Recording apparatus and method which takes into account image information being recorded

A heat transfer recording apparatus for transferring the ink of an ink sheet to a recording medium to thereby effect the recording of images on the recording medium has ink sheet conveying means for conveying the ink sheet, recording medium conveying means for conveying the recording medium, recording means for acting on the ink sheet to effect the recording of images on the recording medium, counting means for counting the number of bits of black information of image data recorded by the recording means, and control means for controlling so as to change the recording period by the recording means in conformity with the number of the bits of black information counted by the counting means.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a recording apparatus such as a heat transfer 
recording apparatus in which for example, the ink of an ink sheet, is 
transferred to a recording medium to thereby record the images on the 
recording medium, and to a facsimile apparatus. 
The term "a recording apparatus such as a heat transfer recording 
apparatus" covers, both a facsimile apparatus as well as apparatuses such 
as of an electronic typewriter, a copying apparatus and a printer 
apparatus. 
2. Related Background Art 
Description will hereinafter be made of a heat transfer printer taken as an 
example of the recording apparatus. 
Generally, a heat transfer printer uses an ink sheet comprising base film 
having heat-melting (or heat-sublimating) ink applied thereto, and the ink 
sheet is selectively heated by a thermal head correspondingly to an image 
signal and the ink melted (or sublimated) is transferred to recording 
paper to thereby accomplish the recording of images. Generally, this ink 
sheet is a sheet from which the ink is completely transferred to the 
recording paper by a single image recording (so-called one time sheet) and 
therefore, it has been necessary that after the termination of the 
recording of one character or one line, the ink sheet be conveyed by an 
amount corresponding to the recorded length and then the unused portion of 
the ink sheet be reliably brought to a position for recording. This has 
led to the tendency that the quantity of ink sheet used is increased and 
when compared with an ordinary thermosensitive printer for recording 
images on thermosensitive paper, the heat transfer printer has high 
running costs. 
In order to solve such a problem, there have been proposed heat transfer 
printers in which, as seen in Japanese Laid-Open Patent Application No. 
57-83471, Japanese Laid-Open Patent Application No. 58-201686 and Japanese 
Patent Publication No. 62-58917, recording paper and an ink sheet are 
conveyed with a speed difference therebetween. As described in these 
publications, an ink sheet capable of carrying out plural (n) image, 
recordings (a so-called multiprint sheet) is known and such an ink sheet 
for reducing the running costs in a heat transfer printer. If such an ink 
sheet is used, when recording is to be effected continuously over a 
recording length L, recording can be effected with the length of the ink 
sheet which is conveyed after or during the recording of each image being 
made smaller than the length L (L/n:n&gt;1) (this is called multiprinting). 
In this case, the ink of the ink layer of the ink sheet is heated n times 
and during each heating cycle, a shearing force is created between the 
melted (or sublimated) ink of the ink layer and the ink which is not 
melted (or sublimated) to thereby transfer the ink to the recording paper. 
The ink of this ink layer is easier to melt as the temperature of the ink 
becomes higher. 
On the other hand, the heat generating element of a thermal head for 
heating the ink layer is electrically energized and heated when the image 
information of corresponding recording dots is black. As the amount of 
black image data to be recorded becomes greater, the time for which the 
heat generating element of the thermal head is electrically energized 
becomes longer, and heat is accumulated in the thermal head. In extreme 
cases, even when the thermal head is not electrically energized, part of 
the ink of the ink layer of the ink sheet may be melted and transferred to 
the recording paper, thus causing the "ground stain" of the recording 
paper or so-called "trail-leaving" which is a phenomenon that when shift 
is made to the printing of the next line, the ink recorded in the 
preceding line leaves a trail. This strains the recording paper, which 
causing deterioration of the quality of recorded images. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a recording apparatus 
and a facsimile apparatus which can provide clear-cut recorded images. 
It is another object of the present invention to provide a recording 
apparatus and a facsimile apparatus which can improve the quality of 
recording. 
