JP3106715B2 - Dot printing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dot printing apparatus for printing characters and the like on a printing medium via a dot printing head, and more particularly to a printing method for printing print data by referring to a dot printing state before a current printing position . The present invention relates to a dot printing apparatus that counts the number of appearances of a specific dot printing pattern composed of a combination of presence or absence, and controls the pulse width of an energizing pulse to each heating element in a dot printing head to be sequentially reduced according to the counted number. Things. Also,
The present invention relates to a dot printing apparatus that controls the pulse width of an energizing pulse according to the type of an ink ribbon used for dot printing and the temperature near a dot print head.

[0002]

2. Description of the Related Art Conventionally, in performing heat generation control of a head having a plurality of heat generation elements, printing in which heat generation of each heat generation element is controlled based on a heat generation history before a current printing position for each heat generation element. Various devices have been proposed.

[0003] For example, Japanese Patent Publication No. 64-12146 discloses, for each heating element, the presence or absence of heating data for causing the heating element of the head to generate heat at the current printing position and the presence or absence of heating data for causing the heating element to generate heat immediately before. An element unit comparing means for comparing, and a counting means for counting the number of times the same data continues by comparing whether or not the heat generation data at the current printing position is the same as the heat generation data immediately before the same. When the immediately preceding heat generation data is present as a result of the comparison by the element unit comparison means, the amount of current supplied to the heat generation element is made smaller than in the normal case, and the count value of the count means reaches a predetermined value. Discloses a thermal printer provided with a control means for further reducing the amount of current supplied to the heating element.

According to such a thermal printer, the temperature of the heating element on the head can be kept constant from the start to the end of image recording, and the life of the head can be extended without uneven image density. It is.

[0005]

However, in the conventional thermal printer, the pulse width of the energizing pulse is switched to an energizing pulse of a shorter pulse width when a constant count value is counted by the counting means. The pulse width of the switched energizing pulse is set to a constant width and is not changed. Therefore, when printing is performed for a long period of time, heat generated in the head is inevitable even when the energizing pulse having the pulse width shortened as described above is used.

[0006] As described above, when heat exceeding the heat radiation capability of the head is accumulated in the head, the print density increases, causing unevenness in the print density, and shortening the life of the head due to high thermal fatigue. This problem still remains.

In the conventional thermal printer, printing is performed on recording paper by a head via an ink ribbon. The pulse width of an energizing pulse to a heating element is controlled in accordance with the type of the ink ribbon. Nothing has been done. Here, there are various types of ink ribbons according to the melting temperature of the ink used,
Depending on the thermal printer, it is not possible to control the pulse width of the energizing pulse to the heating element in accordance with the various types of ink ribbons, and accordingly, it is impossible to perform appropriate printing corresponding to each ink ribbon. . As a result, there is a problem that print density unevenness occurs depending on the ink ribbon used.

Further, the ambient temperature in the thermal printer rises due to heat radiation from the head as printing proceeds, and the rise in the ambient temperature affects the heat radiation performance of the head to a considerable extent. In the conventional thermal printer, the pulse width of the energizing pulse to the heating element is not controlled at all according to the internal ambient temperature. Therefore, even from this point, there is a risk that excessive heat is generated in the head, and a risk that the life of the head is shortened remains.

[0009] The present invention has been made to solve the problems of the prior art, printing based on the dot printing state definitive before the current print position by the dot printing head Day
A specific dot print pattern consisting of a combination of the presence or absence of the data is detected, the number of appearances of the specific dot print pattern is counted, and when the predetermined number of appearances is counted, the specific dot print pattern is counted a predetermined number of times. By reducing the pulse width of the energizing pulse to the heating element sequentially by a constant width each time and controlling the pulse width of the energizing pulse so as not to be less than a predetermined pulse width, the heat generation to the dot print head can be extremely efficiently performed. It is an object of the present invention to provide a dot printing apparatus which can be appropriately controlled and can prolong the life of a dot print head without causing unevenness in print density.

Another object of the present invention is to provide a dot printing apparatus capable of controlling the pulse width of a current supply pulse to a heating element according to the type of ink ribbon used and the ambient temperature inside the apparatus.

