JPH0234315B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention is a technology that allows printing ribbons to be effectively used in impact printers such as typewriters and dot matrix printers.

[Prior art]

Generally, two types of printing ribbons are used in impact printers. The first type of ribbon is
This is called a one-time use ribbon, in which the colored material such as carbon at the impression position is completely transferred to the recording carrier, leaving no colored area on the ribbon substrate. Therefore, after the entire length of the ribbon has been used once for printing, the ribbon is discarded and no means for replenishing the ribbon with ink is required. In contrast, the second type of ribbon is typically used by moving it back and forth in front of the printing station many times. Since the dye at the stamping position is used for each stamping, a certain amount of time is required before the ribbon is next advanced and reversed. This is because the dye needs time to "flow" from the surrounding area into the area where it is to be replenished.This means that by reversing the direction of ribbon transport several times, the quality of the print will gradually improve. These printing ribbons, along with their transport mechanisms, are well known, so there is no need to cite prior art examples to explain them. .

As previously mentioned, with the second type of ribbon, a gradual decline in print quality must be accepted until the print quality reaches a minimum acceptable level such that the ribbon must be replaced. This is very simple for a single color ribbon, but
Complications arise when multicolored ribbons are used. This is because not all colors are used with the same frequency. Therefore, for example, the color red is often used when printing pictures, and it will need to be replaced after a certain amount of time.
Colors such as yellow are rarely used and remain new.

Another consideration is that dirt and grime can contaminate the ribbon during ribbon winding, and even if there is still plenty of colorant left, the contaminated ribbon area may be difficult to print. To make the color cloudy or discolored.

Swiss Patent No. 474757 discloses a method and apparatus for measuring the density of printing ink in a multicolor printer. Samples of each color printing ink at each point in time are compared to the respective contrasting color standards;
It is disclosed that the ink under test is applied to a light sensing means for electronic comparison.

This patent also refers to a prior art device that uses complementary color filters to determine the color density of a print.

However, this prior art does not address how to use the printing ribbon economically. There is no suggestion of any means for making a new section of printing ribbon available at the printing station, especially when high-quality printing operations are carried out.

[Summary of the invention]

In contrast, the present invention provides an impact printer that makes good use of printing ribbons. Gives a new ribbon part especially when high quality printing is required,
It provides techniques such as keeping the ribbon in place when there is no signal that special quality is required.

The method of using a printing ribbon with an impact printer of the present invention, whether it is used in a single color ribbon impact printer or a multicolor impact printer, is such that during a printing operation, a predetermined The ribbon is transported in the forward or reverse direction in sections or subsections of length.
The printing condition of the colors in the subsection is constantly monitored, and if the condition of that color or any one color reaches a predetermined tolerance level, the ribbon is printed regardless of the condition of the remaining colors in that subsection. The ribbon is transported to present the next new subsection to the printing station.

According to an embodiment, it would also be possible to directly transfer to a new subsection of the ribbon with manual intervention by an operator if the printing job signals that high quality printing is required.

[Explanation of Examples]

Most of the impact printers used today are typewriters, but dot matrix impact printers are the most popular output printers for digital printers, especially for applications that print alphanumeric characters or pictures. The number of is increasing significantly. Traditionally, most impact printers have used single-color ribbons, but in color imaging systems, it has become increasingly important to produce sharp, accurate color images to represent graphic shapes. There is.

Although the invention can be used with either a single color ribbon impact printer or a multicolor impact printer, the invention will be described using the example of a multicolor dot matrix printer. The functions of this printer will be briefly explained below.

The printer 1 of FIG. 1 includes a platen 2 and a record carrier, such as a sheet of paper 3, carried by it.
The platen 2 is supported by frames 4 and 5 and indexed by a step motor 9 via a belt 6 and pulleys 7 and 8. Sliding on the shafts 10 and 11 is a printing head 12. It is wound around drums 14 and 15 and can be escaped along the print line by a belt 13 driven by a step motor 16.

