Thermal transfer recorder with ink sheet and recording medium conveyed according to recording mode

In a thermal transfer recording apparatus, an ink sheet and a recording medium are separately conveyed, an image is recorded on the recording medium, and the recording mode is discriminated. The conveyance amounts of the ink sheet and recording medium are controlled in accordance with the recording mode so that the density of the recorded image is maintained constant.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a thermal transfer recording apparatus and 
a facsimile apparatus for recording image on recording medium by 
transferring ink contained in an ink sheet to the aforesaid recording 
medium. 
2. Related Background Art 
Generally, a thermal transfer printer uses an ink sheet with heat meltable 
(or heat sublimable) ink coated on the base film thereof, and selectively 
heats such ink sheet by the thermal head in response to image signals in 
order to transfer the molten (or sublimated) ink to a recording sheet for 
image recording. Usually, an ink sheet of the kind is such that the 
contained ink is completely transferred to the recording sheet for one 
image recording (the so-called one-time sheet). Therefore, it is necessary 
to convey the ink sheet for an amount equivalent to the length of recorded 
one character or one line of image after the image recording has been 
completed, so that the unused portion of the ink sheet should reliably be 
brought forward to the position for the next recording. Thus the 
consumption of the ink sheet becomes great and the running cost of the 
thermal transfer printer tends to be higher than that of a usual thermal 
printer using thermal sheets for recording. 
With a view to solving a problem such as this, a thermal transfer printer 
has been proposed, in which both recording sheet and ink sheet are 
conveyed in the same direction at different speeds, as disclosed in 
Japanese Laid-Open Patent Applications Nos. 57-83471 and 58-201686 or 
Japanese Patent Publication No. 62-58917. As described in the aforesaid 
publications, an ink sheet (multiprint sheet) capable of recording images 
for plural numbers (n) is known. When a length L of recording is 
continuously performed using this ink sheet, it is possible to carry on 
the recording by making the length of ink sheet to be conveyed after each 
image recording has been completed or during the image being recorded 
shorter than the length L by (L/n:n&gt;l). Hence the ink sheet can be used 
more efficiently than the conventional sheet by n times, and it is 
therefore expected that the running cost of the thermal transfer printer 
is lowered. Hereinafter this recording method is referred to as 
multiprint. 
In the conventional multiprint, however, said n value is constant 
irrespective of printing modes. In the case of a thermal transfer printer 
generally in use, the faster the recording speed is, the greater is the 
ratio of the period to energize the thermal head. Consequently, the 
temperature of the thermal head is raised, so that ink contained in the 
ink sheet is easily molten or sublimated. As a result, if this ink sheet 
is employed for a facsimile apparatus or the like for example, the 
recording density becomes thin for a superfine mode, etc. necessitating a 
slower recording speed, whereas the recording density is thick for a 
standard mode which is a higher speed recording. On the contrary, if the 
recording is performed just fine with this ink sheet in the superfine 
mode, the density becomes too high in the standard mode, and there is a 
possibility that the recorded image is smeared. 
Also, in a facsimile apparatus, etc., when the transfer speed is fast, 
requiring a shorter cycle of scanning or recording, the heat is 
accumulated on the thermal head to cause the thermal head to generate a 
higher temperature. Accordingly, the image transfer becomes easier because 
ink contained in the ink sheet is molten. On the other hand, if the 
transfer speed is slow, making the cycle of scanning or recording longer, 
the thermal head is cooled at each of the intervals between the recording 
periods, thus making it difficult to transfer ink contained ink sheet. 
In the conventional apparatus, however, the length (n) to convey the ink 
sheet against the recording sheet is always fixed for a constant value as 
described earlier. Therefore, there is a possibility that the amount of 
ink transfer of the ink sheet varies due to such variations of recording 
cycle, etc., and that the densities of recorded images vary to lower the 
image quality. 
Likewise, in a half tone mode, etc., for example, necessitating a slower 
recording speed, the cycle to energize the thermal head also becomes 
longer, so that the temperature of the thermal head is lowered. Then ink 
contained in the ink sheet tends to be difficult to be molten or 
sublimated. However, since the aforesaid n value is fixedly set for the 
above-mentioned thermal transfer printer, the relative speed between the 
recording sheet and ink sheet remains unchanged even in a state where it 
is difficult to transfer ink contained in the ink sheet. As a result, 
there is a possibility that the amount of ink transfer is reduced to cause 
the density of the recorded image to be lowered. 
As set forth above in detail, there is a possibility that the image quality 
is lowered by the influence of heat accumulation when the recording mode 
(such as standard mode, fine mode, recording cycle, half tone mode, or the 
like) is shifted because the aforesaid n value is constant in the 
conventional multiprint. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide a thermal transfer 
recording apparatus and a facsimile apparatus wherein the image quality is 
not lowered. 
Another object of the present invention is to provide a thermal transfer 
recording apparatus and a facsimile apparatus, in which a constant image 
quality can be maintained even if recording modes are shifted. 
Still another object of the present invention is to provide a thermal 
transfer recording apparatus and a facsimile apparatus, in which the 
constant recording density can be maintained by adjusting the amount to 
convey the ink sheet against the recording medium in response to the 
recording density and/or recording speed. 
Yet another object of the present invention is to provide a thermal 
transfer recording apparatus and a facsimile apparatus, in which an 
excellent image can be recorded by saving the ink sheet by reducing the 
amount to convey the ink sheet against the recording medium when the 
recording speed is fast while making the amount to convey the ink sheet 
large when the recording speed is slow. 
A further object of the present invention is to provide a thermal transfer 
recording apparatus and a facsimile apparatus, in which a half tone image 
can be recorded with a similar density of the other images by increasing 
the amount to convey the ink sheet against the recording medium when the 
half tone image is recorded.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Hereinafter, the embodiments suited for the present invention will be 
described in detail with reference to the accompanying drawings. Each of 
the embodiments hereinafter set forth is an example in which the lowering 
of image quality is not generated even when the recording modes are 
shifted. 
At first, the embodiment, which will be described in conjunction with FIG. 
1-FIG. 5, enables an amount to convey ink sheet to be automatically 
optimized in response to any one of the standard, fine, and superfine 
modes selected (by an operator) as a recording mode. 
DESCRIPTION OF A FACSIMILE APATUS (FIG. 1-FIG. 4) 
FIG. 1-FIG. 4 are views showing an example of a facsimile apparatus to 
which a thermal transfer printer using an embodiment of the present 
invention is applied. FIG. 1 illustrates the electrical connection between 
the control unit and the mechanical unit. FIG. 2 is a block diagram 
showing the schematic structure of the facsimile apparatus. FIG. 3 is a 
cross-sectional view of the facsimile apparatus, and FIG. 4 is a view 
showing the mechanism to convey the recording sheet and the ink sheet. 
At first, the schematic structure of a facsimile apparatus according to the 
present embodiment will be described in conjunction with FIG. 2. 
In FIG. 2, a numeral 100 denotes a reading unit comprising a motor for 
conveying original, CCD image sensor, etc. to read an original 
photoelectrically and output it into control unit 101 as digital image 
signals. Next, the structure of this control unit 101 is described. A 
numeral 110 denotes a line memory to store image data from each line of an 
image data. When the original is transmitted or coped, image data of 
one-line portion from reading unit 100 is stored, and when image data is 
received, a one-line data of the decoded image data is stored therein. 
Then an image recording is performed by outputting the stored data into 
recording unit 102. A numeral 111 denotes an encoding/decoding unit to 
encode an image information to be transmitted by MH encoding, etc. and at 
the same time, to decode an encoded image data received and convert it 
into the image data. Also, a numeral 112 denotes a buffer memory to store 
encoded image data to be transmitted or received. Each of these units in 
the control unit 101 is controlled by CPU 113 such as a microprocessor, 
etc. In the control unit 101, there are provided, in addition to this CPU 
113, ROM 114 storing a control program for the CPU 113 and various kinds 
of data and RAM 115 temporarily storing various kinds of data as work area 
for the CPU 113, and others. 
A numeral 102 denotes a recording unit comprising a thermal line head to 
perform recording on recording sheet by the use of thermal transfer 
method. This structure will be described later in detail with reference to 
FIG. 3. A numeral 103 denotes an operation unit including instruction keys 
for each function such as transmission start, etc., input keys for 
telephone numbers, and others; 103a designates a switch for instructing 
the kind of ink sheet to be used, which indicates that a multiprint ink 
sheet is in use when the switch 103a is on, and that .an ordinary ink 
sheet is in use when the switch is off; also 103b designates a switch for 
shifting the recording speeds from high to low and vice versa. In this 
respect, the recording speed can be shifted in response to a judgement 
based on a communication protocol with the equipment of the side of the 
other party as described later, and not necessarily by manual operation; 
104 denotes an indication unit usually installed adjacent to the operation 
unit 103 to display the state of each of the functions, systems, etc.; 105 
is a power source to supply electric power to the entire system; 106 is a 
MODEM (modulator/demodulator); 107 is a network control unit (NCU) for 
performing an automatic receiving by detecting a ringing tone and line 
control; and 108 is a telephone set. 
Next, with reference to FIG. 3, the structure of recording unit 102 is 
described. Hereinafter a unit which is common in each of the figures will 
be designated by a same number. 
In FIG. 3, a numeral 10 denotes a rolled sheet formed by an ordinary 
recording sheet 11 which is wound around a core 10a. This rolled sheet 10 
is accommodated in the apparatus freely rotatably so that the recording 
sheet 11 can be supplied to the thermal head unit 13 by the rotation of 
platen roller 12 in the direction indicated by an arrow. In this respect, 
a numeral 10b denotes a rolled sheet housing in which the rolled sheet 10 
can detachably be accommodated. Further, a numeral 12 denotes a platen 
roller for conveying the recording sheet 11 in the direction indicated by 
an arrow b and at the same time, for pressing the ink sheet 14 and 
recording sheet 11 between the platen roller and the heat generating 
resistor 132 of thermal head 13. The recording sheet 11 is conveyed by the 
further rotation of platen roller 12 in the direction towards exhausting 
rollers 16 (16a and 16b) after the image recording has been completed by 
the heat generation of thermal head 13, and is cut into the unit of one 
page by the engagement of cutters 15 (15a and 15b) when the image 
recording for the one-page portion is completed. 
A numeral 17 denotes an ink sheet supply roller with ink sheet 14 wound 
around thereon. A numeral 18 denotes an ink sheet winding roller driven by 
a motor for conveying ink sheet which will be described later to take up 
the ink sheet 14 in the direction indicated by an arrow a. In this 
respect, these ink sheet supply roller 17 and ink sheet winding roller 18 
are detachably accommodated in an ink sheet housing 70 in the main body of 
the apparatus. Further, a numeral 19 denotes a sensor for detecting the 
remaining quantity of ink sheet 14 and the speed at which ink sheet 14 is 
being conveyed. Also, a numeral 20 denotes an ink sheet sensor for 
detecting the presence of ink sheet 14; 21 is a spring compressing thermal 
head 13 against platen roller 12 through recording sheet 11 and ink sheet 
14; and 22 is also a recording sheet sensor for detecting the presence of 
the recording sheet. 
