JP5500372B2 - Printer - Google Patents

Description

  The present invention relates to a printer that performs desired printing on a printing paper.

  Conventionally, in a printing apparatus (label creation apparatus) that prints a desired character while conveying a printing material (tape), a light-absorbing black mark is printed in advance at a predetermined position in the conveyance direction of the printing material, There has been proposed a technique for detecting the position of the printing material in the conveyance direction by including a paper detection sensor that can optically detect the black mark (for example, Patent Document 1). The paper detection sensor used in such a case is a reflection type sensor generally composed of a projector and a light receiver, and the light reflected by the light projection from the projector is detected by the light receiver. The black mark detects the passage of the black mark on the paper detection sensor by utilizing the behavior that the amount of reflected light is smaller than that of the other portions.

JP 2007-76267 A

  By the way, in the case of a normal printer that uses paper printing paper as a printing material among printing apparatuses that perform conveyance control using the reflection type sensor as described above, depending on the user, printing paper that is slightly different in quality is used. May be used. In other words, for example, a paper to be printed that is dirty or yellowed and has a lower whiteness than normal white paper, or faded to become old and deteriorated in light absorption performance (in other words, the blackness is reduced). It may be possible to use printing paper with black marks that have been reduced. Originally, as described above, the black mark is detected by greatly reducing the amount of reflected light received by the light receiver due to the light-absorbing property of the black mark. However, when there is a decrease in whiteness or a decrease in blackness as described above, the behavior of change in the amount of light received by the light receiver is reduced between the black mark and the portion other than the black mark. In this case, the detection accuracy of the black mark is lowered, and as a result, there is a possibility that the conveyance control and printing control of the printing paper cannot be performed with sufficient accuracy.

  An object of the present invention is to provide a printer that can accurately perform conveyance control and print control and reliably print on a printing paper even when the user uses printing paper with reduced whiteness and blackness. Is to provide.

In order to achieve the above object, the first invention provides a conveying means for conveying a printing paper provided with a light-absorbing positioning mark, and a desired printing paper conveyed by the conveying means. A thermal head for performing printing, a light projecting unit capable of projecting light toward a transport path of the printing paper transported by the transport unit, and a light receiving unit capable of outputting a detection voltage value corresponding to the received light amount, An initial value storage means for storing a predetermined initial threshold value predetermined for the detection voltage by the light receiving means, and the initial value storage means stored in the initial value storage means in accordance with an update instruction signal Threshold value updating means for calculating a new threshold value instead of the initial threshold value, and the detected voltage value of the light receiving means after the calculation of the new threshold value by the threshold value updating means is the new value. When the threshold value is reached, the mark detection means for detecting the positioning mark and the conveyance means to start conveyance according to the input of the print instruction signal, and the detection result of the mark detection means In response to the update instruction signal, a printing transport control unit that controls the transport operation of the transport unit based on the detection result, a print control unit that controls the printing operation of the thermal head based on the detection result of the mark detection unit, and An update conveyance control means for controlling the conveyance means so as to convey the printing paper by a predetermined distance, and the initial threshold corresponds to a range of the detection voltage value by the light receiving means. The predetermined initial white corresponding voltage value Vw0 and the initial black corresponding voltage value Vb0 and the value Vb0 + k0 (Vw0−Vb) calculated using the initial coefficient k0. ); (Where k0 is a number less than 1), and the new threshold value is calculated while the conveyance unit conveys the printing paper by the predetermined distance based on the control of the update conveyance control unit. A value Vb1 + k1 (Vw1−Vb1) calculated using the actual white corresponding voltage value Vw1 and actual black corresponding voltage value Vb1 acquired based on the detected voltage value output by the light receiving means and the newly set actual coefficient k1. And the update conveyance control means controls the conveyance means to continuously convey the predetermined distance corresponding to the plurality of sheets to be printed in response to the update instruction signal, The optical sensor is configured such that the light projecting unit emits light and the light receiving unit outputs a detection voltage value for each of the plurality of sheets of paper to be continuously conveyed, and the update transport control. means Based on the plurality of detection voltage values output from the light receiving unit corresponding to each of the plurality of printing papers, while the transporting unit transports the plurality of printing papers by the predetermined distance based on the control, White variation width detecting means for detecting a variation range of the whiteness degree of the plurality of printing papers, and black color for detecting a variation range of the blackness degree of the plurality of positioning marks respectively provided on the plurality of printing papers A variation range detection unit, wherein the threshold update unit includes a variation range of the whiteness level detected by the whiteness variation range detection unit, a variation range of the blackness level detected by the black variation range detection unit, Among these, k1 is set so as to shift to the side where the fluctuation range is small, and k1 set according to the fluctuation range and the light receiving means with respect to the plurality of sheets to be printed Among the plurality of output detection voltage values, the detection voltage value relating to the printing paper having the lowest whiteness level, and the plurality of detection voltage values output by the light receiving unit with respect to the positioning marks of the plurality of printing papers. When the blackness is the lowest, the new threshold value is calculated based on the detected voltage value related to the positioning mark .

  In the printer according to the first aspect of the present invention, when printing is performed, the transport unit transports the printing paper, and the thermal head performs desired printing on the printing paper that is being transported. The paper to be printed is provided with a light-absorbing positioning mark. When reflected light from the light projecting means of the optical sensor is detected by the light receiving means, the positioning mark is compared with the other parts. This reduces the amount of reflected light. For this reason, when light is projected onto the positioning mark, the detection voltage value output from the light receiving means changes (decreases or increases) corresponding to the amount of light. Using this behavior in the positioning mark, the mark detecting means detects the positioning mark, and based on the detection result, the printing conveyance control means controls the conveying operation of the conveying means, and the printing control means is the thermal head. Control the printing operation.

  Here, in the detection of the positioning mark based on the detection voltage value described above, the detection is performed by comparing the detection voltage with a predetermined threshold value. In the first invention of the present application, a predetermined initial threshold value Vb0 + k0 (Vw0−Vb0) based on a predetermined initial white corresponding voltage value Vw0 and an initial black corresponding voltage value Vb0 corresponding to the range of the detected voltage value; Is an initial coefficient that is an initial value of k and is a number less than 1), and Vw0, Vb0, Vb0 + k0 (Vw0-Vb0) are stored in the initial value storage means.

  In this case, at the time of printing on the printing paper, the detection voltage value is relatively large (or relatively small) when light is projected to a portion other than the positioning mark among the printing paper to be conveyed. When the light is projected onto the positioning mark, the detection voltage value becomes small (or becomes large), that is, the magnitude fluctuation assumed within a predetermined fluctuation range. When the detected voltage value reaches the initial threshold value in the fluctuation, the positioning mark can be detected accordingly.

  By the way, depending on the user, for example, a light-absorbing performance is deteriorated by using a printing paper having a lower whiteness than a normal white paper due to dirt or yellowing, or fading and becoming old. In other words, there may be a case in which a printing paper having a positioning mark (with reduced blackness) is used. Originally, as described above, the amount of light received by the light receiving means is greatly reduced due to the light-absorbing property of the positioning mark, and the positioning mark is detected by a large change in the detection voltage. If there is a decrease in whiteness or a decrease in blackness, the change in the amount of light received by the light receiving means by the positioning mark is alleviated. That is, when the amount of change in the detection voltage is reduced, the fluctuation range of the detection voltage is reduced. As a result, even when light is projected onto the positioning mark, the amount of received light reaches the initial threshold value Vb0 + k0 (Vw0-Vb0). It may not be possible to detect the positioning mark.

  Therefore, in the first invention of the present application, the threshold value updating means calculates a new threshold value based on the update instruction signal in consideration of the influence of the decrease in whiteness and the decrease in blackness. In other words, when an update instruction signal is issued, the conveyance unit conveys the printing paper by a predetermined distance under the control of the update conveyance control unit. Based on the detected voltage value from the light receiving means while the printing paper is conveyed by this predetermined distance, the threshold value updating means sets the value of the coefficient k to a real coefficient k1 that is different from k0. , Vw0 is changed to Vw1, and Vb0 is changed to Vb1. As a result, it is possible to newly set a new threshold value Vb1 + k1 (Vw1−Vb1) corresponding to the fluctuation range when the whiteness or blackness is lowered, which is assumed to be narrower than the above fluctuation range. . As a result, when the conveyance means conveys the printing paper under the control of the printing conveyance control means when actually performing printing, a voltage value corresponding to the amount of light received when the positioning mark is projected is set. The threshold value can be made smaller (or larger) than the new threshold value, and the positioning mark can be reliably detected.