The printing heads 12 are arranged, for example, in a row with seven printing heads arranged at equal intervals.
It includes an arrangement of main wires (not shown), the tips of which are directed towards the platen 2, and the rear ends of these wires are coupled to an electromagnet. The electromagnet is coupled via a flexible cable 17 to suitable control equipment well known in the art. Alphanumeric characters and symbols are printed as combinations of individual dots in a 7 x 5 matrix arrangement.
That is, after a suitable number of wires are energized in parallel, they are advanced by a distance of 1/5 or less of one character width, and selectively energized at each actual printing position. Then, when a character is completely printed, escape movement between characters is performed.

These wires connect platen 2 and print head 1.
2 and which extends between the two spools 19 and 20. Print head 12 is supported by means (not shown) for bidirectional movement under control from a control system to be described below. Printing ribbon 18 (FIG. 2) includes four parallel color bands 21-24. for example,
It has yellow (21), magenta (22), cyan (23) and black (24) inks, respectively. By overlaying these inks on each other, printing in a total of seven colors can be obtained. This superimposition method by subtracting colors from the main color has been published in a European patent publication.
It is explained in No. Nr0011722. printing ribbon 18
may alternatively use a different family of colors as disclosed in Swiss Patent No. 610,825. For example, golden yellow, carmine, purple, blue (green)
Color, etc. In addition, other types of colors may include positive primary colors such as red, yellow, blue, and black. Black is often used to increase contrast.

The color bands presented at the print station for printing are conventionally selected by a print control that controls the raising of ribbon fork 25 and ribbon spools 19 and 20. The ribbon is constructed so that inks of different colors do not mix. That is, adjacent bands are impregnated with inks that repel each other,
So that they don't mix or ooze out,
It is also designed to ensure that the quality of the ink does not deteriorate with the ink next to it.

The printers described above are currently capable of printing at speeds of up to 5000 stamps per second. Such speed limits are primarily determined by moving parts, such as the printing wire and its associated electromagnet. By reducing the mass of the wire in the electromagnetic assembly and by improving the materials used in the print head, it will be possible to obtain even higher speeds in the near future.

Recent advances in LSI technology and increased printing speeds have made it more realistic to implement image processing systems based on dot matrix impact printers. However, the high density of multicolored dots required for printing actual images particularly requires precise, clear, and clean dots from the printing head and ribbon assembly. As the ribbon begins to age, it begins to develop faded and indistinct dots, making accurate image reproduction impossible.

In prior art printers, the entire ribbon is treated as a single entity that is subject to uniform aging characteristics, as shown in FIG. It goes without saying that when a ribbon is new, its quality is very good, but as it is used, its quality gradually deteriorates until a low quality threshold is reached that requires the ribbon to be replaced. Uniform wear is achieved by escaping the ribbon in small increments after each impression, but the escaping continues by reversing the direction of movement once all new ribbon sections have been used. and then reverses several times until a low quality threshold is reached.

However, this technique has several problems for use in high resolution color printing. The first problem is
In the case of multi-colored ribbons, all colors are used uniformly and do not wear out. Invariably, only a portion of the ribbon gets stained or faded, or lighter colored ribbon sections turn black or collect dirt. Therefore, some of the color bands have not yet reached the predetermined low quality level and at least some of them can still be used, while other bands have reached the predetermined low quality level. If you stamp an image with the ribbon in this state, the colors will become blurred or faded.

Another problem with conventional printers is that there is no reliable way to monitor ribbon quality. One of the surest signs that the ribbon needs to be replaced is the occurrence of poorly colored prints. But since printing jobs have different quality requirements, it is really difficult to set a low quality threshold. If a job requires high-quality printing, in traditional printers the operator intentionally replaces the ribbon, even if the ribbon is not completely worn out.

The present invention divides the entire ribbon into several subsections (areas) of approximately equal length, and uses said subsections in printing sequentially, such that when a subsection reaches a low quality level, it switches to a new subsection. The above problem is solved by doing this. Figure 4 shows this. That is, one color ribbon is divided into six subsections S1...S6. The lifetime of each subsection is determined by the parameters of the printed color image,
For example, it varies according to frequency of color changes, color dot density, printer speed, resolution, etc. The reason why subsections S2 and S5 deteriorate relatively quickly is that
This may be due to the black color overstriking the light color band, causing the ribbon band of that color to fade or become streaked with high frequency. However, with this technique, one subsection is completely used up before the printer switches to the next subsection, so in the example of Figure 4, subsection S2
It is not acceptable for parts that deteriorate quickly, such as S5 and S5, to degrade the overall print quality.

