JPH01171968A - Label position detector for label printer - Google Patents

Abstract

PURPOSE:To enable reliable detection of labelling position without requiring adjustment and regardless of the type of sheet to be labelled, by setting a reference voltage to an optimal level based on signals produced through conversion of the amounts of light passed respectively through a label detecting section and other section of a sheet into voltages. CONSTITUTION:When a label sheet 10 moves between a LED 1a and a photodetector 1b in a photo-sensor 1 current flowing through the photodetector 1b varies with the amount of light passing therethrough then the current is converted through a detection resistor 3 into a voltage to produce a detection voltage Vd at a point (d), which is provided to a comparator 2. The detected voltage Vd is converted through an A/D comparator 5 into a digital signal which is taken into a CPU6. The CPU6 discriminates higher and lower voltage levels VH, VL of the detected voltage Vd and feeds a digital signal necessary for setting a value of (VH+VL)/2 as a reference voltage Vr to a D/A converter 7. The D/A converter 7 converts the digital signal into an analog voltage to produce the reference voltage Vr which is fed to the comparator 2. The comparator 2 discriminates variations of the detected voltage Vd accurately and inverts the output, thus detecting the labelling position on the mount reliably.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a label position detection device for detecting the position of a label removably attached to a strip-shaped mount in a label printer in order to print at a predetermined position of the label. Regarding.

For example, as shown in FIG. 5, the disaster removal label printer transfers label paper 1o, in which labels 11 are removably attached to a strip-shaped mount 12 at predetermined intervals, in a fixed direction while printing each label 11. Data such as weight and price are printed at a predetermined position, and the printed label 11 is peeled off from the mount 12 and affixed to a product or the like.

In such a label printer, in order to print at a predetermined position on the label 11, it is necessary to accurately detect the position of the label.

Therefore, as shown in, for example, Japanese Utility Model Publication No. 59-25670, conventionally, as shown in FIG. A detection circuit as shown in FIG. 6 using a transmissive photosensor 1 consisting of an element 1b converts the amount of light passing through the portion of the mount 12 to which the label 11 is attached and the portion of the mount 12 alone into voltage. A label position detection device was provided which detects the position of the label 11 by comparing the voltage with a reference voltage Vr using a comparator 2 and determining the above-mentioned two portions.

Alternatively, the position of the label 11 is detected by converting the amount of light reflected by the two parts into a voltage using a detection circuit using a reflective photosensor, and comparing each voltage with a reference voltage to discriminate between the two parts. There were some things.

In addition, a specific detection part (notch, black mark, etc.) indicating the label position is provided on the mount 12, and the two parts are discriminated based on the difference in the amount of light passing through or reflected from the detection part and other parts. It is also possible to detect the position.

However, in such conventional label position detection devices, there are differences in the material and thickness of the labels used.

Due to variations in the optical axis and distance during photo sensor characteristics and installation, and in the case of black marks due to differences in ink material and density, the amount of transmitted light or reflected light changes, resulting in variations in the voltage generated. In some cases, the position of the label cannot be reliably detected due to misalignment.

Therefore, the width of the voltage Vd of the high and low plane levels corresponding to the difference in the amount of light detected from point d of the detection circuit in FIG.
It was necessary to perform the troublesome work of adjusting the variable resistor 8 so as to distribute it accurately to both sides of r.

In addition, as mentioned above, there are various types of label paper, such as those that simply have a label attached to a backing paper, those that have a notch formed as a detection part to indicate the label position, and those that have black marks printed on them. Therefore, when using these different types of label paper, it was necessary to perform the troublesome work of resetting the reference voltage Vr by adjusting the variable resistance in the detection circuit shown in FIG. 6 each time.

Otherwise, it would be impossible to use label paper other than the designated one, which would be difficult for the user to use.

The object of the present invention is to solve the problems in the conventional label position detection device and to eliminate the need for the above-mentioned adjustment work.

In order to achieve the above object, this invention transports a label releasably attached to a strip-shaped mount in a fixed direction, and also moves the label of the mount to print at a predetermined position on the label. The position of the label is determined by converting the amount of light passing through or reflected from the attached part and the mount only part, or the detection part and other parts into voltages, and comparing these voltages with a reference voltage to discriminate between the two parts. In a label position detection device for a label printer configured to detect.

Automatic reference voltage that sets the reference voltage to the optimum voltage level between the higher voltage level and the lower voltage level, based on signals obtained by converting the amount of light passing through or reflected from both parts of the mount into voltage. A setting means is provided.

With the above configuration, even if the amount of transmitted light or reflected light changes due to differences in the type of label paper or the various variations mentioned above, and the detected voltage that converts it to voltage changes, the voltage Since the reference voltage automatic setting means automatically sets the reference voltage to the optimum level based on the reference voltage, there is no need to readjust the reference voltage every time as in the conventional case, and the label position can always be reliably detected.

Hereinafter, the present invention will be specifically explained based on embodiments.

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and the same parts as in FIG. 6 are given the same reference numerals.

In this embodiment, a series circuit of a protective resistor R and a light emitting element 1a, and a light receiving element 1b are connected between the DC power supply Vcc and the ground.
The detection unit 4 is configured by connecting the detection resistor B and a series circuit of the detection resistor B in parallel.

As the light emitting element 1a constituting the transmission photosensor 1, an infrared LED that matches the spectral sensitivity (wavelength) of the phototransistor that is the light receiving element 1b may be used.

When the label paper 10 is moved between the light emitting element 1a and the light receiving element 1b as shown in FIG. The detected voltage Vd obtained at point d after being converted into a voltage is input to the negative input terminal of the comparator 2 via the input resistor R2.