Subsequently the structure of reading unit 100 will be described. 
In FIG. 3, a numeral 30 is a light source for irradiating original 32, and 
the reflected light from original 32 is inputted into CCD sensor 31 
through an optical system (mirrors 50 and 51, and lens 52), which is 
converted into electrical signal. The original 32 is conveyed by carrier 
rollers 53, 54, 55, and 56 driven by a motor (not shown) for conveying 
original in accordance with a speed at which the original 32 is being 
read. In this respect, a numeral 57 denotes an original stacker. The 
plural sheets of originals 32 stacked on this stacker 57 are separated one 
by one by the cooperation of carrier roller 54 and pressurized separator 
58 while being guided by slider 57a and conveyed to reading unit 100. Then 
after being read, the original is exhausted onto tray 77. 
A numeral 41 denotes a control board constituting the major part of control 
unit 101. From the control board 41 various controlling signals are output 
to each of the units in the apparatus. Also, a numeral 105 denotes a power 
source to supply electric power to each unit; 106 is a MODEM board unit; 
and 107 is an NCU board unit having functions to relay telephone lines. 
Further, FIG. 4 is a perspective view showing the details of mechanism to 
convey both ink sheet 14 and recording sheet 11. 
In FIG. 4, a numeral 24 designates a motor for conveying recording sheet to 
rotationally drive platen roller 12 to convey recording sheet 11 in the 
direction indicated by an arrow b which is opposite to the direction 
indicated by an arrow a. Also, a numeral 25 designates a motor for 
conveying ink sheet to convey ink sheet 14 in the direction indicated by 
an arrow a by rotating capstan roller 71 and pinch roller 72. Further, 
numerals 26 and 27 are transmission gears to transmit the rotation of 
motor 24 for conveying recording sheet to platen roller 12; 73 and 74 are 
transmission gears to transmit the rotation of motor 25 for conveying ink 
sheet to capstan roller 71; and 75 is a sliding clutch unit. 
Here, by setting the ratio between gears 74 and 75 so as to make the length 
of ink sheet 14 taken up by the winding roller 18 driven by the rotation 
of gear 75a longer than the length of ink sheet conveyed by capstan roller 
71, the ink sheet 14 having been conveyed by capstan roller 71 is reliably 
taken up by winding roller 18. Then, an amount equivalent to the 
difference between the amount of ink sheet 14 taken up by winding roller 
18 and that of ink sheet 14 conveyed by capstan roller 71 is absorbed by 
sliding clutch unit 75. In this way, it is possible to restrict the 
variation of the speed (amount) to convey ink sheet 14 caused by the 
changing diameter of winding roller 18 as the winding advances. 
FIG. 1 is a diagram showing the electrical connection between control unit 
101 and recording unit 102 in a facsimile apparatus according to the 
present embodiment, and a unit which is common in the other figures is 
designated by a same reference number. 
The thermal head 13 is a line head. Then, this thermal head 13 comprises a 
shift register 130 for inputting a one-line portion of the serial 
recording data from control unit 101 and shift clock 43; a latch circuit 
131 for latching data in shift register 130 by latch signal 44; and a heat 
generating element comprising a heat generating resistor for one line 
portion. Here, the heat generating resistor 132 is divided into m blocks 
indicated by numerals 132-1 to 132-m for driving. Also, a numeral 133 
denotes a temperature sensor installed on thermal head 13 for detecting 
the temperature of thermal head 13. The output signal 42 of this 
temperature sensor 133 is inputted into said CPU 113 after an A/D 
conversion executed in control unit 101. Thus CPU 113 detects the 
temperature of thermal head 13 to adjust the amplitude of strobe signal 47 
or the driving voltage of thermal head 13 and changes the applied energy 
to thermal head 13 in accordance with the characteristics of ink sheet 14. 
A numeral 116 is a programmable-timer. Its timing is set by CPU 113, and 
when the start of timing is instructed, the timer starts timing to actuate 
CPU 113 to output interrupt signal, time-out signal, etc. respectively at 
each time indicated. 
In this respect, the characteristics (kinds) of ink sheet 14 may be 
determined by the use of the aforesaid switch 103a in operation unit 103 
or the detection of marks, etc. printed on ink sheet 14, or the detection 
of marks, cut-off, projection or the like provided for a cartridge, etc. 
A numeral 46 is a driving circuit to receive the driving signal for thermal 
head 13 from control unit 101 to output strobe signal 47 for driving 
thermal head 13 by the unit of each block. In this respect, the driving 
circuit 46 enables the applied energy to thermal head 13 to be changed by 
adjusting the voltage output to source line 45 which supplies electric 
current to the heat generating element 132 of thermal head 13 in 
accordance with instruction from control unit 101. A numeral 36 is a 
driving circuit including a motor for driving cutter to drive cutters 15 
for its engagement. A numeral 39 is a motor for exhausting sheet to 
rotatably drive exhausting sheet rollers 16. Numerals 48, 49, and 35 are 
motor driving circuits to drive motor 24 for conveying recording sheet, 
motor 25 for conveying ink sheet, and motor 39 for exhausting sheet 
respectively. 
Numeral 141 and 142 are motor control signals respectively for controlling 
the step number and excitation of each of the motors 24 for conveying 
recording sheet and 25 for conveying ink sheet. In this respect, motor 24 
for conveying recording sheet, motor 25 for conveying ink sheet, and motor 
39 for exhausting sheet are stepping motors in the present embodiment. 
