JP3417827B2 - Thermal print head - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal print head. 2. Description of the Related Art A thermal print head used in a thermal printing section of a facsimile or the like is configured to drive a large number of heating dots arranged in a row on an insulating substrate by a driving IC. In the case of a so-called thick film type thermal print head, the heating dots are comb-shaped common electrode patterns in which a heating resistor formed so as to extend linearly by printing or the like on an insulating substrate is penetrated into its lower layer. Formed by segmenting Each heating dot is conducted to one end of an individual electrode, and the other end of the individual electrode is conducted to an output pad on the drive IC by wire bonding. The drive IC turns on a predetermined output pad in accordance with the print data, and a current flows between the individual electrode corresponding to the turned on output pad and the common electrode pattern, thereby driving a predetermined heating dot by heating. . For example, in the case of performing A4 size printing at a printing density of 200 dpi (8 dots in 1 mm), 1,728 heating dots are formed. At present, it is difficult to drive all the heat generating dots by one IC chip due to the semiconductor manufacturing circumstances and the like. Therefore, a plurality of IC chips are mounted on a substrate, and each drive IC has a predetermined number. Each heating dot is driven. Each drive IC has a built-in shift register having a predetermined number of bits corresponding to the number of output pads.
By cascading the data out and data in terminals of C, all shift registers are substantially continuous. In the case of A4 size printing, the printing data is 1728 bits per line, and the printing data for one line from the data-in terminal of the driving IC arranged at the end of the plurality of driving ICs. Is input serially. Thus, according to the print data held in the 1728-bit shift register, each output pad is turned on at the timing of the strobe signal commonly input to each drive IC. Conventionally, the number of output bits of this type of driving IC for a thermal print head is preferably basically a multiple of 8 bits from the viewpoint of data transfer between the driving ICs. , For example, 32 bits,
64 bits, 96 bits, 128 bits, etc.
It is simply a multiple of 32 bits. The number of bits per chip is gradually increasing because high integration of ICs has become possible. [0005] By the way, one line 1
In general, the printing drive according to the 728-bit print data is not performed simultaneously but is performed in a time-division manner. The reason is that when all of the 1,728 dots generate heat, the amount of current flowing through the common electrode increases, and the voltage drop of the common electrode wiring becomes conspicuous, causing problems such as printing unevenness, and the need for a large-capacity power supply. This is because it is necessary to make settings and the cost increases. Therefore, after the print data of 1728 bits is input, a strobe signal for controlling the print timing is transmitted to the drive IC for the left half of the heating dot and the drive IC for the right half of the heating dot. The input is shifted. [0007] For example, when a thermal print head having an A4 width of 1728 dots is formed using a 64-bit drive IC, the number of drive ICs used is 27.
Then, when printing is performed by the two-split control, for example,
Inevitably, the drive ICs are divided into 13 drive ICs on the left side and 14 drive ICs on the right side. This also causes print unevenness. In addition, a power supply capacity corresponding to the number of heat generation dots handled by the 14 drive ICs is set. For a portion handled by the 13 drive ICs, The power capacity is wasted. In order to further reduce the size of the printing apparatus mainly by further reducing the power supply capacity, it is conceivable to perform printing control in four divisions. Even in this case,
Since 27 is not divisible by 4, the same problem as in the case of the two-division control as described above occurs. Further, in recent years, in addition to a printing apparatus having an 8-inch thermal print head, which is substantially equivalent to the A4 width, a 2-inch terminal printer used as a cash register or in a railway car, for example, A 3 inch terminal printer used for payment of water and water bills, a 4 inch terminal printer used for medical equipment, and a 10 inch printer are also in practical use. These printers require, for example, about 400 heating dots for the above-mentioned 2-inch printer.
