JP2546338B2 - Impact printer - Google Patents

Description

The present invention relates to an impact printer.

(Prior Art) The first feature of the impact printer is that it is possible to print on a medium with a large number of copies.
The copying ability is almost determined by the impact force of the print head. As a method of further improving the copying ability by using this print head, an overlapping printing method of printing the same data twice or more at the same location is an excellent method. According to this method, it is possible to obtain an effect equivalent to that the copying ability is improved by 10 to 20%.

(Problems to be Solved by the Invention) However, in this method, when the overprinting mode is designated, the overprinting is performed regardless of the set sheets, so that the throughput, that is, the throughput of the unit time is reduced, When the amount of paper is small, the copying function is exerted more than necessary, and there is a problem that the reverse effects such as crushed characters and blurring occur.

Therefore, the present invention provides an impact printer capable of solving the above-mentioned problems of the prior art and improving the copying ability.

(Means for Solving the Problems) An impact printer according to the present invention includes a print data buffer that stores print data, a paper thickness detection unit that detects the thickness of the paper to be printed, and a print counter that counts the number of overprints. And a print buffer for fetching data to be overprinted from the print data buffer, and a print control unit for performing control for printing the read print data. .

(Operation) According to the present invention, since the impact printer is configured as described above, either overlay printing or normal printing is controlled by the detection value of the sheet thickness detected by the sheet thickness detecting means.

Therefore, the present invention can eliminate the above-mentioned problems and provide an impact printer that improves the copying ability.

Embodiment An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing the main part of one embodiment of the present invention. In the figure, the print start command decoder 1 receives a print start command for a row, and sends a print start signal to a paper thickness detection circuit 2 and an overprinting control circuit 7, which will be described later. The paper thickness detection circuit 2 detects the thickness of printing paper having a plurality of copies. The fixed data 3 stores the fixed data of the paper thickness that allows clear copying in advance.
The comparison circuit 4 compares the sheet thickness detected by the circuit 2 with the sheet thickness stored in the fixed data 3. The mode latch 5 latches the overprint mode when the paper thickness detection value by the comparison circuit 4 is larger than the fixed data. Mode latch 5
One of the output sides of is connected to one input terminal of the AND circuit 8. The other output side of the mode latch 5 has the opposite polarity to the one described above and is connected to one input terminal of the AND circuit 9. The print data buffer 6 receives the received data and latches it as print data, and the output side of the buffer 6 is connected to the other input ends of the AND circuits 8 and 9. Overprint control circuit 7
Is a control circuit that counts the data of the print start command decoder 1 which is also a line delimiter command and prints the same data twice or more at the same location on the same line. The print control circuit 10 is a control circuit for directly printing the contents of the print data buffer 6 or for printing via the overlay print control circuit 7. The print control circuit 10 outputs a signal for overlay printing to the print data buffer 6
And the data in the print data buffer 6 is held.

Next, referring to FIG. 2 showing a block diagram of the paper thickness detection circuit of FIG. 1, FIG. 3 explaining the structure of the paper thickness detection and FIG. 4 explaining the detection of the paper thickness, the paper thickness detection circuit will be described. The block diagram will be described. In FIG. 3, the rotation of the motor is converted into vertical movement of the print head mounted on the carriage shaft by the slide cam via the idle gears A and B. As shown in FIGS. 4A and 4B, a sensor including a slit plate, a light emitting diode and a light receiving diode is attached to the carriage shaft. The number of slits in the slit plate is detected by the sensor, and the movement distance of the print head due to the rotation of the carriage shaft is detected. In FIG. 2, the paper thickness detection circuit includes a forward circuit 14, a reverse circuit 15, and a motor stop circuit 1.
6, paper thickness control 17, sensor 18, motor 19.

Next, the operation of the paper thickness detection circuit will be described with reference to FIG. 5, which is a paper thickness detection operation flowchart. First, the reverse circuit 15 is operated to separate the print head from the paper, and while the slit and the sensor detect the print head position, the motor stop circuit 16 is operated to reach the pre-adjusted home position position. Subsequently, the forward circuit 14 is operated to detect that the print head has hit the paper, and the motor stop circuit 16 is operated. The sheet thickness is detected from the movement distance of the print head at this time. The detected value of the sheet thickness thus detected is compared with the fixed data 3 to determine whether or not the overprint mode is set.

