JPH08290602A - Thermal build-up controller for line type thermal transfer printer - Google Patents

Abstract

PURPOSE: To prevent the density irregularity without providing a page buffer even when a printing period between lines is constant by preventing the density irregularity due to the thermal build-up of a thermal head and the tailing phenomenon for an arbitrary print pattern. CONSTITUTION: A print data correcting calculator 18 reads the residual heat quantity SJ corresponding to a head element which is desired to be used from a residual heat quantity one-line storage memory 15 for storing the residual heat quantity of each head element by one line and obtains print data dJK based on the residual heat quantity SI and the input data DJK corresponding to the head element. A residual heat quantity calculator 19 calculates the latest residual heat quantity corresponding to the element based on the residual heat quantity SJ and the print data dJK, and stores it in the corresponding address of the memory 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat storage control device for a line type thermal transfer printer.

[0002]

2. Description of the Related Art Conventionally, there has been known a line type thermal transfer printer having a thermal head composed of head elements for one line and printing ink by transferring ink line by line. Generally, it is considered that the printing speed of the printer is faster, and the printing time interval between each line tends to be shortened so that the line type thermal transfer printer can also perform printing at higher speed.

Therefore, the thermal head of the line type thermal transfer printer prints the next line before the heat generated by printing one line is completely discharged.
That is, heat is accumulated (stored) in the thermal head. Since the thermal head transfers the ink having the density (gradation) according to the temperature to the paper, the heat storage causes a large density unevenness between the print start line and the final line. .

As a method of suppressing such density unevenness, the residual heat quantity of the thermal head is estimated from past input data, the input data is corrected based on the estimated value to create print data, and this print data is converted into this print data. A method of printing based on this is conceivable. The configuration of the line type thermal transfer printer to which the above method is applied will be described below with reference to FIG.

In FIG. 3, reference numeral 1 is a data input means for sequentially inputting data from a computer or the like line by line. Here, in each data Djk, j is a variable that represents the element number of the thermal head, and if the number of head elements forming the thermal head is n,
It takes an integer value that satisfies 1 ≦ j ≦ n. Further, k is a variable indicating a line number, and takes an integer value satisfying 1 ≦ k ≦ L, where L is the number of lines forming one page. In addition,
Hereinafter, the k-th line data will be represented by Dk.

Reference numeral 2 is a distribution means, and for each data Djk sequentially input by the data input means 1,
(M + 1) threshold values Ti are used to sort into m groups (where i is a variable that takes an integer value of 1 or more and m or less). Here, the respective threshold values T0 to Tm are T0 <... <
The relationship of Ti-1 <Ti <... <Tm is satisfied. For example, Djk that satisfies Ti-1 <Djk ≤ Ti is distributed to the i-th group.

A counting means 3 counts the number of data Djk for each group distributed by the distribution means 2, that is, the number of transfer dots Si for each group, with respect to the data Dk for one line. Reference numeral 4 denotes a residual heat quantity estimating means, which estimates and calculates the heat quantity (residual heat quantity Q) remaining in the thermal head after printing one line for the data for one line by the following equation (1).

[Equation 1] In the above equation (1), T is a printing cycle for each line, Ai is a count assigned to each group, f is a predetermined function, and these parameters and functions are the characteristics of the thermal head, printer, ink, etc. It is set in advance based on the usage environment.

Reference numeral 5 is a print data calculation means for calculating the print data djk actually transferred to the thermal head by the following equation (2).

[Equation 2] In the above equation (2), F is a function preset according to the environment of use. Also, hereinafter, the kth data for one line is represented by dk.

6 is a print data transfer means for transferring the print data dk for one line calculated by the print data calculation means to the thermal head side, and 7 is based on the print data transferred from the print data transfer means. It is a thermal head driving means for driving the thermal head. Next, the operation of the line type thermal transfer printer having the above configuration will be described with reference to FIG.

