JPH06166201A - Thermal head - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a thermal head capable of reducing the number of drive circuits and improving the manufacturing yield without complicating the connection of the thermal head. [Structure] The thermal head includes a large number of heating resistors R1 to R1.
It is composed of R1728 and a plurality of drive circuits 3, etc.,
Heating resistors R1 to R3, R10 to R12, ..., R172
One ends of 0 to R1722 are connected to the common electrode VH1, and the heating resistors R4 to R6, R13 to R15, ..., R1723.
One end of R1725 is connected to the common electrode VH2, and the heating resistors R7 to R9, R16 to R18, ..., R1726 to
One end of R1728 is connected to the common electrode VH3. 19
The electrode pad row 4a connected to the individual electrodes 21 of the two heating resistors is composed of three rows and 64 columns of electrode pads P1 to P192, and the electrode pad row 4b for grounding is provided at the center of the bottom surface for signals. The electrode pad row 4c of is disposed below the bottom surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal head used in a facsimile machine, an image recording apparatus and the like.

[0002]

2. Description of the Related Art FIG. 16 is a circuit diagram showing an electrical configuration of an example of a conventional thermal head. This thermal head is composed of a large number of heating resistors R1 to R1728, a plurality of drive circuits 9 and the like, and in FIG.
The heat generating resistors are connected to one drive circuit 9, and the 576 heat generating resistors and the nine drive circuits 9 are divided into a total of three blocks B1 to B3 to perform a printing operation.

FIG. 17 is a circuit diagram showing an example of the drive circuit 9 shown in FIG. The drive circuit 9 outputs a print signal DI composed of serial data from an external clock signal CL.
A shift register SR that converts the data into parallel data for each predetermined number of bits by transferring in synchronization with K and outputs the parallel data.
1 to SRn and an external latch signal LAT,
A plurality of latch circuits L1 to Ln for storing the outputs of the shift registers SR1 to SRn and a strobe signal S from the outside.
Each latch L is controlled by TBI and print control signal BEO.
A plurality of gate elements G1 to Gn for opening and closing the outputs of 1 to Ln
And a plurality of switching elements T1 to Tn for controlling the current flowing through the heating resistors R1 to Rn by the outputs of the respective gate elements G1 to Gn.

One end of each of a large number of heat generating resistors R1 to Rn formed on the thermal head is connected to each of the switching elements T1 to Tn.
n is connected to the drain side and each heating resistor R
The other ends of 1 to Rn are commonly connected to the output side VH of the external power source 70, and the external power source 70 is connected to the terminal GND2 to which the source sides of the switching elements T1 to Tn are commonly connected.
The ground side of is connected.

This operation will be described with reference to the timing chart shown in FIG. The print signal DATA for 1728 pixels formed as one scanning line is input to and transferred to the shift registers SR1 to SRn of each drive circuit 9 in synchronization with the clock signal CLK, and the print signal for 64 pixels is provided in each drive circuit 9. DATA is converted into parallel data, respectively.

Next, the latch signal LAT is inverted, and the outputs of the shift registers SR1 to SRn of the drive circuit 9 are stored in the respective latch circuits L1 to Ln.

Next, when the print control signal BEO is inverted to the low level and the strobe signal STB1 is inverted to the low level, the block B composed of the heating resistors R1 to R576.
Each of the gate elements G1 to G of the nine drive circuits 9 corresponding to 1
n is opened, and each of the switching elements T1 to Tn is opened based on the print signal DATA stored in each of the latch circuits L1 to Ln.
Becomes selectively conductive. Then, the heating resistors R1 to R1
An electric current selectively flows through R576 to generate heat, heat the thermal paper or the thermal transfer film, and perform the printing operation of 1/3 of one scanning line corresponding to the block B1.

Similarly, when the strobe signal STB2 is inverted to the low level, the heating resistors R577 to R115 are similarly set.
When a current flows selectively to 2 to generate heat, the printing operation of 1/3 of one scanning line corresponding to the block B2 is performed, and the strobe signal STB3 is inverted to the low level, the heating resistors R1153 to R1728 are generated. A current selectively flows to generate heat, and the printing operation is performed on a portion of 1/3 of one scanning line corresponding to the block B3. In this way, a series of images are recorded by printing one scanning line and repeating the above-described operation while stepwise conveying the thermal paper or the thermal transfer film.