[0011]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention has a plurality of heating elements, and prints via an ink ribbon by selectively applying an energizing pulse to each heating element. A dot print head for printing characters and the like on a medium, and a specific dot comprising a combination of presence or absence of print data with reference to a current print position by the dot print head and a dot print state before the current print position. Print pattern detection means for detecting a print pattern, and count means for counting the number of appearances of the specific dot print pattern detected by the print pattern detection means according to the progress of printing by the dot print head,
A first control for sequentially reducing the pulse width of the energizing pulse by a constant width each time the specific dot print pattern is counted a predetermined number of times by the counting means when the predetermined number of appearances is counted by the counting means; Means.

Further, the present invention further includes a pulse width detecting means for detecting a pulse width of the energizing pulse, and a pulse width of the energizing pulse having a predetermined pulse width via the pulse width detecting means. When detected, a pulse width control means for controlling the pulse width of the energizing pulse so as not to be less than the predetermined pulse width is provided.

A second control means for controlling a pulse width of the energizing pulse in accordance with the type of the ink ribbon detected by the ribbon detection means; Is done. Further, the apparatus further comprises a temperature detecting means disposed near the dot print head, and a third control means for controlling a pulse width of the energizing pulse based on a detection result by the temperature detecting means.

[0014]

Upon [action] In the present invention having the above configuration, for printing characters and the like on the printing medium through the ink ribbon by dot printing head, the printing by the print pattern detecting means
A specific dot print pattern composed of a combination of the presence or absence of data is detected, and the number of appearances of the detected specific dot print pattern is counted via a counting means.

When the number of appearances of the specific dot pattern counted by the counting means is counted a predetermined number of times, each time the specific dot printing pattern is counted a predetermined number of times thereafter, the dot printing head is controlled by the first control means. The pulse width of the energizing pulse applied to each of the heating elements is sequentially reduced by a constant width. Thereby, even when dot printing is performed for a long time, excessive heat is not applied to the dot print head.

After that, when it is detected by the pulse width detecting means that the pulse width of the energizing pulse has reached the predetermined pulse width, the pulse width of the energizing pulse is changed to the predetermined pulse width by the pulse width controlling means. It is controlled so as not to be as follows. As a result, dot printing is performed with the minimum necessary printing energy without excessive heating of the dot printing head.

Further, according to the present invention, the pulse width of the energizing pulse to the heating element of the dot print head is controlled via the second control means in accordance with the type of the ink ribbon detected by the ribbon detection means, and the temperature detection means is controlled. The pulse width of the energizing pulse is controlled by the third control means on the basis of the detection result detected by. Thus, dot printing is performed with an energizing pulse having an appropriate pulse width according to the melting temperature of the ink applied on the ink ribbon and the ambient temperature inside the apparatus.

[0018]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a tape printer according to an embodiment of the present invention;

FIG. 1 is a plan view of the tape printing apparatus shown with the storage cover of the tape cassette storage section opened. In FIG. 1, a tape printer 1 has a character input key 2 for inputting characters such as characters over a plurality of lines, a print key 3 for instructing the start of printing, and a modification of characters and the like input from the character input keys 2. , A keyboard 6 provided with various keys such as a return key 5 for instructing execution of various processes and line feed, a liquid crystal display 7 for displaying characters and the like input from the keyboard 6, and a tape to be described later. A cassette storage unit 8 for storing the cassette 13 is provided.

The cassette housing 8 is driven to rotate by a pulse motor (not shown),
A ribbon winding shaft 9 for rotating the ribbon winding spool 21 to wind the thermal ink ribbon 17 is provided upright.
Further, a tape feed roller shaft 10 for rotating a tape feed roller 27 to be described later, which is rotatably driven by a tape feed motor 40 to be described later via an appropriate transmission mechanism, is provided obliquely forward (on the keyboard 6 side). Has been established.

Further, a thermal head 11 for printing on a later-described film tape 15 via a thermal ink ribbon 17 is fixedly provided in front of the cassette housing section 8. Further, in the rear of the cassette housing portion 8, the tape cassette 13 described later is present in the cassette housing part 8, or
In addition , a thermal ink ribbon 17 described later stored in the tape cassette 13 (the thermal ink ribbon 17 is formed of a lettering tape ink, a gold ink, a black ink, and a blue ink in accordance with the type of ink applied to the ribbon film. (There are four types of ink ribbons) is provided.

This detector K has three photocouplers P
1, P2, P3, and the photocoupler P1,
At P2 and P3, a discriminating member (not shown) provided on the back surface of the tape cassette 13 when the tape cassette 13 is mounted in the cassette accommodating section 8 is inserted and the discriminating member selects the photocouplers P1, P2 and P3. The presence of the tape cassette 13 and the type of the ink ribbon stored in the tape cassette 13 are detected by shutting off the tape cassette 13.

