JP2848650B2 - Printer device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer printer using a thermal line head, which is caused by a decrease in the density of a heating element at a boundary of a block when the thermal line head is divided and driven. It eliminates white lines between blocks and can be widely used especially for color image printers.

2. Description of the Related Art Conventionally, a method of recording by energizing all the heating elements of one line of a thermal line head at the same time is common. However, when energizing simultaneously, the sum of currents flowing through all the heating elements becomes a very large value. The scale of the device increases. In addition, during the time when the heating element is radiated and cooled after the recording of one line, the current flowing through the heating element becomes zero, and a cycle of a large current and zero is repeated, so that the transient characteristics of the voltage fluctuation with respect to the load fluctuation become important. In addition, it is very difficult to design a power supply device, and the device itself becomes heavy and expensive.

Therefore, a method is generally used in which all heating elements of one line of a thermal line head are divided into a plurality of blocks and divided and driven at different timings, mainly in terms of current capacity.

Hereinafter, an example of the above-described conventional printer will be described with reference to the drawings. As an example, all the heating elements of the thermal line head are divided into two blocks,
A case where value recording is performed will be described. FIG. 2 is a block diagram of a conventional example of the above-described printer apparatus, and FIG. 3 is a timing chart thereof.

2 and 3, reference numeral 21 denotes a clock generation circuit that generates a clock CK1, 22 denotes a counter that divides the clock CK1, and 23 denotes an address that decodes an output CK2 of the counter 22 and generates a memory read address AD. The generation circuit 24 decodes the output CK2 of the counter 22 and outputs the data transfer clock CLK, strobe STB, enable ENB1, ENB2
A thermal line head control signal generating circuit for generating each thermal line head control signal; 25, a line memory for storing print data for one line of the thermal line head; 26, a parallel print read from the line memory 25 A parallel-in serial out shift register 27, 28 for converting the data DT into serial data SD by the data transfer clock CLK, 27, 28 converts the serial data SD into parallel data corresponding to the heating element of the thermal line head by the data transfer clock CLK. A serial-in-parallel-out shift register; 29, 30 are latches for latching the converted parallel data by the strobe STB; 31, 32 are heating element drive circuits 33, 34 for passing a recording current to the heating element; , The thermal line head constituting the second block That.

With respect to the conventional printer configured as described above,
Hereinafter, the operation will be described. The clock CK1 generated by the clock generation circuit 21 is frequency-divided by the counter 22, and the frequency-divided clock CK2 is decoded by the address generation circuit 23 to generate the read address AD of the line memory 25.
Further, the clock CK2 is decoded by the thermal line head control signal generating circuit 24 to generate the data transfer clock CLK, the strobe STB, and the thermal line head control signals of the imbles ENB1 and ENB2. The 8-bit parallel print data DT of the first block read from the line memory 25 by the address AD is converted into serial data SD by the parallel-in-serial-out shift register 26 by the data transfer clock CLK. The parallel data is converted into parallel data corresponding to the heating element of the thermal line head by the data transfer clock CLK by the in-parallel shift registers 27 and 28, and is latched by the latches 29 and 30 by the strobe STB. The latched data is sent to the heating element drive circuits 31 and 32. And enable E
By activating NB1, a recording current flows through the heating element of the thermal line head 33, and recording of the first block is performed. On the other hand, during the recording of the first block, the print data of the second block is read from the line memory 25, is converted into serial data by the parallel-in serial out shift register 26, and is sent to the thermal line head. Converted to parallel data corresponding to the heating element by 27, 28
It is latched by latches 29 and 30 by STB. The latched data is sent to the heating element drive circuits 31 and 32. By activating the enable ENB2, a recording current flows through the heating element of the thermal line head 34, and the recording of the second block is performed.

FIG. 4A is a timing chart showing the timing of the energizing pulse applied to the thermal line head when printing is performed at the maximum density, and FIG. 4B is a diagram showing the main scanning direction of the heating element array of the thermal line head. It is a figure showing an average temperature distribution. Here, for example, at the time of printing the first block, since the temperature of the adjacent second block is still low, the heating element of the first block on the boundary with the second block is deprived of heat by the second block. As a result, the temperature is lower than that of the central heating element. When printing the second block, since the first block cools down, the heating element of the second block at the boundary with the first block does not lose heat toward the first block. Temperature is lower than that of the heating element. As a result, the average temperature distribution of the thermal line head is shown in FIG. 4 (b).
And the print density is reduced at the boundaries of the blocks and remains as white streaks. The effect of the thermal line head switching line on the recorded image is large,
In particular, in an apparatus for recording a color image or the like having a gradation, an aesthetic factor is lost, which is a serious problem.

