Printer device

Abstract

To provide a printer device capable of surely detecting the presence of a printed label even when the label is at a position irradiated with external light.SOLUTION: Provided is a label printer, including a light irradiation unit that irradiates, with light, an area on which an already-printed label is present and which is irradiated with external light, a light irradiation control unit that switches between light irradiation and non-irradiation performed by the light irradiation unit, a light receiving unit that acquires a light signal from the area where the already-printed label is present in synchronization with the light irradiation and non-irradiation switched by the light irradiation control unit, and a label presence or absence determination unit that determines the presence or absence of a label on the basis of a first signal acquired by the light receiving unit when the light irradiation unit does not irradiate the area with light and a second signal acquired by the light receiving unit when the light irradiation unit irradiates the area with light.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] FIELD An embodiment of the present invention relates to a printer device. [Background technology]

[0002] Printers that print on label paper eject labels after they have been separated from the release paper by a peeling unit. The holding member that holds the ejected labels may be equipped with a peel sensor that detects whether or not a printed label is present (see, for example, Patent Document 1). The peel sensor is comprised of an inexpensive optical sensor and is installed on the outside of the label printer's housing, along with the holding member that holds the ejected labels.

[0003] In such printer devices, the peel sensor is susceptible to the influence of external light, and there is a possibility that the presence or absence of a label may be erroneously detected. Summary of the Invention [Problem to be solved by the invention]

[0004] The problem to be solved by the present invention is to provide a printer device that can reliably detect the presence of a printed label even if the label is in a position illuminated by external light. [Means for solving the problem]

[0005] The printer device of the embodiment comprises a light irradiation unit, a light irradiation control unit, a light receiving unit, and a label presence / absence determination unit. The light irradiation unit irradiates light onto an area illuminated by external light where a printed label is present. The light irradiation control unit switches between irradiating and not irradiating light by the light irradiation unit. The light receiving unit acquires a light signal from the area where a printed label is present, in synchronization with the light irradiation control unit's irradiating and not irradiating light. The label presence / absence determination unit compares a first signal acquired by the light receiving unit when the light irradiation unit is not irradiating light and a second signal acquired by the light receiving unit when the light irradiation unit is irradiating light. and a threshold value that monotonically decreases as the level of the first signal increases. Based on this, the presence or absence of a label is determined. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a diagram showing an example of a schematic structure of a label printer according to a first embodiment. [Figure 2] FIG. 2 is a diagram illustrating the structure and operating principle of the peel sensor provided in the label printer according to the first embodiment. [Figure 3] FIG. 3 is a diagram showing an example of a signal output detected by the peel sensor under external light. [Figure 4] FIG. 4 is a functional block diagram showing an example of the functional configuration of the label printer. [Figure 5] FIG. 5 is a flowchart showing an example of the flow of the printing operation of the label printer according to the first embodiment. [Figure 6] FIG. 6 is a flowchart showing an example of the flow of processing for determining the presence or absence of a label in the flowchart of FIG. [Figure 7] FIG. 7 is a diagram illustrating a method for setting a threshold value for determining the presence or absence of a label depending on the intensity of external light. [Figure 8] FIG. 8 is a cross-sectional view showing an example of the internal structure of the label printer according to the second embodiment. [Figure 9] FIG. 9 is a diagram illustrating the structure and operating principle of a label sensor provided in a label printer according to the second embodiment. [Figure 10] FIG. 10 is a diagram showing an example of a signal output detected by the label sensor under external light. [Figure 11] FIG. 11 is a flowchart showing an example of the flow of the printing operation of the label printer according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0007] (First embodiment) A first embodiment of a label printer according to the present invention will be described in detail below with reference to the accompanying drawings.

[0008] (Overall configuration of label printer) The schematic configuration of a label printer 10 according to the first embodiment will be described using Figure 1. Figure 1 is a diagram showing an example of the schematic structure of the label printer according to the first embodiment. The label printer 10 is an example of a printer device in the present disclosure.

[0009] The label printer 10 includes a label roll 12, which is a roll of label paper 13, an example of printing paper, inside a housing 11. The label printer 10 performs printing while pulling out the label paper 13 from the label roll 12.

[0010] The label paper 13 is wound into a roll with labels 14 affixed to release paper 15. The label paper 13 pulled out from the label roll 12 is conveyed toward the discharge port 21 while being sandwiched between a platen roller 17 and a thermal head 16. At this time, the label 14, which is the printing surface, is positioned on the thermal head 16 side. The platen roller 17 is rotated by a drive motor 18, such as a stepping motor.

[0011] The thermal head 16 has a structure in which multiple heating elements are aligned, and prints on the label 14 held between the thermal head 16 and the platen roller 17 by heating the heating elements corresponding to the print pattern. Note that the label printer 10 may also use a printing method in which an ink ribbon (not shown) is held between the thermal head 16 and the label 14, and ink on the ink ribbon heated by the thermal head 16 is transferred to the label 14.

[0012] The back side of the label 14 is an adhesive layer, and the label 14 is attached to the release paper 15 by this adhesive layer. After printing is completed, the label paper 13 is separated into the label 14 and the release paper 15 at the peel bar 19. The peel bar 19 is a V-shaped columnar member with two surfaces that intersect at an acute angle. The peel bar 19 is installed along the Y axis. Before printing begins, the release paper 15 is folded back downward (toward the negative side of the Z axis) at the intersection of the two surfaces of the peel bar 19 and is sandwiched between the platen roller 17 and the peel roller 20. Therefore, when the platen roller 17 rotates and printing is performed on the label 14, the release paper 15 is transported in the negative direction of the Z axis while being sandwiched between the platen roller 17 and the peel roller 20. The label 14 attached to the release paper 15 is then separated from the release paper 15 at the intersection of the two surfaces of the peel bar 19.

