US3906355A

US3906355A - Method and apparatus for testing an aperture board in a high speed printer

Info

Publication number: US3906355A
Application number: US492340A
Authority: US
Inventors: Akinori Watanabe; Katsuhide Tanoshima
Original assignee: Oki Electric Industry Co Ltd
Current assignee: Oki Electric Industry Co Ltd
Priority date: 1974-07-26
Filing date: 1974-07-26
Publication date: 1975-09-16
Anticipated expiration: 1992-09-16

Abstract

A test system for detecting the presence of an obstructed aperture in an ink mist type printer is disclosed. The ink mist type printer operates on the principle that an ion stream modulated by an aperture board according to the pattern of the character to be printed, charges the ink mist, which is then attracted by an electric field to the surface of the paper. If an aperture of said aperture board is obstructed a portion of the printed character will not be evident. In order to detect the aperture, a conductive board is inserted between the aperture board and the paper, and an amplitude and/or pattern of an electric current in the conductive board due to the ion stream shows the presence and location of the obstructed aperture.

Description

United States Patent [191 Watanabe et al.

[ METHOD AND APPARATUS FOR TESTING AN APERTURE BOARD IN A HIGH SPEED PRINTER [75] Inventors: Akinori Watanabe; Katsuhide Tanoshima, both of Tokyo, Japan [73] Assignee: Oki Electric Industry Co., Ltd., Tokyo, Japan [22] Filed: July 26, 1974 [21] Appl. No.:, 492,340

[52] US. Cl. 324/33; lOI/DIG. 13; 324/71 EB [51] Int. Cl. G01N 27/60 [58] Field of Search 324/33, 71 R, 71 EB;

10l/DIG. 13

[451 Sept. 16, 1975 Primary ExaminerAlfred E. Smith Assistant ExaminerWm. H. Punter Attorney, Agent, or FirmLewis H. Eslinger; Alvin Sinderbrand 57 ABSTRACT A test system for detecting the presence of an 0bstructed aperture in an ink mist type printer is disclosed. The ink mist type printer operates on the principle that an ion stream modulated by an aperture board according to the pattern of. the character to be printed, charges the ink mist, which is then attracted by an electric field to the surface of the paper. If an aperture of said aperture board is obstructed a portion of the printed character will not be evident. In order to detect the aperture, a conductive board is inserted between the aperture board and the paper, and an amplitude and/or pattern of an electric current in the conductive board due to the ion stream shows the presence and location of the obstructed aperture.

4 Claims, 5 Drawing Figures METHOD AND APPARATUS FOR TESTING AN APERTURE BOARD IN A HIGH SPEED PRINTER BACKGROUND OF THE INVENTION The present invention relates to a method and an apparatus for testing an aperture board.

The operational speed of an information processing system including a computer system has recently been improved, thus requiring the use of a high speed peripheral device including a printer. A conventional high speed printer is a line printer with a type drum or a type train. However, this line printer has many disadvantages, some of which are that the operational speed is not enough for the latest information processing system, high level of noise and/or limitation of the number of printing types. In order to overcome these disadvantages of the prior line printer, some high speed printers with new operational principles have been developed. Among them, one of the most promising is an ink mist type printer. The ink mist type printer operates at high speed. i.e. 8,000 lines per minute, with a low noise level. Further, it can type not only alphanumeric characters but also Chinese or Japanese characters.

The operational principle of an ink mist type printer is that an ion stream generated by corona discharge passes through apertures of an aperture board and ionizcs an ink mist, and the movement of the electrically charted ink mist is acceleratedby a negative electrode and is attached to paper according to the pattern of characters.

The disadvantage of the prior ink mist type printer is that the ink mist obstructs apertures of the aperture board and prevents the passages of the ions. The obstructed apertures create incomplete printed characters with missing portions and the source of the trouble cannot be located until the printing operation is actually performed. Therefore, both paper and operational time are wasted.

SUMMARY OF THE INVENTION The general purpose of the present invention is to provide an ink mist type printer with a facility, for testing the patency of apertures.

It is an object, therefore. of the present invention to overcome the disadvantages of the prior ink mist type printer by providing a method of testing an aperture board if apertures are obstructed.

It is also an object of the present invention to provide an apparatus for testing an aperture board if apertures are stopped up. According to the present invention, a conductive board is inserted between the aperture board and the paper and an amplitude and/or pattern of an electric current on the conductive board due to the ion stream shows the presence of an obstructed aperture, since the ion stream cannot go through the aperture.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and other objects, features, and attendant advantages of the present invention will be appreciated as they become better understood by reference to the accompanying drawings wherein:

FIG. 1 shows (the explanatory) sectional view of a conventional ink mist type printer;

FIG. 2 shows a sectional view of an ink mist generator in the conventional ink mist type printer;

FIG. 3 shows a perspective view of a conventional aperture board;

FIG. 4 shows a block diagram of a test device according to the present invention; and

FIG. 5 shows the detailed structure of the conductive board of FIG. 4.

v DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the operational principle of an ink mist type printer will be explained to provide a basis for under standing of the present invention.

