JPH09267504A - Line thermal head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize the high accuracy of thermal history control and acceleration of printing speed of a thermal printing mechanism with low cost by turning ON and OFF of application of a driving voltage to a plurality of heating resistors by a driving circuit at a heating group unit. SOLUTION: Heating resistors are divided at a unit of two dots, an heating groups A1 to A8 are constituted corresponding to one side 16 dots. Transistors Q1 to Q8 for constituting switching means for turning ON, OFF the application of a driving voltage VDD are provided corresponding to the groups. On the other hand, the heating resistors of a line thermal head TH 1 are set in size of the direction perpendicular to the arraying direction by two dots, and twice of the prior art. Printing of twice is conducted per one line. Thus, since the data processing sped of a print controller can be decelerated at the same temperature history control and printing speed as those of prior art, the necessity of high speed processing hardware and software is eliminated to make it possible to reduce the cost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line thermal head having heating resistors arranged in a line.

[0002]

2. Description of the Related Art FIG. 9 is a block diagram showing a structural example of a thermal printing mechanism for printing on a thermal medium by using a line thermal head TH having heating resistors arranged in a line. First, the configuration of the line thermal head TH will be described. The n-dot line thermal head TH includes an n-bit shift register SR for converting serial data D, which is print data input in synchronization with the clock signal CLK, into parallel data, and the shift register SR.
Latch LT for holding the parallel data input from the latch LT in accordance with the latch signal L, and an n-bit AND gate G for selecting the fetch of the parallel data input from the latch LT by the strobe signal STB.
1 to Gn (collectively referred to as G), Q1 to Qn (collectively referred to as Q) of n bits of transistors which are turned on / off in accordance with data input from the AND gate, and one end thereof has a power supply voltage. A heating resistor r1 commonly connected to VDD and the other end of which is connected to the ground via the transistor Q.
.About.rn (collectively referred to as r). The shift register SR, the latch LT, the gate G, and the transistor Q constitute a drive circuit that turns on / off the application of the drive voltage VDD to the heating resistor r. Therefore, AN
Only when both the output of the latch LT input to the D gate G and the strobe signal STB are valid (“1”), the transistor Q corresponding to the AND gate G is turned on, and the voltage VDD is applied to the heating resistor r. Is applied to drive the drive current.

The print control unit 2, which receives print data from the CPU 1 via the bus B, generates serial data D based on the print data, and supplies this serial data D together with the clock signal CLK to the shift register SR. , The latch signal L and the strobe signal STB are appropriately generated and given to the latch LT and the gate G.

The print control unit 2 includes a line thermal head T
Predetermined processing, that is, temperature history control is performed on the serial data D and the strobe signal STB so that the print quality obtained by H becomes optimum. In this temperature history control, the print controller 2 controls the line thermal head TH
The ratio of the effective period and the ineffective period of the strobe signal STB is changed based on the detection signal S input from the temperature sensor T incorporated in the heat generating resistor corresponding to each dot of the line thermal head TH. Serial data D according to the drive status of the
Is changed and applied to the line thermal head TH.

[0005]

In order to perform such temperature history control, the print control unit 2 generates serial data D a plurality of times each time the line thermal head TH prints one line. Line thermal head TH
Have transferred to. That is, the higher the accuracy of the temperature history control, the more the number of times of serial data transfer required for printing one line increases. Therefore, in order to perform high-speed printing while performing such highly accurate temperature history control, the transfer rate of serial data from the print controller 2 to the line thermal head TH must be high. Here, the data transfer rate Vd is expressed by the following equation (1). Vd = Nd.Cd / tp (1) where Nd: number of dots of the line thermal head Cd: number of data transfers per line tp: printing time per line For example, Nd = 512 dots, Cd = 9 times, tp = 2m
If s, Vd is 2.304 Mb according to the equation (1).
It / s. In order to realize a high data transfer speed of Mbit / s level, the data processing speed of the print control unit 2 may be increased. To this end, the functions originally realized by software are processed at high speed. It has to be composed of possible hardware circuits and special software must be developed for high-speed processing, resulting in high cost.