FIG. 19 is a circuit diagram showing the electrical construction of another example of the conventional thermal head. This thermal head is composed of a large number of heating resistors R1 to R1728, a plurality of driving circuits 9 as shown in FIG. 17, and backflow prevention diodes D1 to D1728 interposed between the two. Heating resistors R1 to R3, R10 to R12, ..., R
One end of 1720 to R1722 is connected to the common electrode VH1, and the heating resistors R4 to R6, R13 to R15, ..., R1.
One end of each of 723 to R1725 is connected to the common electrode VH2, and the heating resistors 7 to R9, R16 to R18, ..., R17.
One ends of 26 to R1728 are connected to the common electrode VH3. On the other hand, the other ends of the heating resistors R1, R4, R7 are connected to the switching element T1 of the drive circuit 9 via the diodes D1, D4, D7, and the heating resistors R2, R5, R8.
The other end of the heating resistor R is connected to the switching element T2 of the drive circuit 9 through the diodes D2, D5 and D8.
The other ends of 3, R6 and R9 are connected to the switching element T3 of the drive circuit 9 through the diodes D3, D6 and D9. Similarly, one switching element of the drive circuit 9 is connected so as to drive the three heating resistors respectively connected to the common electrodes VH1, VH2, VH3.

Explaining this operation, first, in each drive circuit 9, a block B including heating resistors R1 to R3 is provided.
1, a block B4 including heating resistors R10 to R12,
Similarly, the printing signal corresponding to the block B3n-2 (where n is a natural number of 1 or more; the same applies hereinafter) is input and transferred, and each switching element T1 to Tn of each drive circuit 9 is transferred.
Is selectively conducted, and when electric power is supplied to the common electrode VH1 for a predetermined time, each heating resistor of the block B3n-2 is selectively conducted to generate heat, and the printing operation is performed.

Next, in each drive circuit 9, the heating resistors R4.about.
Block B2 consisting of R6, heating resistors R13 to R15
Block B5 consisting of
When the print signal corresponding to 1 is input and transferred, each switching element T1 to Tn of each drive circuit 9 is selectively turned on, and when power is supplied to the common electrode VH2 for a predetermined time, each heat generation of the block B3n-1 is performed. The resistor selectively energizes to generate heat and perform a printing operation.

Next, in each drive circuit 9, the heating resistors R7 to R7.
Block B3 composed of R9, heating resistors R16 to R18
Similarly, a printing signal corresponding to a block B3n is input and transferred, each switching element T1 to Tn of each drive circuit 9 is selectively conductive, and power is supplied to the common electrode VH3 for a predetermined time. When supplied, each heating resistor of the block B3n is selectively energized to generate heat,
Performs printing operation. In this way, by supplying electric power by time-sharing the three common electrodes VH1, VH2, and VH3 with respect to the output of one switching element, the number of switching elements and the like of the drive circuit 9 is reduced to 1/3 and the heat generation resistance is reduced. The bodies R1 to R1728 can be driven in three divisions.

[0013]

However, as shown in FIG.
In the thermal head shown in FIG.
Since it is necessary to provide the same number of shift registers SR1 to SRn, latch circuits L1 to Ln, and switching elements T1 to Tn as the number of 28, a large number of drive circuits 9 must be mounted on the thermal head. There is a problem that the manufacturing cost rises.

On the other hand, in the thermal head shown in FIG.
Since the shift registers SR1 to SRn, the latch circuits L1 to Ln, and the switching elements T1 to Tn, which are ⅓ of the number of the heating resistors R1 to R1728, are sufficient, the number of the drive circuits 9 to be mounted can be reduced. However, the current limiting diodes D1 to D1728 for preventing the sneak of the current flowing through the commonly connected heating resistors must be newly mounted, which causes a problem of increasing the number of components. Furthermore, since many connections between the diodes D1 to D1728 and each drive circuit 9 intersect, the multilayer wiring part 13 must be formed on the substrate of the thermal head, which increases the number of manufacturing steps and the manufacturing yield. And a large circuit. In particular, since the thermal head drives a large number of heating resistors, it must be an element having a large area, and increasing the area of the multi-layer wiring portion significantly reduces the manufacturing yield.

