JPS63202489A - Abnormal print density detection system - Google Patents

Abstract

PURPOSE:To prevent trouble such as breakdown of ink ribbon or pin in print head, by storing print density data sequentially then detecting abrupt droppage of print density from record of the print density data and alarming occurrence of abnormality. CONSTITUTION:When printing is finished, a processor 4 controls an inserter 18 to read out the print density of final line printed onto a print medium through an optical sensor 7 in the way of discharge of the print medium. Then the print density is converted into a digital value through an A/D converter 8 and stored into RAM 6, then print density data are expelled from memory area of RAM 6 in the order of oldness to disappear. The processor 4 sends an address of a character density memory area of RAM 6 storing the oldest density data and an address storing the newest density data to RAM 6, then reads out respective density data and operates a differential density which is compared with a predetermined value. If it is judged that the density is thin, an alarm sending circuit 19 is controlled to send an alarm for requiring replacement of an ink ribbon.

Description

[Detailed Description of the Invention] [Summary] In an impact printer, when the ink ribbon is no longer being fed, the print density data is stored in order to prevent damage to the ink ribbon or pin breakage of the print head due to entanglement of the ink ribbon. The data is stored sequentially, and from the history of this print density data, a sudden drop in print density is detected and the occurrence of an abnormality is notified.

[Industrial application field]

The present invention relates to an impact printer that prints characters, etc. by striking a printing medium through an ink ribbon, and is equipped with means for optically reading the printed characters, etc., and particularly relates to an impact printer that is equipped with means for optically reading the printed characters, etc. 2. Description of the Related Art Print Density Abnormality Detection Method for Detecting Ribbon Abnormal Conditions Examples of impact printers equipped with optical reading means for detecting print density include passbook printers used in banking operations. This passbook printer uses an optical sensor, such as a self-scanning image sensor, to determine the presence or absence of printing on the passbook, and then sets the passbook in a predetermined position.

By the way, the ink ribbon of an impact printer generally moves to feed the ink ribbon as it prints.
If the ink ribbon is not fed due to a failure,
It is necessary to be able to detect an abnormal state of the ink ribbon because it may damage the ink ribbon and, if the ink ribbon becomes entangled with the print head, the pins of the print head may be damaged.

[Conventional technology]

When a conventional passbook printer sucks in a passbook, it uses an optical sensor to read the characters, etc., sets the line to be newly printed on the passbook at the printing position, so-called line setting, and after printing, ejects the passbook. Along the way, newly printed characters are read by an optical sensor, and the output of the optical sensor is compared with a predetermined threshold to determine the density.

As a result of this density determination, if it is determined that the print density has become lighter, an alarm is sent to instruct the ink ribbon to be replaced.

[Problem that the invention seeks to solve]

As mentioned above (conventionally, the output of the optical sensor is compared with the darkness value to judge the density and only detect that the print has become lighter, but the print density after printing is sequentially memorized and the print density is Since there is no means to detect the tendency of changes in the ink ribbon, even if the ink ribbon cannot be fed and the print density suddenly drops, only a warning that the print density is low will be sent out, and the occurrence of an abnormal state of the ink ribbon will be recognized. It is impossible to do so.

Therefore, if the ink ribbon is continuously struck at the same location, it will be damaged, and if the ink ribbon gets entangled with the print head, the pins of the print head will break, which is a serious problem.

[Means for solving problems]

FIG. 1 is a block diagram of the principle of the present invention.

The calculation comparison means 1 sequentially stores the print density data read by the print density detection means 2 in the storage means 3.

The storage means 3 is, for example, a first-in, first-out memory, and old print density data is erased every time new print density data is entered, so the density data of a certain number of characters depending on the memory capacity is stored sequentially from the newest to the oldest. The data is stored as data indicating a concentration gradient.

FIG. 2 is a diagram explaining the operation of FIG. 1.

When the vertical axis shows the print density and the horizontal axis shows the number of prints, the density of the characters detected by the print density detection means 2 gradually decreases as the number of prints increases, as the ink ribbon wears out. Therefore, the print density data stored in the storage means 3 is data representing a density gradient, compared to the print density ■ when the number of characters shown at point a is the same as the print density ■ when the number of characters is shown at point b.

Since the storage means 3 erases the density data of old characters each time density data of a new character is entered, the density of ■ and ■ gradually decreases, but the inclination angle does not change. The arithmetic comparison means 1 compares the density of ■ and the density of When this happens, an alarm is sent to notify that the ink ribbon needs to be replaced.

For example, if the ink ribbon stops feeding when the number of characters indicated by 0 points due to a failure occurs, as the number of printed characters increases,
The print density begins to decrease rapidly as shown by the dotted line. This is because the pins of the print head continuously strike the same position on the ink ribbon.

Therefore, the density of the latest character indicated by point b is as shown in ■.
The angle of inclination decreases rapidly and becomes larger as shown by the dashed line.