It is still another object of the present invention to provide a recording 
apparatus and a facsimile apparatus in which undesirable heat accumulation 
in recording means such as a thermal head can be prevented. 
It is yet still another object of the present invention to provide a 
recording apparatus and a facsimile apparatus in which, in view of the 
above-described example of the prior art, the number of black picture 
elements is counted and when the number of black picture elements exceeds 
a predetermined value, provision is made to wait for a time to radiate 
heat until the recording of the next line, thereby reducing the influence 
of the heat accumulation in a recording head.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
An embodiment which will now be described as an example of a recording 
apparatus is a heat transfer recording apparatus, in which the black 
information of image data recorded by recording means which acts on an ink 
sheet to effect the recording of images on a recording medium is counted 
and the recording period by the recording means is changed correspondingly 
to the counted black information. 
Some preferred embodiments of the present invention will hereinafter be 
described in detail with reference to the accompanying drawings. 
Description of a Facsimile Apparatus (FIGS. 1-4) 
FIGS. 1-4 show an example in which a heat transfer printer using an 
embodiment of the present invention is applied to a facsimile apparatus. 
FIG. 1 shows the electrical connections between the control unit 101 and 
the recording unit 102 of the facsimile apparatus, FIG. 2 is a block 
diagram schematically showing the construction of the facsimile apparatus, 
FIG. 3A is a side sectional view of the facsimile apparatus, FIG. 3B is a 
pictorial perspective view of the facsimile apparatus, and FIG. 4 shows 
the conveying mechanisms for a recording sheet and an ink sheet. 
The construction of the facsimile apparatus will first be described briefly 
with reference to FIG. 2. 
In FIG. 2, the reference numeral 100 designates a reading unit which reads 
an original and outputs it as an image signal to the control unit 101. The 
construction of the control unit 101 will now be described. The reference 
numeral 110 denotes a line memory for storing therein the image data of 
each line of image data. In the line memory 110, image data for one line 
from the reading unit 100 is stored during the transmission of an original 
(the case of the facsimile mode) or the copying of the original (the case 
of the copy mode), and one line data of the decoded received image data is 
stored during the reception of the image data. The stored data is output 
to the recording unit 102, whereby image formation is effected. The 
reference numeral 111 designates a coding/decoding unit for coding 
transmitted image information as by MH coding and decoding the received 
coded image data and converting it into image data. The reference numeral 
112 denotes a buffer memory for storing the transmitted or received coded 
image data therein. These portions of the control unit 101 are controlled, 
for example, by a CPU 113 such as a microprocessor. The control unit 101 
is further provided with an ROM 114 storing the control program of the CPU 
113 and various data therein, and an RAM 115 for temporarily preserving 
various data as the work area of the CPU 113. 
The reference numeral 102 designates a recording unit which is provided 
with a thermal line head (having a plurality of heat generating elements 
over the recording width) which effects image recording on a recording 
sheet by the heat transfer recording method. The construction of this unit 
will be described later in detail with reference to FIG. 3. The reference 
numeral 103 denotes an operation unit including instruction keys for 
various functions such as the starting of transmission, etc. and telephone 
number input keys, and the reference character 103a designates a switch 
for indicating the kind of an ink sheet 14 used. When the switch 103a is 
ON, it indicates that a multiprint ink sheet is mounted, and when the 
switch 103a is OFF, it indicates that an ordinary ink sheet (one time ink 
sheet) is mounted. The reference numeral 104 denotes an indicating unit 
usually provided adjacent to the operation unit 103 to indicate various 
functions, the state of the apparatus, etc. The reference numeral 105 
designates a power source unit for supplying electric power to the entire 
apparatus. The reference numeral 106 denotes a modem modulator-demodulator 
for effecting the AC-DC conversion of transmitted and received signals, 
the reference numeral 107 designates a net control unit (NCU) for 
effecting communication control between it and a line, and the reference 
numeral 108 denotes a telephone set provided with dial keys for 
telephoning. 
The construction of the recording unit 102 will now be described in detail 
with reference to FIG. 3. In FIG. 3, portions common to those in FIG. 2 
are given identical reference numerals. 