As shown in FIG. 4, the printer is
Data input means 1 for data D11, D2 for one line
When 1, ..., Dn1 are input, first, initial setting is performed (steps S1 and S2). Next, it is judged whether or not the transfer of the final line is completed (step S3).
In this case, since the processing of the first line (k = 1) is being performed, the determination result is “YES” and the processing is continued.

Next, in steps S4 to S11, a process of classifying each data D11, D21, ..., Dn1 into m groups and a process of counting the number of transfer dots Si for each group are performed. Then, these processes are completed, and step S
When the determination result in 5 is "NO", the calculation using the above-described equations (1) and (2) is performed (step S12,
S13), the calculated print data d11, d21, ..., dn1
The printing is performed based on (step S14).

Thereafter, similar processing is performed on the second line, the third line, .... However, even if the line to be processed is changed, the transfer dot number Si is not reset and is sequentially added. This makes it possible to perform control that predicts the heat storage state of the thermal head. Then, the process for the n-th line is completed,
The process ends if the decision result in the step S3 becomes "NO".

[0013]

By the way, the density unevenness in the line type thermal transfer printer changes variously depending on the printing pattern. Further, in the line type thermal transfer printer, a "tailing phenomenon" occurs in which the density of dots following the dots transferred with high density becomes high. However, in the above-mentioned line type thermal transfer printer, the residual heat quantity Q obtained by the equation (1) is obtained regardless of the printing pattern.
If the values are the same, the same control is performed, and there is a disadvantage that it is not possible to remove the density unevenness and the tailing phenomenon that change or occur corresponding to the print pattern.

In particular, in a sublimation type printer that attempts to obtain a print quality equivalent to that of a photograph, print energy is different for each gradation (density) and the effect of heat storage on the head is delicate, so the print pattern is considered. There is a need for a method or apparatus for properly controlling printing energy based on the accumulated heat storage condition.

By the way, the data input means 1 of the line type thermal transfer printer shown in FIG.
(Page buffer). Therefore, the printer is configured so as to prevent a situation in which the data of the line to be processed has not been input from the computer side. Although RAM has become cheaper in recent years, for example, a large-capacity page buffer for storing one page of image data is still expensive.

However, in the case where the large-capacity page buffer is not provided, if the data transfer from the computer side is slow, the above situation will be caused, and the printer cannot predict until the printing of the next line. It is necessary to interrupt the printing operation for a certain period of time. In this case, when the printing is restarted, the residual heat amount Q of the thermal head is decreased according to the waiting time, but the printer does not consider the interruption at all, so the calculated residual heat amount Q was not interrupted. In this case, the residual heat amount becomes the same as that in the case, and the difference from the actual residual heat amount increases. Therefore, the printer has a problem that an expensive page buffer is indispensable to prevent the occurrence of color unevenness. Of course, as described above, even if the page buffer is provided, a sufficient effect cannot be obtained.

The present invention has been made in view of the above circumstances, and it is a first object of the present invention to prevent the occurrence of density unevenness and tailing phenomenon due to heat storage of a thermal head for an arbitrary print pattern. A second object is to prevent the occurrence of density unevenness without providing a page buffer even when the printing cycle between lines is not constant.

[0018]

According to another aspect of the present invention, there is provided a heat storage control device for a line type thermal transfer printer, wherein a print data for one line is supplied to a driving means of a thermal head so that the paper has a density corresponding to the print data. Each head element that is built in a line-type thermal transfer printer that transfers ink in a fixed cycle and that constitutes the thermal head based on the amount of heat remaining in the thermal head due to a printing operation and input data supplied from an external device. In a heat storage control device of a line type thermal transfer printer for determining print data for each and supplying the print data to the driving means, a residual heat quantity storage means for storing only one line of residual heat quantity which is the quantity of heat remaining in each head element, The residual heat quantity corresponding to the head element to be used is read from the residual heat quantity storage means, and the residual heat quantity is read. And a correction calculation unit for obtaining print data based on the input data corresponding to the head element, a latest residual heat amount corresponding to the head element based on the residual heat amount and the print data, and the residual heat amount. It is characterized in that it is provided with a residual heat quantity calculation means to be stored in the storage means.