In this embodiment, four types of ink ribbons 17 are used as described above as the types of the ink ribbons 17, and the photocouplers P1, P2, and P3 are used.
Is "H" issued based on the selective blocking by the discriminating member
Signal and the "L" signal in combination with the tape cassette 13
This is for detecting the ink ribbon 17 inside. The configuration of the detector K is described in Japanese Patent Application No. Hei 3-217860.
And the configuration described in Japanese Patent Application No. Hei 3-217861, the detailed description of which is omitted here.

Further, the cassette storage section 8 includes a storage cover 1 rotatably supported behind the tape printer 1.
2, the tape cassette 13 is exchanged in the open state.

Next, the configuration of the tape cassette 13 will be described with reference to FIG. FIG. 2 is a plan view showing a state in which the tape cassette 13 is stored in the cassette storage section 8 (the tape cassette 13 is shown without the upper case). The structure of the tape cassette 13 is the same when the ink ribbon 17 is a black ink ribbon or a blue ink ribbon.
Is a lettering tape ink ribbon, the double-sided pressure-sensitive adhesive tape 19 described later is unnecessary as is well-known, so that the double-sided pressure-sensitive adhesive tape 19 and the spool 20 for winding the tape are removed. I have.

Further, when the ink ribbon 17 is a gold ink ribbon, the shape of the guide lever 29 for guiding the ink ribbon 17 to the ribbon take-up spool 21 is different from that of the other ink ribbons 17. Incidentally, FIG. 2 shows a tape cassette 13 containing a black ink ribbon.

In FIG. 2, a tape spool 16 around which a transparent film tape 15 is wound
A ribbon spool 18 around which the thermal ink ribbon 17 is wound, and an adhesive tape spool 20 around which a double-sided adhesive tape 19 with release paper is wound with the release paper side facing out, are provided. 20 is rotatably supported in cooperation with a support portion provided on the lower surface of the upper case (not shown).

A ribbon take-up spool 21 is similarly rotatably supported between the spools 16, 18, and 20, and the ribbon take-up spool 21 is engaged with the ribbon take-up shaft 9 to form a ribbon take-up. By driving the take-up shaft 9, the thermal ink ribbon 17 used for printing is wound up.

Further, the thermal head 11 is disposed in a concave portion 22 provided in the lower case 14, and the thermal head 11 is opposed to a position where a platen roller 24 rotatably supported by a roller holder 23 can be pressed against the thermal head 11. Are located. The thermal head 11 includes a number of heating elements (the thermal head 1 of the tape printer 1 according to the present embodiment).
1 is provided with 128 heating elements), and prints characters and the like on the film tape 15 via the thermal ink ribbon 17.

The tape discharge section 25 of the lower case 14
(The lower left side in FIGS. 1 and 2), the tape pressing roller 26
Is rotatably supported, and a tape feed roller 27 rotatably supported by the roller holder 23 is opposed to the tape press roller 26 at a position where the tape feed roller 27 can be pressed.

In the cassette storage section 8, a roller holder 23 is pivotally supported by a support shaft 28 in front of the tape cassette 13 (lower side in FIGS. 1 and 2), and the roller holder 23 is not shown. The print position and the release position can be switched by a manual switching mechanism (FIGS. 1 and 2 both show a state where the print position is switched to the print position).

In the roller holder 23, the platen roller 24 and the tape feed roller 27 are rotatable, and when the roller holder 23 is switched to the printing position, the thermal head 11 and the pressing roller 2 are moved.
6 are arranged so as to be pressed against. The tape feed roller 27 is driven to rotate by the above-described tape feed roller shaft 10, and at the same time, the press roller 26 is driven to rotate in conjunction with the tape feed roller 27 by a gear mechanism (not shown).

The pressure contact roller 26 and the tape feed roller 27 cooperate with each other to form the adhesive of the double-sided adhesive tape 19 on the film tape 15 on which characters or the like are printed by the thermal head 11 via the thermal ink ribbon 17. The surface is pressure-bonded, and finally the tape T is created and the tape T is sent out in the direction of arrow J.

Next, a control system of the tape printer 1 configured as described above will be described with reference to FIG. FIG. 3 shows a control block diagram of the tape printing apparatus 1, and the control apparatus 3
It is configured with 0 as the core. The control device 30 is a CPU 3
1, a ROM 32, a CGROM 33, and a RAM 34, which are connected to each other via a bus 35 and also to an input / output interface 36.

