JP2705354B2 - Printing device with print density detection function - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing device.

[0002]

2. Description of the Related Art In a printing apparatus for printing characters on a print medium using an ink ribbon, the printing density gradually decreases while the same ink ribbon is repeatedly used, and it is necessary to replace the ink ribbon soon. Become. Conventionally, such a decrease in print density has been detected by the following method. (1) The user looks at the print result. (2) Count the number of lines printed by one ink ribbon or the total number of printed characters. (3) The printing result is represented by pixels, the printing density of each pixel is binarized, and the number of black pixels is counted.

[0003]

The first method is the most common, but this method requires a person to look at the print result, and the detection result is not objective.

A second method is to detect the print density indirectly by counting the number of print lines or print characters instead of directly detecting the print density. Therefore, the detection result does not always accurately represent the actual print density.

In the third method, the print density is directly detected. However, since the density is detected only by the number of black pixels, when the characters to be printed are complicated, even if the density is low, the high density is obtained. On the contrary, in the case of a simple character, even if the actual density is high, it is detected as a low density.

SUMMARY OF THE INVENTION An object of the present invention is to provide a printing apparatus having a printing density detecting function capable of solving such a problem, accurately detecting the printing density, and accurately notifying the user of a decrease in the printing density. It is in.

[0007]

According to the present invention, there is provided a printing apparatus for printing a character on a predetermined print medium based on a given character code, wherein the character printed on the print medium is divided into pixels. A reading unit that binarizes the print density of the data and outputs the data, a counting unit that counts the number of data of a predetermined value among the data output by the reading unit, and the data that is counted by the counting unit The standard value for the number of
A standard value generation unit that outputs according to the complexity of the character based on the character code, the number of data counted by the counting unit, and the standard value output by the standard value generation unit are compared, and the result is compared. And a determination unit that outputs a signal representing the signal.

[0008]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an example of a printing apparatus according to the present invention. When the character code is given, the printing unit 2 prints the character represented by the code on a printing paper set in advance. The reading unit 3 reads the characters printed by the printing unit 2 from a predetermined range on the paper, represents the read characters by pixels, and binarizes the print density of each pixel using a predetermined print density as a threshold. ,
Output the data. The counting section 4 receives the data from the reading section 3 and counts the number of pixels, that is, black pixels, whose print density exceeds the above threshold, based on the value. This count value increases as the print density increases, and increases as the printed characters become more complex. The black pixel number calculation unit 1 receives the codes of the characters to be printed from the outside, confirms that they are printed within the readable range of the reading unit 3, and outputs the received character codes to the printing unit 2. Further, a black pixel number calculation unit 1
Calculates the standard value of the counting result of the counting unit 4 according to the complexity of the character based on the received code, and outputs it to the determination unit 5. The determination unit 5 compares the count value of the counting unit 4 with the standard value from the black pixel number calculation unit 1, and when the count value is smaller than the standard value, a predetermined value indicating that the print density has decreased. Output a signal.

Next, the operation will be described. When a code of a character to be printed is given from outside, the black pixel number calculation unit 1 confirms that these are printed within the readable range of the reading unit 3 and outputs the received character code to the printing unit 2. I do. The black pixel number calculation unit 1 also calculates a standard value of the counting result of the counting unit 4 according to the complexity of the character based on the received code, and outputs the standard value to the determination unit 5.

When the character code is given from the black pixel number calculation unit 1, the printing unit 2 prints the character represented by the code on a printing paper set in advance. The reading unit 3 reads the characters printed by the printing unit 2 from a predetermined range on the paper, represents the read characters by pixels, and binarizes the print density of each pixel using a predetermined print density as a threshold. And output that data. The counting unit 4 receives the data from the reading unit 3 and counts the number of black pixels based on the value.

The determination unit 5 compares the count value of the black pixels counted by the counting unit 4 with the standard value from the black pixel number calculation unit 1. If the count value is smaller than the standard value, the print density is determined. Is output.

[0012]

As described above, in the printing apparatus having the print density detecting function of the present invention, when a printed character is represented by a pixel, the number of black pixels is counted, and the counted value is set to a standard value. The print density is detected and determined by comparing with the standard value. At this time, a standard value is set according to the complexity of the printed character. Therefore, the print density is accurately detected irrespective of the characters to be printed, and it is possible to accurately notify the user of the decrease in print density.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an example of a printing apparatus having a print density detection function according to the present invention.

[Explanation of symbols]

 1 black pixel number calculation unit 2 printing unit 3 reading unit 4 counting unit 5 judgment unit

Claims (3)

(57) [Claims] A printing apparatus for printing characters on a predetermined printing medium based on a given character code, wherein the characters printed on the printing medium are divided into pixels, and the printing density of each pixel is determined. A reading unit for binarizing and outputting the data, a counting unit for counting the number of data of a predetermined value among the data output by the reading unit, and a standard for the number of data counted by the counting unit A value, a standard value generation unit that outputs the value according to the complexity of the character based on the character code, and compares the number of data counted by the counting unit with the standard value output by the standard value generation unit. A printing unit having a print density detection function, comprising: a determination unit that outputs a signal indicating the result. Wherein said predetermined value, the printing density printing apparatus having a print density detecting function according to claim 1, characterized in that corresponding to the print density of pixels above a predetermined concentration. 3. The printing apparatus according to claim 1, wherein the reading unit reads a plurality of characters printed on the print medium.