By the way, when a character or symbol is printed by using such a line thermal head, a character and a symbol are printed in the same size as the number of dots of the font, and as described below, the character is printed. In some cases, the characters are enlarged and printed to a size that is an integral multiple of the number of dots in the font.
FIG. 10 shows a dot printing state when an 8-dot font, that is, a character represented by 8 dots on each side, for example, "A" is printed with a size of 16 dots on each side. x1
The symbols x1 to x16 indicate dot positions corresponding to the arrangement direction (line direction) of the heating resistors of the line thermal head, and y1 to y16 correspond to the direction perpendicular to the arrangement direction, that is, the print medium conveyance direction. The dot position is shown. The hatched rectangular area corresponds to the dots printed by applying the drive voltage to the heating resistor.
On the other hand, the blank rectangular area corresponds to the dot on which the heating voltage is not applied and the printing is not performed. As shown in FIG. 10, when a character in an 8-dot font is doubled and printed at a size of 16 dots on a side, it is not necessary to handle the print data in units of 1 dot, and 2 dots in the vertical and horizontal directions. It is possible to handle print data in units of.

As shown in FIG. 11 (a), 4-bit data (0H) as shown in FIG. 11 (b) is obtained by the combination of the arrangement of the two rectangular carla bits a1 to a4.
There is a Carla code K indicating ~ FH). 12 is shown in FIG.
Similar to 0, the dot printing state is shown when such a Carla code K is printed with a size of 16 dots on a side. As shown in FIG. 12, the carla code K is represented by two carla bits in each of the vertical and horizontal directions.
That is, theoretically, the Carla code K is represented by two dots in the vertical and horizontal directions (actually, since the minimum vertical and horizontal dimensions of the Carla code are determined according to the reading ability of the Carla code reader, the minimum size is equal to or larger than the minimum dimension. It is necessary to print the Carla code with the number of dots in the vertical and horizontal directions so that the size will be).
Therefore, the Carla code indicated by 2 dots vertically and 8 dots
It is not necessary to handle print data in units of 1 dot in order to double the size and print with a size of 16 dots on a side.
It is possible to handle in units of vertical and horizontal 8 dots. That is, only when characters or symbols having a predetermined number of dots on one side are enlarged N times for printing by the line thermal head, if the print data is handled and printed in units of N dots, the print data can be obtained in units of 1 dot. It is possible to reduce the total amount of print data to be processed in the heat history control and the like, and to reduce the cost for high-speed processing of print data, as compared with the case of handling.

The present invention has been made under such circumstances, and an object thereof is to make at least one of a character, a symbol and a code whose one side is represented by a predetermined number of dots N times the predetermined number of dots (N). It is an object of the present invention to provide a line thermal head capable of realizing high accuracy of heat history control of a thermal printing mechanism for printing with a print size of (integer) and high speed of printing at low cost.

[0010]

According to the present invention, a plurality of heating resistors arranged in a line corresponding to dots and ON / OFF of driving voltage application to each heating resistor are determined based on print data. A line thermal head for driving at least one of a character, a symbol and a code whose one side is represented by a predetermined number of dots in a print size N times the predetermined number of dots (N is an integer). The heat generating group is configured by dividing the plurality of heat generating resistors in units of N, and the drive circuit turns on / off the application of a drive voltage to the plurality of heat generating resistors. It is characterized in that it is performed in units of groups. According to the above configuration, since the heat generating group is configured by dividing the plurality of heat generating resistors in units of N, print data is supplied to the drive circuit in units of heat generating groups to turn on the application of the drive voltage to the heat generating resistors. Since it can be turned off, the number of print data required for printing per line can be reduced.

