
Also, each drive transistor 68_-1~ 68_-288Has
Each diode 70 has a polarity as shown in FIG._-1~ 7
0_-288Are connected to each other, and their anodes are all commonly connected to the second detector.
It is input to the output circuit 56.

On the other hand, the common connection end 72 of each of the printing coils 60 _{-1 to} 60 _-288 is connected to the first detection circuit 54. FIG. 3 is an explanatory diagram of a detailed circuit configuration of the first detection circuit 54. In the figure, each printing coil 60 _{-1 to} 60 _-288
The common connection end 72 of is connected to the terminal 74. Therefore, the voltage change appearing at the common connection terminal 72 is input to the base of the transistor 80 via the resistor 76 and the diode 78. The comparator 82 outputs the output of the transistor 80 divided by the resistors 84a and 84b and the resistors 86a and 86b.
The output of the power supply 88 divided by is compared and the comparison output Cout1 is emitted. The comparison output Cout1 is input to the print control unit 50.

FIG. 4 is an explanatory diagram of a detailed circuit configuration of the second detection circuit 56. In the figure, each diode 70 _{-1 to} 7
A signal input via the terminal 90 to which the anodes of _0-288 are commonly connected is input to the base of the transistor 96 via the resistor 92 and the diode 94. Comparator 98
Compares the output of the transistor 96 divided by the resistors 100a and 100b with the output of the power supply 104 divided by the resistors 102a and 102b, and outputs a comparison output Cout2. The comparison output Cout2 is input to the print controller 50.

On the other hand, the comparison output Cout2 is the input signal 30
The output of the delay circuit 106 that delays by 0 μs is input to the AND gate circuit 108. The output of the AND gate circuit 108 is connected to the relay circuit 66. Therefore, the AND gate circuit 108 outputs the comparison output C
A signal for turning off the relay 66 is output only when out2 continues for a predetermined time or longer.

[0017] As described above, the print control unit 50, when driving the printing pins, each of the drive transistor 68 _-1 6
A drive signal lasting _{150 μs} is _applied to _8-288 . On the other hand, since the delay time of the delay circuit 106 is 300 μs, no output signal is obtained from the AND gate circuit 108 unless a short circuit occurs in each transistor during the printing operation of the impact printer.

However, the comparison output Cout2 is long for a short circuit of the transistor, that is, the delay circuit 1
When the delay time of 06 is continuously output for 300 μs or more, the relay 66 is turned off by the output of the AND gate circuit 108, so that the power supply to each transistor is immediately stopped. Therefore, even when the impact printer is in operation, it is possible to prevent the occurrence of fire due to the short circuit of the transistor.

FIG. 5 is a flow chart of an abnormal state detection process by the print control unit 50. In the figure, first, the print control unit 50 includes a relay 66.
Is set to the off state, and the output Cout1 of the first detection circuit 54 is confirmed. Output Cout1 of the first detection circuit 54
Is “1”, the print control unit 50 determines that the connection of the terminals of the power supply 64 is abnormal, and displays the abnormality of the power supply terminal on the operator panel (not shown) of the impact printer.

On the other hand, when the output Cout1 of the first detection circuit 54 is "0", the print control unit 50 proceeds to the process of step. In step, the print controller 50 confirms the output Cout2 of the second detection circuit 56. When the output Cout2 is "1", the print control unit 50 recognizes that at least one of the 288 transistors 68 is in a short state. Then, on the operator panel (not shown), it is determined that the printed board on which the driving transistor 68 is mounted is defective, and the replacement instruction is displayed.

When the output Cout2 is "0", the print control unit 50 sets the value of the internal register n (not shown) to "1", and proceeds to step processing. Next, the print control unit 50 gives a drive signal only to the n-th drive transistor 68 _-n according to the value of the internal register n. Here, the value of the internal register n is n = 1.
Therefore, the drive signal is applied only to the drive transistor 68 _-1 . In this state, the print control unit 50 controls the first detection circuit 5
Check the output Cout1 of 4. If the output Cout1 is “0”, the process proceeds to step S1 and the output Cout1 is “1”.
If, then go to step. The print control unit 50 further confirms the output Cout2 of the second detection circuit 56. When the output Cout2 is "0", it is recognized that the driving transistor 68 _-n (68 _-1 ) is in the open state, and the driving transistor 68 _-n.
Instruct to replace only the printed board on which is mounted. On the other hand, when the output Cout2 is "1", it is recognized that the print coil 60 for the nth print pin is open, and the replacement of the print block in which the print coil 60 is mounted is instructed. The print controller 50 outputs the output Cou of the second detection circuit 56.
When t2 is "0", it is displayed on the operator panel that the detection circuit is abnormal. On the other hand, when the output Cout2 is "1", the drive signal given to the n-th drive transistor 68 _-n is turned off and the value of the internal register n is added. Finally, it is checked whether the value of the internal register n exceeds 288. If the value of n is 288 or less, the process returns to step and the process for the next driving transistor 68 _-n is executed.

On the other hand, when the value of n exceeds 288, it is considered that there is no abnormality in the printing coil 60 and the driving transistor 68, the detection process is terminated, the relay is turned off, and the normal printing operation mode is set. enter.

[0023]

As described above, in the impact printer according to the present invention, the detection circuit commonly connected to each printing coil and the detection circuit commonly connected to each driving transistor are used to detect both of them. By checking the combination of circuit outputs, it is possible to detect all coils open, transistor short, transistor open, power terminal short, and detection circuit abnormality with a simple configuration.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a detailed configuration of a drive circuit.

FIG. 2 is an explanatory diagram of a configuration of an embodiment of an impact printer.

FIG. 3 is an explanatory diagram of a detailed circuit configuration of a first detection circuit 54.

FIG. 4 is an explanatory diagram of a detailed circuit configuration of a second detection circuit 56.

FIG. 5 is an abnormal state detection flowchart.

[Explanation of symbols]

 54 first detection circuit 56 second detection circuit 60 printing coil 64 power supply 68 driving transistor

Claims (1)

[Claims] 1. A power source (64), a plurality of printing coils (60) commonly connected to the power source (64), and each of the printing coils (60) for driving the respective printing coils (60). A plurality of transistors (68) provided corresponding to the coil (60); a first detection circuit (54) for detecting a voltage change between the power supply and the printing coil (60); The printing coil (60) and the transistor (68)
A second detection circuit (5 for detecting a voltage change between the
6) and a determination means (50) for determining whether or not an abnormal state has occurred based on the detection outputs of the first and second detection circuits (54, 56).
And an impact printer, which comprises: