Printer control apparatus for synchronously controlling driving of recording head and transfer of data

A control apparatus of a printer causes a recording head to form an image by a dot matrix while scanning the recording head in a predetermined direction relative to a recording medium. The control apparatus includes a transfer unit for transferring recording data stored in a memory to the recording head, a drive control unit for driving and controlling scanning of the recording head, and a synchronizing unit for synchronously driving the transfer unit and the drive control unit.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a printer control apparatus. 
2. Related Background Art 
A so-called serial type recording apparatus (to be referred to as a serial 
printer hereinafter) having a movable part (to be referred to as a 
carriage hereinafter) with a recording head reciprocative in a direction 
perpendicular to a feed direction of a recording medium (to be referred to 
as a recording sheet or a sheet hereinafter) such as a sheet of paper or 
an OHP sheet is proposed in various forms of recording heads according to 
various recording schemes. Recording heads used in serial printers and, 
particularly, a printer for forming character, graphic, and other images 
by a dot matrix are classified into a wire dot recording head, a 
heat-sensitive recording head, a thermal transfer recording head, and an 
ink-jet recording head. 
In a conventional printer of this type, processing for developing recording 
character codes or the like into dot data and transferring the dot data to 
a recording head is performed by a central processing unit (CPU). 
When a recording speed is increased, carriage control, print data 
conversion, and its transfer cannot cope with the recording speed by 
processing of the CPU itself. In order to solve this problem, a line 
buffer for storing a one-scanning component (i.e., one-line data) of the 
recording data (print data) for the recording head is arranged, the print 
data is converted in advance, and the converted data is transferred. 
However, in so-called bidirectional printing for recording data during 
reciprocal movement of the carriage, the carriage is completely stopped 
during development of the next data upon completion of one-line printing, 
resulting in inconvenience. 
When print data transfer is performed by only hardware, the CPU is 
overloaded to align the currently transferred data with the carriage 
position although the CPU is free from transfer of data which is being 
currently printed, and the problem posed by high-speed printing cannot yet 
be solved. 
In an arrangement for recording data while the data is being exchanged with 
a host device, data exchange must be performed even during printing. When 
high-speed printing is to be performed, contention occurs between an 
interruption of an interface arranged to exchange the data and the 
printing operation, thus posing another problem. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to solve the conventional problems 
described above. 
It is another object of the present invention to provide a printer control 
apparatus for causing a recording head for forming an image by a dot 
matrix to record an image by scanning the recording head in a 
predetermined direction, comprising drive control means for driving and 
controlling scanning of the recording head, communication means for 
performing communication of data associated with recording, and 
synchronizing means for synchronously driving the communication means and 
the drive control means. 
It is still another object of the present invention to cause the 
synchronizing means to drive transfer means in synchronism with the 
communication means and the drive control means, the transfer means being 
arranged to transfer data to the recording head from storage means for 
storing recording data to be supplied to the recording head. 
It is still another object of the present invention to provide a printer 
control apparatus, wherein a circuit for driving and controlling scanning 
of the recording head and a data communication circuit are synchronously 
driven to reduce the load of the CPU to perform high-speed printing, and 
wherein the circuit for transferring data from the storage means for 
storing recording data to the recording head can also be controlled in 
response to the common synchronization signal, thereby further reducing 
the load of the CPU. 
It is still another object of the present invention to provide a printer 
control apparatus for causing a recording head for forming an image by a 
dot matrix to record an image by scanning the recording head in a 
predetermined direction, comprising transfer means for transferring data 
to the recording head from storage means for storing the recording data to 
be supplied to the recording head, drive control means for driving and 
controlling scanning of the recording head, and synchronizing means for 
synchronously driving the transfer means and the drive control means. 
It is still another object of the present invention to provide a printer 
control apparatus wherein a circuit for transferring data from storage 
means for storing recording data to a head and a circuit for driving and 
controlling scanning of the recording head are controlled by a common 
synchronization signal, so that a CPU can be concentrated on data 
conversion of the next line during printing, thereby performing high-speed 
recording. 
It is still another object of the present invention to provide a printer 
control apparatus for causing a recording head for forming an image by a 
dot matrix to record an image by scanning the recording head in a 
predetermined direction, comprising transfer means for supplying recording 
data to the recording means from storage means for storing the recording 
data to be supplied to the recording head, drive control means for driving 
and controlling scanning of the recording head, and synchronizing means 
for synchronously driving the transfer means and the drive control means. 
It is still another object of the present invention to provide a printer 
control apparatus for causing a recording head for forming an image by a 
dot matrix to record an image by scanning the recording head in a 
predetermined direction, comprising drive control means for driving and 
controlling scanning of the recording head, communication means for 
performing recording data communication, and synchronizing means for 
synchronously driving the communication means and the drive control means.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Preferred embodiments of the present invention will be described in detail 
with reference to the accompanying drawings. The present invention may be 
applied to a system constituted by a plurality of devices or a system 
constituted by a single device. The present invention is also applicable 
to software in which programs run in a system or apparatus to perform 
predetermined processing. 
FIGS. 1A and 1B are perspective views showing an outer appearance of an 
electronic typewriter as an apparatus capable of employing the present 
invention. 
The electronic typewriter includes a keyboard 1 which has keys 2 including 
character input keys (alphanumeric keys) and control keys. The keyboard 1 
can be folded upon pivotal movement of the keyboard 1 about a hinge 3, as 
shown in FIG. 1B. A paper feed tray 4 feeds a sheet-like recording medium 
to a printer. When the typewriter is not used, the paper feed tray 4 is 
folded to cover the printer, as shown in FIG. 1B. The electronic 
typewriter also includes a feed knob 5 for manually setting a recording 
medium or removing it, a display 6 for displaying an input sentence or the 
like, and a handle 7 used to carry the electronic typewriter. 
FIG. 2 shows an arrangement of the printer according to this embodiment. 
A head cartridge 9 has an ink-jet recording head to be described in detail 
with reference to FIGS. 3 and 4. A carriage 11 carries the head cartridge 
9 thereon and scans it in directions indicated by a double-headed arrow S. 
A hook 13 mounts the head cartridge 9 on the carriage 11. The hook 13 is 
operated by a lever 15. A marker 17 is formed on the lever 15 to indicate 
a scale to read a print position and a set position of the recording head. 
A support plate 19 supports an electrical connector for the head cartridge 
9. A flexible cable 21 connects the electrical connector and a controller 
in the main body. 
A guide shaft 23 reciprocally guides the carriage 11 in the directions of 
the arrow S and is inserted into a bearing 25 of the carriage 11. A timing 
belt 27 is fixed to the carriage 11 and transmits a mechanical power to 
move the carriage 11 in the directions of the arrow S. The timing belt 27 
is looped around pulleys 29A and 29B arranged at both sides of the 
typewriter. A driving force is transmitted from a-carriage motor 31 to the 
pulley 29B through a transmission mechanism such as a gear mechanism. 
A convey roller 33 defines a recording surface of a recording medium (to be 
also referred to as a recording sheet) and conveys the recording sheet 
during recording. The convey roller 33 is driven by a convey motor 35. A 
paper pan 37 guides a recording medium from the paper feed tray 4 to a 
recording position. Feed rollers 39 are located in a recording medium feed 
path and urge the recording medium against the convey roller 33 and convey 
the recording medium. A platen 34 is located at a position opposite to jet 
ports of the head cartridge 9 and defines the recording surface of the 
recording medium. Discharge rollers 41 are located from the upstream side 
to the recording position and the downstream position of the recording 
medium convey direction to discharge the recording medium toward a 
discharge port (not shown). Spurs 42 are arranged in correspondence with 
the discharge rollers 41 and urge the rollers 41 toward the recording 
medium to cause the discharge rollers 41 to generate a convey force for 
the recording medium. A release lever 43 releases biasing of the feed 
rollers 39, a press plate 45, and the spurs 42 at the time of setting a 
recording medium. 
The press plate 45 prevents the recording medium from floating near the 
recording position and assures a tight contact state of the recording 
medium with respect to the convey roller 33. In the main body, the 
recording head is an ink-jet recording head for performing recording by 
injecting ink. A distance between the ink jet port forming surface of the 
recording head and the recording surface of the recording medium is 
relatively small. At the same time, a distance between the recording 
medium and the jet port forming surface must be strictly controlled in 
order to prevent their contact. Therefore, it is very effective to prevent 
this contact by arranging the press plate 45. A scale 47 is formed on the 
press plate 45, and a marker 49 is formed on the carriage 11 in 
correspondence with the scale 47. The print position and set position of 
the recording head can be read. 
A cap 51 made of an elastic material such as rubber is formed at a home 
position opposite to the ink jet port forming surface of the recording 
head. The cap 51 is brought into contact with or separated from the 
recording head. The cap 51 is used to protect the recording head in a 
non-recording mode or to restore ejection of the recording head. Ejection 
recovery processing is to drive energy generation elements arranged inside 
the ink jet ports and utilized to eject ink and to eject the ink from all 
jet ports, thereby removing bubbles, dust, and a viscous ink not suitable 
for recording (this operation is called a preliminary jet operation), and 
to eliminate any defective jets by forcibly ejecting the ink from the jet 
ports. 
A pump 53 applies a suction force for forcible ink discharge and draws ink 
during jet recovery processing by forcible discharge or jet recovery 
processing by the preliminary jet operation. A waste ink tank 55 stores 
waste ink drawn by the pump 53, and a tube 57 causes the pump 53 and the 
waste ink tank 55 to communicate with each other. 
A blade 59 wipes the jet port forming surface and can be moved between a 
position where the blade 59 extends toward the recording head to wipe the 
ink during head movement and a retracted position where the blade 59 is 
not engaged with the jet port forming surface. The arrangement shown in 
FIG. 2 also includes a motor 61, and a cam device 63 for receiving power 
from the motor 61 and drives the cap 51 and the blade 59. 
A detailed arrangement of the head cartridge 9 will be described below. 
FIG. 3 is a perspective view showing the outer appearance of the head 
cartridge 9 integrally having a jet unit 9a serving as an ink-jet 
recording head main body and an ink tank 9b. Referring to FIG. 3, a 
ratchet 906e is formed on the cartridge 9 to engage with hook 13 of 
carriage 11 to mount the head cartridge 9 thereon. As is apparent from 
FIG. 3, the ratchet 906e is formed inside the entire length of the 
recording head. A positioning abutment (not shown) is formed near the jet 
unit 9a of the head cartridge 9. A head opening 906f receives a flexible 
board (electrical connector) standing on the carriage 11 and a support 
plate for supporting a rubber pad. 
FIGS. 4A and 4B show exploded and perspective views of the head cartridge 
shown in FIG. 3. The head cartridge may be of a disposable type integrally 
including an ink storage tank serving as an ink source. 
Referring to FIG. 4A, a heater board 911 on which an electrothermal 
conversion element (jet heater) and a wiring of, e.g., A1 for supplying 
power to the electrothermal conversion element are formed on an Si 
substrate by a film formation technique. A wiring board 921 is arranged 
for the heater board 911, and the corresponding wiring lines are connected 
by wire bonding or the like. 
A top plate 940 has a partition wall for defining an ink path and a common 
liquid chamber. In this embodiment, an orifice plate portion is integrally 
made of a resin material. 
The heater board 911 and the top plate 940 are sandwiched between a metal 
support 930 and a press spring 950, so that the heater board 911 and the 
top plate 940 are brought into tight contact with and fixed to each other. 
However, note that the support 930 may be adhered to the wiring board 921, 
and the support 930 may have a positioning reference for the carriage 11 
for scanning the recording head. The support 930 also serves as a member 
for dissipating heat and cooling the heater board 911 upon driving of the 
typewriter. 
A supply tank 960 serves as a sub-tank for receiving an ink from the ink 
tank 9b serving as an ink source and guiding an ink to a common liquid 
chamber formed between the heater board 911 and the top plate 940. A 
filter 970 is located inside the supply tank 960 near an ink supply port 
to the common liquid chamber. The supply tank 960 has a lid member 980. 
An absorber 900 is arranged in the ink tank main body 9b. A supply port 
1200 supplies ink to the recording element consisting of the members 911 
to 980. Before the unit is arranged in a portion 1010 of the ink tank main 
body 9b, an ink is injected into the supply port 1200 to cause the 
absorber 900 to absorb the ink. 
The cartridge main body has a lid member 1100. An outer air communication 
port 1300 is formed in the lid member 1100 to cause the interior of the 
cartridge to communicate with cuter air. A liquid repellant 1300A is 
located inside the outer air communication port 1300 to prevent the ink 
from leaking from the outer air communication port 1300. 
When the ink tank 9b is completely filled with the ink through the supply 
port 1200, the jet unit 9a consisting of the members 911 to 980 is located 
at the portion 1010. In this case, positioning or fixing can be performed 
by fitting projections 1012 formed on the ink tank main body 9b into holes 
931 formed in the support 930, thereby finishing the head cartridge 9 
shown in FIG. 4B. 
The ink is supplied from the interior of the cartridge to the supply tank 
960 through the supply port 1200, a hole 932 formed in the support 930, 
and a guide port formed in the lower surface of the supply tank 960 in 
FIG. 4A. The ink passes through the supply tank 960 and flows from the 
guide port to the common liquid chamber through an appropriate supply tube 
and an ink guide port 942 of the top plate 940. Packings made of silicone 
rubber, butyl rubber, or the like are fitted in the connecting portions of 
the above ink communication, thereby assuring sealing and an ink supply 
path. 
FIGS. 5A and 5B are a plan view and a left side view, respectively, showing 
a detailed structure of the carriage 11. 
Referring to FIGS. 5A and 5B, a support plate 606 extends upright from the 
bottom portion of the carriage 11. The support plate 606 supports a 
flexible board 604 and supports rubber pads 605 having projections 605A 
formed in correspondence with terminal pads formed on the board 604. 
An abutment member 607 stands upright on the bottom of the carriage in 
front of the support plate 606. The abutment member 607 has a small 
thickness to assure a maximum ink tank space within the limited space of 
the head cartridge 9 and the carriage 11. For this reason, three ribs 608 
are formed on the member 607 to reinforce the strength of the member 607. 
An extension direction of each rib 608 is a movement direction of the 
carriage 11 so as to provide a high strength corresponding to a turning 
direction during mounting/removal of the head cartridge. The ribs 608 are 
formed so that they extend from the jet surface of the head cartridge 9 by 
about 0.1 mm when the head cartridge 9 is mounted. Therefore, even if the 
recording sheet extends into the movement path of the recording head due 
to some reason, the recording sheet is not brought into contact with the 
jet surface, so that damage to the jet surface can be prevented. 