A heat storage control device for a line type thermal transfer printer according to a second aspect is the one according to the first aspect, wherein a dummy printing means for permitting / prohibiting the supply of the print data obtained by the correction calculating means to the driving means. When the unprinted input data is less than one line at the print start timing, the dummy printing unit prohibits the supply of the print data obtained by the correction calculation unit to the driving unit, The correction calculation means is characterized in that the data representing the lowest gradation is used in place of the input data and the print data is obtained at the constant cycle.

[0020]

According to the first aspect of the invention, the correction calculation means reads out the residual heat quantity corresponding to the head element to be used from the residual heat quantity storage means for storing the residual heat quantity of each head element for one line. , Print data is obtained based on the residual heat amount and the input data corresponding to the head element. Further, the residual heat quantity calculation means calculates the latest residual heat quantity corresponding to the head element based on the residual heat quantity and the print data, and stores it in the residual heat quantity storage means.

According to the second aspect of the invention, when the unprinted input data is less than one line at the print start timing, the dummy printing means drives the print data obtained by the correction calculation means. Supply to the print data is prohibited, and the correction calculation means uses the data representing the lowest gradation in place of the input data to obtain the print data at a constant cycle that coincides with the time of printing execution.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a heat storage control device for a line type thermal transfer printer according to an embodiment of the present invention. The heat storage control device shown in this figure has a thermal head composed of n head elements, It is built in a line type thermal transfer printer capable of printing L lines and controls it. In addition to the heat storage control device and the thermal head, the line type thermal transfer printer has a CPU (central processing unit) that controls the drive mechanism of the thermal head and the operation of each unit. Further, the respective parts shown in FIG. 1 are synchronized by the same clock.

In FIG. 1, reference numeral 11 denotes a line buffer having a storage capacity of at least one line, and data to be printed supplied from an external device such as a computer (hereinafter referred to as input data DJK, DK is the Kth) Of the input data for 1 line, where J and K are integers and satisfy 1 ≦ J ≦ n and 1 ≦ K ≦ L, respectively)
Is temporarily stored for one line, and after the data for one line is stored, the stored data is sequentially output dot by dot at a preset timing. The line buffer 11 is configured to clear the stored contents when all the data are output.

Reference numeral 12 denotes an input incomplete detection section for detecting whether or not one line of input data DK has been input to the line buffer 11, and outputs data representing the detection result. Thirteen
Is an input data switching unit provided in the latter stage of the line buffer 11, and outputs the input data DJK from the line buffer 11 through or outputs it according to the output data of the input incomplete detection unit 12, or there is no transfer dot. It is switched whether to output data "0" (representing the lowest gradation). This data “0” is input to the input data switching unit 13
May be generated or may be supplied from the outside.

Reference numeral 14 is an address setting section, which is a C (not shown).
An address corresponding to a value obtained by adding 1 to the head element number J input from PU is generated. Reference numeral 15 is a residual heat quantity 1 line storage memory (residual heat quantity storage means) composed of a RAM having a storage capacity of 1 line, and stores the residual heat quantity for each head element for 1 line. The amount of residual heat referred to here means the amount of heat remaining in the head element at any point from immediately after the dot transfer to the next transfer timing, when focusing on a certain head element.

Reference numeral 16 denotes a residual heat quantity temporary storage shift register capable of storing data for 3 dots, which reads data for 1 dot from an address generated by the address setting section 14 of the memory 15 and sequentially shifts and stores it. . Reference numeral 17 denotes a parameter setting unit connected to the CPU bus, which sets parameters used in various calculations to be described later to values input via the CPU bus. In addition, the CPU bus is
The memory 15 and the shift register 16 described above are connected.