In the same manner, for the 3-inch, 4-inch and 10-inch devices, a predetermined number of heat-generating dots corresponding to the size are required. Therefore, in order to mount a different number of drive ICs for each type of printer and perform appropriate printing with a small power supply, drive control such as the above-described division control must be performed. However, in the prior art, no specific means has been found for mounting the same type of drive IC with appropriate compatibility in the various printers exemplified above. For this reason, for example, by using a plurality of drive ICs having the above-described output bit number of 64, 2
Even if the total number of output bits of the appropriate number of drive ICs is appropriately made to correspond to the number of heat-generating dots of the above-described various printers in order to manufacture printers of inches, 4 inches, 8 inches and 10 inches. In the same manner as described above, uniform drive control cannot be performed, and the drive control is hindered. The present invention has been conceived in view of such circumstances. When manufacturing various thermal print heads having different inch sizes at a print density of 200 dpi, the same drive IC is used. The object is to make the drive control as simple as possible. Means for Solving the Problems In order to solve the above problems, the present invention employs the following technical means. That is, the thermal print head of the present invention uses heat-generating dots arranged at a density of 200 dpi.
The driving IC is divided into every predetermined number of dots you continuously driven in charge a plurality equipped with a thermal print head, sets the number of output bits of the drive IC 144, the driving IC, 3 , 4, 6, 12 or 14 pieces are mounted, and the size is 2 inches, 3 inches, 4 inches, 8 inches or 10 inches. The operation and effect of the present invention, for example, consider the case where an A4-size (8-inch size) thermal print head is constructed using a 144-bit drive IC. in this case,
The number of heating dots is 1728. In this case, the number of mounted drive ICs is 1728/144 = 12. This 12 is not only divisible by 2 or 4 but also divisible by 3. Therefore, in the case of performing the time-division printing control by two divisions, a strobe signal whose timing is temporally shifted is given to each of the six left driving ICs and the six right driving ICs. 1,728 heating dots can be divided into 864 dots on the left side and 864 dots on the right side, and time-division driving can be performed. When time division control is performed by four divisions, twelve drive ICs are divided into four groups of three, and a strobe signal whose timing is shifted is supplied to each group. 1,728 heating dots can be driven by, for example, four division control of 432 dots from the left side. Further, in the case of performing time division control by three divisions, twelve drive ICs can be divided into three groups of four. By applying strobe signals with shifted timings to the three groups of four, it is possible to perform a divided drive in which 1728 dots of heat generated per line are divided into three times, for example, 576 dots from the left. . Regardless of whether two-part control is performed, four-part control is performed, or three-part control is performed, the number of divided heating dots is the same. Therefore, the current capacity required for printing each divided group of heating dots is equal, and the voltage drop of the common electrode in the printing state is also equal. Therefore, printing unevenness such as different printing density for each divided group does not occur. Further, the current capacity of the power supply is not wasted depending on the group. Then, by using the drive IC having the output bit number of 144 bits, for example, the A4 size 172 is output.
Considering the case of manufacturing a thermal print head having 8 heating dots, as described above, 12 drive ICs can be divided into four groups of three and four divided into four groups. Some 3
It is possible to easily manufacture a small-sized thermal print head using only the drive ICs. Similarly, the A4-size thermal print head can control 12 drive ICs into three groups of four drive ICs and divide the drive ICs into three groups.
Since two drive ICs can be divided into two groups of six and controllable in two groups, thermal print heads having different sizes can be formed using only one of these groups, four and six drive ICs. It can be easily manufactured. As described above, the drive IC having the output bit number of 144 can be mounted on the thermal print head having the heat-generating dots of A4 size 1728 dots (8 inch size) as described above and appropriate division control can be performed. at the same time,
By using only a predetermined number of drive ICs, which is one group in the case of performing the division control, another small-sized thermal print head can be easily manufactured.