During normal printing, the print head operates the reverse circuit 15 from the contact position with the above-mentioned paper, and leaves a gap of a certain value for printing.

Next, a block diagram of the overlay printing control circuit of FIG. 1 is shown. The overlay printing control circuit will be described with reference to FIG. The overprinting control circuit includes a mode setting circuit 11 for setting the number of overprinting, a print counter 12 for counting down the number of overprinting, and a data buffer extracting circuit 13 for extracting data to be overprinted.

Next, the operation of this circuit will be described. Mode set circuit 11
Receives the mode data which is the overprinting information from the mode latch 5 of FIG. 1, and the data of the overprinting number N is set. Upon receiving the print start signal from the print start command decoder 1, the print counter 12 is loaded with the initial value of the number of overprints from the mode setting circuit 11 by this signal. The number of overprinting times loaded in the print counter 12 is “−” by one print end signal of the print control circuit 10.
1 ”. When the value of the print counter 12 becomes "0", the data of the mode setting circuit 11 is reset and the printing of one line is completed. The data buffer fetch circuit 13 sends the same data to the print control circuit 10 the number of times designated by the print counter 12.

Here, the operation of the embodiment of the present invention will be described. The paper thickness detection circuit 2 operates according to the print start signal received by the print start command decoder 1 to detect the thickness of the print paper. The detected sheet thickness is compared with the fixed data 3 and the comparison circuit 4. When the detected sheet thickness is larger than the fixed data stored in the fixed data 3, the print data in the print data buffer 6 is sent to the overlay print control circuit 7 by the mode latch 5 and is sent through the print control circuit 10 to be the same. The same data is overprinted on the location. When the detected thickness of the paper is smaller than the above-mentioned fixed data, the mode latch 5 causes the print data in the print data buffer 6 to bypass the overlay print control circuit 7 and perform normal printing.

(Effects of the Invention) As described in detail above, according to the present invention, means for detecting the thickness of a sheet is provided, and when the number of sheets is equal to or larger than the number of copies, the same data is overlapped twice or more at the same position. Since printing is performed and normal printing is performed when the number of sheets of paper is less than the number of copies, it is possible to efficiently improve the copying ability if necessary. Further, in normal printing, overlay printing is performed. By bypassing the control circuit, the print data can be read directly from the print data buffer and printed, so there is no need to read the print data via the overlay print control, and the control to read the print data is reduced and the processing speed can be increased. At the same time, it is not necessary to largely change the control program at the time of normal printing from the control program of the existing apparatus, so that the control program can be easily changed.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a sheet thickness detection circuit, FIG. 3 is a diagram for explaining a sheet thickness detection structure, and FIG. 4 is a diagram for explaining sheet thickness detection. 5, FIG. 5 is a flow chart of the paper thickness detection operation, and FIG. 6 is a block diagram of the overlay printing control circuit. 1: Print start command decoder 1: Paper thickness detection circuit, 3: Fixed data 4: Comparison circuit, 5: Mode latch 6: Print data buffer 7: Overlay print control circuit 8, 9: AND circuit 10: Print control circuit

Claims (1)

(57) [Claims] 1. A print data buffer for storing print data, a sheet thickness detecting means for detecting the thickness of a sheet to be printed, a print counter for counting the number of times of overprinting, and data for overprinting from the print data buffer. An overlay printing control circuit having a data buffer fetch circuit for fetching data, and a print control unit for performing control for printing the read print data are provided, and the thickness of the sheet detected by the sheet thickness detecting means is a predetermined thickness. In the above case, the overlay printing control circuit reads the print data to be overprinted from the print data buffer until the print counter reaches a predetermined count value, and the print control unit overlays the read print data. When the thickness of the sheet detected by the sheet thickness detecting means is less than a predetermined thickness, Serial print controller reads the print data from the overprint control circuit the print data buffer, bypassing the direct impact printer, characterized in that control to the normal printing.