Reference numeral 18 denotes a print data correction calculation unit (correction calculation means), which outputs data for 3 dots stored in the shift register 16, parameters set by the parameter setting unit 17, and the input data switching unit 13. Based on the data (that is, the input data DJK or "0"), the calculation of the following formula (3) is performed, and the print data dJK representing the print energy for the Jth dot
Is output.

(Equation 3)

In the above equation (3), γ and δ are parameters set by the parameter setting unit 17, f is an arbitrary function preset based on the environment of use, and is a concrete expression in the above equation (3). An example in which the function f is applied is shown below.

[Equation 4] Although not shown, the print data dJK sequentially output from the print data correction calculation unit 18 is accumulated in the buffer (dummy printing unit) for one line and is supplied to the drive circuit of the thermal head.

Reference numeral 19 denotes a residual heat amount calculation unit (residual heat amount calculation means) for calculating the residual heat amount SJ in each head element of the thermal head, and the data for three dots stored in the shift register 16, the parameter setting unit 17, and the printing. Print data d output from the data correction calculation unit 18
The following equation (5) is calculated based on JK, and
The residual heat quantity of the th head element is calculated. The residual heat amount calculation unit 19 is sent to the address setting unit 14 (J-1).
Is input, the calculated residual heat amount is supplied to the memory 15, and the residual heat amount at the address corresponding to the J-th head element is updated.

(Equation 5) In the equation (5), α is a parameter set by the parameter setting unit 17, F is an arbitrary function preset based on the usage environment, and a specific function F is applied to the equation (5). An example is shown below.

(Equation 6)

The operation of the heat storage control device having the above configuration will be described below with reference to FIG. FIG. 2 is a flow chart for explaining the operation of the heat storage control device of the line type thermal transfer printer according to this embodiment. First, when the printer is turned on to be in a printable state and a signal indicating the start of printing is supplied from an external device, step SB1
Is processed. Specifically, "00 ... 0" and "0,0" are supplied to the memory 15 and the shift register 16 via the CPU bus of FIG. 1, respectively, and initialization is performed.

Further, the parameter setting unit 17 is provided with a CPU
The parameters α, γ, δ used in the above-described equations (3) to (6) are supplied via the bus, and these parameters are used in the calculation by the print data correction calculation unit 18 and the residual heat amount calculation unit 19. Is set. Further, "1" is substituted for the variable K, and the processing for the first line is set.

Next, at step SB2, the variable FL for switching between the normal processing mode and the dummy processing mode, which will be described later, is set to the value "0" indicating that the normal processing mode is selected.
And "0" is input to the address setting unit 14 as the head element number J, and from the address corresponding to "0 + 1" of the memory 1, that is, "1",
The residual heat amount S1 is supplied to the shift register 16. As a result, the contents of the shift register 16 are "0, 0, S1.
After that, "1" is input to the address setting unit 14 as the head element number J, and the contents of the shift register 16 become "0, S1, S2". In parallel with this, the line buffer 11 Input data DJK is sequentially input to and is temporarily stored.

Next, in step SB3, the line buffer 11 for the input data D11, D21, ..., Dn1 for one line.
It is determined whether or not the temporary storage in is incomplete. If this determination result is "YES", the process proceeds to step SB4, and the variable FL is set to the value "1" representing the "dummy process mode". Then, the process is step SB.
Go to 5.

On the other hand, if the decision result in the step SB3 is "NO", the process directly proceeds to the step SB5 (normal process mode). In step SB5, it is determined whether the printing of one page is completed. In particular,
The K representing the current line is compared with the maximum number L of lines. Here, since K = 1 <L, the above determination result is “YES”, and the process proceeds to step SB6.

In step SB6, it is determined whether the variable FL is "0", that is, the normal processing mode. If this determination result is "YES", the process proceeds to step SB7, and if "NO", the process proceeds to step SB8. Step SB7 is processing in the normal processing mode,
In this process, 1 stored in the line buffer 11
Of the input data for one line, the input data for one dot DJK
(Here, D11) is supplied to the print data correction calculation unit 18.