[0013] The label 14 separated from the release paper 15 is discharged from the discharge port 21 and remains at a position above the holding member 22.

[0014] A peel sensor 23 is installed inside the holding member 22 to detect the presence or absence of a label 14. The peel sensor 23 detects whether a label 14 that has been peeled from the label paper 13 is present above the holding member 22. When the peel sensor 23 detects the label 14, the label printer 10 temporarily stops feeding and printing the label paper 13. When the user removes the label 14 that has been printed from above the holding member 22, the peel sensor 23 detects that the label 14 is not present, and resumes feeding and printing the label paper 13. The structure and operating principle of the peel sensor 23 will be described later.

[0015] (Structure and operating principle of peel sensor) The structure and operating principle of the peel sensor 23 will be described using Figures 2 and 3. Figure 2 is a diagram illustrating the structure and operating principle of the peel sensor provided in the label printer according to the first embodiment. Figure 3 is a diagram showing an example of a signal output detected by the peel sensor under external light.

[0016] The peel sensor 23 includes a light-emitting element 31 and a light-receiving element 34. The light-emitting element 31 emits light at a predetermined cycle by the action of a drive circuit (not shown). The light-emitting element 31 is, for example, an LED (Light Emitting Diode). Hereinafter, the light-emitting element 31 will also be referred to as LED 31. Note that the wavelength of the light emitted by the light-emitting element 31 does not matter, but it is preferable to use near-infrared light, which is invisible light. It is also preferable that the light-receiving element 34 has high sensitivity to light of the same wavelength as the light emitted by the light-emitting element 31. For this reason, a filter that transmits light of the wavelength emitted by the light-emitting element 31 may be provided on the surface of the light-receiving element 34.

[0017] The light receiving element 34 outputs an electrical signal corresponding to the amount of light received in synchronization with the timing of light emission by the light emitting element 31. The light receiving element 34 is, for example, a photodiode. In this way, the peel sensor 23 is a reflective sensor in which the light receiving element 34 detects reflected light of the light emitted by the light emitting element 31.

[0018] The light-emitting element 31 emits light toward the top of the holding member 22 through a gap 35 in the paper transport mold 27 formed above the holding member 22. The light-receiving element 34 detects reflected light from the label 14 placed at the back (positive side of the Z axis) of the gap 35. The gap 35 is formed by cutting out a part of the paper transport mold 27 in the direction in which the label 14 is discharged, i.e., along the X axis.

[0019] The detection state Sa shown in FIG. 2 shows a state in which emitted light 32 emitted from the LED 31 is reflected by the label 14, and reflected light 33 is detected by the light receiving element .

[0020] At this time, as shown in the detection state Sb, the emitted light 32 emitted by the LED 31 passes through the gap 35 and is reflected by the back surface (adhesive layer) of the label 14. Then, the reflected light 33 is detected by the light receiving element 34.

[0021] On the other hand, when there is no label 14 above the paper transport mold 27, as shown in the detection state Sc in Fig. 2, the emitted light 32 emitted by the LED 31 passes through the gap 35 and then penetrates above (to the positive side of the Z axis) the paper transport mold 27. Therefore, the emitted light 32 emitted by the LED 31 is not detected by the light receiving element 34.

[0022] Next, the signal output detected by the peel sensor 23 under external light 38 will be described with reference to FIG.

[0023] The paper transport mold 27 is located at a position facing the outside of the housing 11 so that the label 14 can be easily removed after printing. Therefore, the printed surface of the label 14 after printing is irradiated with external light 38 in the environment in which the label printer 10 is placed. The external light 38 includes indoor lighting such as fluorescent lights, incandescent bulbs, and LED lights, as well as sunlight. Such external light 38 may adversely affect the peel sensor 23's detection of the presence or absence of the label 14.

[0024] The detection state Sd shown in FIG. 3 shows a state in which the label 14 on which printing has been completed is placed on the paper transport mold 27, and external light 38 is shining on the printed surface of the label 14.

[0025] In the detection state Sd, emitted light 32 from the LED 31 is reflected by the back surface (adhesive layer) of the label 14, generating reflected light 33. The light-receiving element 34 then detects the reflected light 33. At this time, if external light 38 is irradiating the surface of the label 14, some of the external light 38 will pass through the label 14 and reach the light-receiving element 34 together with the reflected light 33, depending on the intensity of the external light 38 and the transmittance of the label 14. Therefore, in the detection state Sd, the light-receiving element 34 outputs a larger sensor output V than when there is no external light 38, regardless of whether the LED 31 is irradiating emitted light 32 or not.

[0026] The sensor output V obtained when the LED 31 irradiates the emitted light 32 is larger than the sensor output V obtained when the LED 31 does not irradiate the emitted light 32 by an amount corresponding to the magnitude of the reflected light 33. Therefore, regardless of the intensity of the external light 38, the peel sensor 23 can determine that a label 14 is present when the difference between the sensor output V obtained when the LED 31 irradiates the emitted light 32 and the sensor output V obtained when the LED 31 does not irradiate the emitted light 32 is equal to or greater than a preset threshold value.

[0027] The detection state Se shown in FIG. 3 shows a state in which the label 14 is not present on the paper transport mold 27 and external light 38 is shining on it.