These motors, however, are not limited thereto, and for example, DC motors 
or the like may also be applicable. 
DESCRIPTION OF RECORDING PROCESS (FIG. 1-FIG. 5) 
FIG. 5 is a flowchart showing image recording process for a one-page 
portion in a facsimile apparatus according to the present embodiment. The 
control program for executing this process is stored in ROM 114 in control 
unit 101. This process is started when the image recording action is ready 
to start with the one-line portion of image data stored in line memory 110 
for the image to be recorded. 
First, at a step S1, the image to be recorded is detected to determine 
whether the image is to be recorded in the standard mode, fine mode, or 
superfine mode. This discrimination takes place during the process of 
receiving or transmitting facsimile signals. Here, if the image is to be 
recorded in the standard mode, the process proceeds to a step S2 where the 
multiprinting number n is set at "6" while the loop number nl is set at 
"4". If the image is to be recorded in the fine mode, the process proceeds 
to a step S3 where with n=5, the loop number nl is set at "2". Further, if 
the image is to be recorded in the superfine mode, the process proceeds to 
a step S4 where with n=4, the loop number nl is set at "1". 
When the value n and the loop number nl thus established, the process 
proceeds to a step S5 to output a one-line portion of recording data in 
serial to shift register 130. Then, when the transportation of the 
recording data for the one line is completed, latch signal 44 is output at 
a step S6 to store the one-line portion of recording data in latch circuit 
131. Next, at a step S7, motor 25 for conveying ink sheet is driven to 
convey ink .sheet 14. At this juncture, if a multiprinting has been 
instructed by switch 103a, the ink sheet is conveyed in the direction 
indicated by an arrow a in FIG. 4 for a portion of (l/n) of the height of 
one line (1/15.4 mm) of recording sheet 11. The adjustment of n value such 
as this can be executed by changing the step number of motor 24 for 
conveying ink sheet by motor control signal 142. 
Then, at a step S8, motor 24 for conveying recording sheet is driven to 
convey recording sheet 11 in the direction indicated by an arrow b for a 
one-line portion (1/15.4 mm). In this respect, this one-line portion is a 
length equivalent to the length of one dot of the image to be recorded by 
thermal head 13. Next, the process proceeds to a step S9 to energize each 
of the blocks of heat generating element 132 of thermal head 13. Then, 
when the entire blocks m of thermal head 13 are all energized to complete 
the image recording across the width of the one line, the process proceeds 
to a step S10 to set -1 for the loop number established at either one of 
the steps S2 to S4. Thus, at a step S11, the loop number is examined to 
determine whether it becomes to be "0", and if it is not found to be "0", 
the process returns to the step S7 and record again the image of the same 
line. 
Hence in the present embodiment, a same data is recorded four times across 
the width of the recording line in the standard mode and two times in the 
fine mode so as to make the density of the recorded lines in the sub-scan 
direction (that is, perpendicular to the direction of recording sheet 
conveyance) equal as compared with the case of superfine mode recording. 
In this way, when the recording for one line is completed, the process 
proceeds to a step S12 from the step S11 to examine whether or not the 
image recording for one page has been completed. If the image recording 
for one page has not been completed as yet, the process proceeds to a step 
S13 to determine whether or not recording data for the next line has been 
transported to thermal head 13 during the course of the aforesaid 
processing step. If the transportation has been completed, the process 
returns to the step S6 to latch a one-line portion of image data to latch 
circuit 131 by latch signal. However, if the transportation has not been 
completed as yet, the process proceeds to a step S14 to execute the 
transportation until the entire data of the next line is completely 
transported to thermal head 13 and returns to the step S6. 
When the image recording for one page has been completed at the step S12, 
the process proceeds to a step S15 to convey a predetermined amount of 
recording sheet 11 in the direction towards exhausting sheet rollers 16 
(16a and 16b). Then at a step S16, cutters 15 (15a and 15b) are driven to 
engage with each other to cut recording sheet 11 into a unit of one page. 
Subsequently, the recording sheet 11 thus cut is exhausted by exhausting 
rollers 16 to the outside of the apparatus and at the same time, the 
remaining recording sheet 11 is withdrawn at a step S17 for a distance 
equivalent to the space between thermal head 13 and cutters 15. Thus the 
recording process for one page is terminated. 
As the above describes, according to the present embodiment, it is possible 
to prevent any variations in the density of the recorded line regardless 
of the recording mode used by making the n value great in the standard 
mode where the amount of recording sheet conveyed is large and the 
recording speed is fast while making the n value small in such mode as 
superfine where the amount of recording sheet convey is small and the 
recording speed is slow. 
Also, according to the present embodiment, it is possible to perform 
recording in standard mode using a small amount of ink sheet used, and the 
ink sheet is effectively saved as compared with the cases of fine and 
superfine mode recordings. 
In addition, according to the present embodiment, the n values are 
established in response to the transmitting and receiving modes because 
the example has been taken of a facsimile apparatus, but the present 
invention is not limited to this. For example, it is also possible to 
adjust the value in response to the recording density and recording speed 
in the direction of sub-scanning. 
As set forth above, according to the present embodiment, the ratio of the 
amounts to convey recording medium and ink sheet is made greater when the 
recording density is rough or the recording speed is fast, and that of the 
amounts to convey recording medium and ink sheet is made smaller when the 
recording density is fine or the recording speed is slow. Hence there is 
an effect that the recording density can be maintained almost at a 
constant level. 
