JPS6023061A - Method for detection of head break down of thermal printer - Google Patents

Abstract

PURPOSE:To detect the disorders of a large number of heating units for a short time, by a method wherein to detect the disorders of heating units, power is applied for the power application time when the color developing paper is not developed and when a heating unit is normal, the detection of the next heating unit is immediately carried out. CONSTITUTION:Drivers 32 are connected to the circuit of data latch and picture signal drive circuit 30 and the circuit 33 for detection of heating unit break down is parallely connected to respective transistors Tr1-Tr3 29 by letting diode 44 to lie. The maximum value of ON time of L1-L6 is determined to be T (the time when thermal color development paper is not developed even if power is applied to heating units 26) and L1-L6 are successively turned on. If IHOPN becomes L within a time T, the time on detection of its L level is so set as to become the next detection timing.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a thermal printer that performs thermal printing by selectively energizing a large number of heating elements, and particularly relates to a method for detecting abnormalities in individual heating elements. The present invention relates to a head breakage detection method for a thermal printer.

Technical Background and Problems There are generally two types of thermal printing using thermal printers: a method that uses thermal paper and a method that prints on plain paper using an ink ribbon coated with heat-melting ink. Printing is clearer than that produced by other printing devices such as line printers, and the size of the heating element has improved to 8 DOT/in as semiconductor technology has improved, making it possible to express characters and images down to the minute details. ing.

Therefore, not only in the field of office equipment such as facsimiles, but also
With the development of POS, it has also begun to be used in the field of barcode printing.

Therefore, the nitric acid in the barcode is JAN, UPC.

In standards such as EAN, numbers are composed of 7 modules, for example, the composition of 7 modules for odd parity of the number 5 is 01.
It is expressed as 10001 (black is 1). Here, at a magnification of 1x, 0.33 owo is taken as 1 module, and becomes white or black. A collection of 13 digits of these 7 modules forms a standard version, which is read by a laser scanner or the like and registered in a register.

Therefore, the problem with barcodes is that if one heating element is destroyed, that is, if it is heated, for example, the number 5, 0I100OI, becomes otoo.

1 or O]lOO'00, resulting in a reading error. however.

Since barcodes require C/D calculations, they are almost never read as other numbers, and since there are rules for odd and even parity, an odd parity error occurs in the black tree.

In this way, even if there is an error in the ID0T of the heating element, the barcode will be printed, so the worker will not be able to discover the abnormality, and even if he or she checks the condition of the bar like a lover, there will be a considerable amount of trouble. Since it takes time, checking by human visual inspection is impossible.

OBJECTS OF THE INVENTION An object of the present invention is to provide a method for detecting a broken head 4 of a thermal printer, which can detect at high speed when one of a number of heating elements breaks down.

Summary of the Invention The present invention detects an abnormality in a heating element by a heating element destruction detection circuit during a time when each heating element is not operating for recording purposes,
Furthermore, the heating element is energized for abnormality detection for a certain period of time without generating the thermal energy required for recording, thereby ensuring that normal recording operations are not affected at all. It is possible to detect an abnormality in the heating element, and if a signal indicating that the heating element is normal is output even during this energization time, the detection timing of the next heating element is shifted to, and a large number of heating elements can be detected at high speed. It is structured so that it can be carried out.

Embodiments of the Invention First, an apparatus for printing a bar code and its operation will be explained based on FIGS. 1 to 6. first,
The CPU 3 to which the weighing section 1 and the switch 2 are connected includes:
Program memory 4 consisting of ROM and RAM, RO
A P'LU memory 51 consisting of M, a display/key device 6, and a CPU 27 for controlling the printer are connected. This CPU 2 7 has ROM and RAM
A program memory 8 consisting of a ROM, a character generator 9 consisting of a ROM, and a print buffer 0 consisting of a RAM are connected. Further, a label detector 11, a pulse motor drive 13 for driving a pulse motor I2, a common drive 15 for controlling a thermal head 14, an image signal drive 16, a detection circuit 17, and a detection circuit drive I8 are connected to the CPU 27. ing.

Next, what is shown in FIG. 2 is the printer section.