[0028] In the detection state Se, the emitted light 32 from the LED 31 passes through the gap 35 (see FIG. 2) in the paper transport mold 27 and is emitted into space. Therefore, reflected light generated by the emitted light 32 is not detected by the light receiving element 34. At this time, if external light 38 is irradiating the surface of the paper transport mold 27, the external light 38 passes through the gap 35 and reaches the light receiving element 34, causing the light receiving element 34 to output a sensor output V corresponding to the intensity of the external light 38. This state is independent of the emission state of the emitted light 32 from the LED 31. Therefore, in the detection state Se, there is almost no difference between the sensor output V obtained when the LED 31 irradiates the emitted light 32 and the sensor output V obtained when the LED 31 does not irradiate the emitted light 32. Therefore, regardless of the intensity of external light 38, peel sensor 23 can determine that label 14 is not present if the difference value between the sensor output V obtained when LED 31 irradiates emitted light 32 and the sensor output V obtained when LED 31 does not irradiate emitted light 32 is less than a preset threshold value.

[0029] Below, we will explain how to determine the presence or absence of a label 14 based on the waveform of the actual sensor output V. The sensor output example Ca shown in Figure 3 is an example of the sensor output V when there is a label 14 on the paper transport mold 27 and there is no external light 38.

[0030] The LED 31 repeatedly switches between an on state and an off state at predetermined timing. In the case of the sensor output example Ca, the LED 31 is on from time ta to time tb and from time tc to time td. On the other hand, the LED 31 is off before time ta, from time tb to time tc, and after time td. The period during which the LED 31 is on is defined as an on period pa, and the period during which the LED 31 is off is defined as an off period pb. The lengths of the on period pa and the off period pb can be set arbitrarily. Furthermore, the ratio (duty ratio) between the on period pa and the off period pb is not important.

[0031] At this time, the sensor output V output by the light receiving element 34 exhibits a pulse waveform as shown in the sensor output example Ca. That is, during the extinction period pb of the LED 31, a very small sensor output V is obtained. Then, during the illumination period pa, a sensor output V corresponding to the emitted light 32 of the LED 31 is obtained. A difference value ΔV is generated between the sensor output V during the illumination period pa and the sensor output V during the extinction period pb.

[0032] Here, the sensor output V is generated using positive logic, i.e., the greater the amount of light received by the light-receiving element 34, the greater the sensor output V that is output. The sensor output V may also be generated using negative logic, i.e., the greater the amount of light received by the light-receiving element 34, the smaller the sensor output V that is output.

[0033] 3 shows an example of the sensor output V when there is no label 14 on the paper transport mold 27 and no external light 38. The timing of turning on and off the LED 31 in the sensor output example Cb is the same as that described in the sensor output example Ca.

[0034] At this time, as shown in the sensor output example Cb, the sensor output V output by the light receiving element 34 is substantially constant regardless of the on / off state of the LED 31. That is, the difference value ΔV between the sensor output V during the on period pa and the sensor output V during the off period pb is very small.

[0035] From a comparison between the sensor output example Ca and the sensor output example Cb, it can be seen that when there is no external light 38, the difference value ΔV between the sensor output V during the light-on period pa and the sensor output V during the light-off period pb is compared with a threshold, and if the difference value ΔV is equal to or greater than the threshold, it can be determined that the label 14 is present. Also, if the difference value ΔV is less than the threshold, it can be determined that the label 14 is not present.

[0036] 3 shows an example of the sensor output V when there is a label 14 on the paper transport mold 27 and external light 38. The timing of turning on and off the LED 31 in the sensor output example Cc is the same as that described in the sensor output example Ca.

[0037] At this time, the sensor output V output by the light-receiving element 34 exhibits a pulse waveform as shown in sensor output example Cc. That is, a small sensor output V is obtained during the off period pb of the LED 31. The sensor output V obtained during the off period pb of the LED 31 is larger than the sensor output V obtained at the same timing in sensor output example Ca by the amount of external light 38 that has passed through the label 14 and reaches the light-receiving element 34. Then, a larger sensor output V is obtained during the on period pa compared to the off period pb. A difference value ΔV is generated between the sensor output V during the on period pa and the sensor output V during the off period pb.

[0038] 3 shows an example of the sensor output V when there is no label 14 on the paper transport mold 27 and there is external light 38. The timing of turning on and off the LED 31 in the sensor output example Cc is the same as that described in the sensor output example Ca.

[0039] At this time, as shown in the sensor output example Cd, the sensor output V output by the light receiving element 34 is approximately the same value according to the intensity of the external light 38, regardless of whether the LED 31 is on or off. In other words, the difference value ΔV between the sensor output V during the on period pa and the sensor output V during the off period pb is very small.

[0040] A comparison of the sensor output example Cc and the sensor output example Cd reveals that when external light 38 is present, the difference ΔV between the sensor output V during the light-on period pa and the sensor output V during the light-off period pb is compared with a threshold value, and if the difference ΔV is equal to or greater than the threshold value, it can be determined that the label 14 is present. Also, if the difference ΔV is less than the threshold value, it can be determined that the label 14 is not present.

[0041] That is, regardless of the presence or absence of external light 38, when the difference value ΔV between the sensor output V during the light-on period pa and the sensor output V during the light-off period pb is compared with a threshold, it can be seen that if the difference value ΔV is equal to or greater than the threshold, it can be determined that the label 14 is present. Also, it can be seen that if the difference value ΔV is less than the threshold, it can be determined that the label 14 is not present.

[0042] (Label printer functional configuration) The functional configuration of the label printer 10 will be described with reference to Figure 4. Figure 4 is a functional block diagram showing an example of the functional configuration of the label printer.

[0043] The control unit (not shown) of the label printer 10 has the configuration of a computer and operates by executing a control program stored in the control unit. The control unit realizes, as functional units, a light irradiation unit 41, a light irradiation control unit 42, a light receiving unit 43, a label presence determination unit 44, and a print control unit 45, all of which are shown in Figure 4.