The operation lever 15 for attaching or detaching the head cartridge is 
supported on the carriage 11 to be pivotal about a shaft 601d. The hook 13 
is used to attach or detach the head cartridge 9 when part of the hook 13 
is engaged with the head cartridge 9 upon movement of engagement of the 
hook 13 with part of the operation lever 15. The hook 13 performs 
attachment or detachment described above since an elongated hole 603c 
formed in the hook 13 is guided by a guide shaft 601e formed on the 
carriage 11. 
Since an attaching/detaching mechanism including the operation lever 15 and 
the hook 13 is arranged sideways the carriage 11, i.e., the mechanism is 
arranged in the movement direction of the carriage 11, the mechanism does 
not occupy a large dead space during movement of the carriage. 
The positioning abutment portion for mounting the head cartridge will be 
described below. 
Horizontal positioning abutment portions 601a are formed at side portions 
of the abutment member 607. Horizontal positioning is performed by an 
abutment portion 601f formed on the support plate 606 in addition to the 
abutment portion 601a. 
An abutment portion 601b is used to position the head cartridge in the 
back-and-forth direction and is formed at a lower side portion of the 
abutment member 607. 
Abutment portions 601c are used to position the head cartridge in the 
vertical direction and are formed at a lower side portion of the abutment 
member 607 and a lower side portion of the support member. 
FIGS. 6A and 6B are a plan view and a left side view, respectively, showing 
a state wherein the head cartridge 9 is mounted on the carriage 11. 
Referring to FIGS. 6A and 6B, an abutment portion 906a is formed on the 
head cartridge 9 to be brought into contact with the abutment portion of 
the carriage 11 at the time of mounting the recording head. Abutment 
portions 906b and 906c correspond to the abutment portions 601b and 601c. 
Engaging relationships of the respective parts upon mounting of the 
recording head will be generally described with reference to FIG. 6A. 
The abutment portion 906a of the head cartridge 9 abuts against the 
abutment portion 601a. At the same time, the abutment portion 906a and a 
ratchet 906 of the head cartridge 9 receive a left force by a biasing 
force of a coil spring 610 through the hook 13. Therefore, the head 
cartridge 9 receives a moment rotated about the above abutment. At this 
time, a board 906d formed in the head abuts against an abutment portion 
601f. As a result, the horizontal positioning of the head cartridge 9 is 
performed, and this position is maintained. 
A projection 605A of the, rubber pad 605 is compressed and deformed by 
contact with the board 906d. By this deformation, a force is generated to 
bring the terminal pad of the flexible board 604 into tight contact with 
the terminal of the board 906d. In this case, since the abutment portion 
601f is kept in contact with the board 906d, a deformation amount of the 
projection 605A is kept constant, thereby obtaining a stable contact 
force. 
In FIGS. 6A and 6B, a compressed and deformed state of the projection 605A 
is not illustrated. 
Positioning of the head cartridge 9 in the back-and-forth and vertical 
directions is performed during mounting of the head cartridge 9. 
FIG. 7 shows an arrangement of a control system in a character processing 
apparatus according to this embodiment. 
A CPU 100 comprises a microprocessor serving as a main controller. The CPU 
100 performs predetermined processing on the basis of data input from the 
keyboard 1 and control signals. A quartz oscillator 102 generates 
fundamental clocks which define operation timings of the respective 
components. A ROM 104 stores programs corresponding to recording control 
sequences executed by the CPU 100 and other permanent data. A RAM 106 has 
storage areas for work data used as registers and a development area for 
documents (texts). A ROM 108 is used as a character generator. A display 
controller 110 causes a display such as a liquid crystal display (LCD) to 
display data. 
A head controller 114 (to be described in detail with reference to FIG. 12) 
generates control signals (COM1 to COM8 and SEG1 to SEG8) for a head 
driver 116 for driving jet energy generation elements of the jet unit 
(recording head) 9a. A motor driver 118 drives the carriage motor 31 and 
the convey motor 35. The drive control signals COM1 to COM4 for the 
carriage motor 31 are supplied from the head controller 114, and drive 
control signals PM1 to PM4 for the convey motor 35 are supplied from the 
CPU 100. 
A RAM 120 serves as a buffer for storing one-line received data or one-line 
recording data obtained by processing the one-line received data. An 
address data bus 122 connects the components 104, 106, 108, 110, and 114. 
A control signal R/W switches the read and write states of the components 
104 to 108 and 114. 
FIG. 8 shows an electrical arrangement of the recording head and the head 
driver 116. 
In this embodiment, the jet unit 9a has 64 jet ports. Reference characters 
#1 to #64 represent numbers corresponding to the positions of the jet 
ports formed in the jet unit 9a. Heating resistors R1 to R64 serve as jet 
energy generation elements formed in correspondence with the jet ports #1 
to #64. The heating resistors R1 to R64 are divided into blocks each 
consisting of eight heating resistors. Switching transistors Q1 to Q8 in a 
common driver circuit C are respectively connected to the blocks. The 
transistors Q1 to Q8 are turned on/off to connect/disconnect the 
energization path in response to control signals COM1 to COM8. Diodes D1 
to D64 are arranged in energization paths for the heating resistors R1 to 
R64 to prevent a reverse flow. 