The ROM 32 stores various programs.
1 and various programs necessary for controlling the tape printing apparatus 1 are stored. The CPU 31 performs various calculations based on various programs stored in the ROM 32. The ROM 32 stores the following arithmetic expressions used for performing such an operation and various data tables (see FIGS. 5, 6, 7, and 8 described later) necessary for performing such an operation. Have been.

[0036]

(Equation 1)

Equation 1 is an arithmetic expression for controlling the drive of the thermal head 11 in accordance with the ambient temperature in the tape printing apparatus 1 detected via the thermistor 41 and the detection circuit 42 described later. , T is an energizing time (energizing pulse width) of an energizing pulse (described later) of MAIN to be applied to each heating element of the thermal head 11, A is a coefficient obtained experimentally (see FIG. 7), and TH is a thermistor 41.
Represents a digital value obtained by A / D-converting the value detected by the detection circuit 42 through the detection circuit 42, and T0 represents a reference conduction pulse width (see FIG. 6). It is to be noted that only the MAIN energizing pulse is made variable in the energizing time (pulse width) of the pulse by using the equation (1).

Here, each data table stored in the ROM 32 will be described. FIG. 5 is a data table showing a print pattern of two dots before the current dot position based on the current print position (dot position). This is used as a reference when variably controlling the width. Here, the mark ○ indicates that print data exists, and the mark × indicates that print data does not exist.

In FIG. 5, the first pattern from the top indicates a pattern in which print data exists at the current dot position and printing is performed at one dot position and two dot positions before the current dot position. In this case, the MAIN energizing pulse (2 m
s is applied to the heating element, and the current dot is printed.

Similarly, the second pattern indicates a pattern in which print data exists at the current dot position, and printing is performed at a position one dot before and printing is not performed at a position two dots before. In this case, an energizing pulse of SUB1 (having a pulse width of 1 ms) is applied to the heating element in addition to the energizing pulse of MAIN, and the current dot is printed.

Further, the third pattern indicates a pattern in which print data exists at the current dot position, and printing is not performed at a position one dot before and printing is performed at a position two dots before. In this case, an energizing pulse of SUB2 (having a pulse width of 0.5 ms) is applied to the heating element in addition to the energizing pulse of MAIN, and the current dot is printed.

The fourth pattern is a pattern in which print data exists at the current dot position, and printing was not performed at positions one dot before and two dots before. In this case, the energizing pulses of MAIN, SUB1, and SUB2 are applied to the heating element, and the current dot is printed. Here, the fourth pattern is selected as a specific pattern required for performing drive control of the thermal head 11 described later.

Next, FIG. 6 will be described. FIG. 6 shows that when the drive control of the thermal head 11 is performed in accordance with the ambient temperature in the tape printing apparatus 1 based on the above equation 1, the numerical data of T0 necessary for calculation is converted into ink. This is shown as a table corresponding to the type of ribbon. FIG. 7 similarly shows the numerical value of A in Equation 1 as a table corresponding to the type of ink ribbon. FIG. 8 shows a table in which the minimum value of the MAIN energizing pulse is associated with the type of the ink ribbon so that the pulse width of the MAIN energizing pulse does not become a fixed value or less during the drive control of the thermal head 11 described later. is there.

Returning to FIG. 3 and continuing the description of the control block diagram, the CGROM 33 stores dot pattern data corresponding to each character such as a character input from the keyboard 6 and stores the dot pattern data. C
The data is read from the GROM 33 and transferred to an image buffer 34F described later.

Further, the RAM 34 is for temporarily storing various calculation results calculated by the CPU 31. The RAM 34 is provided with various memories as shown in FIG.

In FIG. 4, a text memory 34A sequentially stores code data corresponding to a character input from the keyboard 6 as document data, and a main pulse conduction width memory 34B stores the above equation (1).
This stores the pulse width of the MAIN energization pulse calculated by the following. Further, the minimum energization width memory 34C stores the value of the pulse width of the minimum energization pulse read from the table of FIG. 8 stored in the ROM 32 according to the type of the ink ribbon 17 detected by the detector K. Things.

The counter memory 34D stores a predetermined count value (2 for the lettering ink ribbon) corresponding to the type of the ink ribbon 17 detected by the detector K.
A count value of 500 is set, and a count value of 2000 is set for the gold ink ribbon, the black ink ribbon, and the blue ink ribbon. Further, the temperature memory 34
E stores a digital value obtained by A / D-converting the value of the ambient temperature detected by the thermistor 41 by the detection circuit 42.