Subsequently, as an embodiment wherein the image quality is not lowered 
even when recording modes are shifted, an example will be described, in 
which an action is taken to adjust an amount to convey ink sheet against 
recording medium for a recording in response to the recording speed 
detected by detecting means for detecting recording speed or the recording 
speed instructed by an equipment on the side of the other party. In this 
respect, the aforesaid FIG. 1 to FIG. 4 and the descriptions thereof are 
referenced in the embodiment hereinafter set forth. 
Now, FIGS. 6A-6C are flowcharts showing the receiving and recording 
processes in a facsimile apparatus according to the present embodiment. 
The control program for executing these processes is stored in ROM 114 in 
control unit 101. Here it is assumed that the installation of multiink 
sheet has already been detected by control unit 101 by means of switch 
103a, etc. 
First, at a step S1, CML is turned off, and at a step S2, the processing is 
examined to determine whether it is for a receiving or not. If the mode is 
not receiving, the other processing required is executed at a step S4. If 
the mode is a receiving, the process proceeds to a step S3 to turn CML on. 
Thus, at a step S5, a preparatory procedures for the receiving mode are 
taken to input a transmission speed being received from the transmitter 
side and store it RAM 115. Thus, subsequently, the image signals being 
transmitted from the equipment of the other party are inputted and stored 
in line memory 110 after decoding. 
Next, the process proceeds to a step S6 and when a one-line portion of 
recording data is decoded and stored in line memory 110, that portion is 
output in serial to shift register 130. Then, at a step S7, the 
transportation of recording data for one line is examined to verify its 
completion, and when the transportation is terminated, latch signal 44 is 
output at a step S8 to store recording data for one line in latch circuit 
131. Next, the process proceeds to a step S9 to find its recording mode. 
If it is found to be superfine mode at the step S9, the process proceeds 
to a step S10 to set "1" in line counter 1. Also, at a step S11, if fine 
mode is found, the process proceeds to a step S12 to set "2" in 1, and if 
the mode is other than those (i.e. , standard mode) , the process proceeds 
to a step S13 to set "4" in 1. This value of line counter 1 indicates the 
number of lines constituting a one line of image data corresponding to 
each of the recording modes. For example, while in the case of superfine 
mode, a one line of image data is recorded in one line, in the case of 
standard mode where the density of recording pixels is the lowest, a one 
line of image data comprises a four-line portion of the same image data. 
Next, the process proceeds to a step S14 to convey recording sheet 11 for 
one half step. At a step S15, the transmission speed instructed from the 
equipment of the side of the other party and recorded in RAM 115 at the 
step S5 is read to examine whether or not this speed is 9,600 (b/s). If it 
is found to be 9,600 b/s, ink sheet 14 is conveyed at a step S16 for four 
half steps (n=25/4). Against this, if the transmission speed is 7,200 b/s, 
the process proceeds to a step S18 to convey ink sheet 14 for five half 
steps (n=25/5). Also, if the transmission speed is other than those, the 
process proceeds to a step S19 to convey ink sheet 14 for six half steps 
(n=25/6). 
Thus, the process proceeds to a step S20 energize one of the blocks of heat 
generating resistor 132 of thermal head 13. Then at a step S21, an 
examination is made to determine whether or not the entire blocks of heat 
generating resistor 132 of thermal head 13 have been energized. If the 
entire blocks have not been energized, the process proceeds to a step S25 
to transport the next line of image data to shift resistor 130 of thermal 
head 13 at the step S25 to step S28. Thus, at the step S27, when the 
period to energize (600 .mu.s) is over, process proceeds to the step S20 
to energize the next block. In this respect, according to the present 
embodiment, the thermal head 13 is divided into four blocks (m=4) for 
driving, and for example, the time required for recording one line in 
superfine mode is approximately 2.5 ms (600 .mu.s .times.4 blocks). 
At the step S21, when the entire blocks are energized to complete the one 
line recording, the process proceeds to the step S22 to set -1 in 1 to 
examine whether or not the 1 line has been recorded in response to each of 
the recording modes, and at the step S23, if no 1 line is found to be 
recorded, the process returns to the step S14 to convey recording sheet 11 
for one half step and ink sheet 14 for four to six half steps in 
accordance with the transmission speeds, and again record one line for the 
same data. 
When the 1 line recording is thus executed in accordance with each of the 
recording modes, the process proceeds from the step S23 to the step S24 to 
examine whether or not the recording processing for one page has been 
completed. If the recording processing for one page has not been 
completed, the process returns to the step S6 to execute the aforesaid 
image recording processing. 
If the image recording for one page has been completed, the process 
proceeds to a step S29 to convey recording sheet 11 for a predetermined 
amount in the direction towards exhausting sheet rollers 16 (16a and 16b) 
and at the same time, to drive cutters 15 (15a and 15b) and a step S30 to 
engage with each other to cut recording sheet 11 into a unit of one page. 
Then the recording sheet 11 thus cut is exhausted by exhausting sheet 
rollers 16 to the outside of the apparatus and at the same time, the 
remaining recording sheet 11 is withdrawn at a step S31 for a distance (a 
predetermined amount--.alpha.) equivalent to the space between thermal 
head 13 and cutters 15 at the step S31. 
At a step S32, the presence of recording data for the next page is 
examined, add if there is no more data for the next page, the process 
proceeds to a step S33 and returns to the step S1 after having taken the 
final procedures. Also, if there is recording data for the next page, the 
process proceeds from the step S32 to a step S34 to examine whether or not 
there is any shift in mode for transmission speed, etc. If there is any 
shift, the process returns to the step S5. If there is no instruction for 
mode shifting, an intermediate processing is executed at a step S35, and 
the process returns to the step S6 to execute the aforesaid processing. 