On/Off transistors Q9 to Q16 in a segment driver S are connected to 
corresponding heating resistors of the respective blocks. The transistors 
Q1 to Q16 are turned on/off to connect/disconnect the energization paths 
for the heating resistors in response to ON/OFF states of control signals 
SEG1 to SEG8. FIG. 9 is a timing chart for driving the head having the 
above-mentioned arrangement. The common control signals COM8 to COM1 are 
sequentially turned on at a given position in the head driving direction. 
Upon turning on of each common signal, one corresponding block is selected 
to be energized. Therefore, segment-control signals SEG8 to SEG1 are 
turned on/off in accordance with the image to be recorded within the 
block. Thus, the heating resistors are selectively energized to eject the 
ink upon heating, thereby performing dot recording. 
FIG. 10 is a circuit diagram showing the main part of the carriage motor 31 
and the motor driver 118, and FIG. 11 is a timing chart for driving the 
carriage motor 31 and the motor driver 118. In this embodiment, the 
carriage motor 31 comprises a stepping motor having coils .phi.1 to 
.phi.4. The switching transistors Tr1 to Tr4 connected to the respective 
coils are properly driven in response to drive signals CM1 to CM4, thereby 
driving the motor in accordance with a two-phase excitation scheme, as 
shown in FIG. 11. 
FIG. 12 is a block diagram showing a detailed arrangement of the head 
controller 114 according to this embodiment. 
A print timing pulse generator 151 receives from the CPU 100 a signal 
(start signal) for instructing data read access from a recording data 
storage area of the buffer so as to start recording and outputs the 
recording head drive control signals COM1 to COM8 and SEG1 and SEG8 at 
timings based on the clock signals CLK. In the buffer or RAM 120, PB 
serves as an area (print buffer) having a one-line data capacity and for 
developing printing data; and IB, an area (reception buffer) for 
developing data received for recording. An address of one of the areas PB 
and IB is selected by a selector 153. 
An address counter 155 comprises an up/down counter. A start address in the 
recording data development area PB stored in a start address register 157 
is set in the address counter 155. In response to a start signal, the 
counter 155 performs a count-up operation in response to the clock signal 
CLK and outputs a count value. This count value represents a read address 
of the recording data development area PB, i.e., a print address read out 
for recording (print). A comparator 159 compares a print address output 
from the address counter 155 with an end address of the area PB which is 
stored in an end address register 161. The comparator 159 determines a 
coincidence between these two addresses, i.e., an end of read access to 
the set end address. 
The print timing pulse generator 151 disables an enable signal EN1 for 
enabling an operation of the address counter 155 during a period except 
for a period for generating the signals COM1 to COM8 and stops an 
operation of a gate 163. The operation of the address counter 155 is also 
stopped when the comparator 159 outputs a coincidence signal. 
A dot step counter 165 receives the clock signal CLK, i.e., a clock CLK for 
determining a print timing and outputs a signal for driving the carriage 
motor 31 as a stepping motor stepwise every predetermined number of dots 
in the scanning direction. The signal as a shift clock from the dot step 
counter 165 is input to a shift register 167 for generating the excitation 
signals CM1 to CM4. A start phase pattern register 169 sets a phase 
pattern at the start of the carriage motor 31. 
In this embodiment, the address counter 155 comprises an up/down counter, 
and the shift register 167 comprises a bidirectional register. The 
counting direction of the address counter 155 is switched in response to, 
e.g., a scanning direction switching signal (direction signal) supplied 
from the CPU 100 to change the read order of the data from the recording 
data buffer PB. At the same time, the shift direction of the shift 
register 167 is changed to change the rotational directs on of the motor 
31, thereby performing so-called bidirectional printing. In this 
embodiment, an ACCEL/DECEL controller 171 is arranged to supply an 
acceleration/deceleration shift clock different from the shift clock 
output from the dot step counter 165 so as to cause the motor speed to 
reach a recording speed before the carriage reaches the recording area in 
the carriage scanning direction and to immediately stop the carriage motor 
after the recording area. The ACCEL/DECEL controller 171 includes a 
frequency divider or a doubler for dividing or doubling a predetermined 
clock signal (the clock signal CLK may be used) at a predetermined 
frequency division or doubling ratio, a memory (e.g., a predetermined area 
of the ROML 104) for storing a frequency division or doubling ratio table 
corresponding to an acceleration or deceleration pattern, and the like. 
An IB control counter 175 outputs an IB address (reception address) signal 
for a destination to the selector 153 when received data is to be stored 
in the reception buffer IB. A start address of the reception buffer IB 
which is stored in an IB start address register 177 is set in the IB 
control counter 175. The IB control counter 175 starts a count-up 
operation in response to a write signal, continues it in synchronism with 
the clock signal CLK, and outputs a count value. A comparator 179 compares 
the reception address output from the counter 175 with the end address of 
the reception buffer IB which is stored in an IB end address register 181. 