The image buffer 34F stores dot pattern data read out from the CGROM 33 in correspondence with the character code data stored in the text memory 34A. The dot printing is performed in accordance with the dot data stored in the image buffer 34F. Further, the reference counter 34G is incremented by one each time the above-described specific pattern (see FIG. 5) is counted. As the processing proceeds, the incremented count value and the counter memory 34
It is provided to compare with the count value set in D.

The description of the control block diagram will be continued with reference to FIG.
6, and a liquid crystal display 7 and a display controller 37 are connected to the control device 30 via an input / output interface 36. When a character is input from the keyboard 6, the code data of the character is stored in a text memory. The dot patterns corresponding to the characters input via the keyboard 6 based on the dot pattern generation control program and the display control program are displayed on the liquid crystal display 7 while being sequentially stored in the LCD 34.

The thermal head 11 has a drive circuit 38.
, And prints the dot pattern data transferred to the image buffer 34F. In synchronization with this, the tape feed motor 40 controls the feed of the tape T via the drive circuit 39.

Further, a thermistor 41 and a detection circuit 42 are connected to the control device 30 via the interface 36, and an analog value of the ambient temperature inside the tape printer 1 detected by the thermistor 41 is detected by the detection circuit 42. After being subjected to / D conversion, it is input to the CPU 31. CPU3
1 stores such A / D converted value of the temperature memory 34E, and performs drive control of the thermal head 11 based on the A / D conversion value.

Next, the operation of the tape printer 1 configured as described above will be described with reference to FIG. FIG.
Is a flowchart of a drive control program for the thermal head 11, and the control starts when the print key 3 is pressed. First, in step (hereinafter abbreviated as S) 1, various memories and the like of the RAM 34 are initialized, and at the same time, the reference counter 34 G is set to 0.

In S2, it is determined via the detector K which type of the ink ribbon 17 is contained in the tape cassette 13 stored in the cassette storage section 8. If it is determined that the ribbon is a lettering ink ribbon, the process proceeds to S3. If it is determined that the ribbon is a golden ink ribbon, the process proceeds to S4. If it is determined that the ink ribbon is the black ink ribbon, the process proceeds to S5, and if it is determined that the ink ribbon is the blue ink ribbon, the process proceeds to S6.
Move to

At S3, the value T0 corresponding to the ink ribbon for lettering is read from the table of FIG. 6, and similarly, the value of the coefficient A of the ink ribbon for lettering is read from the table of FIG. Then, using these values, the pulse width T of the energizing pulse of MAIN is calculated based on the above equation (1). The calculated value T is stored in the main pulse width memory 34B. Also, the minimum value Tmin of the MAIN energizing pulse corresponding to the lettering ink ribbon is read from the table of FIG. 8 and stored in the minimum energizing width memory 34C. Further, a value of 2500 which is a count value corresponding to the ink ribbon for lettering is set in the counter memory 34D.

In step S4, the T0 value is read from the table of FIG. 6 and the value of the coefficient A is read from the table of FIG. According to 1, the pulse width T of the MAIN energizing pulse is calculated. The calculated value T is stored in the main pulse width memory 34B. Further, the MAIN corresponding to the golden ink ribbon is obtained from the table of FIG.
The minimum value Tmin of the pulse is read out and stored in the minimum conduction width memory 34C. Further, a value of 2000 which is a count value corresponding to the gold ink ribbon is set in the counter memory 34D.

Similarly, in S5, the value of T0 is read from the table of FIG. 6 and the value of the coefficient A from the table of FIG. 7 corresponding to the black ink ribbon. The pulse width T is calculated. The calculated value T is stored in the main pulse width memory 34B. Also, the minimum value Tmin of the MAIN pulse corresponding to the black ink ribbon is read from the table of FIG. 8 and stored in the minimum power supply width memory 34C. Further, a value of 2000 which is a count value corresponding to the black ink ribbon is set in the counter memory 34D.

Similarly, in S6, the value of T0 is read from the table of FIG. 6 and the value of the coefficient A from the table of FIG. 7 corresponding to the blue ink ribbon. The pulse width T is calculated. The calculated value T is stored in the main pulse width memory 34B. Further, the minimum value Tmin of the MAIN pulse corresponding to the blue ink ribbon is read from the table of FIG. 8 and stored in the minimum power supply width memory 34C. Further, a value of 2000 which is a count value corresponding to the blue ink ribbon is set in the counter memory 34D.