On the other hand, step SB8 is a process in the dummy process mode, and in this process, "0" is input from the input data switching unit 13 to the print data correction calculation unit 18 as the input data DJK (D11 in this case). Supplied. That is, in the normal processing mode, the actual input data is the processing target, whereas in the dummy processing mode, the dummy data “0” is the processing target. Step S described above
When the process of B7 or SB8 ends, the process proceeds to step SB9.

In step SB9, the print data correction calculation unit 18 performs a calculation process for calculating the print data dJK. This calculation is performed by the equation (4), the input data DJK output from the input data switching unit 13, the shift register 1
6 and the parameters γ and δ set by the parameter setting unit 17. here,
Since the stored contents of the shift register 16 are "0, S1, S2", the print data d11 corresponding to the first dot in the line is the residual heat amount S1, S2 of the corresponding head element and the head element adjacent to the corresponding head element.
It becomes the value based on.

Next, at step SB10, the residual heat quantity calculation unit 19 performs calculation processing to calculate the residual heat quantity S1 of the first head element after the dots are transferred at the density corresponding to the print data d11. It This operation is
This is done based on the equation (6), the stored contents of the shift register 16, the parameters α, γ, δ set by the parameter setting unit 17, and the print data d11.

The value S1 obtained here is a value based on the residual heat amounts S1 and S2 of the corresponding head element and the head element adjacent to that element, that is, the previous transfer end, as in the case of obtaining the above-mentioned print data d11. It becomes a value based on the residual heat amount S1 of the subsequent element and the current residual heat amount S2 of the surrounding elements. The residual heat amount S1 obtained in this way is overwritten and stored in the address corresponding to "1" in the memory 1.

Next, at step SB11, it is judged whether or not the print data d11 to dm1 for one line is output. That is, it is determined whether J is smaller than m. Since J = 1 here, the determination result in this step is “YES”, and the process proceeds to step SB12, where 1 is added to J. Then, the process returns to step SB6. After that, the processes of steps SB6 to SB12 are repeated until J ≧ m in step SB11.

In this iterative process, the difference from the above case is that when 1 <J <m, the shift register 1
The stored contents of 6 are "SJ-1, SJ, SJ + 1". That is, the print data dj1 is calculated based on the residual heat amounts of the self element and the two elements adjacent to the self element. When J = m, the stored contents of the shift register 16 are "Sm-1, Sm, 0",
The print data dm1 is calculated based on the residual heat amount of the self element and one element adjacent to the self element. The print data d11, d21, ..., Dm1 for one line is obtained by the above-described repetitive processing, and the residual heat amounts S1 to Sm stored in the memory 15 are updated. The print data d11, d21, ..., Dm1 are stored in a line buffer (not shown).

The judgment result in step SB11 is "NO".
If so, the process proceeds to step SB13. Step S
At B13, it is determined whether FL is "0", that is, whether it is the normal processing mode. If this determination result is "YES", the process proceeds to step SB14.
In step SB14, print data d11, d21, ..., Dm1 for one line stored in a line buffer (not shown).
Is supplied to a thermal head driving means (not shown), and printing for one line is performed. Therefore, the paper or thermal head is fed by one line in the paper feed direction. Next, 1 is added to the line number K (step S
B15), and the process returns to step SB2.

On the other hand, the determination result of step SB13 is "N
If “O”, the process proceeds to step SB16,
The following process (dummy process) is performed. In step SB16, the dummy processing means (not shown) operates so that the print data dk from the print data correction calculation unit 18 is not supplied to the thermal head, and actual printing (driving of the thermal head) and addition of K are not performed, The time waiting is performed so that the processing cycle is the same as when the actual printing is performed. Then, the process returns to step SB2. After that, the above-described processing is repeated until the result of the determination in step SB5 becomes “NO”, that is, until the printing of the line for one page is completed.

