JPS5919827B2 - impact printer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an impact printer equipped with an ink replenishment mechanism for an ink ribbon.

In conventional impact printers, ink ribbons are used as consumables and are replaced with new ink ribbons when the print density becomes low.

Especially in printers that print OCR characters and printers used in financial institutions, the ink ribbons must be replaced early because the print must be clear. Although the base fabric is still usable, used ink ribbons are currently being replaced or discarded.
As running costs become higher, there are more opportunities for operators to be bothered. Therefore, printers have been proposed that replenish the ink by impregnating a sponge-like roller with ink and bringing the ink ribbon into contact with it, but this limits the amount of ink that can be replenished, which extends the life of the ink ribbon. In particular, with long ink ribbons, the ink content of the ribbon is not constant, which tends to cause differences in print density. In addition, some ticket vending machines use a pump to supply ink from an ink tank to the ribbon, but since the amount of ink on the ribbon used to print tickets is constant, the amount of ink is constant in proportion to the number of tickets sold. It simply replenishes ink to the ribbon, and if this is applied to a serial printer, etc., if the number of prints per unit time is large, the amount of ink contained in the ribbon will tend to be insufficient, and conversely, if the number of prints is small, the amount of ink contained in the ribbon will be insufficient. The ink content of the ribbon is too high and the print density is unstable. Therefore, an object of the present invention is to eliminate differences in print density by keeping the ink content of the ribbon constant in an impact printer equipped with an ink replenishment mechanism.

In order to achieve the above object, the present invention includes an ink pump mechanism that supplies a fixed amount of ink to an ink replenishing member using replenishment pulses, and a system that monitors the number of prints per fixed time and determines the number of occurrences of the replenishment pulse. and an ink replenishment control circuit that controls the amount of ink supplied from the ink pump mechanism, and increases or decreases the amount of ink replenishment depending on the number of prints per fixed time.

The present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an embodiment of the impact printer of the present invention. In the figure, 1 is a wire impact type print head, 2 is a platen, 3 is printing paper, and 4 is pulled out from a ribbon cartridge 5.
and the printing paper 3 and then the ribbon cartridge 5 again.
An ink ribbon 6 is drawn into the ink ribbon, 6 is an ink tank storing ink for replenishment, 7 is connected to the ink tank 6 by a tube 8, and a predetermined amount of ink is dispensed each time the shaft 7a rotates at a certain pitch. An ink pump 9 for delivering ink is a ratchet 1 supported coaxially with the ink pump 7.
0 is a pawl that engages with the teeth of the ratchet 9, 11 is a brunge magnet that operates the pawl 10 in the direction of the arrow via an arm 12, and 13 is in contact with the ribbon guide roller 14, and the ink pump 7 This is an ink vat to which ink is supplied via 8.

FIG. 2 shows the structure of the ink pump 7 in detail, in which a flexible tube 8 enters through one opening 7c of the outer wall 7b, passes through the interior as shown, and exits from the other opening 7d. It will be done. When a plurality of rollers 7e are arranged concentrically within the pump and the shaft 7a of the ink pump rotates,
A disk 7f supporting these rollers rotates. The tube 8 inside the pump is pressed by the roller 7e, and because its inner diameter is small, the ink flow path is blocked and no ink is delivered as long as the shaft 7a remains stationary. When the shaft 7a rotates, the roller 7e moves accordingly, and the ink is pushed out. The amount of ink sent out at this time depends on the amount of movement of the roller 7e, that is, the amount of rotation of the shaft 7a. This pump is commercially available. In the impact printer configured as described above, ink is replenished to the ink ribbon 4 as follows.

First, when the plunger magnet 11 is excited, the claw 10
rotates the ratchet 9 by one tooth.

This causes the shaft 7a to rotate, and a predetermined amount of ink is delivered from the ink pump 7. This ink is supplied to an ink bud 13 through a tube 8, and further supplied to an ink ribbon 4 via a guide roller 14. Therefore, as the number of times the plunger magnet 11 is energized increases, the amount of ink replenishment increases, and conversely, as the number of times the plunger magnet 11 is energized, the amount of ink replenishment decreases. It will be controlled by the excitation pulse. The above excitation pulse will be referred to as a replenishment pulse, and the ink replenishment control circuit that generates this replenishment pulse will be described next.

FIG. 3 is a block diagram showing a simplified configuration of the ink replenishment control circuit.