The arithmetic and comparison means 1 compares the density of ■ and the density of ■, and when the difference in density becomes larger than a predetermined value, it recognizes that an abnormality has occurred in the ink ribbon and sends out an ink ribbon abnormality alarm.

[Effect]

With the above configuration, the storage means 3 can store the history of the print density data detected by the print density detection means 2, so the calculation comparison means 1 determines whether the ink ribbon is normal or abnormal from this history. You can.

〔Example〕

FIG. 3 is a block diagram of a circuit showing one embodiment of the present invention.
FIG. 4 is a flowchart illustrating the operation of FIG. 3.

The Bromo Nosa 4 reads the program from the ROM 5 and operates. When the print medium is inserted into the inserter 18, the inserter control circuit 17 is controlled to insert the print medium into the inserter 1.
8 as shown in FIG. 4, and the print medium read by the optical sensor 7 is recognized through the A/D conversion circuit 8.
Controls setting the print line at the print position.

The processor 4 stores print data from the host device via the interface circuit 9 in the RAM 6, reads this print data, detects a character code, reads the corresponding character pattern from the character generation circuit 10, and outputs the print head control circuit to the print head control circuit. 11 to a print head 12 for printing.

At this time, the processor 4 drives the space motor 16 via the space control circuit 15 to position the print head 12 at the printing position. When the - character is printed, the line feed control circuit 13 is controlled to drive the line feed motor 14 to move the print medium so that the next line can be printed.

When printing is completed, the processor 4 controls the inserter 18 to eject the print medium, but during ejection, the optical sensor 7 reads the print density of the last line printed on the print medium, and the A/D conversion circuit 8 reads the print density of the last line printed on the print medium. Once converted into a digital value, it is stored in the RAM 6. In this way, the oldest printing density data stored in the RAM 6 is pushed out of the storage area of the RAM 6 and disappears.

The processor 4 stores the address where the oldest density data is recorded in the character density storage area of the RAM 6, and the address where the latest density data is recorded, that is, the density data corresponding to point a in Figure 2 is recorded. RA address and the address where the density data corresponding to point b is recorded.
M6, each density data is read out, and the difference in density is calculated and compared with a predetermined value given in advance.

If the density data at point A in Figure 2 is larger or smaller than the density data at point a, if the density difference is within a predetermined value,
Next, the processor 4 compares the latest density data, that is, the density data at point b, with the dark value, and when it determines the density and determines that it is light, controls the alarm sending circuit 19 to replace the ink ribbon. Sends the requested alert.

If the density data at point b is smaller than the density data at point a, and the difference in density is greater than or equal to a predetermined value, it is determined that an abnormal state has occurred in the ink ribbon, and the alarm sending circuit 19 is controlled to detect an abnormality in the ink ribbon. Sends out an alert to notify the user.

〔Effect of the invention〕

As explained above, since the present invention is capable of detecting an abnormal state in which the ink ribbon has stopped feeding, if the apparatus is stopped by detecting the ink ribbon abnormal state, problems such as damage to the ink ribbon or broken bottle of the print head can occur. Occurrence can be prevented.

[Brief explanation of the drawing]

Figure 1 is a block diagram of the principle of the present invention. Figure 2 is a diagram explaining the operation of Figure 1. Figure 3 is a block diagram of a circuit showing an embodiment of the present invention. Figure 4 is a block diagram of the circuit shown in Figure 3. It is a flowchart explaining the operation. In the figure, 1 is an arithmetic comparison means, 2 is a print density detection means, 3 is a storage means, 4 is a processor, 5 is a ROM,
6 is RAM. 7 is an optical sensor, 8 is an A/D conversion circuit, 9 is an interface circuit, 10 is a character generation circuit, 11 is a print head 171J? 1
1 circuit, 12 is the print head, 13 is the line feed control circuit,
, 14 is a line feed motor, 15 is a space control circuit, 16 is a space motor, 17 is an inserter control circuit,
18 is an inserter, and 19 is an alarm sending circuit. Figure 11 Repair Figure 1 Figure 1's ψ01'th or 9th clear pattern Figure 2 Wood Igo August, 7-Actual self Ikuri *qr=Toji's B゛D・So7 Figure 5

Claims (1)

[Scope of Claims] An impact printer that prints characters, etc. by striking a print medium via an ink ribbon, comprising a print density detection means (2) for reading the density of characters, etc. printed on the print medium; and the print density detection means. Storage means (3) for sequentially storing the print density data sent out by the means (2); and an operation for reading old print density data and new print density data stored in the storage means (3) and comparing the densities. A comparison means (1) is provided, and if the new print density data stored in the storage means (3) is lighter than the old print density data and the density difference is greater than a predetermined value, an abnormal state occurs in the ink ribbon. A printing density abnormality detection method is characterized in that it is determined that