FIG. 1 shows a basic structure of an ink mist type printer. The principle of typing in an ink mist type printer is to attach an ion stream to an ink mist which types or draws characters on printing medium like a sheet of paper. Said ion stream is controlled by an electric field on an aperture board according to the pattern or shape of printed characters. In FIG. I, an aperture board 1 is positioned between a positive electrode 6 and printing medium 7. The printing medium 7 is just ordinary paper. A negative electrode 8 is provided hehind the printing medium 7 and doubles as a platen. The positive electrode 6 is straight and has a sharp point. Several thousand volts applied to the positive electrode 7 generates a corona discharge and an ion stream 9.

The strength of the electrical field required for corona discharge depends upon the shape of the positive electrode 7 and is generally 1000l300 V/mm. The movement of the ion stream 9 generated on the positive electrode 7 is accelerated by the negative electrode 8 and passes through apertures 2 of the aperture board 1, the structure of which is shown in detail in FIG. 3, wherein reference number 3 is a dielectric layer, and 4 and 5 are conductive layers. The

conductive layers

4 and 5 are separated by a plurality of cells shown as 5a, 5b, 5c, and each

cell

5a, 5b, 5c, is insulated from the others. A voltage E is applied to each cell of the

conductive layers

4 and 5, and the distribution of voltage E is related to the pattern or shape of the char acter to be printed. An electric field generated in the apertures by said voltage E prevents or accelerates the passage of the ion stream according to the polarity of the voltage E, therefore, the density of the ion stream which comes out of the aperture board I is modulated according to the pattern of the character. Voltage E is supplied by a character generator (not shown).

There is an ink mist between the aperture board 1 and printing medium 7. The ion stream 9 modulated by theaperture 1 attacks and charges the particles of the ink mist, then, the charged particles 10 of the ink mist are accelerated by the negative electrode 8 and attach to the surface of the printing medium 7. Thus. the pattern of the character is printed on the printing medium in ink.

FIG. 2 shows the structure of an ink mist generator, which comprises an ink tank 20 containing, ink 21. an ink inlet 22, an ink outlet 23, and ultrasonic wave exciters 24. The depth of the ink 21 in the ink tank 20 is maintained automatically at a desirable depth by the ink stream through the inlet 22 and the outlet 23. The cxciters 24 generate ultrasonic waves and generate ink mist 10, the diameter of which is 5-20 ;1.. The ink mist 10 is transported by an air stream 25 to an ink guide 17 (FIG. 1), and the ink mist 10 is directed along arrow Y in the same direction as the movement of the paper 7.

The moving speed of the ink mist is almost the same as that of the paper 7. The ink mist which is not used for printing isgathered and condensed in a tank (not shown).

One problem of an ink mist type printer is, as explained before, that apertures of the aperture board are sometimes obstructed by ink mist, thus creating missing portions in the printed character.

FIG. 4 shows a block diagram of an apparatus for testing the patency of apertures. In FIG. 4, the same reference numbers refer to the same members as those of FIG. 1. A conductive board 11 is inserted, vertically movable, between the aperture board 1 andthe paper 7. The conductive board 11 is connected electrically to the input of an amplifier 12, the output of which is, in turn, connected to a waveform shaping circuit 13. The output of the waveform shaping circuit 13 is applied to a memory 14. On the other hand, each cell of the conductive layer 5 is connected to an output of a drive circuit 15, the input of which is connected to the output of a selection circuit 16. Since there are a plurality of cells on the conductive layer 5, there must be provided a plurality of drive circuits 15, however, only one representative drive circuit is shown.

In a test operation, the conductive board 11 is inserted between the aperture board 1 and the printing medium 7 by a drive mechanism shown in FIG. 5. The selection circuit 16 in FIG. 4 scans and selects a particular cell on the conductive board 5 in a predetermined order. The drive circuit 15 generates an electric field in an aperture in the selected cell in the direction of the negative electrode 8. Accordingly, if the selected aperture is not obstructed, an ion stream generated on the positive electrode 6 passes through the selected aperture to the conductive board 11, in which a small current flow is created. The small current is amplified by the amplifier l2 and its waveform is shaped by the shaping circuit 13. The output signal of the shaping cir cuit 13 is a digital signal,- which is stored in a particular address of the memory 14. The selection of the address of the memory 14 is synchronized with the selection of the cell on the conductive layer 5 by the selection circuit 16. However, if the aperture is obstructed a current does not flow in the conductive board 11, thus the digital signal zero, instead of one. is stored in the memory 14. Therefore, in the memory 14 the address which stores zero information shows the position or address of the obstructed aperture.