Reference numeral 15 in the figure is a time counter that counts the time it takes to print, for example, 100 characters, and counts up every time a timing pulse TM of a certain period is applied.
It is reset by a 100 character pulse generated every time a 0 character is printed. 16 is a decoder that generates a signal on output lines 16a and 16b depending on whether the count value of the time counter 15 is above a certain value; 17 is a replenishment amount instruction register that sets the output of the decoder 16 with a 100-character pulse; Reference numeral 18 denotes a replenishment pulse generation circuit that generates replenishment pulses of a number or period according to the contents of the replenishment amount instruction register 17, and 19 a plunger magnet 11.
This is a drive circuit for passing excitation current through the

In the above configuration, when the printing speed is high, the time interval between 100-character pulses is shortened, and the value counted by the timing counter 15 during that time becomes small. On the contrary, this means that the number of prints per certain period of time is large. On the other hand, when the printing speed is low, the time interval at which the 100-character pulse is output becomes wider, and the count value of the timing counter 15 becomes larger during that time, indicating that the number of prints per fixed time is small. The decoder 16 outputs a signal to the output line 16a when the content of the timing counter 15 is greater than or equal to a predetermined value, and outputs a signal to the output line 16b when it is smaller than the predetermined value. The output of this decoder 16 is set in the replenishment amount instruction register 17. Every time a 100-character pulse is generated, the replenishment pulse generating circuit 18 compares the contents stored in the replenishment amount instruction register 17 with the next output signal from the decoder 16 to determine the number of replenishment pulses to be generated. The amount of ink supplied from the ink pump 7 by one replenishment pulse is constant as described above, and the timing of generation of the replenishment pulse depends on the ink ribbon running time between the ink bud 13 and the printing section and the ink content of the ink bud 13. Determined according to quantity.

Now, while there is no major change in the number of prints per fixed time and the same output signal is continuously sent out from the decoder 16, a fixed number of replenishment pulses are sent out from the replenishment pulse generation circuit 18.

The output signal of the decoder 16 is transmitted from the output line 16a to the output line 16.
When the printing is switched to b and sent out, this indicates that the number of prints per fixed time has changed from a small number to a large number. The replenishment pulse generation circuit 18 detects this change by comparing it with the contents stored in the replenishment amount instruction register 17, and increases the number of replenishment pulses compared to before. When the output of the decoder 16 switches in the opposite direction to the above, this indicates that the number of prints per fixed time has changed from a larger number to a smaller number.
The replenishment pulse generation circuit 18 reduces the number of replenishment pulses than before. Considering the remaining amount of ink contained in the ink pad 13 at the time of the previous replenishment, the reduction includes the number of replenishment pulses being O, that is, the number of replenishment pulses equal to 1.
It also includes pauses. As described above, according to the present invention, the amount of ink consumed for printing is known by monitoring the number of prints per a certain period of time, and the number of replenishment pulses for supplying a certain amount of ink is determined according to this amount. Therefore, the amount of ink to be replenished increases or decreases depending on the amount of consumed ink, that is, the number of prints per certain time, and the amount of ink impregnated into the ink ribbon remains almost constant, resulting in the print density. It has a stabilizing effect.

However, the present invention is not limited to the above-mentioned embodiment, and the number of replenishment pulses may be set in three stages or more finely, and an ink-impregnated roller may be provided in the part that replenishes ink to the ink ribbon. The ink ribbon may be brought into direct contact with this roller and replenishment ink may be supplied.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of the impact printer of the present invention, FIG. 2 is a cross-sectional view showing the components shown in FIG. 1 in detail, and FIG. 3 is an ink replenishment control according to the present invention. FIG. 3 is a block diagram of the circuit. 1... Print head, 4... Ink ribbon, 5... Ribbon cartridge, 6...
・Ink tank, 7... Ink pump, 8...
...Pipe, 9...Rachietsu, 10...
...Claw, 11...Plunger magnet, 13
・・・・・・Ink bump, 15・・・Time counter, 16・・・Decoder, 17・・・・・・
Replenishment amount instruction register, 18...Replenishment pulse generation circuit.

Claims (1)

[Claims] 1. In an impact printer having an ink ribbon ink replenishment mechanism, an ink pump mechanism that supplies a certain amount of ink to an ink replenishment member by a replenishment pulse, a monitoring means for monitoring the number of prints per a certain period of time, and a monitoring means for monitoring the number of prints per a certain time. An impact printer comprising: an ink replenishment control circuit that controls the amount of ink supplied from the ink pump mechanism, including determining means for determining the number of generated replenishment pulses based on an output.