Therefore, the positioning mark can be detected with high accuracy regardless of the behavior of the detection voltage due to the decrease in whiteness or blackness. As a result, even if the user uses printing paper with a lower whiteness than normal or printing paper with positioning marks with reduced blackness, printing transport control and printing control Can be reliably printed on the paper to be printed. Further, the threshold value is changed based on the worst condition among whiteness and blackness detected by the optical sensor for each of a plurality of printing papers, that is, a condition with little difference between black and white. As a result, the positioning mark can be reliably detected with high accuracy on any of a plurality of sheets of printing paper, and printing on the printing paper can be performed.

  According to a second invention, in the first invention, based on the detection voltage value by the light receiving unit while the transport unit transports the printing paper by the predetermined distance based on the control of the update transport control unit, Whiteness determination means for determining whether the whiteness level of the printing paper has reached a predetermined whiteness standard, and the threshold value updating means determines whether the whiteness level of the printing paper is determined by the whiteness determination means. When it is determined that the predetermined white reference is not reached, k1 is set to a value smaller than k0.

  Thereby, for example, even when the user uses a printing paper that is dirty or yellowed and has a whiteness lower than that of a normal white paper, by setting k1 to a value smaller than k0, The threshold value can be changed to a value closer to black. As a result, the positioning marks can be detected with high accuracy, and printing on the printing paper can be performed reliably.

  According to a third invention, in the first invention, based on the detection voltage value by the light receiving unit while the conveyance unit conveys the printing paper by the predetermined distance based on the control of the update conveyance control unit, Blackness determination means for determining whether or not the blackness level of the positioning mark has reached a predetermined blackness standard, and the threshold value updating means is configured such that the blackness level of the positioning mark is determined by the blackness level determination means. Is determined to have not reached the predetermined black reference, k1 is set to a value larger than k0.

  Thereby, for example, even when the user uses printing paper provided with a positioning mark whose light absorption performance is deteriorated due to fading or becoming old (blackness is reduced), k1 is set. By setting the value larger than k0, the threshold value can be changed to a value closer to white. As a result, the positioning marks can be detected with high accuracy, and printing on the printing paper can be performed reliably.

In a fourth aspect based on the first aspect , the update transport control means has different transport speeds for each printing paper when the plurality of printing papers are continuously transported. As described above, the apparatus includes a conveyance speed setting unit that controls the conveyance unit.

When optical detection is performed by emitting and receiving light on a positioning mark on a printing paper to be conveyed, the distance from the optical sensor to the printing paper may affect the detection accuracy. In the fourth invention of the present application, the conveyance speed setting means makes the conveyance speeds different at the time of detection by the optical sensor for each of the plurality of printing sheets. If the conveyance speeds are different from each other, the distances from the printing paper to the optical sensor are also different from each other. In other words, a plurality of detections with slightly different accuracy can be performed. Thereby, it is possible to reduce the influence of variations in accuracy of the optical sensor when performing the initial threshold correction, and to further change the effective threshold.

  According to the present invention, even when the user uses a printing paper with reduced whiteness or blackness, the conveyance control and the printing control can be performed with high accuracy, and printing can be reliably performed on the printing paper. it can.

1 is a perspective view illustrating an external configuration of a portable printer according to an embodiment of the present invention. It is a sectional side view by the II-II section in Drawing 1 showing the internal structure of a portable printer. It is the disassembled perspective view seen from the front side diagonally upward direction showing the internal structure of a portable printer. It is a functional block diagram showing the functional structure of a portable printer. It is a circuit block diagram of a paper detection sensor. It is explanatory drawing which represents notionally the structure of a to-be-printed paper. It is a time chart which shows the change of the detection voltage value before and after a paper detection sensor detects a black mark with the schematic diagram of the arrangement | positioning relationship between the light projection range of a light projector, and a black mark. It is a time chart showing the threshold value update example when whiteness is low, and the time chart showing the threshold value update example when blackness is low. It is a flowchart showing the detailed procedure of the update process of a threshold value. It is a flowchart showing the detailed procedure of the threshold coefficient determination process of step S200 of FIG. It is a flowchart showing the detailed procedure of a printing process. It is a time chart showing the threshold value update example in the modification which performs whiteness and blackness detection on a plurality of sheets and determines the coefficient k1. It is a flowchart showing the detailed procedure of a threshold coefficient determination process. It is a circuit block diagram showing the other example of a paper detection sensor. It is a time chart showing change of a detection voltage value before and after detecting a black mark when other examples of a sheet detection sensor are used. When another example of the sheet detection sensor is used, a time chart showing an example of threshold update when the whiteness is low, and a time chart showing an example of threshold update when the blackness is low.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. This embodiment is an embodiment when the present invention is applied to a portable printer.

  The external configuration and internal structure of the portable printer 1 according to the present embodiment will be described with reference to FIGS. 1, 2, and 3. In the following description, the lower left direction in FIG. 1 is front, the upper right direction is rear, the upper left direction is left, and the lower right direction is right. Further, in the following description, when referring to the front, rear, left, right, top, and bottom directions for each component, description will be made in correspondence with each direction in a state in which each component is attached to the portable printer 1.

  1 to 3, the portable printer 1 is configured to print various types of print data received from an external device 2 (see FIG. 4 described later) such as a PC terminal or a mobile phone via wired communication or wireless communication. Print on paper 53. The portable printer 1 is roughly assembled by assembling a substantially rectangular parallelepiped housing 100 that is made of a resin material and that constitutes the outer shell of the apparatus, and a chassis assembly 50.

  The housing 100 includes a top cover 101 that constitutes the upper part of the outer shell of the apparatus, an under cover 102 that constitutes the lower part of the outer shell of the apparatus, and a cover member 103 that can be opened and closed on the front side of the top surface of the top cover 101.

  In the housing 100, a platen roller 111 as a conveying means and a thermal line head 112 which is a kind of thermal head are provided. The thermal line head 112 is provided on a heat radiating plate 114 provided with a shaft member 113 at the rear end, and the heat radiating plate 114 can be rotated around the shaft member 113 by the side chassis members 130L and 130R. It is supported. The main chassis member 150 provided on the inner surface of the under cover 102 is provided with a plurality of coil springs 115 that urge the heat sink 114 that supports the thermal line head 112 toward the platen roller 111. . Thereby, the thermal line head 112 can be pressed against the platen roller 111.

  On the rear side of the housing 100, a battery storage chamber 105 that houses the substantially rod-shaped rechargeable battery 10 is provided. A battery chamber cover 170 is detachably provided in the battery storage chamber 105. In a state where the battery chamber cover 170 is removed, the battery storage chamber 105 opens in the rear portion of the housing 100.

  The chassis assembly 50 includes a main chassis member 150 that is provided on the inner surface of the under cover 102 and constitutes a bottom portion of the chassis assembly 50, and a pair of erected from both longitudinal ends of the main chassis member 150. The side chassis members 130L and 130R are provided. The side chassis members 130L and 130R support the platen roller 111 rotatably by inserting the shaft member 111a of the platen roller 111 into the shaft hole 131. The platen roller 111 is rotated by the drive motor 11 to convey the printing paper 53. Further, the side chassis members 130L and 130R support the heat radiating plate 114 including the thermal line head 112 so as to be rotatable via the shaft member 113 described above.

  The left side chassis member 130L is provided with a drive motor 11 that drives the platen roller 111, and a gear mechanism 132 that includes a plurality of gears that transmits the driving force of the drive motor 11 to the shaft member 111a of the platen roller 111. It has been.

  A beam member 140 is bridged over the side chassis members 130L and 130R and fixed with screws. A guide member 120 that guides the printing paper 53 inserted from the insertion port 104 to the pressure contact portion P between the platen roller 111 and the thermal line head 112 includes a top cover 101, an under cover 102, and a cover that constitute the housing 100. The member 103 is configured as a separate body, and is provided on the side chassis members 130L and 130R by being fixed to the beam member 140.

  The guide member 120 has a horizontal surface 121 that is substantially horizontal when assembled to the chassis assembly 50 and an inclined surface 122 that is inclined from the horizontal surface 121 toward the inside of the apparatus. On the horizontal surface 121 and the inclined surface 122, a plurality of protrusion members 123 formed along the guide direction of the printing paper 53 are provided in parallel in the longitudinal direction.

  In the above configuration, at the time of printing, the printing paper 53 is inserted into the insertion port 104 formed between the top cover 101 and the cover member 103 with the cover member 103 closed. The inserted printing paper 53 is guided to a pressure contact portion P between a platen roller 111 and a thermal line head 112, which will be described later, by a guide member 120 provided below the insertion port 104. The platen roller 111 contacts the printing paper 53 with a predetermined pressing force, and conveys the printing paper 53. The thermal line head 112 performs desired printing on the conveyed printing paper 53. After the printing is completed, the printing paper 53 is discharged from a discharge port 107 formed between the cover member 103 and the under cover 102. At this time, the paper detection sensor 35 (see FIGS. 1 and 3) is provided in the transport path toward the discharge port 107 on the downstream side in the transport direction of the printing paper 53. Based on the detection result of the paper detection sensor 35, conveyance control by the platen roller 111 and printing control by the thermal line head 112 are performed (details will be described later). When a paper jam or the like occurs, the platen roller 111 is released from the thermal line head 112 by opening the cover member 103, and the printing paper 53 can be easily pulled out.