In FIG. 3A, the reference numeral 10 designates a roll of recording paper 
11 which is plain paper wound into the form of a roll on a core 10a. This 
roll of paper 10 is rotatably contained in the apparatus so that the 
recording paper 11 can be supplied to a thermal head unit 13 by the 
rotation of a platen roller 12 in the direction of arrow. The reference 
character 10b denotes a rolled paper loading portion in which the roll of 
paper 10 is removably loaded. The platen roller 12 serves to convey the 
recording paper 11 in the direction of arrow b and press the ink sheet 14 
and the recording paper 11 between it and the heat generating member 132 
of the thermal head 13. The recording paper 11 on which image recording 
has been effected by the heat generation of the thermal head 13 is 
conveyed toward discharge rollers 16 (16a, 16b) by further rotation of the 
platen roller 12, and is cut into a page length by the engagement of 
cutters 15 (15a, 15b) when image recording for one page is terminated, and 
is discharged. 
The reference numeral 17 designates an ink sheet supply roll on which the 
ink sheet is wound, and the reference numeral 18 denotes an ink sheet 
take-up roll driven by an ink sheet conveying motor which will be 
described later to take up the ink sheet 14 in the direction of arrow a. 
The ink sheet supply roll 17 and the ink sheet take-up roll 18 are 
removably loaded in an ink sheet loading portion 70 within the apparatus 
body. The reference numeral 19 designates a sensor for detecting the 
remaining quantity of the ink sheet 14 and detecting the velocity of 
conveyance of the ink sheet 14. The reference numeral 20 denotes an ink 
sheet sensor for detecting the presence or absence of the ink sheet 14, 
and the reference numeral 21 designates a spring for urging the thermal 
head 13 against the platen roller with the recording paper 11 and the ink 
sheet 14 interposed therebetween. The reference numeral 22 denotes a 
recording paper sensor for detecting the presence or absence of the 
recording paper 11. 
The construction of the reading unit 100 will now be described. 
In FIG. 3A, the reference numeral 30 designates a light source for 
irradiating an original 32. The light reflected by the original 32 is 
input to a CCD sensor 31 through an optical system (mirrors 50, 51 and a 
lens 52) and is converted into an electrical signal. The original 32 is 
conveyed correspondingly to the reading speed for the original 32 by 
conveying rollers 53, 54, 55 and 56 driven by an original conveying motor 
(not shown). The reference numeral 57 denotes an original supporting 
table. A stock of sheets of originals 32 supported on this supporting 
table 57 is separated by the cooperation between the conveying roller 54 
and a press-separating piece 58 while being guided by a slider 57a, and 
these sheets are conveyed to the reading unit 100 and are read thereby, 
whereafter they are discharged into a tray 77. 
The reference numeral 41 designates a control base plate constituting the 
main portion of the control unit 101. Various control signals are output 
from this control base plate 41 to the various portions of the apparatus. 
The reference numeral 105 denotes a power source unit, the reference 
numeral 106 designates a modem base plate unit, and the reference numeral 
107 denotes an NCU base plate unit. 
FIG. 4 shows the details of conveying mechanisms for the ink sheet and the 
recording paper 11. 
In FIG. 4, the reference numeral 24 designates a recording paper conveying 
motor for rotatively driving the platen roller 12 and conveying the 
recording paper 11 in the direction of arrow b opposite to the direction 
of arrow a. The reference numeral 25 denotes an ink sheet conveying motor 
for conveying the ink sheet 14 in the direction of arrow a by a capstan 
roller and a pinch roller 72. The reference numerals 26 and 27 designate 
transmission gears for transmitting the rotation of the recording paper 
conveying motor 24 to the platen roller 12, and the reference numerals 73 
and 74 denote transmission gears for transmitting the rotation of the ink 
sheet conveying motor 25 to the capstan roller 71. The reference numeral 
75 designates a slide clutch unit. 
