JPS63194974A - Temperature indicator for thermal head - Google Patents

Abstract

PURPOSE:To obtain a temperature indicator for thermal head which requires no measuring device such as an oscilloscope, by providing a temperature detector for detecting a heating temperature of the thermal head, an A/D converter for converting the output from the temperature detector and an indicator for indicating the state. CONSTITUTION:Temperature of heating element generated in a thermal head 1 is detected through a temperature detector, i.e. a thermister 2, and the information is inputted as an analog signal to an A/D converter 3 where it is converted into a digital signal. If it is required to investigate the temperature of the thermal head 1, a changeover switch 5a in a switching circuit 5 is switched over to a terminal at side B. Consequently, the gate in a first AND gate 11 is closed, and the gate in a second AND gate 12 is opened by digital signals b1, b2, b3, b4 outputted from the A/D converter 3, thereby a status indicator 6 is driven to light the light emission diodes 14-1, 14-2, 14-3, 14-4 corresponding to the temperature of the thermal head 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a thermal head temperature display device useful in image forming apparatuses such as thermal printers and thermal transfer printers using thermal heads.

(Prior Art) Conventionally, a printer using a thermal head performs printing by passing current through a heating element arranged on the head to generate heat. Therefore, in the printing operation,
In order to obtain good prints, it is necessary to rapidly heat the heating element in the area to be printed, and to cool it rapidly after printing. The reason for this is that when the temperature of the heating element gradually rises, the temperature around the heating element also rises during the rising process, and the sharpness or resolution of the print deteriorates.

Furthermore, a similar adverse effect occurs when the temperature of the heating element does not drop rapidly after it rises.

That is, in a thermal printer using a thermal head, temperature control of the head is an essential condition for obtaining good printing effects. For this reason, in the past, a temperature sensor such as a thermistor was attached to the thermal head itself, and operating conditions were set to match a predetermined temperature while monitoring the temperature of the thermal head.

Controls the heat generation power to the head and the printing speed. Furthermore, control is performed such as temporarily suspending the printing operation until the thermal head is cooled down.

However, since these controls are executed by electrical and logic circuits built into the printer, for example, if the printing speed decreases or stops, the temperature of the thermal head may increase. Methods for determining whether or not the temperature has increased, and how much the temperature has increased, have the disadvantage that they must be measured using a special measuring instrument such as an oscilloscope.

(Problems to be Solved by the Invention) As described above, when the printing speed decreases or stops due to printer control, the present invention solves the problem of determining whether or not this is caused by an increase in the temperature of the thermal head. Another object of the present invention is to provide a thermal head temperature display device that solves the problem of having to use a measuring device such as an oscilloscope to check how much the temperature has increased.

[Structure of the invention]

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides an image forming apparatus using a thermal head. an A/D converter that converts an output from an analog signal to a digital signal; a display that displays a state corresponding to the state of the image forming apparatus; and an output of the A/D converter that is displayed on the display. The device is constructed by providing a switching means for switching.

(Function) In other words, (1) the present invention has the above configuration, so that the display unit has an output and a thermal signal to display the status of the image forming apparatus, that is, the number of sheets to be printed, the size of paper, no paper, no ribbon, paper jam, etc. The output for displaying the heat generation temperature of the head can be switched and displayed by the switching means.

Therefore, when it is desired to check the heat generation temperature of the thermal head, by switching the display using the switching means, the heat generation temperature is displayed on the display and can be easily determined.

(Example) The present invention will be described below based on an example shown in FIGS. 1 to 4. FIG. 1 is a block diagram showing the configuration of this device, and FIG. 2 is its circuit diagram.

In FIG. 1, ``■'' is a thermal head, and a temperature detector, such as a thermistor ``2'', for detecting the heat generation temperature of a heating element (not shown) is arranged in this thermal head ``2''. The analog signal detected by the thermistor (2) is input to the A/D converter (2), where it is converted into a digital signal and used to control printing. On the other hand, ) shows the printer status, i.e. number of pages printed, paper size, no paper, no ribbon, etc.
This is a printer status signal generator that detects a paper jam and generates a signal.The output signal (a) of this status signal generator) and the output signal (b) of the above A/D converter (■)
is input to the status display 0 via the switching circuit m■, and is displayed by lighting. In addition, the above display 0
Normally, printer status information such as number of pages printed, paper size, no paper, no ribbon, paper jam, online, ready, etc. is displayed on the operation panel to make it easier for the operator to recognize the status of the printer. .

Further, the output signal (b) of the A/D converter (2) is normally used to control printing by a printer.

An example of the electric circuit shown in FIG. 2 will be described in detail.