FIG. 7 shows the distance to convey a one-line portion of recording sheet 
11 in each of the recording modes. 
Here, in consideration of the half step driving, motor 24 for conveying 
recording sheet is driven to convey recording sheet 11 for 1/15.4 mm at 
one half step. Then, for one line in superfine mode, motor 24 for 
conveying recording sheet is driven for one half step, and for one line in 
fine mode, it is driven for two half steps. Further, in standard mode, it 
is driven for four half steps against one line. 
FIG. 8 shows step numbers required to convey ink sheet 14 for one line in 
each of the recording modes according to the present embodiment. 
In the present embodiment, motor 25 for conveying ink sheet conveys ink 
sheet 14 for a distance of {(1/15.4) .times.1/5.times.1/5}mm at a half 
step. Therefore, in superfine mode, n rotatably drives motor 25 for 
conveying ink sheet for "4", "5", and "6" half steps respectively in the 
order of large, medium, and small to convey ink sheet 14 accordingly. 
Likewise, in fine mode, n drives "8" "10" and "12" half steps respectively 
in the order of large, medium, and small, and in standard mode, the motor 
is driven in the order of n values for "16" "20" and "24" accordingly. 
As above describes, in superfine mode, for example, where n is large, the 
conveying ratio (n) between recording sheet 11 and ink sheet is 
(5.times.5).times.1/4=25/4, where n is medium, the ratio is 
(5.times.5).times.1/5=25/5, and where n is small, the ratio is 
(5.times.5).times.1/6=25/6. Also, whenever recording sheet 11 is conveyed 
for one half step, ink sheet 14 is conveyed for four to six half steps. 
In this respect, since the present embodiment has been described taking a 
facsimile apparatus as an example, the conveying amount of ink sheet 14 is 
adjusted (n value is adjusted) in accordance with the transmission speeds 
as shown in steps S15 to S19. However, in a general thermal transfer 
printer, etc., for example, it is also possible to adjust the conveying 
amount of ink sheet 14 (n value) in response to the states of switch 103b 
for shifting speeds as shown in FIG. 2. 
Also, in the aforesaid embodiment, although the value n is adjusted on the 
basis of the transmission speeds instructed by the equipment of the other 
party, it may be possible to define an n value based on the minimum 
scanning time declared by the equipment of the other party, for example. 
FIGS. 9A and 9B illustrate this. According to the present embodiment, in 
place of the step S5 in FIGS. 6A-6C, the minimum scanning time notified is 
stored in RAM 115 at a step S50, and in place of the steps S15 to S19 
shown in FIG. 6, the conveying length of ink sheet 14 is defined in 
response to each of the minimum scanning times at steps S72 to S80. For 
example, if a minimum scanning time is less than 10 ms, ink sheet 14 is 
conveyed for four half steps (n=25/4) at a step S74. Also, if a minimum 
scanning time exceeds 10 ms but less than 20 ms, ink sheet 14 is conveyed 
for five half steps (n=25/5) at a step S78. Further, if a minimum scanning 
time exceeds 20 ms, the process proceeds to a step S80 to convey ink sheet 
14 for six half steps (n=25/6). 
Furthermore, as another embodiment, it is possible to adjust n values in 
accordance with recording cycles. In other words, if a recording cycle is 
short, the value n should become great, and if a recording cycle is long, 
the value n should become small to perform the respective recordings. A 
flowchart shown in FIGS. 10A-10B illustrate this. 
In other words, a timing is set by timer 116 for the period from the 
completion of current line to the recording of next line becoming 
possible, and an n value is adjusted in accordance with a period thus set 
by such timing. 
Here, as shown in FIG. 10A, a period of 10 seconds is set for timer 116 and 
a processing is inserted between the steps S23 and S24 shown in FIGS. 
6A-6C to start the timing. Then, as shown in FIG. 10B, a processing to 
define an n value in accordance with such timing is provided in place of 
the steps S15 to S19 shown in FIGS. 6A-6C. 
Thus, if the timing by timer 116 is less than 10 ms, ink sheet 14 is 
advanced for four half steps (n=25/4) at a step S98. If it exceeds 10 ms 
but less than 100 ms, ink sheet 14 is conveyed for five half steps 
(n=25/5) at a step S102. Also, if the timer by timer 116 exceed 100 ms, 
the process proceeds to a step S104 to convey ink sheet 14 for six half 
steps (n=25/6). 
In this respect, the established values of n value in the aforesaid 
embodiments are not limited to those defined therein as a matter of 
course. 
As above describes, according to the present embodiment, it is possible to 
save ink sheet for its effective use by adjusting the relative length to 
convey recording sheet and ink sheet in accordance with the recording 
cycles or the minimum scanning times and at the same time, to obtain an 
effect that the recording density is maintained at a constant level to 
improve the quality of recorded image. 
As set forth above, according to the present embodiment, there is an 
advantage that while ink sheet can be saved by making the conveying amount 
of ink sheet against recording medium small when the recording cycle is 
short, an excellent image is recorded by making the conveying amount of 
ink sheet large when the recording cycle is long. 
Subsequently, as an embodiment wherein the image quality is not lowered 
even when the recording modes are shifted, an example will be described, 
in which an image to be recorded is detected to determine whether or not 
it is half tone, and if a half tone image is detected, an action is taken 
to make the conveying amount of ink sheet against recording medium large 
for its recording. In this respect, as in the aforesaid embodiment, FIG. 1 
to FIG. 4 and the descriptions thereof are referenced in an embodiment 
hereinafter set forth. 