Here, by setting the ratio of the gears 73 and 74 so that the length of the 
ink sheet 14 taken up onto the take-up roll 18 by the rotation of a gear 
75a may be greater than the length of the ink sheet conveyed by the 
capstan roller 71, the ink sheet 14 conveyed by the capstan roller 71 is 
reliably taken onto the take-up roll 18. An amount corresponding to the 
difference between the amount of the ink sheet 14 taken up by the take-up 
roll 18 and the amount of the ink sheet 14 conveyed by the capstan roller 
71 is absorbed by the slide clutch unit 75. Thereby, any slack in the ink 
sheet 14 can be eliminated and fluctuations of the conveyance velocity 
(amount of conveyance) of the ink sheet 14 caused by fluctuation the 
take-up diameter of the take-up roll 18 can be suppressed. 
FIG. 1 shows the electrical connections between the control unit 101 and 
the recording unit 102 in the facsimile apparatus of the present 
embodiment, and in FIG. 1, portions common to those in other drawings are 
given identical reference numerals. 
The thermal head 13 is a line head, as previously described. This thermal 
head 13 is provided with a shift register 130 for receiving as inputs 
serial recording data 37 for one line from the control unit 101 and a 
shift clock 43 and storing them therein, a latch circuit 131 for latching 
the data in the shift register 130 by a latch signal 44, and a heat 
generating element 132 comprising heat generating resistance members 
corresponding to one line. The heat generating element 132 is divided into 
m blocks designated by 132-1 to 132-m and these blocks are driven. The 
reference numeral 38 designates a counter for counting the number of black 
data (the number of data causing the heat generating element to generate 
heat and the number of heat generating elements scheduled to generate heat 
next time) of the recording data for one line. In this counter 38, the 
recording data is input to an enable terminal (E), the latch signal 44 is 
input to a clear terminal (CLR), and the serial clock 43 synchronized with 
the recording data is input to a clock terminal (CK), and when the 
recording data 37 is "1", the rising of the clock signal 43 is counted. 
When the result of the counting is greater than a predetermined value, a 
wait signal 34 is output to the control unit 101. For example, where the 
original image reading width in the reading unit 100 is size B4 (2048 
picture elements) and the pulse width causing the heat generating element 
132 of the thermal head 13 is 600 .mu.sec., the wait signal 34 is output 
to the control unit 101 when the result of said counting is 1000 or 
greater. The threshold value of the counter which outputs this wait signal 
34 is not fixed at 1000, but may be suitably selected by the control unit 
101. That is, according to the present embodiment, even when after the 
recording of the present line, the transfer of the data of the next line 
is terminated (the preparation for the recording of the next line is 
completed), if the number of black data exceeds a predetermined value, the 
recording of the next line is not effected until the waiting time has 
passed. 
FIG. 5 shows an example of such timing. Here, at the rising (timing T1-T3) 
of the clock 43 when the recording data 37 is "1" (black data heat 
generating data)), the counter 38 is caused to count up. When the count 
value by the counter 38 exceeds the predetermined value, the wait signal 
34 is output. 
The control unit 101 receives this wait signal 34 as an input and thereby 
begins the waiting operation. During this waiting operation, the control 
unit 101 transfers the recording data to the shift register 130 of the 
thermal head 13, but does not output the latch signal 44 until the waiting 
terminates. This waiting time is counted by a timer 117, and when the 
control unit 101 detects the passage of a predetermined time (in the 
present embodiment, for example, 5 m sec.) on the basis of the output from 
the timer 117, the waiting operation is terminated. 
The reference numeral 133 denotes a temperature sensor mounted on the 
thermal head 13 for detecting the temperature of the thermal head 13. The 
output signal 42 of this temperature sensor 133 is A/D-converted in the 
control unit 101 and input to the CPU 113. Thereby the CPU 113 detects the 
temperature of the thermal head 13, and correspondingly to the detected 
temperature, it changes the pulse width of a strobe signal 47 or changes 
the driving voltage for the thermal head 13 output to a power source line 
45, thereby effecting the control of the applied energy to the thermal 
head 13 conforming to the characteristic of the ink sheet 14. 