The present invention is characterized in that the heating resistors are provided so that the dimension in the direction perpendicular to the arrangement direction corresponds to N dots. According to the above configuration, the printing operation for one line can print N dots in the direction perpendicular to the arrangement direction of the heating resistors of the line thermal head, so that the number of print data to be given to the thermal head can be further increased. Can be reduced.

The present invention has a plurality of heating resistors arranged in a line corresponding to dots, and a drive circuit for turning on / off the application of a driving voltage to each heating resistor based on print data. A line thermal head for printing at least one of a character, a symbol and a code each side of which has a predetermined number of dots in a print size N times (N is an integer) the predetermined number of dots, wherein the heating resistor is The size of at least one of the arrangement direction and the direction perpendicular to the arrangement direction corresponds to N dots. According to the above configuration, if the dimension of the heating resistors in the array direction is set to correspond to N dots, print data may be given to the drive circuit in units of N dots, so printing per line It is possible to reduce the number of print data required to perform the above, and if the dimension in the direction perpendicular to the arrangement direction of the heating resistors is provided so as to correspond to N dots, N dots per line Since it is possible to print minutes, it is possible to reduce the number of print data given to the thermal head.

In the present specification, the characters, symbols, and codes whose one side is indicated by a predetermined number of dots are those which can be indicated by the predetermined dots in the vertical and horizontal directions, respectively. For example, an A dot font (A is an integer) character or symbol corresponds to a character or symbol whose one side is indicated by an A dot. Further, a carla code represented by two vertical and horizontal carla bits corresponds to a code represented by vertical and horizontal two dots. However, in practice, the minimum vertical and horizontal dimensions of the carla code are determined according to the reading ability of the carla code reader, so the carla code is printed with the number of dots in the vertical and horizontal directions that is larger than the minimum dimension. There is.

[0014]

Next, the present invention will be described with reference to the drawings. FIG. 1 is an explanatory view showing an embodiment of a line thermal head of the present invention, showing a relationship between a heating resistor and dots to be printed. FIG. 2 is an explanatory diagram showing the dimensions of the heating resistors that form the line thermal head. In FIG. 1, the same or corresponding parts as those in FIG. 10 showing the conventional example are designated by the same reference numerals, and the description thereof will be omitted.

FIG. 1 shows heating resistors r1 to r16 corresponding to 16 dots in the line thermal head TH1. The line thermal head TH1 is, for example, AN
It is assumed that an 8-dot font character (including a symbol) such as a K character is fixedly set as an area for printing in a size of 16 dots on a side.

In order to print a character of an 8-dot font with double the size of 16 dots on one side, each heating resistor of the line thermal head TH1 may be driven in units of 2 dots. For this reason, each heating resistor is divided into units of 2 dots, and each of the heating groups A1 to A8 corresponds to 16 dots on one side.
Is configured. The drive voltage VD corresponding to each heat generation group
Transistors Q1 to Q8 that form switching means for turning on / off the application of D are provided. On the other hand, FIG.
As shown in (a), the heating resistor of the line thermal head TH has a dimension Ly in a direction perpendicular to the arrangement direction of 2 dots, and the conventional thermal head TH shown in FIG. Is twice the size Ly (for one dot). It should be noted that Lx represents the dimension (one dot) in the arrangement direction of the heating resistors. Therefore, in the direction perpendicular to the arrangement direction of the heating resistors of the line thermal head TH1, two dots are printed by the printing operation for one line. In addition, in FIG. 2 and FIGS. 7 and 8 described later, the hatched portion indicates an electrode portion connected to the heating resistor.