Now, FIG. 11 is a flowchart showing the image recording process for one 
page portion in a facsimile apparatus according to the present embodiment, 
and the control program for executing this process is stored in ROM 114 in 
control unit 101. This process is started when the image recording action 
is ready to start after a one-line portion of image data of the image to 
be recorded has been stored in line memory 110. Then, here, it is assumed 
that the installment of multiink sheet has already been detected by 
control unit 101 by means of switch 103a, etc. 
First, at a step S1, an image received is examined to determine whether it 
is a binary image or a half tone image. This is determined on the basis of 
control information included in the control signal (for example, NSF) 
transmitted from a facsimile apparatus on the transmitting side. This 
control information has been stored in RAM 115 at the time of receiving 
signals, and in accordance with this stored information, the image 
currently stored in line memory 110 is judged for a binary image or a half 
tone image. If it is found to be a binary image, the process proceeds to a 
step S2 to set n at "5". On the other hand, if it is found to be a half 
tone image, the process proceeds to a step S3 to set n at "4". 
Next, at a step S4, a one-line portion of recording data is output in 
serial to shift register 130 of thermal head 13. Then, when the recording 
data for one line has completely been transported, latch signal 44 is 
output at a step S5 to store the one line portion of recording data in 
latch circuit 131. Subsequently at a step S6, motor 25 for conveying ink 
sheet is driven to convey ink sheet 14 for l/n line in the direction 
indicated by an arrow a in FIG. 4. Then at a step S7, motor 24 for 
conveying recording sheet 11 is driven to convey only for one line portion 
(in the present embodiment, 1/15.4 mm). 
Thus, the one-line portion of recording data is transported to thermal head 
13, and when ink sheet 14 and recording sheet 11 are started to be 
conveyed, the process proceeds to a step S8 to energize each unit of 
blocks of heat generating resistor 132 of thermal head 13 to perform the 
transfer recording for the one line. In this respect, at the time of this 
one-line recording, the recording data of the next line, if any exists, is 
sequentially transported to shift register 130 of thermal head 13. 
When the one-line recording is thus performed, the process proceeds to a 
step S9 to examine whether or not the image recording for a one page has 
been completed. If the recording for the one page has not been completed, 
the process proceeds to a step S10 to examine whether or not the next line 
of recording data has already been transported to thermal head completely. 
If the transportation has not been completed, the data of the next line is 
transported at a step S11. The process returns to the step S5 from the 
step S10 when the entire data of the next line has been transported to 
shift register 130 of thermal head 13. Then the aforesaid recording 
process is performed. 
Thus, when the image recording for one page portion is completed at the 
step S9, the process proceeds to a step S12 to convey recording sheet 11 
for a predetermined amount in the direction towards exhausting sheet 
rollers 16 (16a and 16b) and at the same, to drive cutters 15 (15a and 
15b) to engage with each other at a step S23 to cut recording sheet 11 
into a unit of one page. Then, at the same time of exhausting recording 
sheet 11 thus cut to the outside of the apparatus by means of exhausting 
sheet rollers 16, the recording for one page is completed at a step S14 by 
withdrawing the remaining recording sheet 11 for a distance equivalent to 
the space between thermal head 13 and cutters 15. 
Hence, according to the present embodiment, when a half tone image is 
recorded, the conveying length of ink sheet 14 against recording sheet 11 
is longer than when a binary image is recorded. In this way, the amount of 
ink contained in ink sheet 14 transferred onto recording sheet 11 is 
increased as the half tone image is recorded, so that a half tone image 
requiring a slower recording speed can be recorded in the same density as 
a binary image. 
Also, there is an advantage that ink sheet is saved when a binary image is 
recorded because it is possible to elongate the length to convey ink sheet 
against recording sheet by making the n value large. 
As set forth above, according to the present embodiment, there is also an 
advantage that a half tone image can be recorded in the same density as 
the other image by making the amount to convey ink sheet against recording 
medium large when the half tone image is recorded. 
FIG. 12 is a block diagram showing the electrical connection of control 
unit and recording unit of a facsimile apparatus according to another 
embodiment. 
In the aforesaid embodiment, the discrimination between binary image and 
half tone image is judged by control signal transmitted from the equipment 
on the transmitting side. Here, such discrimination is judged by based on 
the receiving image data stored in line memory 110. This judgement is 
performed by binary/half tone image discriminating circuit 151. In 
general, a half tone image is represented by dot patterns in its 
intermediate portion, and as compared with a binary image, the number of 
white-black inversion in the main scanning direction becomes extremely 
great. Therefore, it is possible to discriminate half tone image from 
binary image in accordance with this number, large or small, of the 
white-black inversion in the main scanning direction. 
Hence this binary/half tone image discriminating circuit 151 examines the 
number of white-black inversion of image data in the main scanning 
direction and takes it as a half tone image if such number detected is 
more than a given number. The result is output to CPU 113. Then this 
enables CPU 113 to judge whether the image data currently stored in line 
memory 110 is a half tone image or a binary image. This judgement may also 
be made by control program for CPU 113 stored in ROM 114. 
[Description of Recording Principle (FIG. 13)] 
FIG. 13 is a view showing a state of image recording when an image is 
recorded with recording sheet 11 and in sheet 14 being conveyed in the 
opposite direction using multiink sheet. 
As shown in the figure, recording sheet 11 and ink sheet 14 are pinched 
between platen roller 12 and thermal head 13. The thermal head 13 is 
pressurized by spring 21 under a given pressure against platen roller 12. 
