JP2776346B2 - Information printing system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information printing system, and more particularly to an information printing system having a thermal transfer printer.

[0002]

2. Description of the Related Art In a thermal transfer printer, good printing results cannot be obtained if printing is performed without control due to heat accumulation due to the presence or absence of heat generated by a heating element printed before a currently printed line. This is particularly true in the case where recording is performed in which gradation is expressed by one dot.

Further, in the line thermal transfer head, there is variation in the resistance value of each heating element, and therefore, printing unevenness due to a difference in current value has occurred.

In order to reduce the effect of heat storage on the heating element, for example, Japanese Patent Application Laid-Open Nos.
As disclosed in Japanese Patent Publication No. 31939, there has been proposed a method of correcting the amount of heat generated by a heating element using various correction circuits on a printer. However, since the correction by these circuits corrects image data stored in the memory of the printer, a processing time determined by the access speed of the memory and the number of times of access is required, and therefore, the printing speed of the printer is limited. As a result, there is a disadvantage that the printing speed is reduced.

Here, the heat storage correction in the conventional example will be described in detail. The heat storage correction is performed with the intention of correcting that the heating element gradually becomes hot when the same heating element is continuously energized. For this reason, not only the heat generation of the dot of interest, but also the heat generation of surrounding dots,
The correction also takes into account the heat generation status of surrounding dots.

In practice, it is necessary to read out gradation data of several dots around the dot to be corrected, and perform a correction operation based on the data. In these operations, access such as reading out of gradation data or correction data from a memory is performed, and the access time limits printing speed. Also, the circuit configuration is complicated.
Inconveniently, the scale becomes large.

For example, when referring to six dots around a dot of interest in thermal history correction, tone data of at least a total of seven dots, that is, a target dot and a reference dot, are read out from the memory, and a correction operation is performed on it. Will do.

[0008] system Thus, once the time taken to read data from the memory 100 [MH _Z] Black
Assuming that 4 [clk] = 400 [ns], it takes a total of “7 × 400 [ns] = 2.8 [μs]”. Also, it is necessary to store the calculated data in the memory again.
00 [ns] (this corresponds to 0.4 μs) . Follow
Therefore, 3.2 [μs] is required as a whole.

When this is performed for 2400 dots per line at 300 [dpi], only the access to the memory related to the gradation data is performed to obtain "3.2
[Μs] × 2400 = 8.9 [ms]. at the same time,
When the individual resistance value is also corrected, the individual resistance value data of the heating element is read out from the memory, so that “400 [ns] ×
A time of 2400 = 960 [μs] is added.

Therefore, at least the time required for accessing the memory per line is at least “8.9 [ms] +960 [μs] = 9.86 [m].
s] ".

The access to these memories is performed by processing with firmware (F / W). In addition to the time required to read the gradation data from the memory, the CPU reads the instruction codes and processes the read instructions by the CPU. There was an inconvenience of taking time. On the other hand, in the conventional example, in order to shorten the processing by the firmware (F / W), the DMA (D / D) which reads the data from the memory by the hardware (H / W) is used.
An irect Memory Access) circuit and a circuit for automatically reading out the multiplication result again from the read gradation data and the correction coefficient, and the like, have been used to realize the correction processing.

Further, since the correction operation is performed by multiplying the reference dot by a different coefficient depending on the position of the reference dot with respect to the target dot, calculation using F / W, which takes more time than the memory access time, or the gradation value A DMA circuit that obtains a multiplication result by referring to a table based on the coefficient, an H / W
Needed a multiplier.

[0013]

As described above, in the above conventional example, since the data correction processing is performed by the printer, not only the printing speed of the printer cannot be increased beyond a certain level, but also , H / W (hardware)
However, there has been a problem that the size of the printer becomes large, which hinders downsizing of the printer.

[0014]

It is an object of the present invention to provide an information printing system which improves the disadvantages of the prior art, reduces the data processing on the printer side, and increases the printing speed and size of the printer. That is its purpose.

[0015]

In order to achieve the above object, according to the present invention, a bidirectional communication means is provided between a host device and a printer, and the printer comprises a print head and a print head. A head drive circuit for controlling the operation of the head. The host device has a configuration in which a heat history processing unit that corrects the heat storage by each heating element of the print head and an individual resistance value correction unit that corrects the variation in the resistance value of each heating element are employed.