[0044] The light emitting unit 41 irradiates the area illuminated by the external light 38, where the label 14 on which printing has been completed, with light from the light emitting element 31.

[0045] The light irradiation control unit 42 switches between irradiating and not irradiating light by the light irradiating unit 41 .

[0046] The light receiving unit 43 acquires, by the light receiving element 34, an optical signal from the area where the label 14 on which printing has been completed is present, in synchronization with the light irradiation and non-irradiation by the light irradiation control unit 42.

[0047] The label presence / absence determination unit 44 determines whether or not a label 14 is present based on the sensor output V (first signal) acquired by the light receiving unit 43 when the light irradiation unit 41 is not irradiating light, and the sensor output V (second signal) acquired by the light receiving unit 43 when the light irradiation unit 41 is irradiating light.

[0048] The printing control unit 45 acquires the print content and the instruction to start printing, and instructs each unit of the label printer 10 to start printing. The printing control unit 45 also temporarily suspends printing of the next label if the label presence determination unit 44 determines that a label 14 is present. The printing control unit 45 also instructs each unit of the label printer 10 to start printing of the next label if the label presence determination unit 44 determines that a label 14 is not present. The printing control unit 45 also determines whether a predetermined number of labels 14 have been printed.

[0049] (Flow of printing operations performed by a label printer) The flow of printing processing performed by the label printer 10 will be described using Figures 5 and 6. Figure 5 is a flowchart showing an example of the flow of printing operations of the label printer according to the first embodiment. Figure 6 is a flowchart showing an example of the flow of processing for determining the presence or absence of a label in the flowchart of Figure 5.

[0050] The print control unit 45 instructs each unit of the label printer 10 to start printing (step S11).

[0051] The label presence / absence determining unit 44 performs a label presence / absence determining process to determine whether or not the label 14 is present (step S12). If it is determined that the label 14 is present, the process proceeds to step S13. On the other hand, if it is not determined that the label 14 is present, the process proceeds to step S14. The detailed flow of the label presence / absence determining process will be described later (see FIG. 6).

[0052] If it is determined in step S12 that a label 14 is present, the print control unit 45 temporarily suspends the print operation (step S13), and then returns to step S12 to repeat the label presence / absence determination process.

[0053] If it is determined in step S12 that there are no labels 14, that is, that the labels 14 for which printing has been completed have been removed from the holding member 22, the print control unit 45 determines whether printing has been completed on a predetermined number of labels 14 (step S14). If it is determined that printing has been completed on a predetermined number of labels 14 (step S14: Yes), the label printer 10 ends the processing of Fig. 5. On the other hand, if it is not determined that printing has been completed on a predetermined number of labels 14 (step S14: No), the process proceeds to step S15.

[0054] If it is determined in step S14 that the predetermined number of labels 14 have not been printed, the print control unit 45 resumes printing (step S15).

[0055] The printing control unit 45 increments the number of labels 14 for which printing has been completed (step S16), and then returns to step S12.

[0056] Next, the flow of the label presence / absence determination process will be described with reference to FIG.

[0057] First, the light irradiation control unit 42 controls the light irradiation unit 41 to turn off the LED 31 (step S21).

[0058] The light receiving unit 43 detects the sensor output V (first signal) of the light receiving element 34 (step S22).

[0059] The light irradiation control unit 42 controls the light irradiation unit 41 to turn on the LED 31 (step S23).

[0060] The light receiving unit 43 detects the sensor output V (second signal) of the light receiving element 34 (step S24).

[0061] The label presence / absence determining unit 44 calculates the difference value ΔV between the second signal and the first signal (step S25).

[0062] The label presence / absence determining unit 44 determines whether the difference value ΔV is equal to or greater than the threshold value Th (step S26). If it is determined that the difference value ΔV is equal to or greater than the threshold value Th (step S26: Yes), the process proceeds to step S27. On the other hand, if it is not determined that the difference value ΔV is equal to or greater than the threshold value Th (step S26: No), the process proceeds to step S28.

[0063] If it is determined in step S26 that the difference value ΔV is equal to or greater than the threshold value Th, the label presence determining unit 44 determines that the label 14 is present on the holding member 22 (paper conveying mold 27) (step S27), and then returns to the main routine (FIG. 5).

[0064] If it is determined in step S26 that the difference value ΔV is less than the threshold value Th, the label presence determining unit 44 determines that there is no label 14 on the holding member 22 (paper conveying mold 27) (step S27), and then returns to the main routine (FIG. 5).

[0065] (How to set the threshold) A method for setting a threshold value Th for determining whether or not a label is present will be described with reference to Fig. 7. Fig. 7 is a diagram for explaining a method for setting a threshold value for determining whether or not a label is present, depending on the intensity of external light.

[0066] As shown in the sensor output example Ce in FIG. 7, the sensor output V has a form in which a pulse-like output corresponding to when the LED 31 is on is superimposed on the sensor output V corresponding to when the LED 31 is off. This form is maintained even when the external light 38 becomes stronger, but the stronger the external light 38, the greater the sensor output V. As shown in the sensor output example Cf in FIG. 7, the sensor output corresponding to when the LED 31 is off increases from sensor output Va to sensor output Vb. Furthermore, because the emitted light 32 is constant when the LED 31 is on, the stronger the external light 38, the smaller the ratio of the intensity of the emitted light 32 to the intensity of the external light 38. Therefore, the stronger the external light 38, the smaller the difference value ΔV of the sensor output V.

[0067] That is, in the example shown in FIG. 7, the difference value ΔVb when the external light 38 is strong is smaller than the difference value ΔVa when the external light 38 is weak.

[0068] Therefore, in an environment where the intensity of external light 38 changes, it is difficult to determine the presence or absence of a label 14 by comparing the difference value ΔV with a fixed threshold value Th. For this reason, it is desirable for the label printer 10 to have a function for setting the threshold value Th according to the intensity of external light 38.