  Next, the control system of the portable printer 1 will be described with reference to FIG.

  In FIG. 4, the portable printer 1 has a CPU 12. The CPU 12 performs signal processing according to a program stored in advance in the ROM 14 while using the temporary storage function of the SDRAM 13, thereby controlling the entire portable printer 1. The ROM 14 stores various programs necessary for control, such as a print drive control program.

  In addition, the CPU 12 controls the power supply circuit 15 that performs power on / off processing of the portable printer 1, the motor drive circuit 16 that performs drive control of the drive motor 11 that drives the platen roller 111, and drive control of the thermal line head 112. It is connected to a thermal head control circuit 17 that performs the above.

  The CPU 12 also includes a paper detection sensor 35, a feed key 40 for performing a paper feed operation (see also FIGS. 1 and 3), and a power key 30 for performing a power on / off operation (also FIGS. 1 and 3). Connected). Based on the detection result of the paper detection sensor 35, the CPU 12 detects whether or not the printing paper 53 is inserted into the insertion port 104.

  Further, when the power key 30 or the feed key 40 is depressed, the CPU 12 executes a process corresponding to the depressed key. When the feed key 40 is pressed down, the CPU 12 outputs a control signal to the motor drive circuit 16, drives the drive motor 11, rotates the platen roller 111, and performs a feed process for conveying the printing paper 53 by a predetermined amount. . The feed key 40 is used when, for example, paper feeding is performed to start printing from a midway position in the conveyance direction of the printing paper 53, or when the printing paper 53 whose conveyance direction length is longer than a predetermined length is used. This is operated when the paper is to be discharged after completion. On the other hand, when the power key 30 is depressed in the power-off state of the portable printer 1, the CPU 12 outputs a control signal to the power circuit 15 to perform power-on processing, and when the power key 30 is depressed in the power-on state. Then, a control signal is output to the power supply circuit 15 to perform power-off processing.

  The CPU 12 is connected to the USB interface drive circuit 21, the wireless communication unit 22, and the infrared communication unit 23. The USB interface drive circuit 21 controls communication performed with the external device 2 via a USB cable (not shown) connected to a USB terminal 24 (see also FIG. 1). The wireless communication unit 22 controls wireless communication using radio waves other than infrared rays performed with the external device 2. The infrared communication unit 23 controls infrared communication performed with the external device 2. The external device 2 includes, for example, a CPU 2a, a RAM 2b, and a ROM 2c.

  In the control system configured as described above, when printing is performed by the portable printer 1, the operator (user) inputs print data to be printed on the printing paper 53 using the external device 2 such as a PC terminal or a cellular phone. And a print start instruction is input. As a result, the print data is transmitted from the external device 2 to the portable printer 1 via the USB cable, wireless communication, or infrared communication. When print data is input from the external device 2 in this way, the print data is stored in, for example, a text memory of the SDRAM 13. The stored print data is read again and subjected to predetermined conversion by the conversion function of the control circuit, whereby dot pattern data is generated and stored in a buffer (for example, provided in the CPU 12). Then, the thermal line head 112 is driven via the thermal head control circuit 17, and each heating element is selectively driven to generate heat corresponding to the printing dots for one line, and the dot pattern data stored in the buffer is printed. Do. In synchronization with this, the drive motor 11 controls the conveyance of the printing paper 53 via the motor drive circuit 16.

  In the above basic configuration and operation, the greatest feature of the portable printer 1 according to the present embodiment is that the paper to be printed by the paper detection sensor 35 for performing the transport control and the print control for the paper to be printed 53 as described above. 53 and the detection of the black mark PM on the printing paper 53. The details will be described below in order with reference to FIGS.

  The circuit configuration of the paper detection sensor 35 will be described in detail with reference to FIG.

  In FIG. 5, a paper detection sensor 35 is an optical sensor using an optical technique. In this example, the paper detection sensor 35 includes a projector 35A (light projector) and a light receiver 35B (light receiver). The light projector 35 </ b> A emits light toward the printing paper 53. The light receiver 35B receives the reflected light emitted from the light projector 35A and reflected from the printing paper 53, and outputs a voltage corresponding to the received light amount. Further, the sheet detection sensor 35 has a load resistance R in addition to the projector 35A and the light receiver 35B described above. The projector 35A in this example is composed of a light emitting diode, and its anode terminal 71 is connected to a power source (power supply voltage Vcc) via a resistor R1, and the cathode terminal 72 is grounded. The photoreceiver 35B of this example is composed of a phototransistor, the collector terminal 73 of which is connected to a power source, the emitter terminal 74 is an output terminal for outputting a detection voltage value V, and is grounded through a resistor R2. ing. As a mechanical arrangement, in this example, the light projector 35A and the light receiver 35B are arranged in this order along the conveyance direction of the printing paper 53.

  In the paper detection sensor 35 having such a configuration, the light receiver 35B receives the reflected light Lr via the printing paper 53 when the projector 35A is turned on, and a detection voltage at a level corresponding to the total amount of light received. Outputs the value V. In this example, since the collector side of the phototransistor constituting the light receiver 35B is connected to the power supply side, a higher detection voltage value V is output as the total amount of received light increases (see FIG. 7 described later).

  Next, with reference to FIG. 6, the configuration of the printing paper 53, which is the detection target of the paper detection sensor 35, will be conceptually described.

  In FIG. 6, this example shows a state in which a plurality of printing papers 53 are conveyed in a state where they are coupled via a perforated scheduled cutting line Lc. That is, the scheduled cutting line Lc is formed between the pages on the printing paper 53. In addition, on one side (upper side in the drawing) of each printing paper 53 in the width direction (the direction orthogonal to the transport direction), light absorption is performed so as to straddle the planned cutting line Lc (in this example, it is painted black). A black mark PM (positioning mark) is printed.

  Next, the light emission / light reception behavior of the above-described paper detection sensor 35 when the printing paper 53 having the above configuration is conveyed and printed will be described.

  First, a roll holder (not shown) is set in the portable printer 1, and the printing paper 53 fed out from a paper roll (not shown) stored in the roll holder is inserted into the insertion port 104. Immediately after the insertion, if the leading edge of the printing paper 53 does not reach the detection range of the paper detection sensor 35 (positioned upstream of the paper detection sensor 35 in the transport direction), the light projection from the light projector 35A is performed. There is no reflection by the printing paper 53. For this reason, the amount of reflected light Lr received by the light receiver 35B is very low. When the leading edge of the printing paper 53 reaches the detection range of the paper detection sensor 35, the light reflected from the printing paper 53 by the light projection from the light projector 35A is received by the light receiver 35B, and the platen roller 111 is driven. The conveyance (automatic feed) of the printing paper 53 is started.

  When the printing paper 53 is conveyed toward the discharge port 107 in this way, the black mark PM reaches the detection range of the paper detection sensor 35. At this time, the intensity of the reflected light Lr at the light receiver 35B due to the light projection from the light projector 35A becomes smaller than a predetermined threshold (detailed later) due to the light absorption of the black mark PM. Thereby, the presence of the black mark PM is detected. When the black mark PM is detected, after a predetermined amount of conveyance is performed based on the detection timing and based on the driving force of the platen roller 111, the thermal line head 112 performs printing on the printing area of the printing paper 53. Be started. For example, when the end of the black mark PM is detected, the conveyance of the printing paper 53 is stopped to be in a waiting state for printing, and when a printing instruction is input from the external device 2, the printing paper 53 is slightly reversed in the reverse direction. Printing may be started after conveyance.

  Thereafter, the printing paper 53 is conveyed by a predetermined amount based on the driving force of the platen roller 111, and when the printing paper 53 is discharged from the discharge port 107 (see FIG. 1), the conveyance is stopped. Thus, the printed paper 53 that has been printed is cut by the user along the scheduled cutting line Lc and separated as one sheet. As described above, the print control and the conveyance control after the start of conveyance of the printing paper 53 are performed based on the detection timing of the black mark PM by the sheet detection sensor 35.

  By the way, depending on the user, for example, the printing paper 53 having a lower whiteness than that of a normal white paper is inserted due to dirt or yellowing, or the light absorption performance is deteriorated due to fading. There may be a case where the printing paper 53 having the black mark PM (in other words, the blackness is lowered) is inserted. Originally, as described above, the amount of reflected light Lr received by the light receiver 35B is greatly reduced due to the light absorbing property of the black mark PM, and the detection voltage changes greatly to detect the black mark PM. However, if there is a decrease in whiteness or a decrease in blackness as described above, the change in the amount of light received by the light receiver 35B due to the black mark PM is alleviated. That is, when the amount of change in the detection voltage value V is small, the fluctuation range of the detection voltage value V is small. As a result, even when the black mark PM is projected, the amount of light received by the light receiver 35B is the predetermined amount. There is a possibility that detection of the black mark PM may be difficult because it is not smaller than the threshold value.

