JPH0447958A - Recorder - Google Patents

Abstract

PURPOSE:To keep a printing density constant with respect to a reference printing density regardless of environmental temperature, ink ribbon, and paper by comparing the printing density with the reference printing density directly using a density read sensor. CONSTITUTION:In a fixed fixed density correction of a CPU 4, rectangular areas with respect to at least 2 types of fixed printing data are printed so as to be the smallest possible for a density read sensor 5 for evaluation. At this time, printing of the rectangular areas for evaluation is performed by priority of lower density. The density read sensor 5 reads a printing density at the rectangular areas for evaluation and compares it with a pertinent printing density reference value which is read out from reference density memory means 8. When the printing density is different from the printing density reference value exceeding an allowable range, an operation is performed so as to correct an energizing time and change contents of conversion means 2. If it is within the range, the printing density is determined as a proper density and a pertinent energizing time of the conversion means 2 is fixed. Then, it is determined whether the density read sensor 5 completed the reading or not and the correcting operation will be terminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to printing technology for recording devices, and particularly to constant density printing technology for heat-sensitive and thermal transfer recording devices.

[Prior Art] In a recording device that thermally prints on paper, the print density is affected by the environmental temperature, and tends to be low at low temperatures and high at high temperatures.

In order to correct this, conventional recording apparatuses control the energization time of the thermal head using a sensor that detects the environmental temperature.

FIG. 4 is a block diagram of means for correcting print density in a conventional recording apparatus.

A temperature sensor 41 is installed on the thermal head 9 and inside the recording device 4.
After inputting the voltage output of each temperature sensor to the AD converter 6 and digitally converting it, the CPU 4 reads the value and instructs the head energization time control means 1 to shorten the energization time of the thermal head 9. This works to keep the amount of heat received by the thermal paper or ink constant.

[Problems and Objectives to be Solved by the Invention] However, when trying to keep the print density constant using the conventional method, it is difficult to directly understand the heat dissipation characteristics of the thermal head, printing paper, ink ribbon, etc. relative to the environmental temperature. Therefore, it has been difficult to suppress variations in density when using different types of printing paper or ink ribbons.

Furthermore, when expressing intermediate densities, especially when heat-melting ink is used, due to the melting characteristics of heat-melting ink, at intermediate densities there is a sudden change in density 51 as shown in FIG. If it is difficult to understand the heat dissipation characteristics mentioned above, it will be impossible to keep the intermediate density constant, which will cause a large change in print density, which will cause an error in the intermediate density in the print result, which is a factor that impairs print quality. It had become.

An object of the present invention is to solve this problem by keeping the standard printing density constant.

[Means for Solving the Problems] A recording device of the present invention is a recording device that has a thermal head and thermally prints on paper, and is characterized in that it is equipped with a density reading sensor that measures print density.

[Function] After thermally printing on the paper using an appropriate energizing time, the print density is measured by a density reading sensor. If the density is lower than the standard, the energizing time is extended, and if the density is high,
Shorten the energization time, print again, and measure the print density using the density reading sensor.

This edge-turning allows the print density to be directly compared with the reference, and it is possible to keep the print density constant with respect to the reference.

[Embodiment] An embodiment of the recording apparatus of the present invention will be described with reference to FIGS. 1, 2, and 3.

FIG. 1 is a block diagram showing the configuration of a recording apparatus according to the present invention.

FIG. 2 is a perspective view showing a printing state of the recording apparatus of the present invention.

FIG. 3 is a flowchart showing the procedure for executing constant density correction by the CPU 4 in the recording apparatus of the present invention.

In FIG. 1, the input of the thermal head driving means 1 is connected to the output of a converting means 2 that converts print data indicating print density into the energization time of the thermal head, and the input of the converting means 2 is connected to a print data storage means. 3. A print data input means 7 is connected, and a thermal head 9 is connected to the output of the thermal head drive means 1.

The CPU 4 executes a receiving operation, a printing operation, and a constant density correction operation.

The constant density correction operation is executed only when the printing device is powered on or when an instruction to execute the operation is issued.