Many modifications of the embodiment of FIG. 4 are possible to those skilled in the art. For instance, all cells on the conductive layer 5 may be selected at the same time and in that case, the level or amplitude of the current in the conductive board 11 indicates if there is an obstructed aperture. Further, when no cell on the conductive layer 5 is selected, the presence of the current on the conductive board 11 shows that there is something wrong with an aperture.

FIG. 5 shows a drive mechanism of the conductive board 11. In FIG. 5, the conductive board 11 can move, as indicated by arrow B, vertically along the left guide 30a and the right guide 30b. The movement of the conductive board 11 is restricted by the upper stopper 34 and the lower stopper 35. The arm 11a extends from the end of the conductive board 11 to the plunger magnet 31. A pair of leads 32a and 3212 from the plunger magnet 31 are connected to the direct current source (not shown). The spring 33 pulls the conductive board l 1 downwards. When the plunger magnet 31 is not energized, the conductiveboard 11 is pulled by the spring 33 until the lower end of the board 11 reaches the lower stopper 35. In that condition, the conductive board 11 does not prevent the operation of the ink mist type printer. On the other hand, when the ink mist type printer is tested, the, plunger magnet 31 is energized through the pair of leads 32a and 32b and the plunger magnet 31 attracts the arm 11a in the direction of arrow A and lifts the conductive board 11 against the tension of spring 33 till the upper end of the conductive board 11 reaches the upper stopper 34. In that condition, the conductive board 11 is between the aperture board 1 and the printing medium 7, and the printing operation can no longer be performed, but the test operation, explained above, is carried out instead.

As previously explained, according to the' present invention, an aperture board is tested and the address of the obstructed aperture is found by a simple apparatus. One effect of the present invention is that printing paper is not wasted due to obstructed apertures.

It can be seen that the present invention provides a simple and unique system for testing an ink mist type printer and although it has been described with respect to embodiments, it need not be so limited, as changes and modifications may be made which would fall within the scope of the invention as defined by the appendant claims. I

Finally, reference numbers used in this specification are listed below.

I aperture board 2 aperture 3. dielectric layer 4. 5. conductive layer 6. positive electrode 7 printing medium 8. negative electrode 9 ion It). ink mist l l conductive hoard l la. arm 12. amplifier l3. shaping circuit I4. memory 15. drive circuit 16. selection circuit l7. ink guide 20. ink tank 2 I. ink ink inlet 23. ink outlet 24. ultrasonic wave exciter 25. air stream 3()a,3()b. guide 3 l plunger magnet 3211.321). lead 33. spring 34. upper stopper 35. lower stopper What is claimed is:

1. In the method of testing an ink mist type printer comprising means for generating an ion stream, an aperture board having a plurality of apertures for modulating said ion stream and charging an ink mist flowing in front of the aperture board according to the pattern of characters to be printed, and printing medium arranged parallel to the flow of said ink mist for printing characters by attracting the charged ink mist. theimproved step of inserting a conductive board between said aperture board and said printing medium for de tecting the presence of an obstructed aperture by measuring the electric current created by the ion stream in said conductive board.

2. The method of testing an ink mist type printer as claimed in claim 1, wherein a plurality of said apertures are scanned for locating the address of the obstructed aperture on said aperture board.

3. An ink mist type printer comprising means for generating an ion stream, an aperture board having a pluan electric current in said conductive board for detecting the presence of an obstructed aperture.

4. An ink mist type printer according to claim 3,

wherein said conductive board is pulled downwards by means of a spring and upwards by means of a plunger magnet.

Claims

1. In the method of testing an ink mist type printer comprising means for generating an ion stream, an aperture board having a plurality of apertures for modulating said ion stream and charging an ink mist flowing in front of the aperture board according to the pattern of characters to be printed, and printing medium arranged parallel to the flow of said ink mist for printing characters by attracting the charged ink mist, the improved step of inserting a conductive board between said aperture board and said printing medium for detecting the presence of an obstructed aperture by measuring the electric current created by the ion stream in said conductive board.

3. An ink mist type printer comprising means for generating an ion stream, an aperture board having a plurality of apertures for modulating said ion stream and charging an ink mist flowing in front of the aperture board according to the pattern of characters to be printed, and printing medium arranged parallel to the flow of said ink mist for printing characters by attracting the charged ink mist, characterized in that said ink mist type printer further comprises a conductive board vertically movable between said aperture board and said printing medium, means for applying an electric field to the selected apertures and means for measuring an electric current in said conductive board for detecting the presence of an obstructed aperture.

4. An ink mist type printer according to claim 3, wherein said conductive board is pulled downwards by means of a spring and upwards by means of a plunger magnet.