Successful use of the techniques of the present invention will require continuous monitoring of the quality of the ribbon subsections currently in use. For this purpose, the following 3
The following methods can be considered.

The first monitoring method uses separate counters to count the number of times individual color bands in a ribbon subsection are struck by the printhead wire to produce a dot. When the number of dots resulting from a particular color exceeds the maximum count assigned to that color, the monitoring device generates a signal to the ribbon transport mechanism to advance the ribbon to the next subsection. In presetting the maximum number of counts, print quality requirements can be balanced with ribbon life requirements.

The second monitoring method as shown in FIG. 5 is basically optical, with a light source 26 and a photodetector 27.
including. The idea is that a striped, stained or faded ribbon can be detected by the intensity of the light emitted from it. A photodetector 27 is mounted near the print head 12 and scans the ribbon 18 as the print head is escaped. From light source 26, light passes through short bands of each color on ribbon 18 to a group of optical filters 28-31. Each filter is
Suppresses all light except the light that passes through the color band immediately before it. For example, light passing through the magenta band 22 passes through a corresponding filter 29. The filtered light is passed through a row of light sensing elements 32-35, where it is passed through corresponding filters 28-31, respectively.
The intensity of the color received from the device is converted into an electrical signal. This electrical signal is sent to integrators 36-39. Each integrator adds the signals received at the respective timings to the previous outputs of the respective photo-sensing elements 32 to 35, and sends the output signals to the comparators 40 to 43.
give to one of the One input of each comparator is commonly connected to a threshold voltage, and its output is passed through an OR circuit 44. Separate adjustment functions may be provided at each comparator so that the threshold values for each color are individually preset.

After a certain amount of time, e.g. corresponding to one sweep, if the voltage output from one integrator is below the threshold level of the color associated with it, the detector 27 , signals that one color band in the current subsection has been exhausted. So ribbon 18
is advanced to the next new subsection.

The third monitoring method only involves manual forward movement. This manual advancement motion may be used if for some reason the operator wishes to advance to a new subsection of ribbon 18, such as in a printing job requiring high quality. In this case, the ribbon advances to the next subsection regardless of the state of the current subsection.

The length of this ribbon subsection can be set by the operator prior to printing. The minimum practical length is that the printing head 12 is connected to the left and right stops 4.
5 and 46 (FIGS. 1 and 6). In general, the subsection's length ΔL extends on either side of the above-mentioned travel distance. In the latter case, to ensure uniform aging or wear of the entire subsection,
Ribbon 18 is advanced by a small fraction Δx of the subsection length ΔL every two print head carrier returns.

The above method uses a micro-
It is best implemented in processor-based systems. A block diagram of such a system is shown in Figure 7.
As shown in the figure. For convenience in the following discussion, the operation of this system is divided into three periods: startup, normal operation, and power down.

At startup, microprocessor 47 performs several checkout routines. The microprocessor 47 then uses the non-luminous memory 48.
Read the operating parameters related to the previous operation from
Stored in a suitable device such as random access memory 49. A specific area of this memory 49 is loaded with the maximum number of wire strikes for each color band 22-25 of the ribbon, the length of the ribbon subsection ΔL, the current count of Δx, and the maximum count of Δx. be caught. The previous value of the counter (held in memory 48) is rounded, for example around 1020, and read back into the counter.
Once this is complete, microprocessor 4
7 starts the normal operation of causing the printer to print.