The kind (characteristic) of the ink sheet 14 is indicated by the operator 
manually operating the switch 103a of the aforementioned operation unit 
103. The kind or characteristic of the ink sheet 14 may be automatically 
discriminated by automatically detecting a mark or the like printed on the 
ink sheet 14. As a further alternative, the kind or characteristic of the 
ink sheet 14 may be automatically discriminated by automatically detecting 
a mark, a cut-away or a projection formed on the cartridge of the ink 
sheet. 
The reference numeral 46 designates a driving circuit which receives as an 
input the driving signal for the thermal head 13 from the control unit 101 
and outputs the strobe signal 47 for driving the thermal head 13 at each 
block unit. This driving circuit 46 can change the voltage output to the 
power source line 45 for supplying an electric current to the heat 
generating element 132 of the thermal head 13 by the instructions of the 
control unit 101 to thereby change the applied energy to the thermal head 
13. The reference numeral 36 denotes a driving circuit for bringing the 
cutters 15 into meshing engagement with each other to thereby drive the 
cutters. The driving circuit 36 includes a cutter driving motor, etc. The 
reference numeral 39 designates a sheet discharge motor for rotatively 
driving the paper discharge rollers 16. The reference numerals 35, 48 and 
49 denote driver circuits for rotatively driving the sheet discharge motor 
39, the recording sheet conveying motor 24 and the ink sheet conveying 
motor 25, respectively. A signal 61 input to the driver circuit 48 among 
these driver circuits is a control signal for controlling the driving 
current for the recording sheet conveying motor 24, and the reference 
numeral 62 designates an energization phase signal for changing over the 
energization phase of the recording sheet conveying motor 24. In the 
present embodiment, the sheet discharge motor 39, the recording sheet 
conveying motor 24 and the ink sheet conveying motor 25 are stepping 
motors, but this is not restrictive, and these motors may be, for example, 
DC motors. 
Description of the Recording Operation (FIGS. 1-6) 
FIG. 6 is a flow chart showing the recording process for one page in the 
facsimile apparatus of this embodiment, and the control program for 
executing this process is stored in the ROM 114 of the control unit 101. 
It is to be understood that this process is started by image data for one 
line being stored in the line memory 110 and a state ready to start the 
recording operation being brought about and that the mounting of the 
multiink sheet 14 is discriminated in the control unit 101 by the switch 
103a or the like. 
First, at a step S1, the recording data for one line is serially output to 
the shift register 130. At this time, the counter 38 is counting the bit 
numbers which are "1" (black) among the serial data for one line. Advance 
is then made to a step S2, where whether the wait signal 34 is input from 
the counter 38 is examined. When the wait signal 38 is input, advance is 
made to a step S3, where the wait flag 116 of the RAM 115 is rendered ON, 
and advance is made to a step S4. If at the step S2, the wait signal 34 is 
not input, advance is made to a step S4, where whether the image data for 
one line has been transferred to the shift register 130 of the thermal 
head 13 is examined, and if the transfer is not terminated, return is made 
to the step S1. 
When at the step S4, the transfer of the image data to the thermal head is 
terminated, advance is made to a step S5, where the latch signal 44 is 
output, and the recording data for one line is stored in the latch circuit 
131. At the same time, the counter 38 is cleared by this latch signal 44. 
Subsequently, at a step S6, whether the waiting operation is going on is 
examined, and if the waiting operation is going on, at step S6, waiting 
continues until the termination of the counting of the waiting time is 
reported by the timer 117. 
When the waiting operation is terminated, advance is made to a step S7, 
where the ink sheet conveying motor 25 is driven to convey the ink sheet 
14 by an amount corresponding to 1/n line. Also, at the step S7, the 
recording sheet conveying motor 24 is driven to convey the recording sheet 
11 by an amount corresponding to one line. The length of one line is set 
to about 1/15.4 mm in the facsimile apparatus, but the amounts of 
conveyance of the recording sheet 11 and the ink sheet 14 can be set by 
changing the energization pulse numbers of the recording sheet conveying 
motor 24 and the ink sheet conveying motor 25, respectively. 