In order to reduce the thermal line head switching line, for example, as shown in Japanese Patent Application Laid-Open No. 58-158275, two gradation specifying ROMs are provided, and the gradation time for the heating element at the boundary of the block is increased to increase the conduction time. A method has been devised to prevent a decrease in the recording density by increasing the energy given to the heating element at the boundary of the block by switching to such a ROM.

Problems to be Solved by the Invention However, in the above-mentioned method, there is no effect if the division of the energization time is small, and if it is too large, it appears as a black line, so it is difficult to set the increment of the energization time. is there. Further, since the optimum increment changes depending on the environmental temperature, the heat storage state of the thermal line head, the characteristics of the recording system, and the like, there is a problem that it is very difficult to always perform the optimum correction.

The present invention solves the above-described problem, and does not fix the position of the boundary of each block, equalizes the power at the time of printing of each block, thereby reducing the load at the time of the peak power supply of the thermal line head. It is another object of the present invention to provide a printer device in which white lines due to a decrease in density between blocks are not noticeable.

Means for Solving the Problems In order to solve the above problems, a printer device of the present invention includes a thermal line head, division control means for dividing and controlling all the heating elements of the thermal line head into N blocks, A memory for storing gradation data for one line in the main scanning direction of the thermal line head, a first adder for outputting the sum of the gradation data for one line, and output data of the first adder (N is a natural number of 2 or more and 1 ≦ i ≦ N−1), an address generating means for giving an address to the memory, and gray scale data read from the memory. A second adder for sequentially adding, and a comparator for comparing an output of the second adder with an output of the multiplication / division unit, wherein the division control means is connected to an output of the comparator, and Tone data in block Are controlled so that the total sum of them becomes equal to each other.

According to the above-described configuration, the division control means divides and controls all the heating elements of the thermal line head into N blocks, and records the gradation data of one line in the main scanning direction of the thermal line head in the memory. , The sum of the gradation data for one line is generated, and the multiplier / divider outputs i / N of the output of the first adder (N is a natural number of 2 or more and 1 ≦ i ≦ N−1).
And a read address is given to the memory by the address generating means, the gradation data read from the memory is sequentially added by the second adder, and the output of the second adder is multiplied and divided by the comparator. The output of the comparator is compared with the output of the comparator, and the division control means controls the total sum of gradation data in each block to be equal to each other, so that the load of the power supply at the time of recording in each block is substantially uniform. West,
In addition, the position of the boundary between blocks can be moved for each recording line, and a white line due to switching between blocks can be eliminated.

Hereinafter, a printer according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a printer according to an embodiment of the present invention. The case where N = 4 will be described for easy understanding. In FIG. 1, 1 is a thermal line head, 2 is division control means for dividing and controlling all the heating elements of the thermal line head into four blocks, and 3 is a floor for one line of the thermal line head 1 in the main scanning direction. 4 is a first adder for outputting the sum 階 調 of the gradation data for one line, and 5 is an output of the first adder 4 which is 1/4, 2/4, A multiplier / divider for outputting 3/4; 6 an address generating means for giving an address to the memory 3; 7 a second adder for sequentially adding the gradation data read from the memory 3
Is a comparator for comparing the output of the second adder 7 with the output of the multiplier / divider 5.

The operation of the thus configured printer of this embodiment will be described below. At the same time, one line of the gradation data is written into the memory 3 by means such as a CPU (not shown), and at the same time, the first adder 4 outputs the sum Σ of the one line of the gradation data. In this sum Σ
Of 1/4, 2/4, 3/4 First, when recording the first block, the grayscale data for one line stored in the memory 3 is sequentially read out by the read address generated by the address generating means 6 and given to the second adder 7, and sequentially. At the same time as the addition, data is sent to the thermal line head 1 via the division control means 2. The result of this addition is compared with the output of the multiplier / divider 5 by the comparator 8, and data exceeding Σ / 4 is converted into non-print data by the division control means 2 and sent to the thermal line head 1. When the gradation data for one line has been sent, recording of the first block is performed by the thermal line head 1.