FIG. 3 is a block diagram of a heat-sensitive printing mechanism equipped with the line thermal head TH1 shown in FIGS. 1 and 2, and the same or corresponding parts as in FIG. However, the description is omitted. The line thermal head TH1 has 8 dot font characters on each side.
The heat generating groups A1 to Am (m is an integral multiple of 8) are formed in the number necessary for printing with a size of 6 dots. The data transfer rate Vd for the line thermal head when printing is performed using such a line thermal head TH1 is shown in the following equation (2). Vd = {(Nd / g) · Cd} / tp (2) where Nd: the number of dots of the line thermal head g: the number of heating resistors forming one heating group Cd: the number of data transfers per line tp Printing time per line: Here, as the same condition as in the case of the conventional technique, Nd = 51
If 2 dots, g = 2, Cd = 9 times, and tp = 4 ms, then Vd = 0.576 Mbit / s according to equation (2). In addition, the printing time tp per line is 2 m of the conventional
As shown in FIG. 2, since the heating resistor r is formed with a dimension Ly of 2 dots in the direction perpendicular to the arrangement direction, it becomes 4 ms, which is twice the value of s, as compared with the conventional one per line. This is because double printing (for two dots) is performed. That is, in this embodiment, it is understood that the data transfer rate is reduced to 1/4 as compared with the conventional data transfer rate Vd = 2.304 Mbit / s. Therefore, since the data processing speed of the print control unit 2 can be reduced with the temperature history control and the printing speed having the same accuracy as the conventional one, the function originally realized by software can be configured by a hardware circuit capable of high-speed processing, Since there is no need to develop special software to support high-speed processing, costs can be reduced compared to the past.

FIG. 4 is an explanatory view showing another embodiment of the line thermal head of the present invention, showing the relationship between the heating resistors and the dots to be printed. In FIG. 4, the same or corresponding parts as those in FIG. 12 showing the conventional example are designated by the same reference numerals, and the description thereof will be omitted. FIG. 4 shows heating resistors r1 to r16 corresponding to 16 dots in the line thermal head TH2. The line thermal head TH2 is fixedly set as an area for printing a Carla code with a size of 16 dots on a side.

In order to enlarge the Carla code K represented by 2 dots on one side to 8 times and print on 16 dots on one side, each heating resistor of the line thermal head TH2 may be driven in units of 8 dots. Therefore, each heating resistor is divided into units of 8 dots to form the heating groups B1 and B2. Further, switching means Q1, Q2 for turning on / off the application of the drive voltage VDD is provided corresponding to each heat generation group. On the other hand, referring to FIG. 2A, the heating resistor of the line thermal head TH2 has a dimension Ly in the direction perpendicular to the arrangement direction of 8 dots. Therefore, in the direction perpendicular to the arrangement direction of the heating resistors of the line thermal head TH2, 8 dots are printed by the printing operation for 1 line.

FIG. 5 is a block diagram showing the line thermal head TH2 shown in FIG. 4. The same or corresponding parts as those in FIG. 9 showing the conventional example are designated by the same reference numerals, and the description thereof is omitted. The line thermal head TH2 includes a number of heat generation groups B1 to Bn (n is an integer multiple of 2) required to print a Carla code in a size of 16 dots on a side. The data transfer rate for the line thermal head when printing is performed using such a line thermal head TH2 is calculated by using the above-described equation (2). However, for each condition, Nd = 512 dots, g = 8
If Cd = 9 times and tp = 16 ms, Vd = 0.036 Mbit / s according to the equation (2). The printing time tp per line is 16m, which is 8 times the conventional 2ms.
The reason for s is that the heating resistors are formed in a size of 8 dots in the direction perpendicular to the arrangement direction, and therefore, printing per line is 8 times (8 dots) as compared with the conventional case. That is, the conventional data transfer rate Vd = 2.304.
It can be seen that it is reduced to 1/64 as compared with Mbit / s. Therefore, since the data processing speed of the print control unit 2 can be reduced while maintaining the temperature history control and the printing speed with the same accuracy as the conventional one, the function realized by software can be configured by a hardware circuit capable of high-speed processing. Since it is not necessary to develop a special software for high speed processing, the cost can be reduced compared to the conventional method.

In the above-described embodiment, each of the heat generating groups A1, A2, ..., Am (FIG. 3) and the heat generating groups B1, B2 ,. Although driven by the means Q1, Q2, ..., If the drive current given to the heat generating group exceeds the current capacity of the switching means, as shown in FIG.
Each of the heating resistors r1 to r8 constituting the above may be provided with switching means Q1 to Q8, and the switching means may be on / off controlled by one gate G.