  Therefore, in the present embodiment, in the transporting and printing processes, the normal printing paper 53 (= the printing paper 53 having the normal whiteness and the black mark PM having the normal blackness) is inserted. The normal threshold value (= initial threshold value) that is set in advance is updated to a value (= new threshold value) that corresponds to the decrease in whiteness and blackness described above. Thus, the black mark PM can be detected with high accuracy. The principle of updating the threshold in consideration of the influence of the decrease in whiteness and the decrease in blackness will be described with reference to FIG.

  In the time chart shown in FIG. 7, the horizontal axis represents time T (corresponding to the transport amount), and the vertical axis represents the detection voltage V from the light receiver 35B. It should be noted that the projector 35A is always lit in all the time ranges shown in the figure, and for the convenience of illustration, the light projection range 81 in the A part to E part is shown larger than the actual one.

(A) Behavior when a printing paper having normal whiteness and mark blackness is inserted In FIG. 7, a printing paper 53 having normal whiteness and blackness of a normal black mark PM. Immediately after the start of the conveyance (while T <T1), the light projection range 81 of the light projector 35A is located in the margin of the printing paper 53 (see section A in FIG. 7). In this case, the output voltage value V from the light receiver 35B becomes a high level initial white corresponding voltage value Vw0. The initial white-corresponding voltage value Vw0 is a voltage value close to the power supply voltage value Vcc supplied by the power supply in FIG. 5, but from a predetermined white reference voltage value Rw in consideration of characteristic variations of the sensor element. Is set in advance (for example, at the time of inspection at the time of factory shipment) so as to be an appropriate value that is larger and smaller than Vcc.

  Thereafter, as the printing paper 53 is conveyed as described above, the light projection range 81 of the light projector 35A starts to overlap the black mark PM at a certain timing (T = T1). As the printing paper 53 is transported, the overlapping range of the black mark PM and the light projection range 81 increases (see B section in FIG. 7). Since the black mark PM has light absorptivity, the amount of light reflected by the light receiver 35B decreases as the overlapping range of the black mark PM and the light projection range 81 increases. As a result, when T becomes larger than T1, the detected voltage value V decreases downward from the initial white corresponding voltage value Vw0.

  Thereafter, when the conveyance of the printing paper 53 further proceeds, the light projection range 81 of the light projector 35A completely overlaps the black mark PM at a certain timing (T = T2) (see C section in FIG. 7). In this state, the detected voltage value V that has decreased as described above stops decreasing and becomes the initial black-corresponding voltage value Vb0. The initial black-corresponding voltage value Vb0 is also set in advance (for example, at the time of factory shipment) so as to be an appropriate value smaller than the predetermined black reference voltage value Rb and larger than 0, similarly to the initial white-corresponding voltage value Vw0. Set during inspection). This state is maintained until time elapses thereafter until T = T3 (described later).

  Thereafter, when the conveyance of the printing paper 53 further proceeds, the light projection range 81 of the light projector 35A starts to be separated from the black mark PM at a certain timing (T = T3). Then, as the printing paper 53 is conveyed, the overlapping range of the black mark PM and the light projection range 81 decreases (see part D in FIG. 7). As the black mark PM and the light projection range 81 overlap with each other, the amount of light reflected by the light receiver 35B increases. As a result, when T becomes larger than T3, the detected voltage value V increases to the right from the initial black corresponding voltage value Vb0.

  Thereafter, when the conveyance of the printing paper 53 further proceeds, the light projection area 81 of the light projector 35A is completely separated from the black mark PM at a certain timing (T = T4) (see the portion E in FIG. 7). As a result, the detected voltage value V that has increased as described above returns to the initial white-corresponding voltage value Vw0.

(B-1) Behavior when a printing paper with low whiteness is inserted On the other hand, as shown in FIG. 8 (a), the whiteness is higher than that of the normal white printing paper due to contamination or yellowing. In the case where the printing paper 53 having a low value is inserted, immediately after the conveyance is started (corresponding to the range of T ≦ T1 described above), the detection voltage V from the light receiver 35B is the initial white-corresponding voltage. The actual white corresponding voltage value Vw1 is a level different from the value Vw0 (smaller than the white reference voltage value Rw). This is because the whiteness of the portion other than the black mark PM of the printing paper 53 is lower than that of the normal printing paper, so that light cannot be reflected with a sufficiently high reflectance, and the light receiver 35B has a sufficient amount of light received. This is because the reflected light Lr cannot be received.

  Thereafter, similarly to FIG. 7, the detected voltage value V decreases to the right and then arrives at a certain timing (corresponding to T = T2 described above). The value at which the detected voltage value V stops decreasing is the aforementioned initial black corresponding voltage. The actual black corresponding voltage value Vb1 is larger than the value Vb0. For a while from this timing (corresponding to the range of 2 ≦ T ≦ T3 described above), the detected voltage value V is maintained at the actual black corresponding voltage value Vb1.

  Thereafter, the detection voltage value V again increases to the right. At a certain timing (corresponding to T = T4 described above), the increased detected voltage value V returns to the actual white corresponding voltage value Vw1.

  As is apparent from the above description, when the printing paper 53 having a low whiteness is used, the printing paper 53 having the normal whiteness shown in FIG. 7 is used (FIG. 8 ( The characteristic line changes toward the center of the figure as a whole (refer to the arrow to the solid line in FIG. 8A). Particularly in this case, in the change of the characteristic line, the difference between Vb0 and Vb1 is smaller than the difference between Vw0 and Vw1. That is, the fluctuation center of the fluctuation range of the detection voltage value V is slid downward (close to black) in the figure. As a result, the fluctuation range of the detected voltage value V (the actual white corresponding voltage value Vw1 to the actual black corresponding voltage value Vb1) due to the decrease in the whiteness of the printing paper 53 is the fluctuation range of the detected voltage value V (the above initial value). The white corresponding voltage value Vw0 to the initial black corresponding voltage value Vb0) is smaller. In this example, the fluctuation range of the detection voltage value V is reduced from “Vw0−Vb0” to “Vw1−Vb1”.

(B-2) Behavior when printing paper with low blackness of black mark PM is inserted On the other hand, as shown in FIG. When the printing paper 53 having the black mark PM is inserted, immediately after the conveyance is started (corresponding to the range of T ≦ T1 described above), the detection voltage V from the light receiver 35B is the initial white color. The actual white corresponding voltage value Vw1 is different from the corresponding voltage value Vw0.

  Thereafter, similarly to FIG. 7, the detected voltage value V decreases to the right and then arrives at a certain timing (corresponding to T = T2 described above). The value at which the detected voltage value V stops decreasing is the aforementioned initial black corresponding voltage. The actual black corresponding voltage value Vb1 is greater than the value Vb0 (greater than the black reference voltage value Rb). This is because the black mark PM of the printing paper 53 is lower in blackness than the black mark PM of the normal printing paper, so that the light cannot be sufficiently absorbed, and the reflected light of a certain amount of light received by the light receiver 35B. This is because Lr is received. For a while from this timing (corresponding to the range of 2 ≦ T ≦ T3 described above), the detected voltage value V is maintained at the actual black corresponding voltage value Vb1.

  Thereafter, the detection voltage value V again increases to the right. At a certain timing (corresponding to T = T4 described above), the increased detected voltage value V returns to the actual white corresponding voltage value Vw1.

  As is clear from the above description, when the printing paper 53 having the black mark PM having a low blackness is used, the printing paper 53 having the normal whiteness shown in FIG. 7 is used. Compared to the case (corresponding to the broken line in FIG. 8B), the characteristic line as a whole changes toward the center of the figure (see the arrow to the solid line in FIG. 8B). In particular, in this case, in the change of the characteristic line, the difference between Vb0 and Vb1 is larger than the difference between Vw0 and Vw1. That is, the fluctuation center of the fluctuation range of the detection voltage value V is slid upward (toward white) in the figure. As a result, as described above, the fluctuation range of the detected voltage value V (the actual white corresponding voltage value Vw1 to the actual black corresponding voltage value Vb1) due to the decrease in the blackness of the black mark PM of the printing paper 53 is the detected voltage value. This is smaller than the fluctuation range of V (the initial white corresponding voltage value Vw0 to the initial black corresponding voltage value Vb0). In this example, the fluctuation range of the detection voltage value V is reduced from “Vw0−Vb0” to “Vw1−Vb1”.