In the receiving operation, print data is read from the print data input means 7 and temporarily stored in the print data storage means 3.

In the printing operation, temporarily stored print data is read from the print data storage means 3 and output to the conversion means 2.

The printing data is converted by the converting means 2 into the energizing time of the thermal head 9 and outputted to the thermal head driving means 1, and the thermal head 9 generates heat according to the energizing time and thermally prints on the paper 10.

Then, in the constant density correction operation, while performing rectangular printing for evaluation of density correction, the density of the rectangular printing is measured from the density reading sensor 5, and after correction is added by comparing it with the reference density,
Perform rectangular printing again, check the density, and repeat until the density falls within the allowable range for the standard density.

The paper 10 is conveyed in the direction of arrow a, as shown in FIG.

The density reading sensor 5 detects the paper 10 when the thermal head 9
It is mounted at a position where the density of the printed area can be read after it is printed.

In the converting means 2, an appropriate initial value of head energization time is stored in advance by the CPU 4 immediately before the start of correction, but by changing the stored conversion value by the CPU 4, the output energization can be changed even if the input is the same print data. Time can be changed.

The concentration reading sensor 5 receives C via an AD converter 6.
Connected to PU4.

In FIG. 3, in processing 31, the CPU 4 executes constant density correction by printing a rectangular area to the minimum necessary density of the density reading sensor 5 for at least two types of fixed print data for evaluation.

At this time, the rectangular areas for evaluation are printed in descending order of density.

In process 32, the print density of the print in the rectangular area for evaluation is read by the density reading sensor 5, and the corresponding print density reference value is read out from the reference density storage means 8 and compared.

As a result of the comparison, if the print density is different from the print density reference value beyond the allowable range, processing 33 is executed, and if it is within the allowable range, the print density is determined to be appropriate and the conversion means 2 Processing 34 by fixing the corresponding energization time
Execute.

Process 33 executes the following calculations to correct the energization time and change the contents of the conversion means 2.

The print density comparison reference values stored in the reference density storage means 8 are L sO, , L sn from the lowest one, and the density read from the density reading sensor 5 is LO from the lowest one.

, , Ln, and if the energization time used when printing each density is TO, , , Tn, then for the density of LO, , , Ln that exceeds the allowable range when compared with LsO, , Lsn, that density The energization time Ti when printing is corrected using the following formula.

Δti=(Ti-Ti-1)x(Lsi-Li)/
(Li-L 1-1) (i=1.,,n)Δ
to=(TI-TO)x(LsO-LO)/(Ll
-Lo) Ti=Tf+Δti In process 34, it is determined whether the density reading sensor 5 has finished reading the printing of all the evaluation rectangular areas, and if it is not tied, processes 32 and 33 are executed, If it has been completed, it is further determined whether the printing in all the evaluation rectangular areas is within the allowable range for the corresponding print density standard value, and if not, processing 31, processing 32, and processing 33 are executed again, and all If it is within the allowable range, the constant concentration correction operation is stopped.

[Effects of the Invention] According to the present invention, by directly comparing the print density and the reference print density using a density reading sensor, the reference print density can be achieved regardless of the environmental temperature, ink ribbon, or paper. However, since it is possible to keep the density constant, it is possible to suppress variations in printing density even for different ink ribbons and papers, and also to suppress density errors in intermediate density.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a recording apparatus according to the present invention. FIG. 2 is a perspective view showing a printing state of the recording apparatus of the present invention. FIG. 3 is a flowchart showing the procedure for executing constant density correction by the CPU 4 in the recording apparatus of the present invention. FIG. 4 is a block diagram of means for correcting print density in a conventional recording apparatus. FIG. 5 is a print density characteristic diagram of heat-melting ink. 29. . 50. . 60. . 81. . Conversion means Concentration reading sensor AD converter Reference concentration storage means and above Applicant Seiko Epson Co., Ltd. Agent Patent attorney Kizobe Suzuki and 1 other person Figure 2 9 Pumar Hetzle Figure 4

Claims (1)

[Claims] A recording device that has a thermal head and thermally prints on paper, the recording device comprising a density reading sensor that measures print density.