The processes in S3, S4, S5, and S6 are performed alternately. Therefore, the main pulse width memory 34B, the minimum width memory 34C,
The counter memory 34D does not need to be provided corresponding to each ink ribbon, and one memory may be provided for each.

After the necessary processing is performed in accordance with the type of the ink ribbon as described above, the digital value obtained by A / D converting the detection value from the thermistor 41 by the detection circuit 42 in S7 is stored in the temperature memory 34E. Is stored. In S8, it is determined whether or not the current dot corresponds to a specific pattern (the fourth pattern in FIG. 5) among the patterns shown in FIG. If it is not a specific pattern (S8: NO), the process proceeds to S15. If it is determined that the pattern is a specific pattern (S8: YES), the process proceeds to S15.
At 9, the count value of the reference counter 34G is incremented by one.

In S10, S3, S4, S5 or S3
At 6, it is determined whether the count value set in the counter memory 34D is equal to the count value of the reference counter 34G. If they are not the same (S10: NO), S
The flow proceeds to step S15, and if they are the same (S10: YES), the value of 16 × 175 / TH is calculated from the pulse width T of the MAIN energization pulse stored in the main pulse energization width memory 34B by calculating in S3 and the like. The subtracted value is stored again in the memory 34B as the pulse width of the energizing pulse T of MAIN (S11). When the count value of the reference counter 34G exceeds the count value of the counter memory 34D by such processing, the pulse width T of the energizing pulse of MAIN is reduced by a value of 16 × 175 / TH. Here, the values of 16 and 175 are values experimentally obtained.

At S12, the reference counter 3
4G is reset to 0 to prepare for the subsequent processing. In S13, it is determined whether the pulse width T of the MAIN energizing pulse is smaller than the value obtained by adding (TH-105) × 9 to the value Tmin stored in the minimum energizing width memory 34C. If it is larger (S13: NO), S
The process proceeds to S15, and if smaller (S13: YES), S1
At 4, the value obtained by adding the value of (TH−105) × 9 to the minimum value Tmin is stored in the main pulse conduction width memory 34B again as the pulse width T of the conduction pulse of MAIN.
Here, the calculated minimum value Tmin is given by (TH−105) ×
The value obtained by adding the value of 9 (the value on the right side in the equation of S13) is a constant. The values of 105 and 9 are values experimentally obtained.

Thereafter, in S15, an energizing pulse of MAIN having a pulse width T is applied to the heating element corresponding to the current dot position of the thermal head 11, and dot printing is performed on the printing medium. Here, the pulse width T is made variable according to the count value of the specific pattern, the type of the ink ribbon 17 and the ambient temperature inside the tape printing apparatus 1.
Printing is performed using a MAIN energizing pulse having a pulse width T stored in 4B.

At this time, as described with reference to FIG. 5, it is determined which pattern in FIG. 5 corresponds to the current dot position as a reference, and S is determined based on the determination result.
The energization pulses of UB1 and SUB2 are selectively applied to the heating elements.

For example, when the pattern corresponds to a specific pattern, in addition to the MAIN energizing pulse at that time, SU
The B1 and SUB2 energizing pulses are applied, and in cases other than the specific pattern, only the MAIN energizing pulse (first pattern in FIG. 5), the MAIN energizing pulse and the SUB1 energizing pulse (second pattern in FIG. 5) , The MAIN energizing pulse and the SUB2 energizing pulse (third pattern in FIG. 5) are applied in accordance with the determined pattern, and printing is performed.

In S16, it is determined whether or not printing of all the print data has been completed. If not completed (S16: NO), S8 is performed to perform the processing again.
Returning to step (S16: YES), a series of drive control processing ends. Here, one specific example will be described for easier understanding. Here, it is assumed that the tape cassette 13 containing a lettering ink ribbon as the ink ribbon 17 is housed in the cassette housing unit 8.

When the print key 3 is depressed, initialization is performed in S1, and then the detector K detects in S2 that the tape cassette 13 has a built-in lettering ink ribbon, and the flow advances to S3. In S3, as described above, the pulse width T of the MAIN energizing pulse is calculated based on Equation 1 and stored in the main pulse energizing width memory 34B, and the minimum value Tmin of the MAIN energizing pulse is read out to obtain the minimum energizing pulse. It is stored in the width memory 34C. Further, a count value of 2500 is set in the counter memory 34D.