A label 20 of a predetermined size is placed on one side of the long mount 19.
are attached continuously at equal intervals, and the mount 19 is wound up by a winding section (not shown) via a roller 21, a platen 22, a peeling plate 23, and a roller 24. A thermal head 14 is provided on the top of the platen 22 for printing in contact with the label 20, and the peeling plate 23
A label detector 11 for photoelectrically detecting the leading edge of the label 20 is provided at the tip. Further, the platen 22 is connected to the pulse motor 12 via a belt 25.

Next, the structure and operation of the thermal head 14 will be explained based on FIGS. 3 and 4.

First, 256 heating elements 26 of R1-R256 are provided, each connected to a diode 27, and these heating elements 26 are 32 (N pieces) such as R1-R32, R33-R64, etc. Grouped by C0M1~
It is divided into 8 groups (M group). Then, the COM electrode selection circuit 28 selects C0M1 to C0M4 (
C0M
1 is connected to the heating elements 26 of (, OMl and COMB.

Similarly, C0M2 is a heating element 26 of C0M2 and C0M7,
C0M3 is the heating element 26 of C0M3 and C0M6, C0
M4 is connected to the heating elements 2f)L of C0M4 and C0M5, respectively. Two data latch/picture signal drive circuits 30 and 31 are provided which operate in response to a data latch signal from the CPU 27 and a picture signal drive control signal from the picture signal drive 16, and one of these circuits has COMI to C, The heating element 26 of OM 4 is connected,
The heating elements 26 of C0M5 to C0M8 are connected to the other end. The heating elements 26 of the thermal head 14 are arranged in a line perpendicular to the direction in which the label 20 is fed.

Actual printing is performed at the timing shown in FIG. That is, by dividing the 1-line printing cycle into 4 equal parts and intermittently feeding the pulse motor 12, 1/4 line feeding is performed, and COMI and CO
M8, COM 2 and C0M7, C0M3 and C0M6, C
The heating elements 26 of OM 4 and COIv+5 are energized.

Next, the operation will be explained based on flowchart 1- in FIGS. 5 and 6. First, FIG. 5 shows the operation of the CPU 13. After the power is turned on, each connected device is initialized, and the CPU 27, which controls the printer, is given a message that controls the printing position on the label 20 and the printing format 1-.
Transfer amount. Thereafter, the display device 6 is scanned and the main routine is entered. In this main routine.

The scale data from the weighing section 1 is taken in, and modes such as weighing/fixed amount issuing mode, inspection/settlement mode, setting mode, etc. are set. Further, key information is taken in from the key device 6 and processed. After this, if it is in the weighing mode, the data on the scale is multiplied by the unit price to obtain the price, and when the label issuance conditions are set, print F is set to "1", and data such as price is output to the display device 6, Print F is rlJ
If so, check the status of the printing device and print OK.
If so, print data is set and transferred to the CPU 27. After that, print F is reset to "0" and the process returns to the main routine. Also, if the mode is the inspection/accounting mode, the inspection/accounting F is determined, and if the inspection/accounting F is not "0", the status of the device is checked to the printer 1, and if it is OK, the data is set, and the data is set to the CPU2 7. The flag is reset to "0" and the process returns to the main routine. If the mode is the setting mode, each setting task is performed and the process returns to the main routine.

Next, the above C that controls the printer based on FIG.
The operation of PU2 7 will be explained. After turning on the power, initialize each connected device and use the CP'UI 3.
After receiving the feed amount for controlling the printing format, printing position, etc. on the moving wheel 20, the main routine is entered. In the main routine.

First, it is determined whether or not it is paper feeding, and if it is paper feeding, the pulse motor drive 13 is driven, and the pulse motor 12 is driven.
Rotate to feed the paper and return to the main screen. At this time,
If the paper is not being fed, data from the CPU 1.3 is received. If this received data is sending amount data, that data is processed and the process returns to the main process. In the case of print data, the data is processed, the character generator 9 is processed, a print pattern is generated on the print buffer IO, the print pattern is printed, and the process returns to the main screen.