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermal head, which solves the above-mentioned problems, does not complicate the connection of the thermal head, and can reduce the number of drive circuits and improve the manufacturing yield. Is.

[0016]

The present invention is based on a plurality of heating resistors, a shift register for converting a print signal composed of serial data into parallel data, and an output of the shift register and a control signal from the outside. In a thermal head including a drive circuit having a plurality of switching elements for controlling the current flowing through each heating resistor, the drive circuit is composed of a flip chip having a plurality of electrode pads on the bottom surface, and each switching element is controlled. A thermal head is characterized in that a plurality of signals or outputs of each switching element are branched, and the outputs are respectively connected to electrode pads connected corresponding to each heating resistor.

[0017]

According to the present invention, a drive circuit for driving a plurality of heating resistors is composed of a flip chip having a plurality of electrode pads on the bottom surface, and a plurality of control signals for each switching element or a plurality of outputs for each switching element are provided. Branching,
Since the output is connected to the electrode pad that is connected corresponding to each heating resistor, it is not necessary to form a multilayer wiring part on the substrate of the thermal head, and the number of drive circuits is reduced. You can

[0018]

1 is a perspective view showing a thermal head according to an embodiment of the present invention, FIG. 2 is a partially enlarged plan view thereof, and FIG. 3 is a sectional view taken along line XX of FIG. 4 is Y- in FIG.
It is sectional drawing which followed the Y line. An electrically insulating substrate 15 such as alumina Al ₂ O ₃ is fixed on a radiator 14 such as Al, and a conductor 24 having three wiring patterns as shown in FIG. 2 is formed thereon. As an example of a method of forming the conductor 24, a paste containing Ag or the like is applied in a predetermined pattern by a printing method such as screen printing, and then the conductor 24 is baked at a temperature of 600 ° C. to 700 ° C. You can Further, as another example of the method of forming the conductor 24, Al, Ni, or the like is formed on the substrate 15 by using a thin film forming technique such as vacuum deposition or sputtering.
A plurality of wiring patterns can be formed by using a photolithography method after depositing a metal such as Au to a thickness of about 5 μm to 30 μm. Further, in order to reduce the manufacturing cost, a Ni film having a thickness of about 1 μm is formed on the substrate 15 by using the above-described thin film forming technique, and then a plurality of wiring patterns are formed by using a photolithography method. Then, using an electrolytic plating method or an electroless plating method, a Ni layer having a thickness of 20 μm is formed on the wiring pattern.
It is also possible to form it to about 30 μm.

On the other hand, a glaze layer 18 made of glass or the like having an arcuate cross section is formed on an electrically insulating substrate 17 such as alumina Al ₂ O _3, and a heating resistor is further formed on the substrate 17 and the glaze layer 18. The layer 30, the individual electrode 21, and the common electrode 31 are formed, and a plurality of linear heating resistors are formed near the top of the glaze layer 18. A protective layer 32 made of Si ₃ N ₄ or the like is formed so as to cover the surface of the glaze layer 18. Each individual electrode 21 is connected to the flip-chip drive circuit 3. On the other hand, the common electrodes 31 are grouped into groups of three and connected to the through holes 20. Further, a conductor 23 and a through hole 22 connected to the conductor 23 are formed by thick film printing or the like on the upper surface of the substrate 17 opposite to the glaze layer 18.

The substrate 17 and the substrate 15 obtained in this way are bonded together via an electrically insulating adhesive layer 16. As an example of a method of joining the substrates, low temperature firing is performed on the entire surface of the substrate 15 on which the conductors 24 are formed in advance, except for the regions electrically connected by the through holes 20 and 22 formed on the substrate 17. Glaze glass for application is applied by screen printing or the like, and further brought into close contact with the substrate 17 while being positioned, and then the adhesive layer 16 is formed by baking at a temperature of about 400 ° C. to 500 ° C. And can be glued together. Since the low-temperature firing glaze glass is used as the material of the adhesive layer 16, it is possible to perform firing at a temperature sufficiently lower than the firing temperature of the conductor 24, and it is possible to prevent deformation of the conductor 24 during substrate bonding. . By joining the substrate 15 and the substrate 17 in this manner, the electrical connection between the conductor 24 on the substrate 15 and the through holes 20 and 22 of the substrate 17 is achieved.