Subsequently, at a step S8, one block of the heat generating resistance 
member 132 is electrically energized to effect the recording of an image, 
and at a step S9, whether the electrical energization of all blocks (m 
blocks) of the thermal head 13 has been terminated is examined. If at the 
step S9, the electrical energization of all blocks of the thermal head 13 
is not terminated, return is made to the step S8, and after the passage of 
the energization time (about 600 .mu.s), the electrical energization of 
the next block is executed. In this embodiment, the thermal head 13 is 
divided into four blocks and these blocks are electrically energized, and 
the time required for the recording of one line is approximately 2.5 ms. 
If at the step S9, the electrical energization of all blocks of the thermal 
head 13 is terminated and the recording of one line is terminated, advance 
is made to a step S10, where it is determined whether the wait flag 116 is 
ON, that is, whether the number of black picture elements of the image 
data for the recorded one line has been a predetermined value or greater. 
If the wait flag 116 is not ON, advance is made to a step S12, but if the 
wait flag 116 is ON, advance is made to a step S11, where the counting of 
the waiting time (a predetermined time) is started by the timer 117, and 
advance is made to the step S12. The termination of the counting by the 
timer 117 is checked at the step S6 during the recording of the next line. 
At the step S12, whether the image recording for one page has been 
terminated is examined, and if the image recording for one page is not 
terminated, return is made to the step S1, where as previously described, 
the image data for the next one line to be recorded is transferred to the 
thermal head 13 and the aforedescribed recording process is executed. 
Next, when at the step S12, the image recording for one page is terminated, 
advance is made to a step S13, and the recording sheet 11 is conveyed by a 
predetermined amount toward the paper discharge rollers 16a, 16b. Then, 
the movable cutter 15b is driven into meshing engagement with the fixed 
cutter 15a to thereby cut the recording sheet 11 into a page length. 
Subsequently, the recording sheet conveying motor 24 is reversely driven 
to return the recording sheet 11 by a distance corresponding to the 
spacing between the thermal head 13 and the cutters 15, and the cutting of 
the recording sheet 11 is executed. 
Thus, according to the present embodiment, the number of black data 
recorded for each line is counted and when that number is greater than a 
predetermined value, after the recording of the current line, a waiting 
period passes before the next recording is started, whereby the influence 
of the heat accumulation in the thermal head 13 can be reduced. 
Description of Another Embodiment (FIGS. 7 and 8) 
In the previously described embodiment, the waiting operation begins when 
the number of black picture elements in one line has reached a 
predetermined value or greater, and description will now be made of a case 
where a table for determining the waiting time in conformity with the 
number of black picture elements is prepared and the waiting time is 
changed in conformity with the number of black picture elements. 
First, FIG. 11 is a table showing the relation between the count value 
indicative of the number of black picture elements and the waiting time, 
and this table is stored in the RAM 115. In this table, the waiting time 
becomes so longer as the count value becomes greater. For example, the 
waiting time when the count value is 1000 is 5 msec. 
FIG. 7 is a flow chart illustrating such another embodiment. 
Description will be made only of the differences of this flow chart from 
the flow chart of FIG. 6. First, at a step S23, the count value 34a from 
the counter 38 is input to and stored in the RAM 115. When the recording 
for one line is terminated, advance is made to a step S29, where the 
waiting time conforming to the count value is determined using the table 
shown in FIG. 11 and which is read at the step S23 and stored in the RAM 
115. This time is then set in the timer 117, and the time counting by the 
timer 117 is started. The termination of this time counting by the timer 
117 is checked at a step S25 during the recording of the next line, and at 
the step S25, waiting continues until the time counting by the timer 117 
is terminated. 
FIG. 8 shows the time counting by the counter 38, and as in the case of 
FIG. 5, when the recording data 37 is "1", counting up is done at the 
rising of the clock 43. 
In this embodiment, the number of black dots in the recording data in one 
line is counted by the counter 38, although this is not restrictive, and 
counting may be effected by software. 