(C) Setting of Threshold Value (c-1) Initial Setting of Threshold Value In the portable printer 1 of the present embodiment, basically detection based on the presence of the black mark PM as described above with reference to FIG. Using the fluctuation of the voltage value V (initial white-corresponding voltage value Vw0 → initial black-corresponding voltage value Vb0 → initial white-corresponding voltage value Vw0), it is detected that the black mark PM is at a position facing the paper detection sensor 35. As a result, the position in the transport direction of the printing paper 53 is detected. Specifically, an initial threshold value TH0 (see FIGS. 7, 8A, and 8B) relating to the detected voltage value V is set in advance at the time of factory shipment, for example. The initial threshold value TH0 is such that k0 (corresponding to the initial coefficient described in each claim) is less than 1 so as to be between the initial white corresponding voltage value Vw0 and the initial black corresponding voltage value Vb0.
TH0 = Vb0 + k0 (Vw0−Vb0) (Equation 1)
It is set by. As is apparent from Equation 1, this initial threshold value TH0 exists in the interval of Vw0 to Vb0, which is the fluctuation range of the detected voltage value V, and approaches Vw0 depending on the value of the threshold coefficient k, or Vb0. It can be set to approach (k0 is the initial value of the threshold coefficient k). As a result, the detected voltage value V decreases in the range of T1 ≦ T ≦ T2 in FIG. 7, and the black mark PM is positioned to face the paper detection sensor 35 when V = TH0 is reached. Can be detected. The initial white corresponding voltage value Vw0, the initial black corresponding value Vb0, the initial threshold value TH0, and the threshold coefficient k0 are stored in advance in, for example, the ROM 14 or an EEPROM provided separately (initial value storage means). .

(C-2) Necessity of Update of Threshold Value Here, as described with reference to FIGS. 8A and 8B, when the whiteness of the printing paper 53 is reduced or the black mark PM When the blackness of the image is reduced, the fluctuation range of the detection voltage value V is reduced, and the actual white corresponding voltage value Vw1 becomes smaller than the initial white corresponding voltage value Vw0 or the actual black corresponding voltage value Vb1 is the initial black corresponding voltage value. It tends to be larger than Vb0. As a result, the actual black corresponding voltage value Vb1 that is the minimum value of the fluctuation range becomes larger than the predetermined initial threshold value TH0, or the actual white corresponding voltage value Vw1 that is the maximum value of the fluctuation range is predetermined. The initial threshold value TH0 may be smaller. In this case, even if the detection voltage value V decreases to the right in T1 ≦ T ≦ T2 due to the presence of the black mark PM, V = TH0 does not occur, so the presence of the black mark PM cannot be detected. The accuracy of conveyance control and printing control of the printing paper 53 in the portable printer 1 is lowered.

(C-3) Threshold Value Update Execution In the portable printer 1 of the present embodiment, in view of the above, the threshold value is updated to a new value instead of the initial threshold value TH0 previously determined by the equation (1). The new threshold value TH1 is used. In the present embodiment, the new threshold value TH1 is
TH1 = Vb1 + k1 (Vw1-Vb1) (Equation 2)
Calculated by As described above, the actual black-corresponding voltage value Vb1 is a value of the detected voltage value V by the black mark PM output from the light receiver 35B when the printing paper 53 to be printed is actually inserted. As described above, the white-corresponding voltage value Vw1 is a value of the detected voltage value V by the printing paper 53 output from the light receiver 35B when the printing paper 53 to be printed is actually inserted.

  As a result, as is apparent from Equation 2, this new threshold value TH1 is based on the same method principle as the above-described setting of the initial threshold value TH0, and is based on the fluctuation range of the detected voltage value V. This is equivalent to a section in which the section is divided by applying a section length of k1 times when a section of Vw1 to Vb1 is 1. Thus, by calculating the new threshold TH1 using the threshold coefficient k1 (corresponding to the actual coefficient described in each claim) different from the threshold coefficient k0 in the case of the initial threshold TH0, the threshold is calculated. The value is updated (TH0 → TH1).

  Specifically, when the whiteness of the printing paper 53 is lowered, in the present embodiment, the actually measured actual white corresponding voltage value Vw1 is smaller than the white reference voltage value Rw. Accordingly, the decrease in whiteness is recognized, and the value of k1 is set to a value smaller than 0.5 (in this example, 0.3 as described later). As a result, as shown in FIG. 8A, the new threshold value TH1 newly set by the above equation 2 is lower (black color) in FIG. 8A than the initial threshold value TH0 before the update. It becomes a mode of sliding to the side.

  Further, when the blackness of the black mark PM of the printing paper 53 is lowered, in the present embodiment, the actually measured actual black corresponding voltage value Vb1 is larger than the black reference voltage value Rb. Accordingly, the decrease in blackness is recognized, and the value of k1 is set to a value larger than 0.5 (in this example, 0.7 as described later). As a result, as shown in FIG. 8B, the new threshold value TH1 newly set by the above equation 2 is higher than the initial threshold value TH0 before the update (white color in FIG. 8B). It becomes a mode of sliding to the side.

  The threshold value update process is provided in the CPU 12 of the portable printer 1 based on an update instruction signal output from the update instruction unit 44 provided in the CPU 2a based on an appropriate operation of the external device 2, for example. It is executed by the update processing unit 45 or the like.

  As a result, even when the user uses the printing paper 53 having a lower whiteness than usual or the printing paper 53 having the black mark PM having a reduced blackness, the detected voltage value V Is reduced to the right in T1 ≦ T ≦ T2 due to the presence of the black mark PM, V reliably reaches TH1 and the presence of the black mark PM can be detected. Therefore, it is possible to perform reliable printing on the printing paper 53 while performing printing conveyance control and printing control with high accuracy.

  As described above, in the present embodiment, the presence of the black mark PM is detected when the detected voltage value V decreases and reaches the new threshold value TH1, but the present invention is not limited to this. That is, the presence of the black mark PM may be detected when the detected voltage value V increases and reaches the new threshold value TH1 (see a modification example (3) described later).

  The control contents of the threshold update process executed by the CPU 12 of the portable printer 1 in order to realize the functions described above will be described with reference to FIG.

  In FIG. 9, for example, this flow is started by turning on the power of the portable printer 1 in a state where the printing paper 53 to be printed is inserted from the insertion port 104.

  First, in step S <b> 10, it is determined whether or not an update instruction signal is input to the update processing unit 45 of the CPU 12 from the update instruction unit 44 of the CPU 12 of the external device 2. Until the update instruction signal is input, the determination is not satisfied and the system stands by in a loop. When the update instruction signal is input, the determination is satisfied and the process proceeds to step S20. In this way, a signal generated by operating an appropriate button (including a power button) or key of the portable printer 1 is acquired as an update instruction signal from the external device 2 without using the update instruction signal. The determination may be satisfied and the process may proceed to step S20.

  In step S20, the white reference voltage value Rw, the black reference voltage value Rb, and the threshold coefficient k0 stored in the ROM 14 or the EEPROM as described above are input.

  Thereafter, the process proceeds to step S200, and the threshold count k1 is determined based on the actual white corresponding voltage value Vw1 and the actual black corresponding voltage value Vb1 output from the light receiver 35B in a state where the printing paper 53 is inserted. (Details will be described later).

  Thereafter, the process proceeds to step S40, and based on the actual white corresponding voltage value Vw1 and actual black corresponding voltage value Vb1 acquired in step S200 and the determined threshold coefficient k1, the update process is performed using the above-described equation 2. The unit 45 calculates a new threshold value TH1 = Vb1 + k1 (Vw1−Vb1). Thereafter, this flow is terminated.

  Next, the detailed procedure of step S200 will be described with reference to FIG.

  First, in step S <b> 210, the CPU 12 outputs a control signal to the motor drive circuit 16 to drive the platen roller 111 by the drive motor 11. Thereby, the conveyance of the printing paper 53 inserted in the insertion port 104 is started.

  Thereafter, the process proceeds to step S220, and the detected voltage value V output from the light receiver 35B is acquired.

  In step S230, it is determined whether the actual white corresponding voltage value Vw1 and the actual black corresponding voltage value Vb1 have been acquired. Specifically, for example, the detection voltage value output from the light receiver 35B at an appropriate sampling period or an integral multiple thereof is the right at the start of detection of the black mark PM in FIGS. 8 (a) and 8 (b). What is necessary is just to determine with the actual white corresponding | compatible voltage value Vw1 having been acquired by having become a horizontal behavior before becoming a descending behavior (that is, it is a substantially constant value in a certain time range). Similarly, the detected voltage value output from the light receiver 35B at an appropriate sampling period or an integral multiple thereof is after the right-down behavior after the detection of the black mark PM in FIGS. 8 (a) and 8 (b). It is only necessary to determine that the actual black-corresponding voltage value Vb1 can be acquired by the horizontal behavior (that is, a substantially constant value within a certain time range). Until both the actual white corresponding voltage value Vw1 and the actual black corresponding voltage value Vb1 are acquired, the process returns to step S220 and the same procedure is repeated. When both the actual white corresponding voltage value Vw1 and the actual black corresponding voltage value Vb1 are acquired, the determination in step S230 is satisfied, and the process proceeds to step S240.