[0069] As described above, the sensor output V corresponding to when the LED 31 is off increases as the external light 38 becomes stronger. The difference value ΔV decreases as the external light 38 becomes stronger. Therefore, it is desirable that the label presence / absence determining unit 44 set the threshold value Th(V) that monotonically decreases in accordance with the sensor output V when the LED 31 is off. More specifically, it is desirable that the label presence / absence determining unit 44 be provided with a threshold value setting table T shown in FIG. 7 and set the threshold value Th(V) that monotonically decreases in accordance with the increase in external light 38. Note that in FIG. 7, the threshold value Th(V) linearly decreases as the sensor output V when the LED 31 is off increases, but this is not limited thereto. For example, the threshold value Th(V) may decrease nonlinearly as the sensor output V when the LED 31 is off increases. Note that the threshold value Th(V) is determined using the results of a previously conducted evaluation experiment, etc.

[0070] Furthermore, although not shown, depending on the lighting conditions in the environment in which the label printer 10 is placed, flicker, in which the brightness of the lighting fluctuates periodically, may occur. When flicker occurs, the fluctuations in the illumination light due to the flicker are superimposed on the sensor output V. Therefore, depending on the timing of acquiring the sensor output V when the LED 31 is off and the sensor output V when the LED 31 is on, a difference value ΔV that differs from the actual value may be calculated.

[0071] To reduce the influence of such flicker, the label presence / absence determining unit 44 may calculate an average value of the sensor output V within each of the periods pb during which the LED 31 is turned off and pa during which the LED 31 is turned on, and may calculate a difference value ΔV from the calculated average value of the sensor output V when the LED 31 is turned off and the calculated average value of the sensor output V when the LED 31 is turned on. Note that instead of calculating the average value, the maximum value within the period or the minimum value within the period may also be calculated.

[0072] (Effects of the embodiment) As described above, the label printer 10 of the first embodiment comprises a light irradiation unit 41 that irradiates light onto an area illuminated by external light 38 where a printed label 14 is located, a light irradiation control unit 42 that switches between light irradiation and non-irradiation by the light irradiation unit 41, a light receiving unit 43 that acquires a light signal from the area where the printed label 14 is located in synchronization with the light irradiation and non-irradiation by the light irradiation control unit 42, and a label presence / absence determination unit 44 that determines the presence or absence of the label 14 based on a first signal acquired by the light receiving unit 43 when the light irradiation unit 41 is not irradiating light, and a second signal acquired by the light receiving unit 43 when the light irradiation unit 41 is irradiating light. Therefore, even if a printed label 14 is in a position illuminated by external light 38, the presence of the label 14 can be reliably detected.

[0073] Furthermore, in the label printer 10 of the first embodiment, the light emitting unit 41 and the light receiving unit 43 are installed on the same side of the label surface of the printed label 14. Therefore, the light emitting unit 41 and the light receiving unit 43 can be installed in a small space.

[0074] Furthermore, in the label printer 10 of the first embodiment, the label presence / absence determining unit 44 determines the presence or absence of a printed label 14 based on the magnitude relationship between the threshold value Th and the difference value ΔV between the level of the first signal and the level of the second signal. Therefore, the presence or absence of the label 14 can be detected by simple signal processing.

[0075] Furthermore, in the label printer 10 of the first embodiment, the label presence / absence determining unit 44 sets the threshold value Th(V) based on the level of the first signal (sensor output V). Therefore, even if the intensity of the external light 38 changes, the presence or absence of the label 14 can be reliably detected.

[0076] The label printer 10 of the first embodiment also includes a print control unit 45 that temporarily suspends printing of the next label 14 when the label presence determining unit 44 determines that a label 14 is present, and starts printing of the next label 14 when the label presence determining unit 44 determines that a label 14 is not present. This makes it possible to prevent printed labels 14 from accumulating at the discharge outlet 21.

[0077] (Second embodiment) A second embodiment of a label printer according to the present invention will be described in detail below with reference to the accompanying drawings.

[0078] (Overall configuration of label printer) The schematic configuration of a label printer 40 according to the second embodiment will be described using Figure 8. Figure 8 is a cross-sectional view showing an example of the internal structure of the label printer according to the second embodiment. The label printer 40 is an example of a printer device in the present disclosure.

[0079] The label printer 40 contains a label roll 12, which is a roll of linerless label paper 26, an example of printing paper, inside a housing 11. The label printer 40 performs printing while pulling out the linerless label paper 26 from the label roll 12.

[0080] The linerless label paper 26 has a print surface on the front side and an adhesive surface on the back side. In other words, the linerless label paper 26 is a label paper without a release paper 15 (see FIG. 1). The linerless label paper 26 is pulled out from the label roll 12 and conveyed toward the discharge port 36 while being sandwiched between the platen roller 17 and the thermal head 16. At this time, the print surface of the linerless label paper 26 is positioned on the thermal head 16 side. The linerless label paper 26 is an example of a label in the present disclosure.

[0081] The thermal head 16 prints on the printing surface of the linerless label paper 26 held between it and the platen roller 17. The label printer 40 may alternatively use a printing method in which an ink ribbon (not shown) is held between the thermal head 16 and the linerless label paper 26, and ink on the ink ribbon heated by the thermal head 16 is transferred to the printing surface of the linerless label paper 26.

[0082] The linerless label paper 26 discharged from the discharge port 36 remains above the holding member 22. The linerless label paper 26 is then cut by a cutter 28 provided upstream of the holding member 22 and removed from above the holding member 22. The cutter 28 is composed of a fixed blade 29 provided on the back side of the linerless label paper 26 and a movable blade 30 provided on the print surface side of the linerless label paper 26, and may be cut manually by an operator or automatically when printing is complete.