Thereafter, in S7, the temperature memory 34E
A detected through the thermistor 41 and the detection circuit 42
The / D conversion value is stored. If the dot at the current dot printing position does not correspond to the specific pattern (S8: N
O) includes the main pulse width memory 34 as described above.
An energizing pulse obtained by combining the MAIN energizing pulse having the pulse width T stored in B with SUB1 and SUB2 is applied to the heating element to perform dot printing (S1).
5).

On the other hand, if the current dot corresponds to the specific pattern (S8: YES), after the value of the reference counter 34G is incremented by 1 (S9), the count value of the counter memory 34D and the value of the reference counter 34G Is determined to be the same (S10), but normally the determination is NO.
Therefore, the main pulse conduction width memory 34B
Are applied to the heating elements, and dot printing is performed (S15).

This dot printing is repeated until it is determined in S10 that the count value of the counter memory 34D is equal to the value of the reference counter 34G, that is, until the reference counter 34G counts 2500 count values (S10). S8, S9, S10, S15). Thus, the pulse width T of the MAIN energizing pulse is not changed until printing is performed 2500 times.

When the count value of the reference counter 34G is 250
If it exceeds 0 (S10: YES), MAIN will be performed in S11.
The pulse T of the energizing pulse is slightly reduced, and the reference counter 3
4G is reset to zero. Unless the determination in S13 becomes YES, the MA whose pulse width T is reduced
The current dot is printed with the IN energizing pulse (S15).

Thus, the reference counter 34G sets 2
After the value of 500 is counted, S1 is continued until the value of 2500 is counted again by the reference counter 34G.
1, the MAIN energizing pulse whose pulse width T is slightly reduced is applied to the heating element (S8, S9, S9).
10, S15).

The dot printing as described above is performed every time the value of 2500 is counted by the reference counter 34G, S1.
The repetition is performed by applying the MAIN energizing pulse whose pulse width T is slightly reduced at 1 to the heating element.

Thereafter, as dot printing progresses, M
When the pulse width T of the AIN energizing pulse is gradually reduced, and YES is determined in S13,
A MAIN energizing pulse (a MAIN energizing pulse having a lower limit pulse width T) having a pulse width T (the pulse width is a constant as described above) calculated in step 3 is applied to the heating element, and the current dot is discharged. Printing is performed (S14, S
15).

The dot printing by the MAIN energizing pulse having the pulse width T calculated in S13 is repeated until the reference counter 34G counts 2500 (S8, S9, S10, S15). When the count value of the counter 34G becomes equal to the value of 2500 (the value of the counter memory 34D) (S10: YE
Also in S), since the pulse width T calculated in S13 is a constant as described above, it does not participate in the calculation in S11 at all, and the determination in S13 becomes YES. Is performed by a MAIN energizing pulse having a pulse width T consisting of the constant calculated in the above. Thus, after the processing in S13, the MAI of the pulse width T consisting of a constant
Dot printing is performed with N energizing pulses.

As described in detail above, in the tape printing apparatus 1 according to the present embodiment, a specific pattern is detected based on the dot printing state two dots before the current dot position by the thermal head 11, and the specific pattern is detected. The number of appearances is counted via the reference counter 34G,
When the predetermined number of appearances is counted, the pulse width T of the MAIN energizing pulse to the heating element is decreased by a fixed width every time the specific pattern is counted a predetermined number of times. Can be controlled very efficiently and appropriately, thereby preventing the thermal head 11 from being overheated and extending the life of the thermal head 11.

When the pulse width T of the MAIN energizing pulse, which is reduced by a certain width every time the specific pattern is counted a predetermined number of times, becomes a certain value, the pulse width T becomes equal to or less than a certain value. Since the control is made so as not to cause the dot, even when a long-time dot printing is performed by the thermal head 11, the printed dot is not blurred, thereby preventing the printing density from becoming uneven. Can be.

Further, in the tape printer 1 according to the present embodiment, the type of the ink ribbon 17 contained in the tape cassette 13 is detected via the detector K, and the MAIN is determined in accordance with the detected type of the ink ribbon 17. Since the pulse width T of the energizing pulse is variably controlled, the MA having an appropriate pulse width T corresponds to the type of the ink ribbon 17, that is, the melting temperature of each ink applied on the ribbon film.
The dot printing can be performed by the IN energizing pulse, and it is possible to prevent the print density from being uneven even when any of the ink ribbons 17 is used.