Here, recording sheet 11 is conveyed by the rotation of platen roller 12 
at a speed Vp in the direction indicated by an arrow b. Meanwhile, ink 
sheet 14 is conveyed by the rotation of motor 25 for conveying ink sheet 
at a speed V1 in the direction indicated by an arrow a. 
Now, when the heat generating resistor 132 of thermal head 13 is heated by 
current from power source 105, the portion 91 of ink sheet 14 indicated by 
slashed lines is heated. Here a numeral 14a denotes the base film of ink 
sheet 14; and 14b is the ink layer of ink sheet 14. When heat generating 
resistor 132 is energized, ink in the heated ink layer 91 is molten, and a 
portion thereof indicated by a numeral 92 is transferred onto recording 
sheet 11. This portion 92 of the ink layer to be transferred is almost 
equivalent to a l/n of the portion of the ink layer indicated by a numeral 
91. 
DESCRIPTION OF INK SHEET (FIG. 14) 
FIG. 14 is a cross-sectional view of ink sheet used for a multiprint 
according to the present embodiment. Here the ink sheet comprises four 
layers. 
First, a second layer is the base film which is a member to support ink 
sheet 14. In the case of multiprint, since heat energy is applied 
repeatedly to a same location, it is advantageous to use a high heat 
resistive aromatic polyamide film or condenser paper, but the conventional 
polyester film can also be applicable. Although the thickness of the film 
should be as thin as possible for a better printing quality from the 
viewpoint of its role as a medium, the thickness of 3-8 .mu.m is desirable 
from the viewpoint of its strength required. 
A third layer is the ink layer containing an amount of ink capable of being 
transferred onto recording paper (recording sheet) repeatedly for n times. 
The components thereof are resin such as EVA, etc. as adhesive, carbon 
black and nigrosine dye for coloring agent, and carnauba wax, paraffin 
wax, etc. for binding agent. These elements are appropriately mixed as 
principle components to enable the layer to withstand a repeated 
application at a same location for n times. It is desirable to coat this 
layer in an amount of 4-8 g/m.sup.2. However, as its sensitivity and 
density differ depending on the coating amount, such amount can 
arbitrarily be selected. 
A fourth layer is the top coating layer to prevent ink in the third layer 
from being transferred by pressure to ink sheet at a location where no 
printing is performed. This layer comprises transparent wax, etc. Thus, 
the fourth layer which is transparent is the only portion to be 
transferred by pressure, and this prevents recording sheet from being 
stained. A first layer is the heat resistive coating layer to protect the 
second layer which is the base film from the heat of thermal head 13. This 
is suited for the multiprint for which heat energy for n lines is often 
applied to a same portion (when black information continues), but its 
application is arbitrarily selective. Also, this is effectively applicable 
to a base film with comparatively low heat resistivity such as polyester 
film. 
In this respect, the composition of ink sheet 14 is not limited to the 
present embodiment. For example, ink sheet can also be formed with a base 
layer and a porous ink retaining layer containing ink which is provided at 
one end of the base layer, or having fine porous netting structure 
provided on the base film to contain ink. Also, as the materials for base 
film for example, film or paper comprising polyamide, polyethylene, 
polyester, polyvinyl chloride, triacetilene cellulose, nylon, etc. can be 
used. Further, although heat resistive coating is not necessarily 
required, its material may also be, for example, silicon resin, epoxy 
resin, fluorine resin, etholocellulose, etc. 
Also, as an example of ink sheet containing heat sublimating ink, there is 
an ink sheet in which a coloring layer containing spacer particles and dye 
comprising guanamine resin and fluorine resin is formed on a substrate 
comprising polyethylene terephtharate, aromatic polyamide film, etc. 
Also, a heating method in thermal transfer printer is not limited to the 
thermal head method using the aforesaid thermal head. The heating method 
using, for example, a current-carrying or laser transfer may also be 
employed. 
Also, in the present embodiment, the description has been made of an 
example in which the thermal line head is used, but the application is not 
limited to this. A thermal transfer printer of so-called serial type may 
also be employed. Further, although the description has been made of 
multiprinting in the present embodiment, the application is not limited to 
this. An ordinary thermal transfer recording using one-time ink sheet can 
be employed as a matter of course. 
Also, the recording medium is not limited to recording sheet. If only a 
material is capable of accepting ink transfer, cloth, plastic sheet or the 
like can be used as a recording medium. Also, the ink sheet is not limited 
to rolled type as shown in the present embodiment. It can be, for example, 
an ink sheet contained in a housing which can detachably installed in the 
main body of recording apparatus, i.e., the so-called ink sheet cassette 
type whereby such housing containing ink sheet is detachably mounted as it 
is in the main body of the recording apparatus. 
Also, in each of the aforesaid embodiments, the description has been made 
of a facsimile apparatus. The present invention, however, is not limited 
to such application. It can also be applicable, for example, to word 
processors, typewriters or copying machines, etc. 
In addition, the ink sheet is not limited to the rolled type as shown in 
the embodiments. It is also possible to employ, for example an ink sheet 
contained in a housing which can detachably installed in the main body of 
recording apparatus, i.e., the so-called ink sheet cassette type, etc. 
whereby such housing containing ink is detachably mounted as it is in the 
main body of the recording apparatus. 
As set forth above in detail, it is possible to provide by the present 
invention a thermal transfer recording apparatus and a facsimile apparatus 
wherein the quality of image recorded is not lowered even when the 
recording modes are shifted.