JPS61213171A - Bar code printer - Google Patents

Abstract

PURPOSE:To enable bar codes with a predetermined line width to be printed under a wide range of temperature variations, by a method wherein a heating pulse is split, the pulse width of each heating pulse is varied depending on variations in temperature, and the pulse-outputting time is shortened with the lapse of printing time. CONSTITUTION:A gate circuit is provided on the output side of a pulse-generating circuit, and pulse trains S1 (a high temperature time pulse train S1H, an intermediate temperature time pulse train S1I, a low temperature time pulse train S1L) are supplied to one input side of the gate circuit. In this case, a gate-controlling signal for shortening the gate-opening time with the lapse of code printing time is supplied to the other input side of the gate circuit. As a result, heating pulse trains S2 (a high temperature time heating pulse train S2H, an intermediate temperature time heating pulse train S2I, a low temperature time heating pulse train S2L) obtained by cutting off the pulse trains S1 for a period of time T proportional to the bar printing time regardlessly of temperature variations are outputted from the gate circuit, and are impressed on desired heating elements in a thermal head to generate heat, thereby printing bar codes on a printing sheet such as a thermal recording paper and an ordinary paper.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a barcode printing device that prints barcodes using a label printer or the like. This invention relates to a barcode printing device that prints a barcode with a thickness of .

(Technical Background of the Invention and Problems Thereof) A conventional printing device of this type is composed of a mono multivibrator and its external time constant circuit such as a capacitor, a resistor, etc. It has a pulse generation circuit that generates one heating pulse with a wide width defined by The heating pulse SH has widths WH, Wl, and WL as shown in FIG. 4 from the change in resistance value.

81, by obtaining the SL and applying this heating pulse to the necessary heating elements of the thermal head to generate heat, a bar code consisting of one or more bars is printed on thermal paper, etc., and the bar code is printed between these bars. It is designed to have a meaning as predetermined information based on the interval between and the thickness of each bar.

Therefore, the printing device described above uses a thermistor to vary the pulse width of the heating pulse, but this thermistor has very poor responsiveness to the effects of ambient temperature and heat accumulation due to heat generated by the heating element. Therefore, as shown in FIG. 5, the thickness of the bar 2 printed on the thermal paper 1 changes from the print start end (A) to the print end (R1 ( (b) It gradually becomes thicker, and information that is completely different from the information that should be printed is printed, resulting in data processing based on incorrect information.

Therefore, in order to solve the above-mentioned problems, as shown in FIG. The width of the bar 2 is varied to prevent the bar 2 from becoming thicker as it approaches the print end side opening. However, in this method, the pulse width of the heating pulse for each temperature is uniformly set to W.
Since the correction effect at high temperatures is greater than that at low temperatures, as a result, the thickness of bar 2 at high temperatures gradually becomes thinner toward the end of printing, and conversely, On the other hand, the thickness of the bar 2 at low temperatures gradually becomes thicker as the print ends in the roni line <, which is a disadvantage, and the conventional method is still not fully satisfactory.

[Purpose of the invention]

The present invention has been made with attention to the above points, and it is possible to print barcodes with a predetermined thickness over a wide range of temperature changes, and to avoid data processing based on incorrect barcode information. The present invention provides a barcode printing device that does the following.

[Summary of the invention]

The present invention provides: a thermal head arranged perpendicularly to bars constituting a bar code to be printed; a pulse generating circuit that applies a heating pulse train to a heating element of the thermal head; and a pulse generating circuit that detects the temperature of the thermal head. a first control circuit that changes the width of each pulse constituting the heating pulse train in response to the temperature detected by the temperature sensing element; and a second control circuit that reduces the number of pulses of the heating pulse train over time.

(Example of the invention) Next, an embodiment of the device of the present invention will be described.

First, in the device of the present invention, a plurality of narrow pulses are generated from a pulse generation circuit, and the width of these pulses is uniquely determined by a time constant of a capacitor, fixed resistance, etc. connected to the pulse generation circuit. shall be determined.

Next, a temperature sensing element such as a thermistor is used as part or all of the resistor to detect a temperature change as a resistance value change, and the time constant is varied to adjust the width of each pulse to 1il.
JID. As a result, as shown in FIG. 1, the pulse train SIH is outputted from the pulse generation circuit at high temperatures with a width narrower than the width uniquely determined as described above, and at low temperatures the pulse train SIH is output with a width narrower than the width uniquely determined as described above. Also, a pulse train SIL with a wider width is output. 811
indicates a pulse train at medium temperature.

Next, a gate circuit is provided on the output side of the pulse generation circuit, and one input side of this gate circuit is provided with the pulse train Sl (high temperature pulse train SIH, medium temperature pulse train 81 L, low temperature pulse train 81 L) obtained as above. ),
At this time, a gate control signal is supplied to the other input side of the gate circuit to shorten the gate opening time as the code printing time elapses. As a result, as shown in FIG. 2, the gate circuit outputs a heating pulse train 82 (high-temperature heating pulse train 82H1 medium-temperature heating pulse train S2I, a low temperature heating pulse train 52L) is output, which is applied to the necessary heating elements of the nine-maru head to generate heat, thereby printing a bar code on a printing sheet such as thermal paper or plain paper.

