JPS62111779A - Printer - Google Patents

Abstract

PURPOSE:To skip a density shortage portion of an ink ribbon without using it for printing to ensure a good printing quality having no missed out portion in printing despite defects in the ink ribbon, by controlling a control system for carrying a transfer recording medium by an information of the density of the transfer recording medium. CONSTITUTION:In a density detect means 10, an emission element 11 and a reception element 12 are so combined as to be opposed to each other across an ink ribbon 3b. The reception element 12 outputs a density signal as an information of the ink ribbon density on the basis of the amount of light sent from the emission element 11 and that transmitting through the ink ribbon 3b. A density shortage detect circuit 20 receives a density signal outputted from the density detect means 10 and outputs a 'density shortage signal' in the presence of a density shortage portion in the ink ribbon, thus a control means 30 controls a winding driver 40 for carrying the ink ribbon and a printing head driver 50 to skip the ink ribbon 3b, which prevents the low density portion in the ribbon 3b from being used for printing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a transfer type printer such as a thermal transfer type or a pressure transfer type.

[Background of the invention]

Generally, transfer printers move the print head intermittently,
While sequentially feeding the ink ribbon against the print head, the print head is pressed against the ink ribbon, and the ink on the ink ribbon is thermally transferred or pressure transferred onto paper, film, cloth, etc. to perform desired printing. .

However, conventional transfer printers carry out printing by regularly transporting the ink ribbon regardless of the state of the ink on the ink ribbon. There are manufacturing defects such as pinholes and uneven coating in the ink layer due to air bubbles and insufficient dispersion of the coloring material, or there are peeling parts of the ink layer such as scratches that occur during the handling process after manufacturing and before use. If the same ink surface is used several to dozens of times, such as with a reusable ink ribbon, where the ink dries up due to the difference in frequency of use, there is a risk that printing omissions may occur. was there. In particular, with the above-mentioned ink ribbon that is used repeatedly, in order to achieve perfect printing without missing prints, if there is even a part of the ink ribbon that is depleted, it is possible to print well in other parts. Even so, the entire ink ribbon had to be discarded, and there was a problem with its economic efficiency.

[Purpose of the invention]

In view of the above circumstances, this invention makes it possible to ensure good print quality without missing prints even if there is a defective part in the ink ribbon.

It is an object of the present invention to provide a printer that can use an ink ribbon efficiently and improves its economic efficiency.

[Structure of the invention]

In order to achieve the above object, the present invention includes a means for detecting density information at an arbitrary point on a transfer recording medium, a means for photoelectrically converting the density signal, and a means for controlling at least a conveyance control system of the transfer recording medium using the electric signal. The printer is equipped with a means to bus printing in areas with insufficient density, and is configured so that printing can be performed only in areas where printing density can be maintained.

〔Example〕

Next, the present invention will be explained based on an embodiment of a thermal transfer printer shown in the accompanying drawings.

In FIG. 1, 1 is the printer body, and 2 is a carriage installed so that it can move left and right.

3 is an ink ribbon cassette attached to the upper surface of the carriage 2, 4 is a platen roller, and 5 is printing paper.

The carriage 2 has a platen roller 4 as shown in the second figure.
A printing head 6 having a heat generating element is attached to the opposite side surface, and a shaft 3 of the winding core of the ink ribbon cassette 3 is attached to the upper surface.
A winding drive shaft 7 for driving the ink ribbon 3a protrudes, and a density detection means 1o for detecting the density of the ink ribbon 3b in the ink ribbon cassette 3 is further provided. 8 is a paper guide.

The ink ribbon 3b in the ink ribbon cassette 3 is wound between a source core and a take-up core (not shown), and a part of the ink ribbon 3b is formed in a recess provided in an example part of the cassette 3 so that the print head 6 can be inserted therein. It is exposed to the outside through an opening (not shown) provided on the back surface of the cassette 3 to accommodate the portion 3c and the concentration detection means 1o.

The density detection means 10 is connected to the ink ribbon 3 as shown in the fourth figure.
The light receiving element 12 is configured by combining a light emitting element 11 and a light receiving element 12 which face each other with b in between. It outputs a density signal as information, and if there is no ink defect in the ink ribbon 3b, the light from the light emitting element 11 is blocked, and the output is not output or becomes small, or the resistance value increases. , a pinhole 15a in the ink ribbon 3b, and an ink depletion part 15.
(b) When a density-decreasing area such as uneven coating 15c exists, the amount of light received increases, and the output also increases or the resistance value increases. Light emitting element 1 constituting this concentration detection means 1o
The optical path 13 of the light projected from 1 to the light receiving element 12 is a long strip in the width direction of the ink ribbon 3b, and its width l is at least the same width as the effective width of the ink ribbon 3b used for printing, or slightly larger. It is set to large. However, if this width l is made too wide beyond the effective printing width, it is undesirable because it will react to areas with insufficient density such as pinholes in areas that are not used for printing. The reason is to stably detect the concentration of the ribbon, and it is not necessary to limit it to this shape.