Next, when recording the second block, the grayscale data for one line stored in the memory 3 is sequentially read by the read address generated by the address generating means 6, and the second block is read.
And the data is sent to the thermal line head 1 via the division control means 2 at the same time as the data is sequentially added. The result of the addition is compared with the output of the multiplier / divider 5 by the comparator 8, and data not exceeding Σ / 4 is converted into non-print data by the division control means 2 and sent to the thermal line head 1. Data from which the addition result exceeds Σ / 4 is sent to the thermal line head 1 as it is. Addition result is 2Σ
Data exceeding / 4 is converted into non-print data by the division control means 2 and sent to the thermal line head 1.
When the transfer of the gradation data for one line is completed, the recording of the second block is performed by the thermal line head 1.

Next, when the third block is recorded, the grayscale data for one line stored in the memory 3 is sequentially read by the read address generated by the address generating means 6 and the second block is read.
And the data is sent to the thermal line head 1 via the division control means 2 at the same time as the data is sequentially added. The result of the addition is compared with the output of the multiplier / divider 5 by the comparator 8, and data not exceeding 2Σ / 4 is converted into non-print data by the division control means 2,
Can be sent to Data from which the addition result exceeds 2/4 is sent to the thermal line head 1 as it is. Addition result is 3
The data exceeding Σ / 4 is converted into non-print data by the division control means 2 and sent to the thermal line head 1. When the transfer of the gradation data for one line is completed, the recording of the third block is performed by the thermal line head 1.

Next, when recording the fourth block, the grayscale data for one line stored in the memory 3 is sequentially read by the read address generated by the address generating means 6 and the second block is read.
And the data is sent to the thermal line head 1 via the division control means 2 at the same time as the data is sequentially added. The result of the addition is compared with the means of the multiplication / division unit 5 by the comparator 8, and data not exceeding 3/4 is converted into non-print data by the division control means 2 and
Sent to Data from which the addition result exceeds 3/4 is sent to the thermal line head 1 as it is. When the transfer of the gradation data for one line is completed, the recording of the fourth block is performed by the thermal line head 1.

As described above, according to the present embodiment, divided driving can be performed so that the recording energy of each block becomes equal,
Power supply load fluctuations can be minimized. Furthermore, the division position of each block can be made different for each line, and an excellent effect that white streaks at the boundaries are not noticeable can be obtained.

Effect of the Invention As described above, according to the printer device of the present invention, it is possible to reduce the load of the thermal line head at the peak power supply by equalizing the power at the time of printing of each block, and to design the transient response characteristics. Becomes easier.

Further, in the thermal line head described in Japanese Patent Application Laid-Open No. 63-107567, the boundary position between blocks is fixed regardless of the number of sub-lines. In addition, in the thermal line head described in JP-A-60-24969, the boundary position between the blocks is fixed,
In the case of an image having little change in shading, the switching position of the block may not change particularly over several lines, and a chain white line may be generated. Since the position is not fixed and changes for each line, the boundary position between blocks moves for each line and does not become a white line, and it is only a thin dot of 1 dot, so it can not be seen by the naked eye,
The white line due to the decrease in density between blocks can be eliminated,
High image quality can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram of a printer according to an embodiment of the present invention, FIG. 2 is a block diagram of a printer according to a conventional example, and FIG.
FIGS. 4A and 4B are timing diagrams of the conventional printer, and FIGS. 4A and 4B are diagrams showing the relationship between the energizing time of each block of the conventional printer and the average temperature distribution of the thermal line head. 1 ... thermal line head, 2 ... division control means, 3
... Memory, 4... First adder, 5.
... Address generating means, 7 second adder, 8 comparator.

Continuation of front page (72) Inventor Masahiro Nakamura 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-63-107567 (JP, A) JP-A-60-24969 (JP) JP-A-63-249772 (JP, A) JP-A-3-108566 (JP, A) JP-A-3-147857 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB Name) B41J 2/355 B41J 2/36 H04N 1/23 H04N 1/032

Claims (1)

(57) [Claims] 1. A thermal line head, division control means for dividing all heating elements of the thermal line head into N blocks, and storing one line of gradation data in the main scanning direction of the thermal line head. Memory, a first adder that outputs the sum of the gradation data for one line, and i / N (N is a natural number of 2 or more and 1 ≦ i ≦ N) of the output data of the first adder. -1), an address generating means for giving an address to the memory, and a second unit for sequentially adding the gradation data read from the memory.
, And a comparator for comparing the output of the second adder with the output of the multiplier / divider. The division control means is connected to the output of the comparator, and controls the gradation in each block. A printer device wherein the sum of data is controlled to be equal to each other.