According to the first aspect of the present invention, first, the application program on the host device (host machine) transfers the image data to the printer drive control unit 11. The printer drive control unit 11 converts the received image data from RGB data into a YM
Processing such as data conversion into C data and γ correction for obtaining a print result similar to the color tone on the monitor 10 is performed to convert the data into bit map data for one screen.

The data of one dot of the bitmap data is a plurality of bits when representing gradation. And
In the heat history processing unit 12 of the printer drive control unit 11,
The heat history processing is performed on all the bitmap data using a heat storage correction calculation formula defined in advance.

When correcting the thermal history of the dot of interest, the more the number of dots to be referred to, the more accurate the correction. Therefore, while evaluating the dots to be referred to, the dots which can obtain the remarkable effect of the correction are selected as the reference dots.

The correction of the individual resistance of the print head by the printer drive control unit is performed by reading the individual resistance of the print head read out from the nonvolatile memory (not shown) of the printer with respect to the gradation data via the bidirectional interface. This is performed based on the value data.

In this correction, correction is performed to reduce the gradation value because a large amount of power flows through the heating element having a small resistance value, and correction is performed to increase the gradation value because a current hardly flows through the heating element having a large resistance value. . As a result, when one line is printed with the same gradation value, a gradation value is obtained such that all the heating elements having different resistance values have the same heat value.

According to the second aspect of the present invention, the above-described printer stores the gradation data stored in the gradation data storage unit and stores the gradation data sent from the host device. A data conversion unit for converting the data into strobe data for determining whether or not to energize the print head.

For this reason, the invention according to claim 2 functions in the same manner as the invention described in claim 1, and further includes a bit map for which the hysteresis and the individual resistance value correction have been completed by the printer drive control unit. The tape is transferred to the printer via the bidirectional interface and stored in the gradation data storage.

Since the gradation data is of a type represented by a plurality of bits of one dot, it cannot be used for temperature control of the heating element as it is. For this reason, the bitmap data is converted by the data conversion unit into data corresponding to the time for energizing the heating element.

According to the third aspect of the present invention, the above-described head drive circuit has a pulse width variable control function for changing the time width of the strobe pulse width according to the temperature of the print head and the number of heating elements that generate heat at the same time. It has a configuration.

For this reason, the third aspect of the invention also functions in the same manner as the second aspect of the invention, and also uses the pulse width variable control function to control the head temperature and the number of simultaneous heating elements in the head drive circuit 14. It is possible to control the amount of electricity supplied to the heating element by increasing or decreasing the value.

Thus, the influence of the heat generated by the individual heating elements and the influence of the variation in the individual resistance values of the heads are corrected by the printer drive control unit on the host machine, and the corrected data is actually output by the printer to the heating element. By converting the data into strobe data corresponding to the energizing time and controlling printing by controlling the strobe pulse width according to the temperature of the print head and the number of simultaneous heating elements, thereby reducing the amount of data processing in the printer. / W (hardware) can be reduced in scale and the printing speed can be improved.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

In FIG. 1, reference numeral 1 denotes a higher-level device,
Reference numeral 2 denotes a printer. Reference numeral 5 denotes a bidirectional I / F cable connecting the host device 1 and the printer 2.
The printer 2 includes a print head 21 and the print head 21.
And a head drive circuit 22 for driving and controlling the operation. Further, the host device 1 includes a bidirectional communication unit (not shown), a heat history processing unit 12 for correcting heat storage by each heating element of the print head 21, and a resistance value of each heating element of the print head 21. And an individual resistance correction unit 13 for correcting variations. Here, the printer drive control unit 11 is configured by the heat history processing unit 12 and the individual resistance value correction unit 13. Reference numeral 10 denotes a monitor for the host device.

Further, the printer 2 includes a gradation data storage unit 23 for storing gradation data sent from a higher-level device, and a print head 21 for storing the gradation data stored in the gradation data storage unit 23. And a data conversion unit 24 for converting the data into strobe data for determining whether or not to supply current to the power supply.