  In step S240, it is determined whether or not the actual white corresponding voltage value Vw1 acquired by repeating steps S220 and S230 is smaller than the white reference voltage value Rw acquired in step S20. If the acquired actual white corresponding voltage value Vw1 is smaller than the white reference voltage value Rw (see FIG. 8A), the determination is satisfied, and the routine goes to Step S250. In step S250, the threshold coefficient k1 is set to 0.3 which is smaller than 0.5. Thereafter, the process proceeds to step S260.

  On the other hand, if the actual white-corresponding voltage value Vw1 is greater than or equal to the white reference voltage value Rw in step S240, the determination in step S240 is not satisfied, and the process proceeds to step S270. In step S270, it is determined whether or not the actual black corresponding voltage value Vb1 acquired by repeating steps S220 and S230 is greater than the black reference voltage value Rb acquired in step S20. When the actual black corresponding voltage value Vb1 is larger than the black reference voltage value Rb (see FIG. 8B), the determination in step S270 is satisfied, and the process proceeds to step S280. In step S280, the threshold coefficient k1 is set to 0.7, which is larger than 0.5. Thereafter, the process proceeds to step S260.

  In step S270, if the actual black corresponding voltage value Vb1 is equal to or lower than the black reference voltage value Rb, the determination is not satisfied, and the routine goes to step S290. In step S290, the threshold coefficient k1 is set to the same value as the initial value k0. Thereafter, the process proceeds to step S260.

  When step S250, step S280, and step S290 are completed, the process proceeds to step S260 as described above. In step S260, it is determined whether the printing paper 53 has reached a predetermined conveyance end position by an appropriate method. Specifically, for example, the horizontal behavior after the upward motion after the detection of the black mark PM is continued in a predetermined time range (the voltage value V is substantially constant for a long time). The conveyance may be finished. Alternatively, after the black mark PM is detected based on the behavior of the voltage value V of the lower left and lower right as described above, the number of pulses output from the motor drive circuit 16 to the drive motor 11 including the pulse motor is counted. The transport distance from the black mark PM may be determined based on the count number, and the transport may be terminated by transporting a predetermined distance. Until the conveyance end position is reached, the determination in step S260 is not satisfied and the loop waits. When the conveyance end position is reached, the determination in step S260 is satisfied, and the process proceeds to step S270.

  In step S <b> 270, the CPU 12 outputs a control signal to the motor drive circuit 16 and stops driving the platen roller 111 by the drive motor 11. Thereby, the conveyance of the printing paper 53 started from step S210 and continuing is stopped, and this flow is ended.

  Next, the control contents of the printing process on the printing paper 53 executed by the CPU 12 in a state where the new threshold value TH1 is obtained by the flow of FIGS. 9 and 10 will be described with reference to FIG. To do.

  In FIG. 11, for example, when the power of the portable printer 1 is turned on, this flow is started.

  First, in step S300, it is determined whether or not the printing paper 53 has been inserted from the insertion port. Specifically, for example, the determination is made based on whether or not the leading edge of the printing paper 53 reaches the light projection range from the light projector 35A and the reflected light Lr having a predetermined size is received by the light receiver 35R. Until the printing paper 53 is sufficiently inserted, the determination in step S300 is not satisfied and the process stands by in a loop. If inserted, the determination is satisfied and the process proceeds to step S310.

  In step S <b> 310, as in step S <b> 210 of FIG. 10, the CPU 12 outputs a control signal to the motor drive circuit 16 and drives the platen roller 111 by the drive motor 11. Thereby, the conveyance of the printing paper 53 inserted in the insertion port 104 is started.

  Thereafter, in step S320, it is determined whether or not the detected voltage value V output and acquired from the light receiver 35B is smaller than the new threshold value TH1 obtained as described above. While the detected voltage value V is equal to or greater than the new threshold value TH1, the determination is not satisfied, and it is considered that the black mark PM has not yet reached the position facing the paper detection sensor 35, and the loop waits. When the detection voltage value V becomes smaller than the new threshold value TH1, the determination in step S320 is satisfied, and the black mark PM reaches the light projection range of the light projector 35A facing the paper detection sensor 35 by conveyance and the black mark PM is detected. (Corresponding to the state of part B in FIG. 7), and the process proceeds to step S330.

  In step 330, it is determined whether or not the detected voltage value V output and acquired from the light receiver 35B is greater than the new threshold value TH1 obtained as described above. While the detection voltage value V is equal to or less than the new threshold value TH1, the determination is not satisfied, and the black mark PM still exists at a position facing the paper detection sensor 35 (completely separated from the light projection range of the light projector 35A). And waits for the loop. When the detected voltage value V becomes larger than the new threshold value TH1, the determination in step S330 is satisfied, and the black mark PM is completely separated from the light projection range of the light projector 35A by conveyance (corresponding to the state of the E portion in FIG. 7). And the process proceeds to step S340.

  Thereafter, in step S340, as in step S270 of FIG. 10 described above, the CPU 12 outputs a control signal to the motor drive circuit 16, and stops driving the platen roller 111 by the drive motor 11. As a result, the conveyance of the printing paper 53 is stopped, and a waiting state for waiting for a printing instruction in the subsequent step S350 is entered.

  In step S350, it is determined whether a print instruction has been issued, that is, whether a print instruction signal including print data has been input from the external device 2. The loop waits until the determination is satisfied. If there is a print instruction, the determination in step S350 is satisfied, and the process proceeds to step S360.

  In step S <b> 360, the CPU 12 outputs a control signal to the thermal head driving circuit 17 to energize the thermal line head 112, and outputs a control signal to the motor driving circuit 16 to convey the printing paper 53 by the platen roller 111. Is resumed. As a result, the dot pattern data stored in the buffer as described above is sequentially printed on the printing paper 53.

  Thereafter, in step S370, it is determined whether printing corresponding to the print data is completed. Until the printing of the print data is completed, the determination in step S370 is not satisfied, and the process returns to step S340 to continue printing. When printing of the print data is completed, the determination at step S370 is satisfied, and the routine goes to step S380.

  In step S380, as in step S260 of FIG. 10 described above, it is determined whether the printing paper 53 has reached a predetermined conveyance end position. Specifically, for example, after the detection timing of the previous black mark PM (step S320 or step S330), the number of pulses output from the motor drive circuit 16 to the drive motor 11 composed of a pulse motor is counted as described above. The transport distance from the black mark PM may be determined based on the count number, and the transport may be terminated by transporting a predetermined distance. Until the conveyance end position is reached, the determination in step S380 is not satisfied and the loop waits. When the conveyance end position is reached, the determination in step S380 is satisfied, and the process proceeds to step S390.

  In step S390, as in step S270, the CPU 12 outputs a control signal to the motor drive circuit 16, and stops driving the platen roller 111 by the drive motor 11. This completes this flow.

  In the above, step S240 functions as the whiteness determination unit described in each claim, and step S270 functions as the blackness determination unit. And step S250, step S280, and step S40 function as a threshold value update means. Further, Step S220, Step S260, and Step S270 function as an update transport control unit.

  Steps S320 and S330 function as mark detection means, and steps S360 to S390 function as printing conveyance control means. Of these, step S360 and step S370 also function as print control means.

  As described above, in the portable printer 1 of the present embodiment, the user uses the printing paper 53 having a lower whiteness than usual, or the printing paper 53 having the black mark PM having a lower blackness. When used, the threshold value TH1 = Vb1 + k1 (Vw1−V1) is used instead of the initial threshold value TH0 = Vb0 + k0 (Vw0−Vb0). As a result, the new threshold value TH1 corresponding to the fluctuation range when the whiteness and blackness are reduced, which is assumed to be narrower than the fluctuation range when the normal printing paper 53 is used, is newly set. Can be set. As a result, even when the printing paper 53 with low whiteness as described above or the printing paper 53 with the black mark PM with reduced blackness is used, the detection voltage due to the reduction in whiteness or blackness is used. Regardless of the behavior, the black mark PM can be detected with high accuracy. As a result, even when the above-described printing paper 53 is used, it is possible to perform reliable printing on the printing paper 53 while performing printing transport control and printing control with high accuracy.

  In the present embodiment, in particular, in step S240, when the whiteness of the printing paper 53 does not reach a predetermined white reference, k is set to a value k1 smaller than k0 (in the above example, k0). By setting k1 = 0.3 smaller than 0.5, the threshold value is changed to a value closer to black. As a result, the black mark PM is reliably detected with high accuracy even when the printing paper 53 that is dirty or yellowed and has a whiteness lower than that of a normal white paper is used. Printing on the paper 53 can be performed.