The light emitting element 11 is a light emitting diode.

Small light bulbs, EL, and even laser scanning can be used, and the light receiving element 12 includes 5BC (silicon blue cell), photodiode, phototransistor,
A CDS light receiving element, a CCD line sensor array, etc. can be used. Further, a photo ink converter element in which a light emitting element and a light receiving element are integrated may be used. Specifically, for example, the light emitting element 1 may be Matsushita Electric's LN-0204.
-RP2, Sharp (7) BS-5 as a light receiving element
00-A etc. can be used.

In order to increase the density detection sensitivity of the ink ribbon of the density detecting means 10, both or one of the light emitting element 11 and the light receiving element 12 has a width Q in the ribbon conveyance direction, which is 1 ms to 2 nm.
It is desirable to provide slits 14 of about i.

Note that this density detection means IO can also function as an ink ribbon end sensor.

FIG. 3 shows a processing system for the density signal output from the density detection means 10, in which 20 is a density deficiency detection circuit and 30 is a control means. The density deficiency detection circuit 20 receives a density signal based on the density information of the ink ribbon outputted from the density detection means 10, and outputs a "density deficiency signal" when a density deficiency area exists on the ink ribbon.

An example of the specific circuit configuration is shown in FIG. This is a filter circuit that is relatively large in area and is used to remove uneven coating that causes a slight decrease in density, as well as induced noise and hum noise from the digital circuit built into the printer. 23 is an impedance conversion circuit; 24 is a diode that removes minute components of the signal (for example, an insufficient density signal corresponding to an insufficient density portion with a diameter of QJmm or less); and 25 is a time and voltage of the density signal, that is, density detection in the ink ribbon 3b. An integrator whose output voltage value changes depending on the degree of ink defect in the part; 26 is the integrator 2;
This comparator circuit compares the output voltage of the integrator No. 5 with a reference voltage and outputs an insufficient concentration signal when the output voltage of the integrator is lower than the reference value. Since the reference voltage of the comparator circuit 26 serves as a reference for determining whether the concentration is good or bad, this reference voltage can be adjusted by the variable resistor 27. 28
29 is a monomulti oscillation circuit that outputs a rising signal with a constant time width in synchronization with the rising edge of the insufficient concentration signal output from the comparison circuit 26, and 29 is a falling signal with a fixed time width in synchronization with the falling edge of the insufficient concentration signal. A mono multi-oscillator circuit that outputs
These rising and falling signals serve as interrupt signals to the CPU of the microcomputer built in the control means 30.

The control means 30 is constituted by a microcomputer. This control means 30 is a monomulti oscillation circuit 28
This is to prevent the area of the ink ribbon 3b where the density has decreased from being used for printing by a method described later when the rising edge signal is received. That is, the ink ribbon 3b is fed idly by controlling the take-up drive device 40 for transporting the ink ribbon and the print head drive device 50.

In the thermal transfer printer according to this embodiment, when the power is turned on, in order to prevent the portion of the ink ribbon 3b located between the density detection means 10 and the print head 6 with a reduced density from being used for printing, the density detection means The ribbon 3b is fed idly over a length corresponding to the distance between the ribbon 10 and the print head 6. Of course, this idle feeding is not a problem if the ribbon feeding amount can be accurately measured regardless of the amount of winding on the winding shaft 3a, but if it changes depending on the amount of winding, the above-mentioned method will occur when the amount of winding is the smallest. It is advisable to set the amount of rotation of the winding drive shaft 7 so that it can be fed by the same distance.Also, it is possible to increase the accuracy of this blank feed and further reduce the amount of the normal portion that is skip fed along with the insufficient density portion. Therefore, the density detection means 10 and the print head 6 are placed as close as possible.
It is more desirable to reduce the length of the ink ribbon 3b between the two.

Next, the operation of the above embodiment will be explained with reference to the signal waveform diagram shown in FIG.

When the power is turned on, first, the ink ribbon 3b between the density detection means 10 and the printing pad 6 is fed a predetermined length, and then the printing operation begins.9Printing operation is performed by tilting the printing pad 6. The ink ribbon 3b is pressed against the print paper 5, and the carriage moves in the width direction of the paper, causing the heating element of the print head 6 to generate heat to thermally transfer the ink on the ink ribbon. As the carriage moves, an equivalent amount of the used ink ribbon is wound onto the winding shaft 3a. The ink ribbon 3b is wound by rotating the winding drive shaft 7 in response to a command from the winding drive device 40. The ink ribbon 3b traveling as a result of this winding passes through the density detection means 10 and its density is detected before being used for printing. If the ink ribbon passing through the density detection means 1O has a defective part of the ink where the density has decreased, the amount of light received by the light receiving element 12 increases when the defective part passes, and a density signal is output from the density detection means 10. Ru. As shown in FIG. 6(a), this concentration signal g has a pulse shape that rises when the front end of the defective portion passes the detector and falls when the rear end passes. Since this concentration signal is a minute signal and contains various kinds of noise, the amplifier circuit 21
Amplify it.