FIG. 5 is a circuit diagram showing an electrical configuration of a thermal head which is an embodiment of the present invention. This thermal head is composed of a large number of heating resistors R1 to R1728 and a plurality of drive circuits 3 and the like, and in FIG.
The individual electrodes 21 of the two heating resistors are connected to one drive circuit 3, and the heating resistors R1 to R3 and R10 are connected.
, One end of R1720 to R1722 is connected to the common electrode VH1, and heat generating resistors R4 to R6 and R13 to R13.
15, ..., One end of R1723 to R1725 has a common electrode V
H2 is connected to the heating resistors R7 to R9, R16 to R1
, ..., One end of R1726 to R1728 has a common electrode VH.
3 is connected. Further, the print signal DAT is sent to each drive circuit 3.
External control signals such as A, strobe signal STB, print control signal BEO, latch signal LAT, and clock signal CLK are input.

FIG. 6 shows a drive circuit 3 which is a flip chip.
FIG. 6 is a bottom view showing the arrangement of the electrode pads of FIG. An electrode pad row 4a connected to the individual electrodes 21 of the 192 heating resistors
Is composed of electrode pads P1 to P192 of 3 rows and 64 columns in which the electrode pads of 3 rows and 3 columns are repeated as shown in the figure. Further, the electrode pad row 4b for grounding the drive circuit 3 is arranged in the center of the bottom surface, and the electrode pad row 4c for signal of the drive circuit 3 is arranged in the lower bottom portion.

FIG. 7 is a partially enlarged view in the vicinity of A in FIG. 5 showing a connection pattern between each heating resistor and the electrode pad of the drive circuit 3. The electrode pads P1 to P3 are heating resistors R1 to R
3, the electrode pads P4 to P6 are heating resistors R4 to R6.
In addition, the electrode pads P7 to P9 are respectively connected to the heating resistors R7 to R9, and the wiring pattern is similarly drawn for every three electrode pads.

FIG. 8 is a circuit diagram showing an electrical configuration of an example of the drive circuit 3. The drive circuit 3 outputs a print signal DI composed of serial data to a clock signal CLK from the outside.
Shift register SR1 for converting into parallel data for each predetermined number of bits and outputting by converting the data in synchronization with
To SRn, a plurality of latch circuits L1 to Ln for storing the outputs of the shift registers SR1 to SRn by a latch signal LAT from the outside, and a strobe signal STB from the outside.
And the print control signal BEO, each latch circuit L1
To a plurality of gate elements G1 to Gn for opening and closing the outputs of Ln
And a plurality of switching elements T that control the current flowing through each heating resistor 2 by the output of each gate element G1 to Gn.
1 to Tn and the output of each switching element T1 to Tn is 3
It is composed of current limiting diodes D1 to D3n which are branched into books and connected in series. For example, the other ends of the diodes D1 to D3n of the first drive circuit 3 are
The heating resistors R1 to R192 are connected via the electrode pads P1 to P192 shown in FIGS. 6 and 7.

Next, the operation of the thermal head equipped with the drive circuit 3 of FIG. 8 will be described with reference to the timing chart of FIG. First, of the 1728 pixel print signals DATA formed as one scanning line,
The print signals DATA of the third, tenth to twelfth, ..., 1720 to 1722 pixels are input and transferred to the shift registers SR1 to SRn in synchronization with the clock signal CLK, and a total of 64 pixels are provided in each drive circuit 3. The print signal DATA of is converted into parallel data. Next, the latch signal LAT
Is inverted and the outputs of the shift registers SR1 to SRn are stored in the respective latch circuits L1 to Ln.

Next, when the print control signal BEO is inverted to the low level, the strobe signal STB is inverted to the low level, and electric power is supplied to the common electrode VH1, the print signals stored in the latch circuits L1 to Ln are stored. Each of the switching elements T1 to Tn is selectively turned on based on DATA, and the heating resistors R1 to R3, R10 to R12,
, R1720 to R1722 selectively generate an electric current to generate heat, heat a recording medium such as a thermal paper or a thermal transfer film, and perform a printing operation of 1/3 of one scanning line.