[0083] A label sensor 24 is installed at the position of the holding member 22 to detect the presence or absence of linerless label paper 26 (label). The label sensor 24 is installed above the holding member 22, facing the label side of the linerless label paper 26, and detects whether the linerless label paper 26 is present. When the label sensor 24 detects the linerless label paper 26, the label printer 40 temporarily suspends the feeding and printing of the linerless label paper 26. When the user removes the linerless label paper 26 on which printing has been completed, the label sensor 24 detects that the linerless label paper 26 is not present, and resumes the feeding and printing of the linerless label paper 26. The structure and operating principle of the label sensor 24 will be described later.

[0084] The functional configuration of the label printer 40 is the same as the functional configuration of the label printer 10 described above (see FIG. 4), so a description thereof will be omitted. In the following description, the same reference numerals as those used in FIG. 4 will be used to describe the functional parts of the label printer 40.

[0085] (Label sensor structure and operating principle) The structure and operating principle of the label sensor 24 will be described using Figures 9 and 10. Figure 9 is a diagram illustrating the structure and operating principle of the label sensor provided in the label printer according to the second embodiment. Figure 10 is a diagram showing an example of a signal output detected by the label sensor under external light.

[0086] The label sensor 24 comprises a light-emitting element 31 and a light-receiving element 34. The light-emitting element 31 emits light at a predetermined cycle under the action of a drive circuit (not shown). The light-emitting element 31 is, for example, an LED. The wavelength of the light emitted by the light-emitting element 31 is not important, but it is preferable to use near-infrared light, which is invisible light. It is also preferable that the light-receiving element 34 has high sensitivity to light of the same wavelength as the light emitted by the light-emitting element 31. For this reason, a filter that transmits light of the wavelength emitted by the light-emitting element 31 may be attached to the surface of the light-receiving element 34.

[0087] The light receiving element 34 outputs an electrical signal corresponding to the amount of light received, in synchronization with the timing at which the light emitting element 31 emits light. The light receiving element 34 is, for example, a photodiode. In this way, the label sensor 24 is a transmission type sensor in which the light receiving element 34 detects transmitted light of the light emitting element 31.

[0088] The light-emitting element 31 and the light-receiving element 34 are installed in opposing positions across the paper transport mold 27 formed on the top of the holding member 22. The light-emitting element 31 emits light toward the top of the holding member 22 through a gap 35 in the paper transport mold 27 formed on the top of the holding member 22. The light-receiving element 34 detects the light that has passed through the gap 35. Note that the gap 35 is formed by cutting out a portion of the paper transport mold 27 in the direction in which the linerless label paper 26 is discharged, i.e., along the X-axis.

[0089] The detection state Sf shown in FIG. 9 shows a state in which the emitted light 32 emitted by the LED 31 is blocked by the linerless label paper 26, and the emitted light 32 is not detected by the light receiving element 34.

[0090] At this time, as shown in the detection state Sg, the emitted light 32 emitted by the LED 31 passes through the gap 35 and then strikes the adhesive surface of the linerless label paper 26. A small portion of the emitted light 32 then passes through the linerless label paper 26 and reaches the light receiving element 34, but because the amount of emitted light 32 that passes through the linerless label paper 26 is small, the light receiving element 34 outputs a sensor output V that is slightly larger than when there is no emitted light 32.

[0091] On the other hand, when no linerless label paper 26 is present above the paper transport mold 27, as shown in detection state Sh in Figure 9, the emitted light 32 emitted by the LED 31 passes through the gap 35 and then penetrates above the paper transport mold 27 (towards the positive Z axis). The light receiving element 34 then detects the emitted light 32 from the LED 31. Therefore, the light receiving element 34 outputs a larger sensor output V than when there is no emitted light 32.

[0092] Next, the signal output detected by the label sensor 24 under external light 38 will be described with reference to FIG.

[0093] The paper transport mold 27 is located on the surface of the housing 11 so that the linerless label paper 26 can be easily removed after printing has been completed. The printed surface of the linerless label paper 26 after printing is irradiated with external light 38 from the environment in which the label printer 40 is placed through the gap between the paper transport mold 27 and the position of the light-receiving element 34. The external light 38 includes indoor lighting such as fluorescent lamps, incandescent bulbs, and LED lighting, as well as sunlight. Such external light 38 may adversely affect the label sensor 24's detection of the presence or absence of linerless label paper 26.

[0094] The detected state Si shown in FIG. 10 shows a state in which the linerless label paper 26 on which printing has been completed is on the paper transport mold 27, and external light 38 is shining on the printed surface of the linerless label paper 26.

[0095] In the detection state Si, the emitted light 32 from the LED 31 strikes the back surface (adhesive surface) of the linerless label paper 26. Some of the emitted light 32 passes through the linerless label paper 26 and reaches the light-receiving element 34, but the sensor output V output by the light-receiving element 34 is very small. If external light 38 is irradiating the surface of the linerless label paper 26 at this time, some of the external light 38 is reflected by the surface of the linerless label paper 26 and reaches the light-receiving element 34. Therefore, in the detection state Si, the light-receiving element 34 outputs a larger sensor output V than when there is no external light 38, regardless of whether the LED 31 is irradiating the emitted light 32 or not. As described above, the sensor output V due to the emitted light 32 from the LED 31 is very small. Therefore, the label sensor 24 can determine that linerless label paper 26 is present when the difference between the sensor output V obtained when the LED 31 irradiates the emitted light 32 and the sensor output V obtained when the LED 31 does not irradiate the emitted light 32 is less than a preset threshold value.

