Recording apparatus

A recording apparatus for recording a pattern by a plurality of dots comprises: discriminating means for discriminating whether or not the dot which exists in the dot series to be recorded next is located obliquely to the dot recorded previously; and control means which, in the case where it is determined by the discriminating means that the obliquely located dot exists, makes a drive of this dot different from an ordinary drive, thereby enabling this obliquely located dot to be recorded for a slightly longer recording time. With this apparatus, particularly, an oblique line can be smoothly and sharply recorded so that a recording quality of a character, figure or the like is greatly improved.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a recording apparatus for recording by use 
of a plurality of dots and, more particularly, to a recording apparatus or 
method which intends to improve sharpness in recording. 
The recording method or apparatus according to the present invention can be 
applied to, for example, a serial printer head,line head or the like which 
forms a desired pattern by a plurality of dots. 
2. Description of the Prior Art 
In a recording method whereby a character, figure or the like is formed by 
a large number of dots, the number of dots is an important factor for 
sharpness in recording. This is because the recording becomes fine and 
sharp when the number of dots is large, while the recording becomes rough 
and unsightly when the number of dots is small. 
However, in a conventional recording method, particularly in case of 
recording an oblique line, if the number of dots is small, each dot is 
separately printed from one another so that there is a drawback such that 
the oblique line resembles a stairway and the recording becomes extremely 
unsightly. 
SUMMARY OF THE INVENTION 
The present invention is made in consideration of the foregoing 
conventional drawback and intends to provide a recording method whereby 
even in a case where the number of dots is small, recording can be 
performed, particularly an oblique line can be smoothly and sharply 
formed. In the recording method of the invention, the dots to draw an 
oblique line, in particular, are made slightly long, thereby providing a 
recording apparatus in which the oblique line becomes smooth and sharp and 
a recording quality of a character, figure or the like is largely 
improved. 
Another object of the invention is to provide a recording apparatus for 
forming a pattern by a dot matrix, comprising: discriminating means for 
discriminating to see if a dot which exists in a dot series to be recorded 
next is located obliquely to the dot previously recorded or not; and 
control means which, when it is determined by the discriminating means 
that there exists a dot that is obliquely located, makes a drive of this 
dot different from an ordinary drive.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
An embodiment of the present invention will now be described in detail 
hereinbelow with reference to the drawings. 
FIG. 1 is a block diagram of a thermal printer which embodies one 
embodiment according to the invention. However, in the embodiment, a case 
where the number of exothermic dots is sixteen is adopted and the 
invention is not limited to this. 
In FIG. 1, an external host computer 1 and a control section 2 to control 
the operation of the printer are connected by a signal line SG1 and data 
is outputted to the control section 2 on a 16-bit unit basis. 
The control section 2 has a control memory 2A in which a control procedure 
as shown in FIGS. 3A and 3B has been stored and a processing section CPU 
2B which executes the procedure stored in this control memory and has a 
timer to count a time. 
The control section 2 is connected to a storage section 3 and an 
operational section 4. Further, the storage section 3 and operational 
section 4 are also connected with each other. In the embodiment, the 
storage section 3 is provided with five 16-bit shift registers (R1, R2, A, 
B, C). 
The control section 2 is connected to a driver 5 through a signal line SG2 
and a strobe control line STB. The driver 5 is connected to heating 
element (HT1 to HT16) of a head 6, respectively. 
The operation of the printer having such an arrangement will then be 
explained with reference to the drawings. 
FIG. 2 is an explanatory diagram schematically showing data and the result 
of recording thereof. FIGS. 3A and 3B are flowcharts of the embodiment. In 
FIG. 2, the data in each cycle (hereinafter, referred to as CY) is 
constituted by sixteen bits. The heating of the corresponding heating 
elements HT1 to HT16 is determined in dependence upon a level of each bit, 
namely, whether it is at a high level "1" or low level "0". In the 
embodiment "1" denotes the heating and an explanation will be made herein 
below by assuming that the bit in each CY corresponding to the heating 
element HT1 is the MSB (most significant bit) and the bit corresponding to 
the HT16 is the LSB (least significant bit). 
First, when initial data of 16 bits (CY1 in FIG. 2) is inputted from the 
host computer 1 through the signal line SG1 to the control section 2, the 
control section 2 stores the data CY1 into the register R2 (ST1 in FIG. 
3A). Subsequently, the data CY1 stored in the register R2 is transferred 
into the register R1 (ST2) and a next data CY2 is stored into the register 
R2 (ST3). 
The control section 2 checks to see if it may drive (main heat H1) the head 
6 or not to record the data CY1 stored in the register R1 (ST4). If the 
main heat H1 can be performed (YES in ST4), the control section 2 reads 
out the data CY1 from the register R1 and transmits it to the driver 5 
through the signal line SG2 and simultaneously makes a strobe signal STB 
active to allow the heating elements HT1 to HT16 to be heated in 
accordance with the heating dot pattern corresponding to the data CY1, 
thereby performing the recording (ST5). 