Next, after the strobe signal STB is inverted to the high level, the fourth to sixth, thirteenth to fifteenth, ...
The print signals DATA of the 723rd to 1725th pixels are synchronized with the clock signal CLK, and the shift registers SR1 to SRn
Is input to and transferred to each drive circuit 3 and the print signals DATA for 64 pixels in total are converted into parallel data in each drive circuit 3. Next, the latch signal LAT is inverted, and the shift register SR
The outputs of 1 to SRn are stored in the respective latch circuits L1 to Ln.

Next, when the strobe signal STB is inverted to the low level and power is supplied to the common electrode VH2, each switching is performed based on the print signal DATA stored in each latch circuit L1 to Ln, as described above. Element T
1 to Tn are selectively turned on, and the heating resistor R4 to
, R1723 to R1725 selectively generate an electric current to heat the recording medium to perform the printing operation of a portion of 1/3 of one scanning line.

Next, after the strobe signal STB is inverted to the high level, the seventh to ninth, sixteenth to eighteen, ..., The first
The print signals DATA of the 726th to 1728th pixels are synchronized with the clock signal CLK, and the shift registers SR1 to SRn
Is input to and transferred to each drive circuit 3 and the print signals DATA for 64 pixels in total are converted into parallel data in each drive circuit 3. Next, the latch signal LAT is inverted, and the shift register SR
The outputs of 1 to SRn are stored in the respective latch circuits L1 to Ln.

Next, when the strobe signal STB is inverted to the low level and power is supplied to the common electrode VH3, each switching is performed based on the print signal DATA stored in each latch circuit L1 to Ln, as described above. Element T
1 to Tn are selectively turned on, and the heating resistor R7 to
, R1726 to R1728 are selectively heated to generate heat, heat the recording medium, and perform the printing operation of a portion of 1/3 of one scanning line. Then, the strobe signal STB is inverted to the high level, and the print control signal BEO is inverted to the high level. In this way, one scanning line is printed, and a series of images is printed by repeating the above-described operation while stepwise transporting the printing medium.

FIG. 10 is a circuit diagram showing the electrical configuration of another example of the drive circuit 3. The drive circuit 3 outputs a print signal DI composed of serial data from an external clock signal C.
A shift register S that converts the parallel data into a predetermined number of bits and outputs the parallel data by transferring in synchronization with LK.
R1 to SRm (where m is a natural number of 1 or more; the same applies hereinafter) and a plurality of latch circuits L1 to Lm that store the outputs of the shift registers SR1 to SRm by an external latch signal LAT, and a strobe signal from the outside. Depending on the STB and the print control signal BEO, each of the latch circuits L1 to L1
A plurality of gate elements G1 to Gm for opening and closing the output of Lm,
A plurality of gate elements S1 to S2m that select the output of each gate element G1 to Gm by external select signals SEL1 and SEL2, and a plurality of gate elements S1 to S2m that control the current flowing through each heating resistor by the output of each gate element S1 to S2m. Switching elements T1 to T2m and each switching element T1
Outputs of T2m to T2m are branched into three and each is connected in series with current limiting diodes D1 to D3n. For example, each diode D1 of the first drive circuit 3
The other ends of D3n to D3n are the electrode pads T shown in FIGS.
The heating resistors R1 to R192 are connected via 1 to T92.

Next, the operation of the thermal head equipped with the drive circuit 3 of FIG. 10 will be described with reference to the timing chart of FIG. First, among the print signals for 1728 pixels formed as one scanning line, the odd-numbered print signals DATA among the 1st to 3rd, 10th to 12th, ..., 1720 to 1722 pixels are clocked. Signal C
In synchronization with LK, the signals are input to and transferred to the shift registers SR1 to SRm, and the print signals DATA for a total of 32 pixels are converted into parallel data in each drive circuit 3. next,
The latch signal LAT is inverted and the shift registers SR1 to SR1
The output of SRm is stored in each of the latch circuits L1 to Lm.