While the heating resistors of the line thermal head are divided to form a heating group as described above, the dimension Ly (FIG. 2) in the direction perpendicular to the arrangement direction of the heating resistors of the line thermal head is conventionally set. It may be set so as to correspond to one dot as in the above. In this case, since the printing operation for one line can print only one dot in the direction perpendicular to the arrangement direction of the heating resistors of the line thermal head, it is not possible to increase the printing time tp per line. Although not possible, the data transfer rate Vd given to the line thermal head can be lowered by reducing the number of print data per line. The number of print data per line corresponds to the product of the number Nd of dots of the line thermal head in the equation (2) and the reciprocal 1 / g of the number of heating resistors forming one heating group. There is. On the contrary, the heating resistors of the line thermal head do not form a heating group, and as shown in FIG. 7, the dimension Lx in the arrangement direction of the heating resistors of the line thermal head TH3 is set to a plurality of dots (for example, 2 dots). ) May be set. In this case, the data transfer rate Vp applied to the line thermal head TH3 can be reduced by reducing the print data per line.

Further, the heating resistors of the line thermal head do not form a heating group, and as shown in FIG. 8, the dimension Lx of the heating resistors of the line thermal head TH4 in the arrangement direction and the direction perpendicular to the arrangement direction are set. Both of the dimensions Ly may be set so as to correspond to a plurality of dots (for example, 2 dots). In this case, since it is possible to perform printing for two dots in the arrangement direction (line direction) of the heating resistors of the line thermal head TH4 and in the direction perpendicular to the arrangement direction, the thermal head T for one line printing operation.
The number of print data to be given to H4 can be reduced, and one line printing operation can be performed in a direction perpendicular to the arrangement direction of the heating resistors of the line thermal head TH4.
Since dots can be printed, the printing data per line can be reduced and the printing time tp per line can be doubled. Therefore, the data transfer speed given to the line thermal head TH4 should be slowed down. You can

In the above-described embodiment, the case where the characters of the 8 dot font or the Carla code is enlarged and printed to the size of 16 dots on each side in the entire area of the line thermal head has been described. Characters, symbols and codes of different sizes may be printed in each area. For example,
The line thermal head may be divided into an 8-dot font area and a Carla code area, and the number of heating resistors forming a heating group may be different in each area.

Further, in the above-mentioned embodiment, the case where the characters and the Carla code of the 8-dot font are enlarged and printed to the size of 16 dots per side has been described. However, the number of dots of the font to be printed by the line thermal head, The type of code and the size when printing (number of dots on one side) are
Of course, it can be set arbitrarily.

[0026]

As described in detail above, according to the line thermal head of the present invention, at least one of a character, a symbol and a code whose one side is represented by a predetermined number of dots is N times the predetermined number of dots (N is an integer). When printing with the print size of), the heat generating group is configured by dividing a plurality of heat generating resistors in units of N units. Therefore, the print data is given to the drive circuit in units of the heat generating groups to determine the drive voltage of the heat generating resistors. Since it suffices to turn the application on and off, it is possible to reduce the number of print data required for printing per line. Therefore, since the data processing speed of the print data given to the line thermal head can be slowed down, unlike the conventional method, the function originally realized by software can be configured by a hardware circuit capable of high-speed processing or high-speed processing can be performed. Since there is no need to develop special software correspondingly,
Higher accuracy of thermal history control of the thermal printing mechanism and higher printing speed can be realized at lower cost than before.

In the above structure, the heating resistor is
Since the dimension in the direction perpendicular to the arrangement direction corresponds to N dots, the printing operation for one line prints N dots in the direction perpendicular to the arrangement direction of the heating resistors of the line thermal head. Therefore, the number of print data to be given to the thermal head can be further reduced. Therefore, the data processing speed of the print data given to the line thermal head can be made slower, so that the thermal history control of the thermal printing mechanism can be made more accurate and the printing speed can be made faster at a lower cost. .