Further, the head drive circuit 22 described above, the indicia
Depending on the temperature of the head and the number of
A pulse width variable control function for changing the time width of the trobe pulse width is provided. That is, the head drive circuit 22, sign
Strike the heating element number of heating temperature and time of the shaped head
A variable pulse width control function is provided for driving the print head 21 by changing the ON (ON) time width of the lobe pulse width .

Next, the operation of the embodiment shown in FIG. 1 will be described. The application program on the host device (host machine) 1 transfers the image data to the printer drive control unit 11. This printer drive control unit 11
The received image data is subjected to processing such as data conversion from RGB data handled by an application program to YMC data handled by a thermal transfer printer, and γ correction for obtaining a print result similar to the color tone on the monitor 10, and processed for one screen. Is converted to bitmap data.

The data of one dot of the bitmap data is a plurality of bits when representing a gradation. For example,
When one dot represents 255 gradations (that is, it can have 255 different densities), one dot data is composed of 8 bits.

Further, in the heat history processing section 12 of the printer drive control section 11, the heat history processing is performed on all the bitmap data by using a previously defined heat storage correction formula.

As an example of the heat storage correction, as shown in FIG. 2, for the dots b and c on both sides of the dot of interest (hereinafter referred to as "dot a") of the print head 21, a coefficient is added to the gradation value. Multiply by α and subtract from dot a. Similarly, a coefficient β is applied to the dots d and f, a coefficient γ is applied to the dot e, a coefficient δ is applied to the dots g and f, and a coefficient ε is applied to the dot h. Subtract from the tone value.

The correction coefficient is determined in consideration of the rate at which each reference dot thermally affects the target dot.
That is, if the amount of heat generated by the dots around the dot of interest is large,
The idea is to reduce the original tone value in order to warm the dot of interest accordingly.

“New gradation value A ′ = gradation value A (b × α + c × β + e × γ + g × δ + h × ε)” The more the number of dots to be referred to at the time of thermal history correction for the target dot, the more accurate the correction. However, the amount of calculation increases and the processing time increases accordingly. Therefore,
The dots to be referred to are selected as the reference dots while the evaluation is performed while the effect of the correction is remarkably obtained. In addition, the optimum value is determined while performing the coefficient and the evaluation.

The correction for the heat storage of each heating element is performed by the above-described calculation, and the gradation data subjected to the thermal history correction is obtained. This is because the printer drive control unit 11 uses the CUP and the memory separately provided in the host machine 1,
This is performed for all the dots of the image data delivered from the application.

In the conventional method, changing the calculation method of the heat history in accordance with the characteristics of the head and the ribbon at the evaluation stage requires the reworking of the correction circuit portion created by H / W (hardware). However, in the embodiment according to FIG. 1, it is possible to easily cope with this by changing a part of the program source of the printer drive control unit 11.

The correction of the individual resistance of the print head 21 by the printer drive control unit 11 is performed by reading the print head 21 from the nonvolatile memory (not shown) of the printer 2 with respect to the gradation data via the bidirectional interface. Is performed based on the individual resistance data.

As an example of the individual resistance correction, the resistance value R of each heating element of the print head 21 which is a thermal transfer head,
Based on the average value Rav of the resistance values of all the heating elements, correction is performed as in the following equation. “New tone value A ′ = tone value A × (R / Rav)”

Here, Rav is the printer drive control unit 11
May be calculated from the resistance value of each heating element, or the Rav value calculated in advance and stored in the nonvolatile memory in the printer 2 may be read by the printer drive control unit 11. Such processing only needs to be executed once when the power of the host machine 1 and the printer 2 is turned on (ON).

In this correction, correction is performed to reduce the gradation value because a large amount of power flows through the heating element having a small resistance value, and correction is performed to increase the gradation value because the current hardly flows through the heating element having a large resistance value. . As a result, when one line is printed with the same gradation value, a gradation value is obtained such that all the heating elements having different resistance values have the same heat value.

The bitmap tape on which the hysteresis and the individual resistance correction have been completed by the printer drive controller 11 is transferred to the printer 2 via the bidirectional interface 5 and stored in the gradation data storage unit 23.