Next, when the print control signal BEO is inverted to the low level, the strobe signal STB is inverted to the low level, and the select signal SEL1 is inverted to the low level to supply power to the common electrode VH1. Based on the print signal DATA stored in the latch circuits L1 to Lm, the switching elements T1 to T2m are selectively turned on, and the heating resistors R1 to R3, R10 to R12,
, R1720 to R1722 with odd numbers selectively flow current to generate heat, heat the recording medium, and perform the printing operation of ⅙ of one scanning line.

Next, after the strobe signal STB is inverted to the high level, the first to third, tenth to twelfth, ..., The first
720 to 1722 pixels of even-numbered printing signal DA
TA is input and transferred to the shift registers SR1 to SRm in synchronization with the clock signal CLK, and the print signals DATA for a total of 32 pixels are converted into parallel data in each drive circuit 3. Next, the latch signal LAT is inverted, and the outputs of the shift registers SR1 to SRm are changed to the latch circuits L1 to L1.
It is stored in Lm.

Next, when the strobe signal STB is inverted to the low level and the select signal SEL2 is inverted to the low level, each switching element T1 is based on the print signal DATA stored in each latch circuit L1 to Lm.
~ T2m selectively becomes conductive, and the heating resistor R1 ~
, R1727 to R1722, an even current flows selectively to generate heat, heat the recording medium, and perform the printing operation of 1/6 of the scanning line.

Similarly, the heating resistors R4 to R6, R13 to R15, ..., R172 connected to the common electrode VH2 are similarly processed.
Select signal S is an odd number from 3 to R1725.
EL1 selects and drives, and even-numbered ones are selected and driven by select signal SEL2. Further, R7 to R9 and R16 to R1 connected to the common electrode VH3
, ..., R1726 to R1728, odd numbered ones are selected and driven by the select signal SEL1, and even numbered ones are selected and driven by the select signal SEL2. In this way, by using the plurality of select signals, the shift registers SR1 to SRm and the latch circuit L
1 to Lm and the number of gate elements G1 to Gm can be reduced, the size of the drive circuit can be reduced.

FIG. 12 is a circuit diagram showing the electrical configuration of another example of the drive circuit 3. The drive circuit 3 outputs a print signal DI composed of serial data from an external clock signal C.
A shift register S that converts the parallel data into a predetermined number of bits and outputs the parallel data by transferring in synchronization with LK.
R1 to SRn and a plurality of latch circuits L1 to Ln that store the outputs of the shift registers SR1 to SRn according to the latch signal LAT from the outside, and the latch circuits L1 to Ln according to the strobe signal STB and the print control signal BEO from the outside. A plurality of gate elements G1 for opening and closing the output of Ln
~ Gn and external select signals SEL1, SEL
2, a plurality of gate elements S1 to S3n that select the output of each gate element G1 to Gn by SEL3, and a plurality of switching elements T1 to T3n that control the current flowing through each heating resistor by the output of each gate element S1 to S3n. When,
The switching elements T1 to T3n are composed of current limiting diodes D1 to D3n connected in series to the outputs. For example, each diode D1 of the first drive circuit 3
-D3n has the other end connected to the electrode pad P shown in FIGS.
It is connected to the heating resistors R1 to R192 via 1 to P192.

Next, the operation of the thermal head equipped with the drive circuit 3 of FIG. 12 will be described with reference to the timing chart of FIG. First, the 1st to 3rd, 10th to 12th, ..., 1720 to 172 of the print signal DATA for 1728 pixels formed as one scanning line
The print signal DATA of 2 pixels is input to and transferred to the shift registers SR1 to SR2 in synchronization with the clock signal CLK, and the print signal DA of 64 pixels in total in each drive circuit 3.
TA is converted to parallel data. Next, the latch signal LAT is inverted and the outputs of the shift registers SR1 to SRn are stored in the respective latch circuits L1 to Ln.

Next, when the print control signal BEO is inverted to the low level, the strobe signal STB is inverted to the low level, and the select signal SEL1 is inverted to the low level to supply power to the common electrode VH1. Based on the print signal DATA stored in the circuits L1 to Ln,
Each of the switching elements T1, T4, ..., T3n-2 is selectively brought into a conductive state, and the heat generating resistors R1 to R3 and R10.
, R1720 to R1722 selectively flow current to generate heat, heat the recording medium, and perform the printing operation of 1/3 of one scanning line.