  In the present embodiment, in particular, when the black degree of the black mark PM does not reach a predetermined black reference in step S270, k is set to a value k1 larger than k0 (in the above example, k0 = By setting k1 = 0.7, which is larger than 0.5, the threshold value is changed to a value closer to white. As a result, the black mark PM can be reliably detected with high accuracy even when the printing paper 53 having the black mark PM that has faded and become old as described above and has reduced blackness is used. And printing on the printing paper 53 can be performed.

  In the above-described embodiment, the threshold value update process illustrated in FIGS. 9 and 10 and the print process illustrated in FIG. 11 are performed as separate processes, but the process is performed separately. However, the present invention is not limited to this. That is, when the printing process as shown in FIG. 11 is executed, the threshold value update process as shown in FIGS. 9 and 10 may be automatically executed.

  The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit and technical idea of the present invention. Hereinafter, such modifications will be described in order.

(1) When the whiteness / blackness detection is performed on a plurality of sheets to determine the coefficient k1, for example, as described above, when the user feeds out the printed sheet 53 from the sheet roll of the roll holder and uses it, it continues to the sheet roll. In some cases, the degree of decrease in whiteness due to the above-described stain / yellowing and the degree of decrease in blackness due to fading, aging, etc. may be slightly different among a plurality of printing papers 53 included in the image. This modification corresponds to such a case, and the black mark PM can be detected with higher accuracy in response to the decrease in the whiteness and the decrease in the blackness in each of the plurality of printing sheets 53. The new threshold value THm is calculated so that it can be performed.

  The principle of threshold value updating in this modification will be described with reference to FIG. 12 corresponding to FIG. 7 of the above embodiment.

  FIG. 12 shows an example of the behavior of each detected voltage value V when three sheets of printing paper 53 are inserted. In this example, the case where the whiteness of these three sheets of printing paper 53 is small is taken as an example. As described above, when the printing paper 53 having a low whiteness is used, the characteristic line changes toward the center of the drawing as a whole, compared to the case of using the printing paper 53 having a normal whiteness. To do. In particular, in this modified example, the actual white corresponding voltage value is Vw1 and the actual black corresponding voltage value is Vb1 in the first sheet 53 to be printed. Similarly, the actual white corresponding voltage value is Vw1 ′ and the actual black corresponding voltage value is Vb1 ′ in the second printing paper 53, and the actual white corresponding voltage value is Vw1 in the third printing paper 53. The actual black corresponding voltage value is Vb1 ".

  Comparing the values relating to each printing paper 53, the actual white corresponding voltage value has a relationship of Vw1> Vw1 ′> Vw1 ″, and the actual black corresponding voltage value has a relationship of Vb1> Vb1 ′> Vb1 ″. ing. As already described, the lower the actual white-corresponding voltage value Vw, the lower the whiteness of the paper, and the more yellowed or smeared. Similarly, the higher the actual black-corresponding voltage value Vb is, the lower the blackness of the black mark PM of the paper is, and more faded or aged deterioration occurs. Therefore, in the present embodiment, in order to ensure highly accurate conveyance control / printing control on the printing paper 53, among the actual white corresponding voltage values Vw1, Vw1 ′, Vw1 ″, the worst condition Vw1 ″ and the above Of the actual black-corresponding voltage values Vb1, Vb1 ′, Vb1 ″, Vb1 having the worst condition is used for calculating the update threshold value. That is, when performing calculation using the above equation 2, Vw1 in equation 2 is substituted. The above Vw1 ″ is used. In this example, Vb1 has the worst condition among the actual black corresponding voltage values Vb1, Vb1 ′, and Vb1 ″. Therefore, Vb1 in Expression 2 is apparently applied as it is. If Vb1 ′ or Vb1 ″ is bad, Vb1 ′ or Vb1 ″ is used instead of Vb1 in the above formula.

  Further, for the determination of the value of k1 in Equation 2, a method different from that in the above embodiment is used. In the above embodiment, the value of k1 is set to 0.3 depending on the magnitude relationship between the actually detected actual white corresponding voltage value Vw1 or actual black corresponding voltage value Vb1 and the white reference voltage value Rw or black reference voltage value Rb. Or 0.7. In this modified example, the black mark PM can be accurately obtained with high accuracy even when the actual white corresponding voltage values Vw1, Vw1 ′, Vw1 ″ and the actual black corresponding voltage values Vb1, Vb1 ′, Vb1 ″ are varied. From the viewpoint of ensuring detection, the value of k1 is switched according to each variation range (variation range). That is, the fluctuation range γw of the actual white corresponding voltage value Vw (in this example, Vw1−Vw1 ″) and the fluctuation range γb of the actual black corresponding voltage value Vb (in this example, Vb1−Vb1 ″) are compared. As shown in the figure, when γw> γb, k1 is set to 0.3 which is smaller than 0.5. As a result, the new threshold value TH1 calculated from the above equation 2 is set to the initial threshold value TH0. Compared to black (in other words, closer to the side with less fluctuation range), it is set in such a manner that it slides. Conversely, when γw <γb, k1 is set to 0.7, which is smaller than 0.5. As a result, the new threshold value TH1 calculated from the above equation 2 is compared with the initial threshold value TH0. Therefore, it is set in such a manner that it is slid toward white (similar to the above, the side closer to the side with less fluctuation).

  In the process executed by the CPU 12 of the portable printer 1 of this modification, the threshold coefficient determination process of step S200 ′ is executed instead of the threshold coefficient determination process of step S200 in FIG. The control content of step S200 ′ will be described with reference to FIG. 13 corresponding to FIG.

  In the flow of step S200 ′ shown in FIG. 13, steps S245 and S275 are newly provided in place of steps S240 and S270 of the flow of step S200 shown in FIG. Further, Step S235 and Step S237 are provided between Step S230 and the newly provided Step S245.

  That is, after the same step S210 and step S220 as in FIG. 10 above, and in step S230, the actual white corresponding voltage value Vw1 and the actual black corresponding voltage value Vb1 are obtained and the determination is satisfied, the newly provided step S235 is performed. Move.

  In step S235, it is determined whether or not all the plurality of sheets (three in this example) of the printing paper 53 have been completed. When counting the total number of sheets (three sheets in this case), the user manually inputs the number of sheets to be printed 53 to be printed (or whiteness / blackness detection target) in advance before processing. To. Alternatively, when the state in which the reflected light Lr on the printing paper 53 is not received continues for a predetermined time, the platen roller 11 recognizes that all the printing paper 53 has been discharged out of the apparatus, and has passed so far. The number of black marks PM may be recognized based on the number of black marks PM. The process returns to step 220 and the same procedure is repeated until the actual white corresponding voltage value Vw1 and the actual black corresponding voltage value Vb1 are obtained for all the print sheets 53. When the actual white-corresponding voltage value Vw1 and the actual black-corresponding voltage value Vb1 are acquired for all the print sheets 53, the determination in step S235 is satisfied, and the process proceeds to newly provided step S237.

  In step S237, the fluctuation range γw of the actual white corresponding voltage value Vw and the fluctuation range γb of the actual black corresponding voltage value Vb are calculated according to the acquisition result in step S230 during the above repetition. As described above, in the example of FIG. 12, the actual white corresponding voltage value is Vw1> Vw1 ′> Vw1 ″, so that γw = Vw1−Vw1 ″, and the actual black corresponding voltage value is Vb1> Vb1 ′> Vb1 ″. γb = Vb1−Vb1 ″. Thereafter, the process proceeds to newly provided step S245.

  In step S245, it is determined whether γb <γw based on the calculation result in step S237. If the fluctuation width γb of the actual black corresponding voltage value Vb is smaller than the fluctuation width γw of the actual white corresponding voltage value Vw (see FIG. 12), the determination is satisfied, and the routine proceeds to step S250 similar to FIG. Set to. On the other hand, if the variation range γb of the actual black corresponding voltage value Vb is equal to or larger than the variation range γw of the actual white corresponding voltage value Vw, the determination in step S245 is not satisfied, and the process proceeds to a newly provided step S275.

  In step S275, it is determined whether γb> γw based on the calculation result in step S237. If the fluctuation width γb of the actual black corresponding voltage value Vb is larger than the fluctuation width γw of the actual white corresponding voltage value Vw, the determination is satisfied, and the process proceeds to step S280 similar to FIG. 10 to set k1 = 0.3. On the other hand, if the variation width γb of the actual black corresponding voltage value Vb is equal to the variation width γw of the actual white corresponding voltage value Vw, the determination in step S275 is not satisfied, and the routine proceeds to step S290 similar to FIG. 10, and k1 is changed to k0. Same value as.