During the printing operation, the number of times the printing wire strikes the ribbon 18 is counted separately for each color. At the same time, photodetector 27 is swept across ribbon 18 looking for bands of faded or dirty color. Flip-flop 51 is later read by processor 47 when the number of strikes for any color exceeds a preset value or an exhausted band is found, or when manual ribbon advance button 50 (FIG. 7) is pressed. It is set as follows. When the return of the print head carrier is signaled by printer 1, an interrupt signal is generated and microprocessor 47 enters the interrupt routine (FIG. 8). Block 52 first checks to see if the reset button has been pressed. The reset flip-flop 51 is considered to be reset because it is desirable that the mechanism be configured so that pressing the reset button 53 while printing is in progress has no effect. Operation therefore proceeds to block 54, which decrements the current carrier count.
Note that the current carrier count represents the number of carrier returns performed since the last time the ribbon was advanced. When the current carrier count reaches zero (block 55), it is reloaded from memory 48 and the ribbon is advanced by Δx (FIG. 9).

When microprocessor 47 determines that ribbon 18 should be advanced, it first checks the direction of advancement. This first checks whether the ribbon should be advanced, retracted, or not advanced at all, such as if the length ΔL of the ribbon subsection is chosen to be equal to the carrier travel distance. The processor determines the number of times the ribbon has previously advanced by Δx by querying whether the current Δx count has reached zero (block 56). If the answer is no, ie, the ribbon has not reached the end of the current subsection, the processor reads the direction flag stored in memory 48 (block 57). block 56
If the answer is YES, the processor asks for the orientation flag when the ribbon is at the end of the subsection. If the ribbon is at the left end of the subsection (block 58), it simply switches directions and begins advancing toward the right end of the subsection. If the ribbon is at the right end of the subsection (block 58), the processor checks the state of flip-flop 51 to see if it should proceed to the next subsection or return to the previous subsection (block 60). The flip-flop 51 is set by a counter 59, a photodetector 27, a manual forward movement, or the like. If photodetector 27 or counter 59 signals that the ribbon is exhausted, or if manual advance button 50 indicates that the ribbon should be transferred regardless of the condition of the ribbon, processor 47 causes counter 59 to reloads and generates an advance signal to the new subsection (blocks 61, 62). If not, processor 47 toggles the direction flag, reloads the count Δx for that subsection, and proceeds back to the previous subsection (blocks 63, 64).

Minimum length ribbon subsection (ΔL)
If selected, this subsection will be long enough to cover the carrier and the ribbon will not be advanced by Δx. Processor 47
indicates that ΔLmin has been selected at power start, and calculates zero for the count Δx.
This value of zero is continuously loaded for a count of Δx, and the ribbon never advances in either direction (block 66).

In summary, the length (ΔL) of each ribbon subsection is set by the operator during start-up or reset operations. While the printer is printing, the microprocessor 47 creates a uniform subsection of the ribbon by gently moving the ribbon back and forth in small increments (Δx) every few carrier returns. Control wear. When ribbon advancement is signaled, the processor causes the ribbon to be transferred to the next subsection, and the process repeats.

Another event that can cause an interrupt to microprocessor 47 is the operator pressing reset button 67. This also causes the microprocessor 47 to enter the interrupt routine of FIG. 8 and load a new parameter (ΔL, counter limit) into memory (block
66, 68). When the reset button 67 is pressed,
Processor 47 believes that a new ribbon region should be introduced. Therefore, the printer needs to be offline when this occurs.

A fault button 69 may be provided which produces a similar result to pressing the reset button 67. However, when the failure button 69 is pressed, parameters are read from the failure list stored in the non-luminous memory 48.

FIG. 10 shows the design concept of the counter 59 of FIG. The purpose of these counters is to
determining the actual number of impacts to be performed in each color band and advancing the ribbon to a new ribbon section when a predetermined maximum number of impacts is exceeded.

As mentioned above, print head 12 is assumed to have seven print wires. Therefore, seven control lines 7 are required to energize these printed wire magnets.
There is 0. These control lines 70 are also coupled to separate logic devices 71, the latter of which are connected to the ribbon transport mechanism 7.
It also receives a vertical position control signal provided along line 72 from 3. A clock signal sent from system clock 74 via line 75 is applied to logic unit 7.
1 with the rest of the printer. Depending on which color band 21-24 is selected, the logic device 71 activates the appropriate one of the counters 76-79 so that the corresponding color band is incremented the number of times the corresponding color band is struck by the printing wire. Counter count decreases. Counters 76 to 79
may be implemented as a binary counter. In this case, each counter may include two areas a and b for counting the lower and upper digit bits, respectively. The inputs to counters 76-79, along with their most significant bits, are stored in map area 80 of memory 48 so that the system can remember the most recent count for each color band 21-24 after a power outage.
Mapping may be performed continuously.

