JPH05212882A - Dot matrix printer - Google Patents

Abstract

PURPOSE:To provide a dot matrix printer which can accurately quickly detect a trouble of a printing head system. CONSTITUTION:A dot matrix printer is a device which performs printing on paper with a printing head 1 having a plurality of printing head pins 4 which are driven electromagnetically. For the dot matrix printer, a piezoelectric element 5 is provided to a platen 2 within a transfer region of the printing head 1. Further, the printing head 1 is moved to a part of the piezoelectric element 5 everytime printing is carried out. A printing head pin 4 is driven for each line thereof with a printing head driving circuit 31 to collide with the piezoelectric element 5. An output signal Sa generated from the piezoelectric element 5 is inputted to a control circuit 32 via a detection circuit 33 thereby. The control circuit 32 judges abnormality of the printing head pin 4 according to the presence of a detection signal from the detection circuit 33.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dot matrix printer capable of detecting abnormalities in print head pins.

[0002]

2. Description of the Related Art A dot matrix printer of this type includes a print head capable of electromagnetically driving a plurality of pins one by one, a platen, a head moving mechanism for moving the print head, and a paper feeding mechanism for supplying print paper. , And a control circuit for controlling them as main constituent elements.

In such a dot matrix printer, each print head has a structure in which a plurality of pins, each of which is independently electromagnetically driven, are bundled. In the case of this print head, the number of dots for expressing one character is generally represented by an extremely large number of dots, for example, 24 dots in the vertical direction and 27 dots in the horizontal direction. Therefore,
For example, in the case of a print head that can print 100 characters per second, each pin may be driven 2700 times per second, so the life of the print head is short, and it fails after about 100 million characters. Will end up. Therefore, the print head is often treated as a consumable part.

On the other hand, the pins in the print head of the dot matrix printer are, for example, 0.2 [mm] to 0.3.
Since it has a diameter of about [mm], it is extremely easy to break. Due to such circumstances, in the case of a form, a slip, etc. output by a computer, there are many occasions where the printed characters with missing dots are seen.

[0005]

However, when printing on an important document such as a bank passbook, there is a possibility that printed characters such as numbers with missing dots may be recognized as different characters, which is a very serious problem. is there.

Therefore, conventionally, it is determined manually by looking at the actually printed characters whether or not there is a dot drop. However, it is impossible to reliably detect the dot drop and it takes time to detect the dot drop. There was a flaw.

In view of the above points, the present invention has an object of providing a dot matrix printer capable of accurately and quickly detecting a failure of a print head system.

[0008]

In order to achieve the above object, a dot matrix printer of the present invention is a dot matrix printer for printing on a printing paper with a print head having a plurality of electromagnetically driven print head pins. From the print head driving means for driving the print head pin for each pin, the generating means for generating a signal according to the print pressure of the driven print head pin outside the printing range, and the generating means for generating for each print head pin. And a determining means for determining normality / abnormality of the print head pin based on the above signal.

[0009]

According to the dot matrix printer having the above-mentioned structure, the print head is moved to the generating means every time constant printing is performed, and the print head driving means drives the print head pins one by one to collide with the generating means. The normality / abnormality of the pin is determined by the determination means based on the presence / absence of the signal from the generation means.

[0010]

The present invention will be described below with reference to the illustrated embodiments.

FIG. 1 is an explanatory view showing an embodiment of a dot matrix printer according to the present invention.

In FIG. 1, the dot matrix printer has a print head 1, a platen 2 and a control system 3. The print head 1 is moved to the left and right in the figure on the sheet of the platen 2 and the print head 1 is moved. Printing is performed by performing a predetermined drive control on the print head pin 4. Therefore, although not shown, a head moving mechanism for moving the print head 1 and a paper feeding mechanism for rotating the platen 2 are provided. Further, the print head 1 can move within the lateral movement range M and can print on the paper within the print range W. The print head 1 includes, for example, 24 print head pins 4, and each print head pin 4 can be driven one by one by a drive mechanism including a spring and a solenoid. Further, on the platen 2, at any position within the lateral movement range M of the print head 1,
A piezoelectric element 5, which is a means for converting a printing force into an electric signal, is arranged to face the print head pin 4 of the print head 1. The piezoelectric element 5 is connected to the control system 3, and the output signal Sa generated by the piezoelectric element 5 is input to the control system 3.
The control system 3 includes a print head drive circuit 31, a control circuit 32 including a microcomputer and the like, and a detection circuit 33. The print head drive circuit 31 can supply the print head drive signal Sv to the print head 1, and can drive the print head pins 4 of the print head 1 pin by pin. The print head drive circuit 31 is driven by the print head drive circuit control signal Sc from the control circuit 32. The control circuit 32 not only controls the entire apparatus, but also performs print control for driving and controlling the head moving mechanism and the paper feed mechanism, and detects an abnormality of the print head pin 4 in response to the digital signal Sd from the detection circuit 33. it can.
The detection circuit 33 uses the analog signal S from the piezoelectric element 5.
a can be taken in, converted into a digital signal Sd, and supplied to the control circuit 32.