Therefore, the same drive IC and the mode of drive control for the same drive IC can be commonly applied to a plurality of types of thermal print heads, which is advantageous in terms of cost and simplifies the manufacturing operation. You can do it. In this case, when the dot density of the heating dots of the thermal print head is 200 dpi, the total number of output bits when three drive ICs each having 144 output bits are used is equal to the total number of output bits of the 2-inch size. The number of heat generation dots required by the print head appropriately corresponds to the number. Similarly, the total number of output bits when four drive ICs are used and the number of heating dots required for a 3-inch size print head properly correspond to each other, and when six drive ICs are used. The total number of output bits and the number of heating dots required by a 4-inch size print head appropriately correspond. Accordingly, when the drive IC is mounted on a thermal print head having 1,728 heating dots of the A4 size and the four-division control, the three-division control, and the two-division control are performed, one group corresponds to two groups. It can be effectively used for thermal print heads of inch, 3 inch and 4 inch sizes. Further, since the total number of output bits when 14 drive ICs are used appropriately corresponds to the number of heat generating dots required by a 10-inch size print head, this type of print head can be used. In this case, the driving ICs can be effectively used, and in this case, the driving ICs can be divided into two groups of seven each, so that the two-part control can be performed well. DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention are described below.
This will be specifically described with reference to the drawings. FIG. 1A schematically shows a planar configuration of a thick film type thermal print head 1. The heating resistors 3 are linearly arranged along one side edge of the upper surface of the insulating substrate 2 having a rectangular shape. This heating resistor 3
A common wiring pattern 4 is arranged in a band-shaped region between the substrate and one side edge 2a of the substrate 2, and both ends of the common wiring pattern 4 are extended to the other side edge 2b of the substrate. The end is connected to the common terminal 5. As shown in detail in FIG. 2, a comb-shaped common electrode 4a is extended from the common wiring pattern 4. On the other hand, the common electrode 4a extends between the comb-shaped common electrodes 4a. One end of the individual electrode 6 extends. The other end of each individual electrode 6 extends to the vicinity of the drive IC 7 mounted on the substrate, and a wire bonding pad 6a is formed at the end. The heating resistor 3 is formed so as to overlap the comb-shaped common electrode 4a and the individual electrode 6 interposed therebetween, as indicated by a virtual line in FIG. Heating dots are defined by the matching comb-shaped common electrode 4a. That is, when the individual electrode indicated by reference numeral 6 in FIG. 2 is turned on, a current flows through the heating resistor 3 in a region surrounded by the two comb-shaped common electrodes 4a surrounding the electrode, and that portion serves as a heating dot. Function. When printing at 200 dpi, the pitch of each heating dot is 0.125 μm.
As described above, 1,728 heating dots are linearly arranged in a line for the A4 size. According to the present invention, the driving IC 7 for driving the heating dots in a predetermined number at a time.
With 144 bits. That is,
As shown in FIG. 3, the drive IC 7 has 144 output pads 8 arranged in a staggered pattern on the upper surface of one side edge. In FIG. 3, reference numeral 9 denotes a data in pad,
Reference numeral 10 indicates a data out pad. Reference numeral 11 denotes a clock pulse input pad, reference numeral 12 denotes a strobe pad, reference numeral 13 denotes a logic power supply pad, and reference numeral 14 denotes a ground pad. The drive IC 7 has a built-in 144-bit shift register corresponding to the output pad 8, and a strobe input from the strobe pad 12 in accordance with print data held in the shift register. The corresponding output pad 8 is turned on by the timing of the signal. Since the driving IC 7 has 144 bits, the driving IC 7 has 1,728 heating dots as shown in FIG.
When configuring a thermal printhead for 4 sizes,
Twelve drive ICs 7 are mounted on the substrate. The output pad 8 of each drive IC 7 and the individual electrode 6
The wire bonding pads 6a are connected by wire bonding as is known. Between the data out pad 10 and the data in pad 9 of the adjacent drive IC 7, the wire is substantially connected to a wiring pattern (not shown) provided on the substrate by wire bonding. The logic power supply pad 13 is commonly connected via a wire bonding to a power supply wiring pattern (not shown) formed on the substrate. The clock pulse input pad 11 is also commonly connected to a clock signal wiring pattern (not shown) formed on the substrate. The same applies to the ground pad. In FIG. 1A, for example, the data in pad 9 (see FIG. 3) in the leftmost drive IC 7 is
The wiring pattern connected to the data-in terminal provided on the substrate is connected by wire bonding. The print data of 1728 bits per line is
It is held in a shift register of a total of 1728 bits which is substantially concatenated as described above. The printing drive is performed according to the timing of the strobe signal input from the strobe pad 12, but usually, not all the heating dots are driven at the same time, but are driven in a time division manner into several groups. FIG. 1B schematically shows a case in which 1,728 heating dots are driven in two groups of 864 dots. Similarly, (c) of FIG.