If the ribbon subsection is new, its corresponding counter will be set to the predetermined maximum count for each color at power start, and if the ribbon subsection has already been used for printing. If so, the count reached at the time of the most recent power outage will be set. If either counter decreases to zero, processor 47 signals so that a new ribbon section is brought into print position.

Various human intervention operations for printers are possible depending on the type of printer. The basic elements for human intervention are shown in FIG. These include a ribbon advance button 50, a reset button 67, a failure button 69, a visual display 81, a ΔL button 82, and a series of microswitches 83. visible display 81
is for displaying the numerical output from the microprocessor 47, and may use a light emitting diode or the like. Further, the micro switch group 83 is for inputting a predetermined count of each color band to the micro processor 47. In place of these micro-switches 83, any suitable setup mode programmed to write such count values directly into random access memory 49 may be used.

The mechanisms described above may be implemented in existing or future printers in a variety of different ways, all of which will benefit from the capabilities and benefits of the present invention. For those skilled in the art:
It will also be readily appreciated that the ribbon subsection control method described above may be implemented as a separate device connected to the printer at the power source, print control lines, or ribbon transport mechanism. Alternatively, if the printer is microprocessor controlled, the invention may be fully integrated within the host printer. In this case, in addition to adding some elements,
The program code for the host microprocessor would also have to be modified slightly. The human intervention means shown in FIG. 7 can be used even in printers that do not have a keyboard. If the printer has a keyboard, the entire human intervention operation may be incorporated into the printer's setup mode. The availability of a microprocessor has the advantage that the quality status of all subsections of the ribbon can be monitored and stored as the ribbon is advanced to a new subsection. Therefore, if a previously used subsection allows printing of the required quality at each point in time, it is also possible to return to that subsection and print at that quality.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the basic components of a wire matrix printer. FIG. 2 shows a multi-color ribbon with its spool and lifting motion. FIGS. 3 and 4 are diagrams showing the number of times the ribbon is used and the degree of deterioration in the quality of the ribbon. FIG. 5 is a diagram illustrating an apparatus for optically monitoring ribbon quality. FIG. 6 shows a minimum or typical length subsection of the ribbon. FIG. 7 is a diagram showing the relationship between each element of the ribbon quality monitor. 8th
9 and 9 are flowcharts illustrating the ribbon interrupt routine and ribbon advance routine, respectively. And FIG. 10 is a schematic diagram of the counter circuit of FIG. 7.

Claims (1)

[Scope of Claims] 1. A platen that supports paper, a printing head that prints while moving in both directions along the axis of the platen, and a printing head that extends in the axial direction of the platen between the platen and the printing head, In an impact type printer having means for supporting a single color or multicolor printing ribbon, within each subsection of a plurality of subsections obtained by dividing the entire length of the printing ribbon in the axial direction so as not to overlap each other; means for repeatedly moving said print head in both directions to permit overlapping impressions; and means for monitoring the condition of the subsection being used by said print head for printing until it reaches a predetermined acceptable limit of use. means for detecting whether the in-use subsection has reached a predetermined usage tolerance limit; an impact printer further comprising means for feeding in the axial direction. 2. The detection means is a means for detecting whether the subsection has reached a predetermined allowable use limit by monitoring the light intensity of the subsection in use with an optical device and comparing it with a reference light intensity. An impact printer according to claim 1, characterized in that the impact printer comprises: 3. The detection means includes means for detecting whether the subsection has reached a predetermined permissible usage limit by counting the number of times the printing head hits the subsection in use and comparing it with a predetermined reference number of times. An impact printer according to claim 1 or 2, characterized in that: 4. The feeding means comprises means for feeding the next subsection of the printing ribbon into presentation at the printing head, regardless of the status of the monitor of the sensing means. The impact printer according to any one of Items 1, 2, and 3.