The detected voltage Vd is also input to the A/D converter 5, converted into a digital signal, and taken into the microcomputer (hereinafter abbreviated as rcPUJ) 6.

Note that the detection voltage Vd is at a high level in a portion of each type of label paper with a large amount of passing light, and is at a low level in a portion with a small amount of passing light.

Therefore, the CPU 5 determines the higher voltage level VH and the lower voltage level VL of the detected voltage Vd, and performs arithmetic processing to add the digital values of both levels to 1/2,
A digital signal for setting (VH + VL)/2 as the reference voltage Vr is sent to the D/A converter 7.

The D/A converter 7 converts it into an analog voltage to generate a reference voltage Vr, which is input to the positive input terminal of the comparator 2 via the input resistor R.

Therefore, the reference voltage Vr is set to the optimum level, and the range of change in the detection voltage Vd is always accurately distributed to both sides of the reference voltage Vr.
accurately determines the change in the detection voltage Vd, that is, the different portions of the label paper, and inverts the output. Thereby, the position of the label on the mount can be detected reliably.

In this embodiment, the CPU 5 and the D/A converter 7 function as automatic reference voltage setting means.

Second, Figures (a), (b), and (Q) each show 10 pieces of label paper.
Examples of different types are shown, (a) is one in which the label 11 is simply attached to the backing paper 12, (b) is one in which notches 13 are formed on both sides of the backing paper 12 as detection parts indicating the label position, (Q ) also has a black mark 14 printed as a detection part.

When each of these label sheets is detected by the label position detection device shown in FIG.
d is the solid line a in FIG. 3, respectively.

This is shown by the dashed line C and the dashed line C.

The solid line a represents the voltage change due to the difference in the amount of light between the portion of the label paper 10 in FIG. ), the -dotted chain line C represents the voltage change due to the difference in the amount of light between only the mount 12 and the notch 13 of the label paper 10 in FIG.
The voltage changes due to the difference in light intensity between the part where the label 11 is attached to the mount 12 of the label paper 10 and the part where the black mark 14 is shown in c) are shown.

According to this embodiment, in any case, Vra, Vr are used as the reference voltages at the optimum voltage level intermediate between the higher voltage level and the lower voltage level of the detection voltage Vd.
b. Vrc is set.

In addition, even if the type of label paper used is the same, the detection voltage Vd changes due to various variations as described above, but since feedback is applied to the reference voltage set by the CPU 6 according to the change, the variation in label paper only increases. Rather, it is possible to perform stable discrimination, taking into account variations in the photosensor itself and changes over time.

FIG. 4 is a circuit diagram showing another embodiment of the invention,
Components similar to those in FIG. 1 are designated by the same reference numerals, and their description will be omitted.

In this embodiment, a reference voltage selection circuit 21 consisting of switching elements S□, S2゜S2 and a plurality of voltage levels (three types in this example) each having different voltage levels suitable for the type of label paper expected to be used are used. ) reference voltage Vr□
, Vr, , Vr3 are provided.

Then, the CPU 13 determines the high and low levels of the digital conversion data of the detection voltage Vd taken in from the A/D converter 5, and sends a signal for selecting the most suitable reference voltage to the reference voltage selection circuit 21, and sends a signal to the reference voltage selection circuit 21 to select the most suitable reference voltage. Turn on one of the S3s.

Among the three types of reference voltages Vr□ to Vr generated by the reference voltage generation circuit 22, the optimum voltage is selected and inputted to the comparator 2 as the reference voltage Vr.

Therefore, in this embodiment, the CPU 6, the reference voltage selection circuit 21, and the reference voltage generation circuit 22 function as an automatic reference voltage setting means.

According to this embodiment as well, it is possible to automatically handle various types of label paper using - number of photosensors. Furthermore, by increasing the number of types of reference voltages that can be selected, it is possible to cope with variations in label paper and photosensors themselves, changes over time, etc. to some extent.

〔Effect of the invention〕

As described above, the label position detection device for a label printer according to the present invention can reliably detect the position of a label without any adjustment, no matter what type of label paper is used.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG.
)(b)(c) are explanatory diagrams of different types of label paper, and FIG. 3 is an illustration of FIG. 2(a)(b)(
C) is an explanatory diagram showing the relationship between the detection voltage and the optimum reference voltage when each type of label paper is detected; FIG. 4 is a circuit diagram showing another embodiment of the present invention; FIG. FIG. 6 is a circuit diagram showing an example of a label position detection device in a conventional label printer. 1...Transmissive photo sensor 1a...Light emitting element 1
b... Light receiving element 2... Comparator 3...
・Detection resistor 4...Detection section 5...A/D converter 6...Microcomputer (CPU) 7...D/
A converter 10... Label paper 11... Label 12... Mounting paper 13... Notch (detection part) 14... Black mark (detection part) 21... Reference voltage selection circuit 22... Reference voltage generation circuit

Claims (1)

[Scope of Claims] 1. In order to transport a label removably attached to a strip-shaped mount in a fixed direction and to print at a predetermined position on the label, only the portion of the mount to which the label is attached and the mount are used. The position of the label is detected by converting the amount of light passing through or reflected from the part or the detection part and other parts into voltage, and comparing these voltages with a reference voltage to discriminate between the two parts. In the label position detection device of the label printer, the optimum voltage level between the higher voltage level and the lower voltage level is determined based on the signal obtained by converting the amount of light passing through or the amount of reflected light from both parts of the mount into voltage. 1. A label position detection device for a label printer, characterized in that a reference voltage automatic setting means for setting the reference voltage is provided.