Therefore, according to the method of the embodiments described above, the pulse width of each pulse is made narrower during iai according to temperature changes using a temperature sensing element, and conversely, the pulse width of the pulse is made wider when the temperature is low. Since the pulse train is controlled so that I! is controlled so that I! It is possible to perform a temperature correction approximately similar to that shown in FIG. 4 described in the conventional example for temperature changes. Furthermore, in this embodiment, since the heating pulse train is divided into a plurality of heating pulse trains and applied to the heating element, the influence of heat exerted on the thermal head can be made smaller than on the heating element. In addition, the pulse output from the pulse generation circuit is gated by the gate circuit, but the gate opening time at this time is uniformly shortened by the same amount of time T as the printing time passes, regardless of the change in 1a. As is clear from Fig. 2, at high temperatures, the temperature correction effect is suppressed by the narrow pulse width.
When the temperature is low, the width of the pulse is wide, so the temperature correction effect is enhanced, so that a barcode of a predetermined thickness can be printed on the printing sheet.

Hereinafter, an example of the main structure of the apparatus of the present invention will be described with reference to FIG. 3. In the figure, 10 is a pulse generation circuit that generates a heating pulse train, which is clocked by C.
It has a mono-multivibrator 11 that generates a plurality of narrow pulse trains S1 in response to LK, and this vibrator 1
1, an external capacitor C and resistors R1 and R
2 time constant circuits are connected, and the pulse width of the pulse S1 generated from the multivibrator 11 is determined to a predetermined width by the time constants of the capacitor C and the resistors R1 and R2. A temperature sensing element 12 such as a thermistor for detecting a temperature change as a resistance value change is connected in parallel to one of the resistors R1 and R2, for example R2.

The first control circuit includes the capacitor C and the resistors R1, R
It consists of two time constant circuits. This temperature sensing element 12
is formed as a part of the resistor R2, and as the temperature increases, the resistance value decreases and the capacitor C
1 By lowering the time constants of resistors R1, R2, etc., the pulse width of pulse train S1 is made smaller, and conversely, when the temperature decreases, resistor T? L
It has a function of increasing the time constant as i becomes larger and increasing the width of the pulse train S1. Reference numeral 13 denotes a gate circuit using, for example, an AND circuit. One input terminal of this gate circuit 13 receives the pulse train S1 outputted from the mono-multivibrator 11, and the other input terminal is connected to a gate circuit. The output end of the IIJI 11 section 14 is connected. The gate control unit 14 supplies the gate circuit 13 with a gate 1IJilO signal S2 that shortens the gate opening time as the printing time passes, and controls the passage of the pulse train S1 by controlling the temperature change from the gate circuit 13. The thermal head 1 outputs a heating pulse S3 corresponding to
5. The second control circuit 17 includes a gate circuit 13 and a gate control section 14. In addition,
A conventionally known thermal head 15 is used.

Furthermore, the second MwJ circuit may be configured to output a pulse train in which the time alII interval increases sequentially as the printing time elapses, and the output of a mono multivibrator that receives this pulse train as input may be applied to the thermal head. can.

In the above embodiment, a mono-multivibrator was used as the pulse generating circuit, but other circuits may be used as long as they have similar functions.

It goes without saying that the same applies to the heating element and the gate circuit.

(Effects of the Invention) As described in detail above, according to the present invention, a heating pulse is divided into a plurality of parts, the pulse width of each heating pulse is varied depending on temperature changes, and the pulse width is changed as the printing time elapses. To provide a barcode printing device that can always print a barcode of a predetermined thickness even over a wide range of temperature changes because the output time is controlled to be short, and there is no need to worry about data processing due to incorrect information. can.

[Brief explanation of the drawing]

1 and 2 are heating pulse trains and time charts of the heating pulse trains for explaining one embodiment of the apparatus of the present invention, FIG. 3 is a configuration diagram showing an example of the apparatus of the present invention, and FIG.
t1! ! 1 is a time chart of a heating pulse train to explain one conventional device, FIG. 5 is a diagram of a barcode obtained by the device shown in FIG. 4, and FIG. 6 is a diagram of another conventional device.
3 is a time chart of a heating pulse train for explaining one device. 81 (SIH, 811%81 L)...Output pulse train of the pulse generation circuit, S2 (S2H182I, 52L)...Heating pulse train, S3...Gate control signal, 10...Pulse generation circuit, 12...・Temperature sensing element, 13... Gate circuit, 14
...Gate control unit, 15...Thermal head. Figure 1 Figure 2 Fu 3 Prisoner 4 Inke 5 Figure 6

Claims (4)

[Claims] (1) A thermal head (15) arranged perpendicularly to the bars constituting the bar code to be printed; a pulse generating circuit (10) that applies a heating pulse train to the heating element of the thermal head; a temperature sensing element (12) that detects the temperature of the head; a first control circuit (16) that changes the width of each pulse forming the heating pulse train in response to the temperature detected by the temperature sensing element; A barcode printing device comprising a second control circuit (17) that reduces the number of pulses of the heating pulse train as the printing time of the bars formed in the direction passes. (2) The barcode printing device according to claim 1, wherein the second control circuit includes a gate circuit that reduces the gate time as the printing time elapses. (3) The barcode printing device according to claim 1, wherein the second control circuit performs control so that the interval between pulses constituting the heating pulse train increases as the printing time elapses. (4) The temperature sensing element is a thermistor and is disposed near the thermal head, the first control circuit includes a CR circuit, the R includes the thermistor, and the pulse generating circuit is a monomultiplier. A vibrator, and the C
2. The barcode printing device according to claim 1, wherein the width of the generated pulse is changed by changing the time constant of the R circuit.