As described above, according to this embodiment, the waiting time 
conforming to the number of black picture elements in one line (the amount 
of heat accumulated in the thermal head) is set from after the recording 
of the current line until the recording of the next line and therefore, a 
heat radiation time corresponding to the amount of accumulated heat can be 
provided. Thereby, the influence of the heat accumulation in the thermal 
head can be reduced and the ground stain of the recording sheet and the 
adherence of the ink sheet to the recording sheet can be reduced. 
Description of the Principle of Recording (FIG. 9) 
FIG. 9 shows the image recording condition when image recording is effected 
with the recording sheet 11 and the ink sheet 14 being conveyed in 
opposite directions. 
As shown, the recording sheet 11 and the ink sheet 14 are nipped between 
the platen roller 12 and the thermal head 13. The thermal head 13 is urged 
against the platen roller 12 by the spring 21 with a predetermined 
pressure. Here, the recording sheet 11 is conveyed at a velocity Vp in the 
direction of arrow b by the rotation of the platen roller 12. On the other 
hand, the ink sheet 14 is conveyed at a velocity V.sub.I in the direction 
of arrow a by the rotation of the ink sheet conveying motor 25. 
When the heat generating resistance member 132 of the thermal head 13 is 
electrically energized and heated by the power source 105, that portion of 
the ink sheet 14 which is indicated by hatching 91 is heated. Here, the 
14a designates the base film of the ink sheet 14, and the 14b denotes the 
ink layer of the ink sheet 4. The ink of the ink layer 91 heated by the 
heat generating resistance member 132 being electrically energized is 
melted, and the portion thereof designated by 92 is transferred to the 
recording sheet 11. This transferred ink layer portion 92 corresponds to 
approximately 1/n of the ink layer designated by 91. 
During this transfer, it is necessary that a shearing force be applied 
along the border line 93 of the ink layer 14b, so that only the portion 
designated by 92 will be transferred to the recording sheet 11. However, 
this shearing force differs depending on the temperature of the ink layer, 
and the shearing force tends to become smaller as the temperature of the 
ink layer becomes higher. So, if the heating time for the ink sheet 14 is 
shortened, the shearing force in the ink layer will become greater. Thus, 
if the relative velocity of the ink sheet 14 and the recording sheet 11 is 
increased, the ink layer to be transferred can be reliably peeled off from 
the ink sheet 14. 
Description of the Ink Sheet (FIG. 10) 
FIG. 10 is a cross-sectional view of the ink sheet used in the 
multiprinting in the previously described embodiment, and in this figure, 
the ink sheet is formed with four layers. 
The second layer is the base film which provides a back-up member for the 
ink sheet 14. In the case of multiprinting, heat energy is applied to the 
same portion of the ink sheet many times and therefore, the base film may 
advantageously be aromatic polyamide film of high heat resisting property 
or condenser paper, but conventional polyester film will also stand use. 
The smallest possible thickness of this film is advantageous in the 
quality of print from its role as a medium, but a thickness of 3-8 .mu.m 
is desirable from the viewpoint of strength. 
The third layer is an ink layer containing an amount of ink transferrable n 
times to the recording sheet. The main components of this layer are resin 
such as EVA as an adhesive agent, carbon black or nigrosine dye for 
coloring, and carnauba wax or paraffin wax as a binding material, and 
these are combined so as to be usable n times in one and the same portion. 
The amount of application of these materials may desirably be 4-8 
g/m.sup.2, but sensitivity and concentration differ depending on the 
amount of application, and the amount of application can be chosen as 
desired. 
The fourth layer is a top coating layer which is not concerned with 
printing, but rather prevents the ink of the third layer from being 
pressure-transferred. The fourth layer is formed of transparent wax or the 
like. Thus, it is only the transparent layer that is pressure-transferred, 
and the ground stain of the recording sheet can be prevented. The first 
layer is a heat resisting coat layer for protecting the second layer, 
i.e., the base film, from the heat of the thermal head. This is suitable 
for multiprinting in which heat energy corresponding to n lines may be 
applied repeatedly to and the same portion of the ink sheet (when black 
information is continuous), but whether it should be used or not is 
optional. Also, this layer is effective for base film of relatively low 
heat resisting property such as polyester film. 