In the figure, the switching circuit (■) is used to select either the signal from the status signal generator) or the signal from the A/D converter (5).
a). Furthermore, the switching circuit ■ is a paper out signal (al) output from the status signal generator ■ of the printer;
Signal without ribbon (a, ).

A first AND circuit (11) that ANDs the outputs of the paper jam signal (al) and the ready signal (a4) and the output when the changeover switch (5a) is switched to the A side terminal, and the A/D conversion. Each output (bt) of the device ■, (bzL (baL cb
A second AND circuit (12) that takes an AND between 4) and the output when the changeover switch (5a) is switched to the B side terminal.
and an OR circuit (13) whose inputs are the outputs of the first AND circuit (11) and the second AND circuit (12). And the above OR circuit (13)
At the output end of the light emitting diode (14-1), (14-2
), (14-3).

A status indicator 0 consisting of (14-4) is connected.

On the other hand, in the A/D converter (2), (STC) is a start signal input terminal, and the start signal is input at a predetermined period. Further, (OSC) is a terminal for inputting a lock necessary for A/D conversion, and in this embodiment, 7 clocks are input to 750. The above A/D converter ■ is a temperature sensor,
In other words, it converts the analog signal input from the thermistor ■ into an 8-bit digital signal, and the output of this A/D converter ■ is divided into the upper 4 bits and the lower 4 bits.
When the RSEL signal (C) is at high level, the upper 4 bits are output, and when the RSEL signal (C) is at low level, the lower 4 bits are output from the signal (b,).
, (bi), (bi).

(b4). In the figure, the switch (15) is for giving a high level or low level signal to the R9EL signal (C).
When it is in the open state, the upper 4 bits are displayed on the display (0), and when it is in the closed state, the lower 4 bits are displayed.

Figure 3 is a cross-sectional view showing the schematic configuration of a printer incorporating this device. It is set by At this time, a detection signal corresponding to the set position, for example, when the A-4 size is set, the cassette size (50) in the display area (50) shown in FIG.
54) lights up to indicate that it is A-4 size plain paper. In addition, a paper feed roller (23) is in rolling contact with the uppermost plain paper (P) at the top of the take-out side of the paper feed cassette (22), and a belt (25) is driven by the 5 feed motor (24).
) to the guide roller (2) coaxial with the paper feed roller (23).
6) rotate counterclockwise through the
is taken out. The leading edge of the taken out plain paper (P) is detected by a photoelectric detector (27) placed on the conveyance path, and this detection signal causes the feed motor (24) to rotate counterclockwise. The above feeding motor (2
4) is connected via a belt (30) to a head roller (29) that comes into contact with the thermal head (28), and further feeds the plain paper (P) by sandwiching it between the head roller (29) and the head roller (29). A pair of paper ejection rollers (3) provided on the paper ejection side of the pair of feeding rollers (31) and the head roller (29).
2) is wound around a belt (33), and the driving force of the head roller (29) is transmitted thereto.

On the other hand, (34) is a transfer ribbon feeding part in which the transfer ribbon (R) is wound, and (35) is a transfer ribbon winding part that winds up the transfer ribbon (R) fed out from the feeding part (34). This winding part (35) is connected to the above-mentioned roller roller (29).
) to the belt (37) from the roller (36) that receives the rotational force of the
The transfer ribbon (R) is rotated clockwise through the transfer ribbon (R).

In the figure, (38) and (38) are rotatable support rollers that support the transfer ribbon feeding section (34), and the transfer ribbon (R) fed out from the feeding section (34) is moved to a brake equipped roller (39). Tension is applied by being held between the pinch rollers (4o) and the guide rollers (4o).
1) and sent to the head roller (29). Thermal head (28) has a heating section formed in the shape of a line to be perpendicular to the conveyance direction of the plain paper (CP) at the overlapping part of the plain paper (P) and the transfer ribbon (R) wound around this head roller (29). ) is provided, and thermal transfer recording is performed by this thermal head (28). After printing, the transfer ribbon (R) is transferred to the thermal head (28).
The plain paper (P) is provided integrally with the transfer ribbon winding section (35) via the ribbon peeling roller (42), while the plain paper (P) is attached to the above-mentioned roll roller (29) under the tension of a spring (not shown). ) is fed out by a plain paper feed roller (43) that makes contact with the plain paper feed roller (43).