FIG. 1D schematically shows a case where time-division driving is performed in three groups of 576 dots, and FIG. 1D shows a case where time-division driving is performed in four groups of 432 dots. For example, as shown in FIG. 1B, in the case where the control is divided into two, the strobe pads of the left six drive ICs out of the twelve drive ICs are shared with the first strobe signal wiring pattern. Connected, 6 drive ICs 7 on the right
Are connected in common to the second strobe signal wiring pattern. Similarly, in the case of three-division control, three systems of strobe signal wiring patterns are required, and in the case of four-division control, four systems of strobe signal wiring patterns are required. FIG. 4 is a timing chart in the case of performing time-division printing control by four divisions. In accordance with the clock pulse signal (CLK), print data of 1728 bits is held in a shift register of a total of 1728 bits in each drive IC connected in cascade. The first between the fall time of the strobe signal STB 1, by 1 to 3 th driving IC, first to 432-th heating dots (D ₁ to D ₄₃₂₎ is heated and driven in accordance with print data, sequentially During the fall of the second to fourth strobe signals STB2 to STB4, the 432 heating dots shown in FIG. 1D are driven to generate heat according to the print data. As can be seen from FIG. 1, in this embodiment, 1
Since the thermal print head of A4 size 1728 dots is driven using the 44-bit drive IC, the number of drive ICs 7 mounted on the substrate is 12. Since the number 12 is divisible by 2, 3 or 4, it is possible to appropriately perform 2-division print control, 3-division print control, and 4-division print control. In other words, division control can be performed so that the number of divided heating dots is the same. As described above, in this embodiment, appropriate print drive control can be performed in response to any of the two-division control, the three-division control, and the four-division control. become able to. Further, the driving ICs 7 enumerated in the above embodiment are used.
Among them, the driving IC 7 whose output bit number is set to 144 bits can be used as described below. In the following description based on FIG. 5 to FIG. 8, the same reference numerals and the same expression form will be used for the components and the display mode of the number of heat generation dots as those of the above-described thermal print head 1 shown in FIG. Therefore, a detailed description thereof will be omitted. That is, a 2-inch thermal print head 1a shown in FIG. 5, a 3-inch (or about 2.7-inch) size thermal print head 1b shown in FIG. 6, and a 4-inch thermal print head 1b shown in FIG. For the print head 1c, the drive IC 7 having the same output bit number 144 as described above is used. In this case, of course, it is assumed that the dot density of the heating dots is 200 dpi (the same applies to the following). The A4 size thermal print head 1 has a size of 8
It supports inch size. The above-mentioned various thermal print heads will be described in detail. The two-inch size thermal print head shown in FIG. 5 uses three drive ICs 7, so that the total number of output bits is 432 bits, which is 2 inches. Appropriately corresponds to the number of heating dots required by the thermal print head of the size. This 2 inch size is
For example, it is used for printing cash registers and tickets in railway vehicles. The three-inch size shown in FIG. 6 uses four drive ICs 7, and the total number of output bits is 576 bits. The four-inch size shown in FIG. Six drive ICs 7 are used, and the total number of output bits is 864 bits. Also, in this case, the total number of output bits corresponds to the number of heating dots required by each of the 3-inch size and 4-inch size thermal print heads. The 3 inch size printer is used, for example, as a terminal printer for adjusting gas and water charges, and the 4 inch size printer is
It is used as a terminal printer for electrocardiograms and other medical devices for diagnosis. As described above, the drive IC 7 used for the A4 size (8 inch size) thermal print head 1 is effective for the 2 inch, 3 inch and 4 inch size thermal print heads 1a, 1b and 1c. Will be used. In the case of the 3-inch size shown in FIG. 6, the drive ICs 7 can be divided into two groups by two to perform two-division control. In the case of the 4-inch size shown in FIG. Dividing the driving ICs 7 into groups of 2 or 3 or 3 or 2
It is possible to perform split control or two-split control. Such division control eliminates the need for a large-capacity power supply, which is convenient for a handy-type terminal printer, and has the same number of divided heating dots to provide uniform drive control. Therefore, problems such as printing unevenness do not occur. FIG. 8 shows a thermal print head 1d having a size of 10 inches by using 14 drive ICs 7 described above. In this case, the above 14
The total number of output bits of each drive IC 7 is 2016, which corresponds to the number of heat generation dots required for a 10-inch size thermal print head. The thermal print head 1d is divided into two groups of seven each, so that two-division control is performed. Also in this case, the same drive IC as above
7 can be used, and the number of divided heat-generating dots becomes the same so that uniform drive control can be performed. The number of heat generating dots required by the thermal print heads 1a, 1b, 1c, 1d of the sizes of 2 inches, 3 inches, 4 inches, 8 inches and 10 inches is determined by the number of thermal print heads. The number is slightly smaller than the total number of output bits of each of the drive ICs 7 mounted on the head. For example, 2
Taking the thermal print head 1a of an inch size as an example, the required number of heating dots is determined by the driving IC in this case.