The comparator 179 determines a coincidence between these two addresses, 
i.e., an end of storage of the received data until the set IB end address. 
The print timing pulse generator 151 disables the enable signal EN1 for 
enabling an operation of the IB control counter 175 during a period of 
generating the signals COM1 to COM8. At this time, the operation of the 
counter 175 is stopped and outputs a busy signal BUSY to the data 
transmission source, thereby informing that the data cannot be received. 
The operation of the counter 175 is stopped when the comparator 179 
determines a coincidence between the IB end address and the reception 
address. 
A data source H serves as a host device for the head controller. Referring 
to FIG. 7, the data source H may be an equipment 132 connected to the data 
bus 122 through a CENTRONIC interface 131, or may be the RAM 106 for 
storing document data (text) input from such an equipment without 
processing. The data received from the data source H is developed in the 
reception buffer IB, and the stored data is read out at an appropriate 
timing prior to recording. The readout data is processed in an appropriate 
recording format and is stored in the recording data buffer PB. 
The registers 157, 161, 169, 177, and 181 can be allocated as predetermined 
areas of the RAM 106. 
FIG. 13 shows a data format of a memory area of the recording data buffer 
area PB and the reception buffer area IB in the RAM 120. In this manner, 
the recording data buffer area PB is defined ranging from a print start 
address PBSTART to a print end address PBEND, which are represented by the 
contents of the start address register 157 and the end address register 
161. The reception buffer area IB is defined ranging from a received data 
start address IB START to a received data end address IB END, which are 
represented by the contents of the IB start address register 177 and the 
IB end address register 181. PB POINT in FIG. 13 represents a pointer 
(print end address pointer) representing an address of an end of printing 
in the recording data buffer area PB and corresponds to the content of the 
address counter 155. IB DATA represents an address (data reception end 
address) of an end of data reception in the reception buffer area IB and 
is associated with the content of the counter 175. 
FIG. 14 is a view for explaining an address map of the recording data 
buffer area PB. 8-bit data are respectively stored at addresses "00" to 
"FF" (these addresses will be represented as addresses $00 to $FF 
hereinafter). One bit corresponds to one dot of recording data. The number 
of bits included in each of the address groups $00 to $07, $08 to $0F, . . 
. $F8 to $FF correspond to 64 dots in the recording elements. In each 
address group, the bits correspond to the jet port numbers #1 to #64, as 
shown in FIG. 14. One-line (i.e., a line recorded by one recording head 
operation) data is developed in the data buffer area PB. For the 
illustrative convenience, the data are illustrated up to address $FF. 
In contrast to the structure of the recording data buffer area 
corresponding to the actual dot recording data, the reception buffer IB 
stores data in the form of, e.g., codes, received from the data source H. 
The reception buffer IB is smaller than the area PB. 
FIG. 15 is a timing chart showing output timings of the signals COM8 to 
COM18 in the recording mode, output timings of the motor drive signals CM1 
TO CM4, data reception timings, and selection timings of the areas PB and 
IB. In FIG. 15, one dot in the scanning direction is caused to correspond 
to one step of the motor. 
As shown in FIG. 15, the buffer area PB is selected to record data at a 
given position in the scanning direction. Addresses (e.g., $00 to $07) at 
which data to be printed are stored at this position are sequentially 
selected, and the signals COM8 to COM1 are sequentially output. The 
signals SEG8 to SEG1 are sequentially output at output timings in 
correspondence with the data shown in FIG. 9, thereby performing 
recording. The buffer area IB is selected at the end of recording at this 
position, and the received data is stored. 
FIG. 16 is a flow chart showing an operation sequence in the recording mode 
according to this embodiment. 
When this sequence is started, the recording data buffer area PB is 
entirely cleared to prepare for writing recording data in step S1. In step 
S3, various registers are set, i.e., a dot count per step, the start and 
end addresses PBSTART and PBEND of the buffer PB, the recording direction, 
the start phase pattern of the carriage motor 31, and the like are set. 
The one-line character codes read out from the reception data buffer IB 
are stored in a predetermined area of, e.g., the RAM 106 by using the 
CGROM 108. The stored data serves as dot data of the first line and is 
written in the recording data buffer PB. 
In step S7, the print start signal is output to the address counter 155 and 
the print timing pulse generator 151 to start a printing operation. During 
printing, data of the next line corresponding to the end-of-print address 
position of the buffer PB is written. More specifically, the present value 
of the address counter 155 is compared with the storage address of the 
next data (step S9). When the data of the present line is determined as 
printed data, data of the next line is written at this address (step S11). 
This write operation is performed by using a period between the common 
drive signals, i.e., a period A in FIG. 15. Since the recording operation 
is performed by operations of the address counter and the timing pulse 
generator, the CPU 100 can perform other processing during any duration of 
the common drive signals. Reception and processing of data to be stored in 
the recording data buffer PB will be described later with reference to 
FIG. 17. 