Further, according to the line thermal head of the present invention, if the dimension of the heating resistors in the arrangement direction is provided so as to correspond to N dots, print data is given to the drive circuit in units of N dots. Therefore, the number of print data required for printing per line can be reduced, and the dimension in the direction perpendicular to the array direction of the heating resistors is
If it is provided so as to correspond to N dots, it is possible to print N dots per line, so that the number of print data to be given to the thermal head can be reduced. Therefore, since the data processing speed of the print data given to the line thermal head can be slowed down, unlike the conventional method, the function originally realized by software can be configured by a hardware circuit capable of high-speed processing or high-speed processing can be performed. Since there is no need to develop special software correspondingly, it is possible to realize higher accuracy of heat history control of the thermal printing mechanism and higher printing speed at a lower cost than before.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of a line thermal head of the present invention.

FIG. 2 is an explanatory diagram showing the dimensions of a heating resistor that constitutes the line thermal head of the present invention.

FIG. 3 is a block diagram of a thermal printing mechanism including the line thermal head of the present invention.

FIG. 4 is an explanatory diagram showing another embodiment of the line thermal head of the present invention.

5 is a block diagram showing a configuration of the line thermal head of FIG.

FIG. 6 is a circuit diagram showing a heat generation group in another embodiment of the line thermal head of the present invention.

FIG. 7 is an explanatory diagram showing dimensions of a heating resistor showing another embodiment of the line thermal head of the present invention.

FIG. 8 is an explanatory diagram showing dimensions of a heating resistor showing another embodiment of the line thermal head of the present invention.

FIG. 9 is a block diagram of a heat-sensitive printing mechanism showing a conventional example.

FIG. 10 is an explanatory diagram of a print state of characters in an 8-dot font.

FIG. 11 is an explanatory diagram of a Carla code.

FIG. 12 is an explanatory diagram of a printed state of a Carla code.

[Explanation of symbols]

TH1, TH2, TH3, TH4 Line thermal heads r1 to r16 (r) Heat generating resistors A1 to Am Heat generating groups B1 to Bm Heat generating groups C Heat generating groups Lx Dimensions of heat generating resistors in the arrangement direction Ly Heat generation in a direction perpendicular to the arrangement direction Resistor dimensions

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[Procedure amendment]

[Submission date] April 1, 1996

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] All figures

[Correction method] Change

[Correction contents]

[Fig. 1]

FIG. 2

[Fig. 7]

[Fig. 8]

[Fig. 3]

[Fig. 4]

[Figure 5]

[Fig. 10]

[Figure 6]

[Fig. 9]

[Fig. 11]

[Fig. 12]

Claims (3)

[Claims] 1. A plurality of heating resistors arranged in a line corresponding to dots, and a drive circuit for turning on / off application of a driving voltage to each heating resistor based on print data. At least one of a character, a symbol and a code whose one side is represented by a predetermined number of dots is N times the predetermined number of dots (N
Is a line thermal head for printing with a print size of, and a heating group is configured by dividing the plurality of heating resistors in units of N, and the drive circuit is
Turning on the application of the drive voltage to the plurality of heating resistors
A line thermal head, characterized in that it is turned off in the unit of the heat generation group. 2. The line thermal head according to claim 1, wherein the heating resistor is provided so that the dimension in the direction perpendicular to the arrangement direction corresponds to N dots. 3. A plurality of heating resistors arranged in a line corresponding to dots, and a drive circuit for turning on / off application of a driving voltage to each heating resistor based on print data. At least one of a character, a symbol and a code whose one side is represented by a predetermined number of dots is N times the predetermined number of dots (N
Is a printing size of an integer), and the heating resistor is provided such that at least one dimension in the arrangement direction and a direction perpendicular to the arrangement direction corresponds to N dots. Line thermal head that is characterized by being