Noise is removed by the filter circuit 22 to form a waveform g' as shown in FIG. . Output Va of integrator 25
gradually rises with a predetermined time constant as shown in FIG. The output of the integrator 25 is the reference voltage vr of the comparison circuit 26.
The output of the comparator circuit 26 rises at the point when the voltage exceeds .

An insufficient concentration signal is output in a form as shown in FIG. 2(d).

This concentration deficiency signal is caused by the output of the integrator 25 being the reference voltage Vf.
It will fall when it falls below . Here, since the output voltage Va of the integrator 25 depends on the density signal of the density detection means, that is, the degree and area of the density deficiency at the detection portion of the ink ribbon 3b, the density deficiency signal also depends on these.

Upon receiving the concentration insufficient signal, one monomulti oscillation circuit 28 sends out a rising signal j with a fixed time width in synchronization with the rising edge of the signal, as shown in the figure (ill), and the other monomulti oscillation circuit 29 In synchronization with the fall of the concentration deficiency signal, a falling signal k having a certain time width is sent out as shown in FIG. 2(f).

When the control means 30 receives the rise signal j as an interrupt signal, it immediately shifts to the defect avoidance mode. That is, first, the normal printing operation continues, but the rising signal j
After input to the CPU, the number of printed characters, that is, the amount of feed of the ink ribbon 3b is counted by a built-in counter. Then, before the insufficient density area on the ribbon that caused the rising signal j reaches the heating element of the print head 6, the take-up drive device
and controls the print head drive device 50, temporarily suspends the printing operation, and starts feeding the ribbon. Specifically, the blank feed is performed from the time when the count result by the counter reaches a certain value. This idle feeding is continued until the detected area with insufficient density passes through the print head 6. In other words, the falling signal k
The idle feeding ends when the count value of the counter that counts the amount of ribbon feeding after is input to the CPU reaches a certain value. Note that if the length of the ink defective part is small, such as a pinhole, after transitioning to the defect avoidance mode by the rising signal j, the falling signal k is sent before actually starting the blank feed.
may be entered, but there is no problem.

In this way, after the ink defective area on the ink ribbon 3b is idle-fed without being used for printing, the normal printing operation returns again and good printing is performed.

Note that, especially in a reusable ribbon, as the number of times the ribbon is repeatedly used increases, the distance between the ink depletion parts becomes narrower. In this case, the ribbon will frequently shift to the defect avoidance mode, resulting in a decrease in printing efficiency.To prevent this, for example, if a single rising signal is input, the ribbon will automatically move to a certain level. It may be configured so that the number of prints is skipped.

〔Effect of the invention〕

As described above, the present invention includes a means for detecting density information at an arbitrary point on a transfer recording medium, a means for photoelectrically converting the density signal, and a means for controlling at least a conveyance control system of the transfer recording medium using the electric signal. It is characterized by
Printing is performed in areas with insufficient density, and printing is performed only in areas where the ink is always in good condition, thereby improving printing quality. In addition, even if there is a part of a reusable recording medium that is so depleted of ink that it is impossible to print, it is possible to print on that part by empty feeding, and as a result, the entire recording medium can be disposed of. It can eliminate the inconvenience caused by this method, and it is economically extremely advantageous, and has various excellent effects.

[Brief explanation of drawings]

FIG. 1 is an external perspective view of a thermal transfer printer according to the present invention, FIG. 2 is a perspective view of the state before an ink ribbon cassette is mounted on the carriage, FIG. 3 is a block diagram showing a density deficiency detection device, and FIG. 4 is a perspective view of the concentration detection means, FIG. 5 is a specific circuit configuration diagram of the concentration deficiency detection circuit, and FIG. 6 is the operating waveform of each part of the concentration deficiency detection device. ) is the output of the filter circuit, (C) is the output of the integrator, (d) is the output of the comparison circuit, (C) and ('')
represents the output of each monomulti oscillator. 3b - Ribbon ink (transfer recording medium) 6 - Print head 10 - 1 degree detection means 20 - 4 degree deficiency detection circuit 30 - Control means

Claims (2)

[Claims] (1) Features include means for detecting density information at an arbitrary point on the transfer recording medium, means for photoelectrically converting the density signal, and means for controlling at least the conveyance control system of the transfer recording medium using the electric signal. printer. (2) The printer according to claim 1, wherein the control means operates to bus the print head surface so that areas with insufficient density on the transfer recording medium are not used for printing.