7 which is slightly less than the total number of output bits of
It is about 420. Here, assuming that various types of thermal print heads are manufactured in the same manner as described above using a drive IC having an output bit number of 64, for example, seven 2-inch size print heads should be used. The total output bit number becomes 448, the total output bit number becomes 640 by using 10 pieces of 3 inch size, and the total output bit number becomes 832 by using 13 pieces of 4 inch size. The total output bit number is 17 by using 27 pieces of 8 inch size.
The total output bit number becomes 2048 by using 32 of the 10-inch size. As described above, the driving I of 64 output bits is used.
When C is used, the used number is 7, 10,
13, 27, and 32. Of these numbers,
Since 7 and 13 are prime numbers, uniform division control cannot be performed.
It is impossible to properly cope with a demand for downsizing of the power supply and a demand for wasteful consumption of the power supply capacity. On the other hand, if a drive IC having the number of output bits of 144 is used, such a problem does not occur.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 (a) is a plan view schematically showing a configuration of a first embodiment of a thermal print head according to the present invention. (b) is 2
FIG. 9 is an explanatory diagram when performing division control. (c) is an explanatory diagram in the case of performing three-division control. (d) is an explanatory diagram in the case of performing four-division control. FIG. 2 is a partially enlarged plan view of the thermal print head shown in FIG. FIG. 3 is an enlarged plan view of an example of a drive IC mounted on the thermal print head of the present invention. FIG. 4 is a timing chart in the case of performing time-division printing control by four divisions. FIG. 5 is a plan view schematically showing the configuration of a second embodiment of the thermal printhead of the present invention. FIG. 6 is a plan view schematically showing a configuration of a third embodiment of the thermal printhead of the present invention. FIG. 7 is a plan view schematically showing a configuration of a fourth embodiment of the thermal printhead of the present invention. FIG. 8 is a plan view schematically showing a configuration of a fifth embodiment of the thermal printhead of the present invention. [Description of Signs] 1 Thermal print head 3 Heating resistor 7 Drive IC

Continuation of front page (56) References JP-A-5-305725 (JP, A) JP-A-62-292060 (JP, A) JP-A-3-153368 (JP, A) JP-A-5-193173 (JP) JP-A-4-279362 (JP, A) JP-A-4-303665 (JP, A) JP-A-3-266657 (JP, A) JP-A-61-102862 (JP, A) Mitsubishi thermal head , Japan, Mitsubishi Electric Corporation, 16 (58) Fields investigated (Int. Cl. ⁷ , DB name) B41J 2/345 B41J 2/335 B41J 2/355

Claims (1)

(57) Patent Claims 1. A thermal print head driving IC has a plurality mounting the charge is divided into every predetermined number of dots density you continuously arranged heating dots of 200dpi to drive The number of output bits of the drive IC is set to 144, and three, four, six, twelve, or fourteen drive ICs are mounted on the drive IC to obtain 2 inches, 3 inches, 4 inches, 8 inches or 10 inches in size,
Thermal print head.