  Step S250, step S280, and step S290 and subsequent steps are the same as in FIG.

  As described above, in the process executed by the CPU 12 of the portable printer 1 of the present modification, the threshold coefficient k1 determined by the procedure of FIG. And the minimum actual white corresponding voltage value Vw (Vw1 ″ in the above example) and the maximum actual black corresponding voltage value Vb (above described above) acquired in connection with the calculation of the fluctuation ranges γb and γw in step S200 ′. In the example, Vb1) is used to calculate a new threshold value TH1.

  In the above, step S237 functions as a white variation width detecting unit described in each claim and also functions as a black variation range detecting unit. Further, the step S40, the step S250, the step S280, and the step S290 function as a threshold value updating unit.

  In the present modification, as described above, the worst condition among the whiteness level and the blackness level detected by the paper detection sensor 35 for each of a plurality of printing papers 53, that is, a condition where the difference between black and white is small. Is updated to a threshold value k1 based on. As a result, the black mark PM can be reliably detected with high accuracy on any of the plurality of printing papers 53, and printing on the printing paper 53 can be reliably performed.

  In the modified example, the actual white corresponding voltage values Vw1, Vw1 ′, Vw1 ″ and the actual black corresponding voltage value Vb, from the sheet detection sensor 35 while sequentially transporting a plurality of printing sheets 53 by the platen roller 11. When Vb ′ and Vb ″ are acquired, the CPU 12 may control the motor drive circuit 16 so that the conveyance speeds of the respective printing papers 53 are different from each other (conveyance speed setting means) function). In this case, there are the following effects.

  That is, when optical detection is performed by emitting and receiving light on the black mark PM of the conveyed printing paper 53, the distance from the paper detection sensor 35 to the printing paper 53 affects the detection accuracy. There is. In the above-described method, the conveyance speeds at the time of detection by the paper detection sensor 35 for each of the plurality of printing papers 53 are made different from each other. When the transport speeds are different from each other in this way, the distance from the printing paper 53 to the paper detection sensor 35 during the transport is also different from each other. In other words, a plurality of detections with slightly different accuracy can be performed. . As a result, it is possible to reduce the influence of variations in accuracy of the paper detection sensor 35 when updating the initial threshold value TH0 to the new threshold value TH1, and to further change the effective threshold value.

  However, it is not always necessary to change the conveyance speed for each printing paper 53, and the detection may be performed while keeping the conveyance speed constant. Even in this case, it is possible to cope with a case where the whiteness is slightly different in each printing paper 53 (yellowing unevenness or the like) or a case where the blackness of the black mark PM is slightly different (fading unevenness or the like).

(2) When the output voltage polarity of the light receiver is reversed In the above embodiment, the phototransistor constituting the light receiver 35B of the paper detection sensor 35 is grounded to the collector (see FIG. 5 above), thereby receiving the light receiver 35B. The higher the received light amount, the higher the detected voltage value V. However, the present invention is not limited to this, and as shown in FIG. 14 corresponding to FIG. 5, the phototransistor of the light receiver 35B is grounded at the emitter, so that the detection voltage value V of a lower level is increased as the amount of light received by the light receiver 35B increases. You may make it output.

  In this case, as shown in FIG. 15 corresponding to FIG. 7, FIG. 16 (a) corresponding to FIG. 8 (a), and FIG. 16 (b) corresponding to FIG. On the black side, the magnitude relationship of the detected voltage value V is reversed. However, also in this case, the initial threshold value TH0 can be updated to the new threshold value TH1 by the same method as described above using the same formulas 1 and 2 as described above, and the same effect can be obtained. Can be obtained.

  In addition, in the above, the arrow shown in each figure of FIG.4, FIG.5, FIG.14 shows an example of the flow of a signal, and does not limit the flow direction of a signal.

  In addition, the flowcharts shown in FIGS. 9, 10, 11, 13 and the like do not limit the present invention to the procedures shown in the above-described flow, and additional procedures can be added within the scope not departing from the spirit and technical idea of the invention. You may delete or change the order.

  In addition to those already described above, the methods according to the above-described embodiments and modifications may be used in appropriate combination.

  In addition, although not illustrated one by one, the present invention is implemented with various modifications within a range not departing from the gist thereof.

1 Portable printer 104 Insertion slot 111 Platen roller (conveying means)
112 Thermal line head (thermal head)
35 Paper detection sensor (optical sensor)
35A Floodlight (lighting means)
35B Light receiver (light receiving means)
53 Paper to be printed Lr Reflected light PM Black mark (positioning mark)

Claims (4)

Transport means for transporting a printing paper provided with a light-absorbing positioning mark;
A thermal head for performing desired printing on the printing paper conveyed by the conveying means;
An optical sensor including a light projecting unit capable of projecting light toward a transport path of the printing paper transported by the transport unit, and a light receiving unit capable of outputting a detection voltage value corresponding to the received light amount;
An initial value storage means for storing a predetermined initial threshold value predetermined with respect to the detection voltage by the light receiving means;
Threshold value updating means for calculating a new threshold value instead of the initial threshold value stored in the initial value storage means in accordance with an update instruction signal;
Mark detection means for detecting the positioning mark when the detection voltage value of the light receiving means reaches the new threshold after the calculation of the new threshold by the threshold update means;
A conveyance control unit for printing that controls the conveyance unit to start conveyance according to an input of a print instruction signal, and controls a conveyance operation of the conveyance unit based on a detection result of the mark detection unit;
Print control means for controlling the printing operation of the thermal head based on the detection result of the mark detection means;
An update conveyance control means for controlling the conveyance means to convey the printing paper for a predetermined distance in response to the update instruction signal;
Have
The initial threshold is
A value Vb0 + k0 (Vw0−Vb0) calculated using a predetermined initial white corresponding voltage value Vw0 and an initial black corresponding voltage value Vb0, which are determined in advance corresponding to the range of the detection voltage value by the light receiving means, and an initial coefficient k0. (Where k0 is a number less than 1),
The new threshold is
An actual white corresponding voltage value acquired based on the detected voltage value output by the light receiving unit while the transport unit transports the printing paper by the predetermined distance based on the control of the update transport control unit. with the calculated value Vb1 + k1 (Vw1-Vb1) by using the real coefficients k1 to be newly set as Vw1 and true black voltage value Vb1,
The update transport control means includes:
In response to the update instruction signal, the conveying means is controlled to continuously convey the predetermined distance corresponding to the plurality of sheets to be printed,
The optical sensor is
For each of the plurality of sheets to be printed continuously conveyed, the light projecting unit performs light projection and the light receiving unit outputs a detection voltage value, and
While the transport unit transports the plurality of print sheets by the predetermined distance based on the control of the update transport control unit, a plurality of light output from the light receiving unit corresponding to each of the plurality of print sheets. Based on the detected voltage value, a white variation width detecting means for detecting a variation range of the whiteness degree of the plurality of printing papers, and a blackness degree of the positioning marks provided on the plurality of printing papers, respectively. Black fluctuation range detecting means for detecting the fluctuation range of
The threshold update means includes
Of the fluctuation range of the white degree detected by the white fluctuation range detection unit and the fluctuation range of the black degree detected by the black variation range detection unit, k1 is shifted so as to shift to the side where the fluctuation range is smaller. And
K1 set according to the fluctuation range, a detection voltage value relating to a printing paper having the lowest whiteness among the plurality of detection voltage values outputted from the light receiving unit with respect to the plurality of printing papers, When the blackness is the lowest among the plurality of detection voltage values output by the light receiving means with respect to the positioning marks of a plurality of sheets of printing paper, the new threshold value is determined based on the detection voltage value related to the positioning marks. A printer characterized by performing a calculation . The printer according to claim 1.
Based on the detection voltage value by the light receiving unit while the conveyance unit conveys the printing paper by the predetermined distance based on the control of the update conveyance control unit, the whiteness degree of the printing paper is predetermined white Having whiteness determination means for determining whether or not the reference is reached,
The threshold update means includes
The printer, wherein when the whiteness determination means determines that the whiteness of the printing paper does not reach a predetermined whiteness standard, k1 is set to a value smaller than k0. The printer according to claim 1.
Based on the detection voltage value by the light receiving means while the conveyance means conveys the printing paper for the predetermined distance based on the control of the update conveyance control means, the degree of blackness of the positioning mark is predetermined black It has a blackness determination means for determining whether or not the standard has been reached,
The threshold update means includes
The printer according to claim 1, wherein when the blackness determination means determines that the blackness of the positioning mark does not reach a predetermined black reference, k1 is set to a value larger than k0. The printer according to claim 1 .
The update transport control means includes:
And a conveyance speed setting unit that controls the conveyance unit so that the conveyance speeds of the respective printing papers are different from each other when the plural printing papers are continuously conveyed. Printer.

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