[0096] On the other hand, the detected state Sj shown in FIG. 10 shows a state in which the linerless label paper 26 is not present on the paper transport mold 27 and external light 38 is shining on it.

[0097] In the detection state Sj, the emitted light 32 from the LED 31 passes through the gap 35 (see FIG. 9) in the paper transport mold 27 and reaches the light receiving element 34. Therefore, the emitted light 32 is detected by the light receiving element 34. At this time, a portion of the external light 38 that hits the surface of the paper transport mold 27 also reaches the light receiving element 34. Therefore, the light receiving element 34 outputs a sensor output V that is the sum of the emitted light 32 from the LED 31 and the reflected light of the external light 38.

[0098] Furthermore, the sensor output V obtained when the LED 31 irradiates the emitted light 32 is greater than the sensor output V obtained when the LED 31 does not irradiate the emitted light 32. Therefore, regardless of the intensity of the external light 38, the label sensor 24 can determine that linerless label paper 26 is absent if the difference between the sensor output V obtained when the LED 31 irradiates the emitted light 32 and the sensor output V obtained when the LED 31 does not irradiate the emitted light 32 is equal to or greater than a preset threshold value.

[0099] Below, we will explain how to determine the presence or absence of linerless label paper 26 based on the waveform of the actual sensor output V. The sensor output example Cg shown in Figure 10 is an example of the sensor output V when linerless label paper 26 is present on the paper transport mold 27 and there is no external light 38.

[0100] In any of the states shown in FIG. 10, the LED 31 repeatedly switches between the on state and the off state at the same timing as described with reference to FIG.

[0101] At this time, the sensor output V output by the light receiving element 34 exhibits a pulse waveform as shown in the sensor output example Cg. That is, during the off period pb of the LED 31, a very small sensor output V is obtained. Then, during the on period pa, a portion of the light 32 emitted from the LED 31 passes through the linerless label paper 26, resulting in a sensor output V that is slightly larger than that during the off period pb of the LED 31. A very small difference value ΔV occurs between the sensor output V during the on period pa and the sensor output V during the off period pb.

[0102] In contrast, the sensor output example Ch shown in Figure 10 shows an example of the sensor output V when there is no linerless label paper 26 on the paper transport mold 27 and no external light 38. The timing of turning on and off the LED 31 in the sensor output example Ch is the same as that explained in the sensor output example Ca (see Figure 3).

[0103] At this time, as shown in sensor output example Ch, the light receiving element 34 generates a sensor output V corresponding to the light emitted 32 from the LED 31 during the lighting period pa of the LED 31. A difference value ΔV is generated between the sensor output V during the lighting period pa and the sensor output V during the extinction period pb. The difference value ΔV generated at this time is larger than the difference value ΔV generated in the sensor output example Cg because the light emitted 32 from the LED 31 is directly incident on the light receiving element 34.

[0104] A comparison of the sensor output example Cg and the sensor output example Ch shows that when there is no external light 38, the difference ΔV between the sensor output V during the light-on period pa and the sensor output V during the light-off period pb is compared with a threshold value, and if the difference ΔV is equal to or greater than the threshold value, it can be determined that no linerless label paper 26 is present. Also, if the difference ΔV is less than the threshold value, it can be determined that linerless label paper 26 is present.

[0105] 10 shows an example of the sensor output V when the linerless label paper 26 is on the paper transport mold 27 and there is external light 38. The timing of turning on and off the LED 31 in the sensor output example Ci is the same as that described for the sensor output example Ca.

[0106] At this time, the sensor output V output by the light-receiving element 34 exhibits a pulse waveform as shown in sensor output example Ci. That is, during the off period pb of the LED 31, the sensor output V is approximately equal to the intensity of the external light 38 reflected by the linerless label paper 26. During the on period pa of the LED 31, part of the light 32 emitted from the LED 31 passes through the linerless label paper 26 and reaches the light-receiving element 34, resulting in a sensor output V that is slightly larger than that during the off period pb of the LED 31. A slight difference ΔV occurs between the sensor output V during the on period pa and the sensor output V during the off period pb.

[0107] In contrast, the sensor output example Cj shown in Figure 10 shows an example of the sensor output V when there is no linerless label paper 26 on the paper transport mold 27 and there is external light 38. The timing of turning on and off the LED 31 in the sensor output example Cj is the same as that explained in the sensor output example Ca.

[0108] At this time, the sensor output V output by the light receiving element 34 exhibits a pulse waveform as shown in the sensor output example Cj. That is, during the LED 31 off period pb, the sensor output V is obtained according to the intensity of the external light 38 reflected by the paper transport mold 27. If the paper transport mold 27 is a dark color with low reflectivity, this sensor output V is smaller in the sensor output example Ci than the sensor output V during the LED 31 off period pb. Furthermore, the sensor output V obtained during the LED 31 on period pa is larger than the sensor output V obtained during the LED 31 off period pb by the amount of the emitted light 32 from the LED 31 that has passed through the paper transport mold 27 and reaches the light receiving element 34. A difference value ΔV larger than the difference value ΔV occurring in the sensor output example Ci occurs between the sensor output V during the on period pa and the sensor output V during the off period pb.

[0109] A comparison of sensor output example Ci and sensor output example Cj shows that when external light 38 is present, the difference ΔV between the sensor output V during the light-on period pa and the sensor output V during the light-off period pb is compared with a threshold value, and if the difference ΔV is equal to or greater than the threshold value, it can be determined that linerless label paper 26 is not present. Also, if the difference ΔV is less than the threshold value, it can be determined that linerless label paper 26 is present.