Next, means for detecting an abnormality in the heating element 26 will be explained based on FIGS. 7 to 11. To simplify the explanation, the description will be made assuming that there are N M groups of one heating element 26 and three groups of six heating elements 26, which are 18 heating elements 26. First, in FIGS. 7 and 8, the other points that are different from FIG. 3 are that a driver 32 is connected to the data latch/image signal drive circuit 30;
The heating element destruction detection circuit 33 is connected in parallel to each transistor 29 of r1 to Tr3 with a diode 44 interposed therebetween as a rectifying element. ' The heating element destruction detection circuit 33 includes an 0HOpN control circuit 34 and an I10 boat 3 that control its operation.
5 is connected. The OHOp N control circuit 34
is connected to the base of a transistor 37 called Tr4 via a resistor 36, and this transistor 37 is connected to the photocoupler 3.
8, and this light emitting diode 39 is connected to the heating element 26 via a current limiting resistor 40. Further, a light emitting diode 41 for confirmation is connected in parallel with the light emitting diode 39 of the photocoupler 38. Further, the I/0 port 35 is connected to a light receiving element 43 which is connected to a power source through a resistor 42 .

Therefore, for the sake of convenience, if we look at FIG. 9 and FIG. 1O, which are shown as operating at H level,
When the OM control signal is output, a normal recording operation is being performed, so the OHo pri control signal is not output. Then, when 1) normal recording operation is not being performed, 0)1opo control signal is output and transistor 37 is turned on. At the timing when this 1-transistor 37 is ON, L1 to L6 are turned ON in sequence, and the transistor 37 is turned ON.
, photocoupler 38, and resistor 40, the heating element 26 is sequentially energized. At this time, when the heating element 26 is normally energized, the light emitting diode 39 emits light and the light receiving element 43' is in a conductive state, but when there is an abnormality in the heating element 26, the light emitting diode 39 does not emit light and the light receiving element 43' is in a conductive state. Since element 43 is in the cut-off state, rDOT 0 in FIG.
As shown in the part marked PENJ, ■To1 o p N is H
As a result, a signal is output from the I10 port 35 to warn that there is an abnormality and to stop the printing operation.

Note that it is possible to check whether the heating element 26 is normal or not by visually observing the light emitting state of the light emitting diode 41.

In addition, the capacity of the photocoupler 38 is 1 when the heating element 26 is energized.
l)it capacity is sufficient.

The details of the timing when L1 to L6 in FIG. 1O are turned on will be explained based on FIG. 11. That is, the maximum value of the ON time of L1 to L6 is defined as T. This time T is a time during which the thermal coloring paper does not develop color even if the heating element 26 is energized. Then, when L1 to L6 are sequentially turned on and IHopN becomes L within 5 hours T, the next dot detection timing is set at the time when the L level is detected. Therefore, when the heating element 26 is checked to be normal, the next heating element 26 is activated without waiting time.
, the detection speed becomes faster. of course,
When the detection of L1 to L6 completes one cycle, the signal is switched to the next COM control signal. Also, during time T, I Hop r
If i does not go to L, this becomes a defective signal as DOT 0PEN.

Effects of the Invention In the present invention, as described above, the energization time for detecting abnormality of the heating element is set to a certain time during which the thermal coloring paper does not develop color, and during this energization time, it is determined that the heating element is normal. Since the detection timing of the next heating element is immediately shifted to when a signal is output, abnormality detection of a large number of heating elements can be performed in an extremely short time.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is a block diagram, FIG. 2 is a side view showing the structure of the main part, FIG. 3 is a circuit diagram, FIG. 4 is a timing chart, and FIG. 6 is a flowchart, FIG. 7 is a circuit diagram, FIG. 8 is a circuit diagram of the heating element destruction detection circuit, FIGS. 9 and 10 are timing charts, and FIG. 11 is a timing chart showing a part of the timing in detail. It is a chart. 26... Heating element, 33... Heating element destruction detection circuit 32
0

Claims (1)

[Claims] A large number of heating elements that generate thermal energy for recording by being selectively energized are arranged in a straight line, and each of the heating elements is heated at a time other than when recording is performed using these heating elements. A certain energization time is set to generate only insufficient thermal energy for recording, and if a signal indicating that the heating element is normal is output within this energization time, the next heating element is detected. A method for detecting head breakage in a thermal printer, characterized in that the head is shifted.