Since the gradation data is of a type represented by a plurality of bits of one dot, it cannot be used for temperature control of the heating element as it is. For this reason, the bitmap data is converted by the data conversion unit 24 into data corresponding to the time for energizing the heating element.

For controlling the temperature of the heating element, the temperature of the heating element is controlled by changing the length of the entire energization time by a strobe signal as shown in FIG. 3, for example. Which pulse of the strobe signal does not generate heat depends on the strobe data when each strobe pulse is applied to the print head 21. If the strobe data is "1" when the strobe pulse is on (ON), the heating element is energized for the strobe pulse width and generates heat. The longer the time for energizing one heating element, the greater the amount of heat generated, so that high density dots can be obtained as a printing result.

Therefore, in order to make the gradation value correspond to the amount of heat applied to the heating element, the strobe data of each strobe pulse may be converted.

For example, if the gray scale data is 8 bits in binary, it can represent up to 255 gray scales, so that 255 strobe pulses are required. Therefore, the grayscale data of 8 bits is converted into the strobe data of 255 bits. The data converter 24 is a circuit that converts strobe data from the above gradation values.

Each strobe pulse is turned on (O
The strobe pulse width of N) is also an element related to the heat generation amount of the heating element. The items to be controlled by the strobe pulse width, the heat storage and to the head itself, the current to the heating element due to an increase in the ground potential caused by the flow to the heating element
There is a decrease.

After the start of printing, the head temperature gradually rises due to the heat storage effect. In order to melt or sublimate the same amount of ink at the same gradation value, the amount of electricity to the heating element must be reduced. No. Strobe width control during printing
It is necessary to perform dynamic processing according to the head temperature and the number of simultaneous heating elements, and thus it is not possible to cope with the problem by correcting the gradation value by the driver in advance. The strobe pulse width is controlled by increasing / decreasing the head temperature or the number of simultaneous heating elements by the head driving circuit 22 to control the amount of power supply to the heating elements.

As described above, the influence of the heat generation of the individual heating elements and the influence of the variation of the individual resistance value of the head are corrected by the printer drive control unit 11 on the host machine 1, and the corrected data is corrected by the printer 2. The print head 2 converts the strobe data into strobe data corresponding to the actual energizing time of the heating element.
By controlling the strobe pulse width according to the temperature of 1 and the number of simultaneous heating elements to perform printing, the amount of data processing in the printer 2 is reduced, the scale of H / W (hardware) is reduced, and printing is performed. Speed can be improved.

[0051]

As described above, according to the present invention,
The heat history correction and individual resistance value correction of each heating element for the print head of the printer, which were performed in the conventional example, are now performed by the host device. Compensation is not required, which greatly reduces the computing power and memory capacity on the printer side, and in this respect, superior information printing that has never been possible before, which has made it possible to increase the printing speed and downsize the printer A system can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing the operation of FIG.

FIG. 3 is a diagram showing an example of temperature control of a heating element according to the present invention.
You.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 High-order apparatus (host machine) 2 Printer 5 Bidirectional I / F cable 11 Printer drive control unit 12 Thermal history processing unit 13 Individual resistance value correction unit 21 Print head 22 Head drive unit 23 Gradation data storage unit 24 Data conversion unit

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁶ , DB name) B41J 2/35 B41J 2/36 B41J 29/38 G06F 3/12

Claims (3)

(57) [Claims] 1. An information printing system comprising a bidirectional communication means between a host device and a printer, the printer comprising a print head and a head drive circuit for controlling the operation of the print head. Wherein the host device is provided with a heat history processing section for correcting heat storage by each heating element of the print head and an individual resistance value correcting section for correcting variation in resistance value of each heating element. Printing system. 2. The printer according to claim 1, wherein the printer stores a gradation data stored in the gradation data sent from the host device, and supplies the gradation data stored in the gradation data storage to the print head. 2. The information printing system according to claim 1, further comprising a data conversion unit that converts the data into strobe data for determining whether the data is strobe data. 3. The print head according to claim 2, wherein
Strobe depending on the temperature and the number of heating elements
Information print system of claim 2 which is characterized in that it comprises a variable pulse width control function of changing the time width of the pulse width.