Operations in steps S9 and S11 are performed for each recording position in 
the scanning direction (step S13). The data of the next line is developed 
in the buffer area PB at the end of recording of data of one line. At the 
end of one-line printing, the recording medium is conveyed by a 
predetermined amount, and re-setting of the scanning direction for 
performing reciprocative printing is performed in step S15. The procedures 
after step S7 are repeated until one-page printing is completed. 
FIG. 17 is a flow chart showing an operation of data reception performed 
after the common signals COM8 to COM1 are output in FIG. 15, i.e., after 
recording is performed at a given position in the scanning direction. 
In this control sequence, the received data end address IB END is set in 
the register 181 in step S21. In step S23, the received data start address 
IB START is set in the register 177. 
In step S25, the received data end address IB END is compared with the 
end-of-data reception address IB DATA. If a coincidence between these 
addresses is detected, since data reception of one line has been 
completed, a signal informing that data reception cannot be performed is 
sent to the data source H. However, if NO in step S27, transmission is 
enabled in step S29. The operations in steps S25, S27, and S29 are 
performed such that the BUSY signal is output from the IB control counter 
175 at the time of comparison or detection of a coincidence or 
noncoincidence, or at the time of release. The data source performs data 
transmission in accordance with the transmission enable operation (release 
of the BUSY signal). 
In step S31, the present values of the end-of-data reception address IB 
DATA and the start address IB START are compared with each other. If a 
coincidence is detected, the data source H does not transmit data, so that 
the CPU waits for data reception. However, when a coincidence is detected, 
the flow advances to step S33, and the content of the address represented 
by the present value of the address IB START is read out and developed 
into dot data. In this manner, the data is stored in a predetermined area 
of the RAM 106. The stored data is developed in the recording data buffer 
PB at an appropriate timing during recording, as described above. 
The value of the address IB START is incremented by one in step S35. The 
CPU then determines in step S37 whether the value exceeds the IB END. If 
YES in step S37, the CPU determines that read access of the one-line 
received data is completed. In this case, this flow is ended. However, if 
NO in step S37, the flow returns to step S25, and the operations in the 
subsequent steps are repeated. 
As described above, according to this embodiment, the print timing pulse 
generator 151 serving as a circuit for transferring the data from the 
recording data buffer PB to the recording head and the dot step counter 
165 serving as a circuit for controlling movement of the carriage are 
controlled by the common sync signals, so that the CPU 100 concentratedly 
performs other processing such as data storage of the next line during 
printing. Therefore, the present invention can cope with high-speed 
printing in the printer. In addition, these circuits are synchronized with 
the IB control counter 175 for controlling data reception, so that the 
load on the CPU 100 during printing can be further reduced, and the print 
throughput can be further increased. 
FIG. 18 shows a relationship between the excitation phase switching time of 
the carriage motor 31 usable in this embodiment and the carriage speed in 
the above embodiment. 
At positions before and after the printing area in which the carriage is 
moved at a constant speed, the carriage is immediately accelerated from an 
initial speed V.sub.0 (=0) to a recording speed V.sub.1 (time t.sub.0 to 
time t.sub.1) and is then decelerated from the speed V.sub.1 to zero (time 
t.sub.3 to time t.sub.4) by the ACCEL/DECEL CONTROLLER 171. As soon as the 
acceleration interval is changed to the constant speed interval, 
overshooting or undershooting occurs, and an allowable recording speed may 
not be necessarily obtained. For this reason, as shown in FIG. 18, a 
region in which printing is not performed during the time interval 
(t.sub.1 to t.sub.2) until the speed is stabilized may be provided, and 
printing is not performed until the speed falls within the allowable speed 
range. A buffer area corresponding to a few dots from the print start 
address PB START in the scanning direction is used as a non-print area 
(i.e., an area in which "0"s are written). The non-print area can be made 
variable in accordance with a recording speed and an acceleration pattern. 
In the above embodiment, data of the next line is written in the buffer PB 
during recording. However, it is preferable to clear the write address 
prior to the above write access of the buffer PB. For this purpose, when 
an address from which print data is read out is immediately cleared, data 
can be directly written at this address even if the address is not cleared 
at the time of write access of data of the next line, resulting in 
convenience. For example, a circuit for clearing the address before the 
address counter value is updated after data is read out from a set address 
can be added to the print timing pulse generator 151. 
However, when an image in addition to characters is to be recorded using 
the typewriter of this embodiment, bidirectional printing is preferably 
inhibited, but recording by one-directional scanning is preferred to 
improve image quality. In this case, upon completion of one-line 
recording, the carriage return is performed to return the carriage to a 
predetermined position. When the carriage return is synchronized with the 
operation of the print timing pulse generator 151, the stored data of the 
next line is cleared upon a carriage return. During the carriage return 
during image recording, clearing or the like is not performed. For this 
purpose, a read/write signal is not sent to the buffer memory 120 to stop 
outputting data from the buffer memory 120. 
In addition, it is effective to add a command for forcibly stopping an 
operation of each component during printing. For example, a forcible stop 
is often required to open the typewriter cover to restart printing. When 
such a command is input, and the interrupted addressing state is 
maintained, the operation is started from the next address at the 
lowermost printing position. Therefore, the operation need not be 
restarted from the beginning. 