Next, after the strobe signal STB is inverted to a high level, the fourth to sixth, thirteenth to fifteenth, ...
The print signals DATA of the 723rd to 1725th pixels are input and transferred to the shift registers SR1 to SRn in synchronization with the clock signal CLK. Next, the latch signal LAT is inverted and the outputs of the shift registers SR1 to SRn are stored in the respective latch circuits L1 to Ln.

Next, when the strobe signal STB is inverted to the low level and the select signal SEL2 is inverted to the low level to supply power to the common electrode VH2, the print signal DATA stored in each of the latch circuits L1 to Ln. , T3n based on
-1 selectively becomes conductive, and the heating resistors R4 to R
6, R13 to R15, ..., R1723 to R1725 selectively generate an electric current to generate heat, heat the recording medium, and perform the printing operation of 1/3 of one scanning line.

Next, after the strobe signal STB is inverted to the high level, the seventh to ninth, sixteenth to eighteen, ..., The first
The print signals DATA of the 726th to 1728th pixels are synchronized with the clock signal CLK, and the shift registers SR1 to SRn
Input to and transferred to. Next, the latch signal LAT is inverted and the outputs of the shift registers SR1 to SRn are stored in the respective latch circuits L1 to Ln.

Next, when the strobe signal STB is inverted to the low level and the select signal SEL3 is inverted to the low level to supply power to the common electrode VH3, the print signal DATA stored in each of the latch circuits L1 to Ln. , T3n based on each of the switching elements T3, T6, ...
Become selectively conductive, and the heating resistors R7 to R9, R
16 to R18, ..., R1726 to R1728 selectively generate an electric current to generate heat and heat the recording medium so that one scan line
The printing operation of the / 3 part is performed. In this way, one scanning line is printed, and a series of images is recorded by repeating the above-described operation while conveying the recording medium.

FIG. 14 is a circuit diagram showing the electrical configuration of another example of the drive circuit 3. The drive circuit 3 outputs a print signal DI composed of serial data from an external clock signal C.
A shift register S that converts the parallel data into a predetermined number of bits and outputs the parallel data by transferring in synchronization with LK.
R1 to SRn and the strobe signal STB and the print control signal BEO from the outside are used to shift each shift register SR1.
To a plurality of gate elements G1 to Gn for opening and closing the outputs of SRn
And a plurality of switching elements T1 for controlling the current flowing through the heating resistor 2 by the outputs of the gate elements G1 to Gn.
To Tn, and the outputs of the switching elements T1 to Tn are branched into three, and each of them is composed of current limiting diodes D1 to D3n connected in series. For example, the first
The other ends of the diodes D1 to D3n of the drive circuit 3 are connected to the heating resistors R1 to R192 via the electrode pads P1 to P192 shown in FIGS. 6 and 7.

Next, the operation of the thermal head equipped with the drive circuit 3 of FIG. 14 will be described with reference to the timing chart of FIG. Two strobe signals STB1 and STB2 are prepared. For example, the strobe signal STB1 is input to the odd-numbered drive circuit 3 and the strobe signal STB2 is input to the even-numbered drive circuit 3. Done.

First, 1728 formed as one scanning line
Of the print signals for pixels, the first to third and tenth to first
2, ..., Half the print signals DATA of the 1720th to 1722nd pixels are input to and transferred to the shift registers SR1 to SRn in synchronization with the clock signal CLK, and a total of 64 print signals DATA are parallelized in each drive circuit 3. Converted to data. Next, the print signal BEO is inverted to the low level, the strobe signal STB1 is inverted to the low level,
When power is further supplied to the common electrode VH1, the switching elements T1 to Tn are selectively turned on based on the print signal DATA stored in the shift registers SR1 to SRn, and the heating resistors R1 to R3 and R10 to R12. ，
..., strobe signal ST among R1720 to R1722
An electric current selectively flows through the heating resistor connected to the drive circuit 3 to which B1 is input to generate heat, heat the recording medium, and perform the printing operation of 1/6 of one scanning line.