A paper ejection tray (44) is held between the above paper ejection rollers (32).
Paper is ejected upwards. Further, (45) is an operation panel provided on the operation surface side of the main body (21), and this operation panel (45) is provided with operation switches and display lamps as shown in FIG. In other words, the JAN indicator lamp (51) lights up when the plain paper (P) in the paper feed cassette (22) is not fed normally or is clogged, and turns off when the normal state is restored after inspection. and,
PAPE! lights up when there is no plain paper CP in the paper cassette (22), and turns off when it is replenished! R.E.M.
PTY indicator lamp (5z) and transfer ribbon feeding section (3
4) When the capacity of the transfer ribbon (R) wound around the device starts to run out, the display blinks, and when the transfer ribbon (R) runs out, the light turns off. Then, the RIBB-ON EMPT turns off when the transfer ribbon (Ro) is replenished.
A Y display lamp (53), a cassette size display lamp (54) that lights up and displays according to the size of plain paper (P) stored in the paper feed cassette (22), and an operation switch for switching from offline to online ( 55) and an indicator lamp (56), and a READY indicator lamp (57) that lights up when the printer is functioning normally and turns off when a JAN or error occurs, and a display area (50) on the main body. A POtlER indicator lamp (58) is arranged that lights up when a POυER switch (not shown) provided on the back side is turned on and turns off when turned off. In addition, the READY indicator lamp (57),
The POVER indicator lamp (58) is connected so that it does not serve any other function. Further, (59) is a push button switch for TEST, and by pressing this push button switch (59), test printing for one A-4 size sheet is performed, for example, and (60) is a push button switch for FEED. By pressing the switch (60), plain paper (P) is taken out from the paper feed cassette (22).

Next, the operation of the present invention based on the above configuration will be explained. In Figs. 1 and 2, the changeover switch (5a) of the changeover circuit The gate of the AND circuit (11-1) of No. 1 is opened and the light emitting diode (1
4-1). Similarly, ribbonless signal (a2)
in case of paper jam signal (a3), light emitting diode (14-3) in case of paper jam signal (a3), and light emitting diode (14-4) in case of ready signal (a4).
), and the status of the printer is displayed on the status display ■. That is, in normal usage conditions, the status of the printer is displayed on the display (3) provided on the operation panel.

On the other hand, the temperature emitted by the heating element (not shown) of the thermal head ω is detected by a temperature detector, that is, the thermistor ■, and the information is input as an analog signal to the A/D converter ■ and digitized by the A/D converter ■. converted into a signal.

If it becomes necessary to check the temperature of the thermal head ω while the printer is operating or during maintenance, first switch the changeover switch (5a) of the changeover circuit ① to the B side terminal. Then, the gate of the first AND circuit (11) is closed, and the digital signals (bt), (b,), (b,) are output from the A/D converter (2).

Since the gate of the second AND circuit (12) is opened by (b4), the status display 0 is driven, and the light emitting diode (14-1
), (14-2), (14-3), (14-4)
can be displayed by lighting up.

In addition, in FIG. 2, when the switch (15) is opened, the R3EL signal (c) is at a high level among the 8 bits.

A digital signal (bxL(b
s), (b,), (b,) and are shown to be input to the second AND circuit (12).

Further, in this embodiment, the changeover switch (5a) is provided on the operation panel, but the present invention is not limited to this, and it may be installed inside the printer so that it can be handled by a service person (Fig. 3). reference).

Therefore, in the electric circuit shown in Figure 2, the changeover switch (
5a) and the switch (15), the temperature of the thermal head (2) can be displayed on the status display (2) in combination with the status of the printer.

〔Effect of the invention〕

As explained above, according to the present invention, there is no need to check the temperature state of the thermal head using a conventional measuring instrument such as an oscilloscope, and the temperature state can be easily determined from the outside. Moreover, according to the present invention, there is no need to provide a dedicated display for displaying the temperature of the thermal head, so it is possible to suppress an increase in the cost of the apparatus.

[Brief explanation of the drawing]

FIG. 1 is a configuration block diagram of a thermal head temperature display device showing an embodiment of the present invention, FIG. 2 is an electric circuit diagram thereof, and FIG. 3 is a sectional view showing a schematic configuration of a printer incorporating this device. , FIG. 4 is a layout diagram showing an example of display lamps and operation switches in the operation section. 1...Thermal head 2...Temperature detector 3...
・A/D converter 4...Printer status signal generator 5...Switching circuit 5a...Switching switch (switching means) 6...Status display (display) Agent Patent attorney Inoue - Power Cylinder 1 Figure 2 N nsc srr.

Claims (1)

[Claims] An image forming apparatus using a thermal head includes: a temperature detector that detects the temperature of heat generated by the thermal head; and an A/D converter that converts the output of the temperature detector from an analog signal to a digital signal. , a thermal head comprising: a display that displays a state corresponding to the state of the image forming apparatus; and a switching means for causing the display to display the output of the A/D converter. Temperature display device.