[0110] That is, regardless of the presence or absence of external light 38, when the difference value ΔV between the sensor output V during the light-on period pa and the sensor output V during the light-off period pb is compared with a threshold value, if the difference value ΔV is equal to or greater than the threshold value, it can be determined that no linerless label paper 26 is present. Also, if the difference value ΔV is less than the threshold value, it can be determined that no linerless label paper 26 is present.

[0111] (Flow of printing operations performed by a label printer) The flow of printing processing performed by the label printer 40 will be described using Figure 11. Figure 11 is a flowchart showing an example of the flow of printing operations of the label printer according to the second embodiment.

[0112] The print control unit 45 instructs each unit of the label printer 40 to start printing (step S31).

[0113] The label presence / absence determining unit 44 performs a label presence / absence determination process to determine whether or not linerless label paper 26 is present (step S32). If it is determined that linerless label paper 26 is present, the process proceeds to step S33. On the other hand, if it is determined that linerless label paper 26 is not present, the process proceeds to step S35. The detailed flow of the label presence / absence determination process is the same as the process flow described above (see FIG. 6). However, only the magnitude relationship between the difference value ΔV of the sensor output V and the threshold value Th differs from that of the first embodiment. That is, in this embodiment, if the difference value ΔV is equal to or greater than the threshold value Th, it is determined that linerless label paper 26 is not present. If the difference value ΔV is less than the threshold value Th, it is determined that linerless label paper 26 is present.

[0114] If it is determined in step S32 that linerless label paper 26 is present, print control unit 45 temporarily suspends the printing operation (step S33).

[0115] Next, the print control unit 45 cuts the linerless label paper 26 using the cutter 28 (step S34). After that, the process returns to step S32. Note that the linerless label paper 26 may be cut by the user himself / herself by operating the cutter 28.

[0116] If it is determined in step S32 that there is no linerless label paper 26, that is, that the linerless label paper 26 on which printing has been completed has been removed from the holding member 22, the print control unit 45 determines whether printing has been performed on a predetermined number of sheets of linerless label paper 26 (step S35). If it is determined that printing has been performed on the predetermined number of sheets of linerless label paper 26 (step S35: Yes), the label printer 40 ends the processing in Fig. 11. On the other hand, if it is not determined that printing has been performed on the predetermined number of sheets of linerless label paper 26 (step S35: No), the process proceeds to step S36.

[0117] If it is determined in step S35 that the predetermined number of linerless label sheets 26 have not been printed, the print control unit 45 resumes printing (step S36).

[0118] The print control unit 45 increments the number of sheets of linerless label paper 26 on which printing has been completed (step S37), and then returns to step S32.

[0119] (Effects of the embodiment) As described above, in the label printer 40 of the second embodiment, the light emitting unit 41 and the light receiving unit 43 are installed in positions facing each other across the label surface of the printed linerless label paper 26. Therefore, compared to when a reflective sensor is used, the amount of external light 38 incident on the light receiving element 34 is reduced, and the effects of external light 38 can be reduced.

[0120] In the first embodiment, it has been described that the peel sensor 23 is configured using a reflective sensor. In the second embodiment, it has been described that the label sensor 24 is configured using a transmissive sensor. However, the peel sensor 23 may be configured using a transmissive sensor, or the label sensor 24 may be configured using a reflective sensor.

[0121] Although the embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. This novel embodiment can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the inventions and their equivalents as set forth in the claims. [Explanation of symbols]

[0122] 10, 40... Label printer (printer device), 11... Housing, 12... Label roll, 13... Label paper, 14... Label, 15... Release paper, 16... Thermal head, 17... Platen roller, 18... Drive motor, 19... Peeling bar, 20... Peeling roller, 21, 36... Discharge port, 22... Holding member, 23... Peeling sensor, 24... Label sensor, 26... Linerless label paper (label), 27... Paper transport mold, 28... Cutter, 29... Fixed blade, 30... Movable blade, 31... Light-emitting element (LED), 32... Emitted light, 33...reflected light, 34...light receiving element, 35...gap, 38...external light, 41...light irradiation unit, 42...light irradiation control unit, 43...light receiving unit, 44...label presence determination unit, 45...printing control unit, Ca, Cb, Cc, Cd, Ce, Cf, Cg, Ch, Ci, Cj...sensor output example, pa...light-on period, pb...light-off period, Sa, Sb, Sc, Sd, Se, Sf, Sg, Sh, Si, Sj...detection state, T...threshold setting table, Th, Th(V)...threshold, V...sensor output (first signal, second signal), ΔV...difference value [Prior art documents] [Patent documents]

[0123] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-49732

Claims

1. a light irradiation unit that irradiates light onto an area illuminated by external light where a printed label is present; a light irradiation control unit that switches between irradiation and non-irradiation by the light irradiation unit; a light receiving unit that receives a light signal from an area where a printed label is present in synchronization with the light irradiation and non-irradiation by the light irradiation control unit; a label presence / absence determination unit that determines the presence or absence of a label based on a magnitude relationship between a difference value between a first signal acquired by the light receiving unit when the light emitting unit is not emitting light and a second signal acquired by the light receiving unit when the light emitting unit is emitting light, and a threshold value that monotonically decreases as the level of the first signal increases; A printer device comprising:

2. The light emitting unit and the light receiving unit are installed on the same side of the label surface of the label on which printing has been completed. The printer device according to claim 1 .

3. The light emitting unit and the light receiving unit are installed at positions facing each other across the label surface of the label on which printing has been completed. The printer device according to claim 1 .

4. The printing device further includes a print control unit that, when the label presence / absence determining unit determines that a label is present, temporarily suspends printing of the next label, and when the label presence / absence determining unit determines that a label is not present, starts printing of the next label. The printer device according to any one of claims 1 to 3.

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