Next, the first to third, tenth to twelfth, ...
Print signal D of the other half of the 1720th to 1722th pixels
ATA is input to and transferred to the shift registers SR1 to SRn in synchronization with the clock signal CLK, and a total of 64 print signals DATA are converted into parallel data in each drive circuit. Next, when the strobe signal STB2 is inverted to the low level, the switching elements T1 to Tn are selectively turned on based on the print signal DATA stored in the shift registers SR1 to SRn, and the heating resistor R1 is turned on.
~ R3, R10 to R12, ..., R1720 to R1722
Strobe signal STB2 is input to drive circuit 3
An electric current selectively flows through the heating resistor connected to the heat generating resistor to generate heat, and the recording medium is heated to perform the printing operation of 1/6 of one scanning line.

Similarly, the heating resistors R4 to R6, R13 to R15, ..., R172 connected to the common electrode VH2 are similarly processed.
3 to R1725 are two select signals SEL1 and SEL
2 drives in a time division manner. Furthermore, the common electrode VH3
, R17 to R9, R16 to R18, ..., R17 connected to
26 to R1728 are likewise two select signals SE.
It is time-divisionally driven by L1 and SEL2. In this way, by adopting the configuration in which the latch circuit is omitted,
It is possible to reduce the size of the drive circuit.

[0049]

As described above in detail, according to the present invention, it is not necessary to form a multilayer wiring portion on the substrate of the thermal head, and the number of drive circuits can be reduced, so that the manufacturing cost of the thermal head can be reduced. And the manufacturing yield can be improved.

[Brief description of drawings]

FIG. 1 is a perspective view showing a thermal head which is an embodiment of the present invention.

FIG. 2 is a partially enlarged plan view of the thermal head shown in FIG.

3 is a sectional view taken along line XX of FIG.

FIG. 4 is a cross-sectional view taken along the line YY of FIG.

FIG. 5 is a circuit diagram showing an electrical configuration of a thermal head that is an embodiment of the present invention.

FIG. 6 is a bottom view showing the arrangement of electrode pads of the drive circuit 3 which is a flip chip.

7 is a partially enlarged view in the vicinity of A in FIG. 5 showing a connection pattern between each heating resistor and the electrode pad of the drive circuit 3. FIG.

FIG. 8 is a circuit diagram showing an electrical configuration of an example of a drive circuit 3.

9 is a timing chart showing the operation of the drive circuit 3 of FIG.

FIG. 10 is a circuit diagram showing an electrical configuration of another example of the drive circuit 3.

11 is a timing chart showing the operation of the drive circuit 3 of FIG.

FIG. 12 is a circuit diagram showing an electrical configuration of another example of the drive circuit 3.

13 is a timing chart showing the operation of the drive circuit 3 of FIG.

FIG. 14 is a circuit diagram showing an electrical configuration of another example of the drive circuit 3.

15 is a timing chart showing the operation of the drive circuit 3 of FIG.

FIG. 16 is a circuit diagram showing an electrical configuration of an example of a conventional thermal head.

17 is a circuit diagram showing an example of a drive circuit 9 shown in FIG.

18 is a timing chart showing the operation of the drive circuit 9 of FIG.

FIG. 19 is a circuit diagram showing an electrical configuration of another example of the conventional thermal head.

[Explanation of symbols]

 3 Drive Circuits 4a, 4b, 4c Electrode Pad Row 14 Heat Dissipator 15, 17 Substrate 16 Adhesive Layer 18 Glaze Layer 20, 22 Through Hole 21 Individual Electrode 23, 24 Conductor 30 Heating Resistor Layer 31 Common Electrode

Claims (1)

[Claims] 1. A plurality of heating resistors, a shift register for converting a print signal composed of serial data into parallel data, and a current flowing through each heating resistor based on an output of the shift register and a control signal from the outside. In a thermal head having a drive circuit having a plurality of switching elements for controlling, the drive circuit is composed of a flip chip having a plurality of electrode pads on the bottom surface, and the control signal of each switching element or the output of each switching element is A thermal head having a plurality of branches, the output of which is connected to an electrode pad connected corresponding to each heating resistor.