Furthermore, the above description has been associated with data reception 
from the data source serving as a host device. However, the present 
invention can be applied to a data transmittable interface portion which 
is then synchronized in data access. This arrangement is effective to 
transfer data to an external device. 
Moreover, the present invention is applicable when a recording head 
including a shift register, a latch, and a driver is to be used to 
serially transfer data. In this case, as shown in FIG. 20, serial data is 
output, data is stored by a shift clock (SCLK) signal and a latch (LATCH) 
signal, and data is output in response to a heat (HEAT) signal. When a 
motor excitation phase (CM) is switched upon heating, the motor operations 
can be synchronized with the heating timings. In addition, in 
consideration of a reception interface, received data may be read after 
one-line data is sent, and then the phase may be switched. 
In the above embodiment, the recording head is exemplified by an ink-jet 
recording head. However, a thermal head may be used in place of the 
ink-jet recording head. 
When the present invention is applied to an ink-jet recording apparatus, a 
bubble-jet recording head provides a best effect in the recording 
apparatus. According to this system, high-density, high-precision 
recording can be achieved. 
Typical arrangements and principles of the above system are preferably 
achieved by using fundamental principles disclosed in U.S. Pat. Nos. 
4,723,129 and 4,740,796. These systems can be applied to any one of a 
so-called on-demand scheme and a continuous scheme. In particular, in an 
on-demand scheme, at least one drive signal is applied to an 
electrothermal converter arranged in correspondence with a liquid path or 
a sheet which holds a liquid (ink) to apply an abrupt temperature rise 
exceeding film boiling in correspondence with recording information, 
thereby generating heat energy in the electrothermal converter, thereby 
causing film boiling on a heat-receiving surface of the recording head. As 
a result, a bubble can be effectively formed in the liquid (ink) in a 
one-to-one correspondence with the drive signal. The liquid (ink) is 
ejected through a jet opening by growth/contraction of this bubble, 
thereby forming at least one droplet. When this drive pulse has a pulse 
form, growth/contraction of the bubble is instantaneously and 
appropriately performed. Ejection of the liquid (ink) at a high response 
speed can be more preferably performed. A preferable pulsed drive signal 
is described in U.S. Pat. Nos. 4,463,359 and 4,345,262. When conditions 
described in the specification of U.S. Pat. No. 4,313,124 associated with 
a rate of temperature rise of the heat-receiving surface are adopted, 
better recording can be performed. 
As a recording head structure, a structure (disclosed in U.S. Pat. Nos. 
4,558,333 and 4,459,600) in which a heat-receiving portion is located in a 
bent portion in addition to the structure (i.e., linear liquid path or 
orthogonal liquid path) as a combination of the jet ports, the liquid 
paths, and electrothermal converters, as disclosed in the respective 
specifications as described above may be incorporated in the present 
invention. In addition, the effects of the present invention also 
incorporate an arrangement (Japanese Laid-Open Patent Application No. 
59-123670) using a common slit as a jet portion of a plurality of 
electrothermal converters and an arrangement based on Japanese Laid-Open 
Patent Application No. 59-138461 in which an opening for absorbing a 
pressure wave of heat energy is caused to correspond to a jet portion. 
Recording can be appropriately and efficiently performed regardless of the 
forms of the recording heads. 
In addition, in the serial type printer described above, the present 
invention is also effective when an interchangeable recording head chip 
electrically connected to the main body to supply an ink from the main 
body when it is connected to the main body, or a recording head cartridge 
including a recording head and an ink cartridge is used. 
A recovery means for the recording head and a preliminary auxiliary means 
are preferably added as components of the printing apparatus of the 
present invention to further stabilize the effects of the present 
invention. More specifically, a capping means, a cleaning means, a 
pressurizing or suction means, an electrothermal converter, and other 
heating elements, or a preliminary heating means as a combination thereof, 
and an arrangement for performing a preliminary jet mode different from a 
recording jet operation are effective to stabilize recording. 
The types and number of recording heads are not limited to specific values. 
For example, only one recording head corresponding to a monochromatic 
color, or a plurality of recording heads corresponding to a plurality of 
inks having different recording colors and different densities may be 
arranged. 
In addition, forms of the apparatus of the present invention may be an 
image output terminal for data processors such as computers, a copying 
machine in combination with a reader, and a facsimile apparatus having 
transmission and reception functions. 
According to the present invention, since the circuit for transferring the 
recording data from the storage mans to the head and the circuit for 
driving and controlling scanning of the recording head are controlled by 
the common sync signals, the CPU can concentrate itself on data conversion 
of the next line during printing, so that the present invention can cope 
with high-speed printing in a printer. 
As has been described above, according to the present invention, the 
circuit for driving and controlling scanning of the recording head and the 
data communication circuit are synchronously driven to reduce the load on 
the CPU and allow high-speed printing. Since the circuit for transferring 
the recording data from the storage means to the recording head is also 
controlled by the common sync signals, the load on the CPU can be further 
reduced.