As described above, according to one embodiment of the present invention, the latest residual heat amount S1 to S for each head element is obtained.
Since m is stored in the memory 15 and the print data dJ is obtained using these, the residual heat amount can be finely obtained for an arbitrary print pattern, and the density (transfer energy) represented by the print data dJ can be obtained. Can be accurately controlled, and therefore, the occurrence of density unevenness and the tailing phenomenon can be prevented.

Further, not only the own head element but also the residual heat quantity of at least one adjacent head element is taken into consideration to perform more precise control of the transfer energy, so that a higher quality printing result can be obtained. it can. Further, when the data input speed from the external device is slower than the printing speed of the printer, the content of the input data DJK is regarded as "0", and the same calculation as that in the normal processing is performed without paper feeding and is the same as that in the normal processing. By repeating the process in a constant cycle, it is possible to prevent the occurrence of density unevenness without providing an expensive page buffer.

In the above-described embodiment, the residual heat quantity of the own head element is calculated based on the residual heat quantity of the own head element and one or two head elements adjacent to the own head element. This is because the head elements are mutually affected by the residual heat amount of the other side, and the configuration is not limited to the above as long as it has the purpose of reducing the error due to such influence.

[0047]

As described above, according to the present invention,
The correction calculation means reads the residual heat quantity corresponding to the head element to be used from the residual heat quantity storage means for storing the residual heat quantity of each head element for one line, and the residual heat quantity and the input data corresponding to the head element. The print data is obtained based on and. Further, the residual heat quantity calculation means calculates the latest residual heat quantity corresponding to the head element based on the residual heat quantity and the print data, and stores it in the residual heat quantity storage means. Therefore,
It is possible to finely determine the residual heat amount for an arbitrary print pattern, and it is possible to prevent the occurrence of density unevenness and tailing phenomenon.

When the unprinted input data is less than one line at the print start timing, the dummy printing means prohibits the supply of the print data obtained by the correction calculation means to the drive means, and The correction calculation means uses the data representing the lowest gradation in place of the input data to obtain the print data at a constant cycle that coincides with the execution of printing. Therefore, even when the data input is slower than the printing speed, it is possible to prevent the occurrence of density unevenness without providing an expensive page buffer or the like.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a heat storage control device of a line type thermal transfer printer according to an embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of the same device.

FIG. 3 is a block diagram showing a configuration of a heat storage control device of a conventional line type thermal transfer printer.

FIG. 4 is a flowchart for explaining the operation of the same device.

[Explanation of symbols]

 11 line buffer 12 input incomplete detection unit 13 input data switching unit 14 address setting unit 15 residual heat amount 1 line storage memory 16 residual heat amount temporary storage shift register 17 parameter setting unit 18 print data correction calculation unit 19 residual heat amount calculation unit

Claims (2)

[Claims] 1. A line-type thermal transfer printer that transfers print data for one line to a drive unit of a thermal head to transfer ink to a sheet at a density according to the print data at a constant cycle, and is incorporated in a print operation. Of the line type thermal transfer printer that determines the print data for each head element constituting the thermal head based on the amount of heat remaining in the thermal head and the input data supplied from the external device and supplies the print data to the driving means. In the storage heat control device, a residual heat amount storage means for storing one line of residual heat amount which is the amount of heat remaining in each head element, and a residual heat amount corresponding to the head element to be used is read from the residual heat amount storage means. At the same time, print data is obtained based on the residual heat amount and the input data corresponding to the head element. Correction current calculation means, and a residual heat quantity calculation means for calculating the latest residual heat quantity corresponding to the head element based on the residual heat quantity and the print data and storing it in the residual heat quantity storage means. Heat storage controller for line type thermal transfer printer. 2. A dummy printing means for permitting / prohibiting the supply of print data obtained by the correction calculation means to the driving means, wherein the unprinted input data is less than one line at the print start timing. In the above, the dummy printing means prohibits the supply of the print data obtained by the correction calculation means to the driving means, and the correction calculation means uses the data representing the lowest gradation in place of the input data. 2. The heat storage control device of a line type thermal transfer printer according to claim 1, wherein the print data is obtained at the constant cycle.