The construction of the ink sheet 14 is not restricted to this embodiment, 
but the ink sheet may be, for example, one comprising a base layer and a 
porous ink retaining layer provided on one side of the base layer and 
containing ink therein. As a further alternative, the ink sheet may be one 
comprising base film and an ink layer of heat resisting property having 
fine porous net-like structure and provided on the base film, the ink 
layer containing ink therein. The material of the base film may be film 
formed, for example, of polyamide, polyethylene, polyester, polyvinyl 
chloride, triacetyl cellulose, nylon or the like, or paper. Further, the 
heat resisting coat layer is not always necessary, but the material 
thereof may be, for example, silicone resin, epoxy resin, fluorine resin, 
etholocellulose or the like. 
As an example of the ink sheet having heat-sublimating ink, mention may be 
made of an ink sheet comprising a substrate formed of polyethylene 
terephthalate, polyethylene naphthalate, aromatic polyamide film or the 
like, and a color material layer provided on the substrate and containing 
spacer particles formed of guanamine resin and fluorine resin and a 
dyestuff. 
The heating system in the heat transfer printer is not limited to the 
thermal head system using the aforedescribed thermal head, but may also 
be, for example, the electrical energization system or the laser transfer 
system. 
Further, in the previously described embodiment, the present invention has 
been described with respect to a case where it is applied to a facsimile 
apparatus as a heat transfer printer, whereas this is not restrictive, but 
the present invention can also be applied, for example, to a word 
processor, a typewriter, a copying apparatus or the like. 
The recording medium is not limited to recording paper, but may be, for 
example, cloth or plastic sheet to which ink can be transferred. Also, the 
ink sheet is not restricted to the roll construction shown in the 
embodiments, but may also be, for example, the so-called ink sheet 
cassette type or the like in which an ink sheet is contained within a 
housing removably mountable in a recording apparatus body and this housing 
can be mounted or dismounted with respect to the recording apparatus body. 
Furthermore, in the above-described embodiments, a thermal head has been 
described as an example of the recording means, but the present invention 
is not restricted thereto. For example, an ink jet head for discharging 
ink to thereby effect recording on a recording medium may be applied as 
the recording means. Such an ink jet head is generally provided with 
minute liquid discharge ports (orifices), a liquid flow path, an 
energy-acting portion provided in a portion of the liquid flow path, and 
energy generating means for generating liquid droplet forming energy 
caused to act on the liquid in said energy-acting portion. As the energy 
generating means for generating such energy, mention may be made of energy 
generating means in which an electromagnetic wave such as laser is applied 
and absorbed into liquid to generate heat and the liquid is carefully 
expelled by the action of the generated heat, or energy generating means 
in which liquid is heated by an electro-thermal conversion member and is 
discharged. Among these, a bubble jet head in which a driving signal for 
providing a rapid temperature rise exceeding nuclear boiling is applied to 
the electro-thermal conversion member to thereby generate heat energy in 
the electro-thermal conversion member and film boiling is caused on the 
heat-acting surface of the head to form a bubble in ink and by the growth 
of this bubble, the ink is discharged through discharge ports permits 
discharge ports to be arranged at a high density and therefore is 
particularly effective to accomplish recording of high resolving power. 
As described above, according to the present embodiment, when the number of 
recording dots for one line is great and the amount of heat accumulated in 
the thermal head becomes great, a time for the heat radiation of the 
thermal head is provided between the recording of the current line and the 
start of the recording of the next line, whereby the ground stain and 
trail-leaving of the recording sheet can be prevented. Thus, according to 
the present embodiment, the number of black picture elements is counted 
and when that number exceed a predetermined value, there is provided a 
time for permitting heat radiation until the recording of the next line, 
whereby the influence of the accumulated heat in the recording head can be 
reduced. 
As described above in detail, according to the present invention, the 
influence of the accumulated heat can be reduced to thereby improve the 
quality of recorded images.