Next, the control section 2 executes the operation to extract the dots 
which are subjected to a subheat H2 from the data CY1 at this time. 
First, the present data CY1 stored in the register R1 is transferred to the 
operational section 4, by which the content of each bit is inverted 
(hereinbelow, referred to as R1). Next, a calculation is made to get AND 
of the content of each bit of the data CY2 at the next time stored in the 
register R2 and the previous content of R1 and the result of calculation 
is stored in the register A (ST6). Thus, the content of which the bits 
which allow the heating elements at the same positions as the present data 
CY1 to heat among the data CY2 at the next time were set to "0" is stored 
in the register A. In this case, only dot 7 is set to "1". 
Subsequently, the control section 2 outputs a shift pulse to the register 
R1 and permits the present data CY1 stored in the register R1 to be 
shifted to the right by only one bit and stores the content into the 
register B (ST7). Namely, in FIG. 2, the present data CY1 is shifted to 
the side of the LSB by one bit. 
Then, AND of the content of each bit stored in the register A and the 
content of each bit stored in the register B is calculated and the result 
of calculation is stored in the register C (ST8). In this case, since a 
comparison is made with respect to the CY1 and CY2, the contents of the 
register C are all "0". 
Then, the control section 2 outputs a shift pulse to the register C, 
thereby allowing the content of the register C to be shifted to the left 
(the side of the MSB) by only one bit (ST9). 
The bits such that the bits of "1" stored in the register A exist at the 
lower oblique positions of such bits among the present data CY1 stored in 
the register R1 are extracted due to the processes in ST7 to ST9 as 
described above and are stored in the register C. In this case, the dot 
from which a dot 7 of the data CY2 is seen at the lower oblique position 
of such dot does not exist in the data CY1, so that the contents of the 
register C are all "0". 
In subsequent steps ST10 to ST12, by a method substantially similar to 
steps ST7 to ST9, the bits such that the bits of "1" stored in the 
register A exist at the upper oblique positions of such bits among the 
present data CY1 stored in the register R1 are extracted and are stored in 
the register B. In this case, a dot 8 from which the dot 7 of the data CY2 
can be seen at the upper oblique position exists in the data CY1, so that 
the contents of the register B become such that the bit corresponding to 
the position of the dot 8 is "1" and the other bits are "0". 
After that, OR of each bit in the registers C and B is calculated and the 
result of calculation is stored in the register R1 (ST13). Subsequently, 
calculation is made to get AND of each bit in the register R1 and the R2 
and the result of calculation is stored in the register R1 (ST14). The 
content of the R2 is obtained by inverting each bit in the register R2 in 
which the data CY2 at the next time has been stored. Due to the process 
ST14, if the dot of the data CY2 at the next time exists at the same 
position as that of the dot 8 to be subjected to the subheat H2, this 
subheat H2 is cancelled. 
In this way, the data for the subheat H2 is finally stored in the register 
R1. In this case, the content of the register R1 is merely such that the 
bit at the position corresponding to the dot 8 of the CY1 is "1". 
Subsequently, the control section 2 checks to see if the subheat H2 can be 
performed or not (ST15). If it is possible (YES in ST15), the control 
section 2 makes the strobe signal STB active and also outputs the subheat 
data stored in the register R1 to the driver 5, thereby starting the 
subheat (ST16). At the same time, the control section 2 makes the counter 
provided therein start, thereby counting the count number (NO in ST17). 
When the count number reaches a predetermined number (YES in ST17), the 
control section 2 makes the strobe signal STB inactive, thereby finishing 
the subheat H2 (ST18). 
In this way, the subheated dot is recorded slightly longer as compared with 
the other dots which were merely subjected to the main heat. 
Unless the recording is completed (NO in ST19), the data stored in the 
register R2 is transferred into the register R1 and the next data is also 
stored into the register R2 (ST2, ST3). In the case, since the data of CY2 
has been stored in the register R2, the data of CY2 is set to the data at 
this time and the data of CY3 is set to the data at the next time due to 
the process in ST2 and ST3, and the foregoing operations are repeated 
similarly hereinafter. 
As described above, the portions of the oblique lines indicated by the 
black dots in FIG. 2 are subheated and are smoothly recorded. 
In the embodiment, the case where the heating elements are arranged in a 
longitudinal line has been described. However, it is apparent that the 
invention can be easily applied even in case of a line head in which the 
heating elements are arranged in a transversal line. 
Further, in the embodiment, the subheat is performed after the main heat. 
However, the subheat may be executed during or before the main heat or may 
be carried out separately from the main heat. 
In addition, the recording method according to the invention is not limited 
to only the thermal printer but may be also applied to a wire dot printer 
or the like.