In the tape printer 1 according to the present embodiment, the printer 1 is connected via the thermistor 41 and the detection circuit 42.
Since the internal ambient temperature is detected and the pulse width T of the MAIN energizing pulse is variably controlled according to the detected ambient temperature, the heat generated in the thermal head 11 depends on the ambient temperature inside the printing apparatus 1. This prevents the thermal head 11 from being properly controlled.

It should be noted that the present invention is not limited to the above-described embodiment, and various modifications and improvements can be made without departing from the scope of the present invention. For example, in the above embodiment, the fourth pattern in FIG. 5 was selected as the specific pattern, but the specific pattern is not limited to this, and the first to third patterns may be selected as necessary. Is also good. It goes without saying that a pattern other than the patterns in FIG. 5 can be selected as the specific pattern.

[0080]

As described above, the present invention detects a specific dot print pattern consisting of a combination of presence or absence of print data based on the dot print state before the current print position by the dot print head, and detects the specific dot print pattern. The number of appearances of the print pattern is counted, and when the predetermined number of appearances is counted, the pulse width of the energizing pulse to the heating element is sequentially reduced by a certain width every time the specific dot print pattern is counted. In addition, by controlling the pulse width of the energizing pulse so that it does not become less than the predetermined pulse width, heat generated in the dot print head can be controlled extremely efficiently and appropriately, and dot printing can be performed without causing unevenness in print density. A dot printing device capable of extending the life of the head can be provided.

Further, the present invention can provide a dot printing apparatus capable of controlling the pulse width of an energizing pulse to a heating element according to the type of an ink ribbon to be used and the ambient temperature inside the apparatus.

[Brief description of the drawings]

FIG. 1 is a plan view of a tape printer in which a storage cover of a tape cassette storage unit is opened.

FIG. 2 is a plan view illustrating a state where a tape cassette is stored in a cassette storage unit.

FIG. 3 is a control block diagram of the tape printer.

FIG. 4 is an explanatory diagram schematically showing various memories provided in a RAM.

FIG. 5 is a data table showing a print pattern of two dots before a current dot position with reference to the current dot position.

FIG. 6 is a data table showing the numerical data of T0 in Equation 1 as a table corresponding to the type of ink ribbon.

FIG. 7 is a data table showing a numerical value of A in Expression 1 as a table corresponding to the type of ink ribbon.

FIG. 8 is a data table showing the minimum value of the MAIN energizing pulse in association with the type of ink ribbon in a table.

FIG. 9 is a flowchart of a drive control program for the thermal head.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 tape printer 2 character input key 3 print key 6 keyboard 11 thermal head 30 controller 31 CPU 32 ROM 33 CGROM 34 RAM 34B main pulse power width memory 34C minimum power width memory 34D counter memory 34E temperature memory 34G reference counter 41 thermistor 42 Detection circuit

Claims (4)

(57) [Claims] 1. A dot print head having a plurality of heating elements, and selectively applying an energizing pulse to each heating element to print a character or the like on a print-receiving medium via an ink ribbon; Based on the current printing position by the dot print head,
Printing by referring to the dot printing state before the current print position
A print pattern detecting means for detecting a specific dot print pattern comprising a combination of the presence or absence of data; and counting the number of appearances of the specific dot print pattern detected by the print pattern detecting means in accordance with the progress of printing by the dot print head. Counting means, and when the predetermined number of appearances is counted by the counting means, the pulse width of the energizing pulse is sequentially increased by a constant width every time the specific dot print pattern is counted a predetermined number of times through the counting means. A dot printing device comprising: a first control unit for reducing the number of dots. 2. A pulse width detecting means for detecting a pulse width of the energizing pulse; 2. The dot printing apparatus according to claim 1, further comprising pulse width control means for controlling a pulse width of the pulse so as not to be smaller than the predetermined pulse width. 3. The apparatus according to claim 2, further comprising: a ribbon detecting unit configured to detect a type of the ink ribbon, and a second control unit configured to control a pulse width of the energizing pulse according to the type of the ink ribbon detected by the ribbon detecting unit. The dot printing device according to claim 1, wherein 4. A method according to claim 1, further comprising: temperature detecting means disposed near said dot print head; and third control means for controlling a pulse width of said energizing pulse based on a result detected by said temperature detecting means. The dot printing device according to claim 1, wherein