The operation of the embodiment thus constructed will be described.

FIG. 2 is a flow chart for explaining the operation of the above embodiment.

First, the control system 3 of the dot matrix printer moves the print head 1 and the platen 2 to execute printing (step S200). While this printing is not completed in units of one line (or one page or the like) (step S201; N), the printing is continued (steps S200 and 201). When this printing is completed, for example, in units of one line (or one page) (step S2
01; Y), the print head 1 is moved to the position of the piezoelectric element 5 (step S202). After the print head 1 reaches the piezoelectric element 5, the control circuit 32 of the control system 3 drives the print head drive circuit 31 to supply a current to the solenoid of the print head 1 to drive the print head pins 4 pin by pin. (Step S203). As a result, the print head 1
If the print head pin 4 is driven normally, it will violently collide with the piezoelectric element 5. Then, the piezoelectric element 5
Converts the kinetic energy received by the collision into electric energy to generate a signal Sa, which is input to the detection circuit 33 of the control system 3. This output signal Sa is detected by the detection circuit 3
After being converted into the digital signal Sd in 3, the signal is input to the control circuit 32. Therefore, the control circuit 32 determines that the print head pin 4 is normal from the digital signal Sd (step S204; Y), and stores it as the normal print head pin 4 (step S205).
This is one of the features of the present invention.

This operation is performed for all the print head pins, and it is determined in step S206 whether or not all the print head pins 4 have been driven. If the drive of all the pins 4 has not been completed (step S206; N), the operation is performed again. Detection of breakage of the print head pin 4 is continued (step S20).
3).

On the other hand, when the control circuit 32 of the control system 3 drives the print head drive circuit 31 to drive the print head pins 4 pin by pin (step S203), the print head pins 4 may be broken or the print head pins 4 may be broken. When the drive circuit system 1 has an abnormality, the print head pin 4 of the print head 1 does not hit the piezoelectric element 5, so that the signal Sa is not generated from the piezoelectric element 5. Therefore, the control circuit 32 determines that the print head pin 4 is abnormal because the digital signal Sd is not present (step S204; N), and stores the print head pin 4 as the abnormal pin 4 (step S207). This is one of the features of the present invention.

Further, when all the driving of the print head pins 4 is completed in the operation of the abnormality determination (step S
206; Y), and shifts to another control.

Thus, the above embodiment operates to judge whether the print head pin 4 is normal or abnormal. It should be noted that the normal or abnormal state of the print head 1 is caused by various causes such as breakage of the print head pin, failure of the print head drive circuit, failure of the control circuit, disconnection of the print head cable, malfunction of the print head pin, and the like. Can be detected.

Further, according to the thickness of the paper, the print head 1
In the case of a printer having a function of automatically adjusting the gap between the platen 2 and the platen 2, since the magnitude of the output signal Sa from the piezoelectric element 5 by the print head pin 4 changes in the gap,
By setting the magnitude of the signal Sa to the digital signal Sd, the operation of the automatic gap adjustment function can be checked at the same time.

Further, in the above embodiment, the abnormality / normality is continuously detected for all the print head pins, but the print head pins are divided into groups, and when the print head pins are different for each group, the above-mentioned one pin is used. The detection operation may be performed for each.

[0022]

As described above, according to the present invention,
Since it is possible to confirm the operation of the print head pin each time a certain amount of printing is performed, it is possible to detect a malfunction of the print head pin and determine whether the print result is good or bad.

Further, according to the above invention, it is possible to reliably judge the quality of the printing result in a short time.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of a dot matrix printer of the present invention.

FIG. 2 is a flow chart for explaining the operation of the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 print head 2 platen 3 control system 4 print head pin 5 piezoelectric element (mechanical-electrical conversion means) 31 print head drive circuit 32 control circuit 33 detection circuit

Claims (1)

[Claims] 1. A dot matrix printer for printing on a print sheet with a print head having a plurality of electromagnetically driven print head pins, comprising: print head driving means for driving the print head pins of the print head pin by pin; Generating means for generating a signal according to the printing pressure of the driven print head pin, and judging means for judging whether the print head pin is normal or abnormal based on the signal from the generating means generated for each print head pin, A dot matrix printer characterized in that it is equipped.