GB1564498A

GB1564498A - Silk screen printing apparatus

Info

Publication number: GB1564498A
Application number: GB3750475A
Authority: GB
Original assignee: Mitchell B R
Current assignee: Mitchell B R
Priority date: 1976-09-10
Filing date: 1976-09-10
Publication date: 1980-04-10

Description

(54) IMPROVEMENTS IN OR RELATING TO SILK SCREEN PRINTING APPARATUS (71) I, BRIAN ROBERT MITCHELL, a British Subject, of Cherry Tree Cottage, Stantway Lane, Westbury-on-Severn, Gloucestershire, do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to silk screen printing apparatus.

According to the invention there is provided silk screen printing apparatus comprising means for supporting an article or material to which printing is to be applied, a first longitudinal scale fixed in relation to the supporting means, a second, lateral scale extending at right angles to the first scale and adjustable along the first scale, at least one silk screen stencil having first indicating means which can cooperate with the longitudinal scale to enable the or each stencil to be placed in a predetermined longitudinal position, and second indicating means which can cooperate with the lateral scale to enable the or each stencil to be placed in a predetermined lateral position.

Printing apparatus in accordance with the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of the apparatus, Figure 2 is a plan view of a stencil plate, and Figure 3 is a view of the stencil plate in the direction of the arrows III--III in Figure 2.

The apparatus comprises a rectangular table 1 having a flat upper surface 2 on which is marked out a grid 3 of regularly spaced lateral and longitudinal lines. Along each of a pair of opposing edges of the surface 2 there is provided a longitudinal scale 4 indicating the longitudinal position of each of the lateral lines of the grid 3. An L-section bar 5 is vertically adjustably fixed to the side of the table 1 beneath each scale 4. At each end of each bar 5 there is a hole 6 which registers with a vertical slot 7 provided in the corresponding side of the table 1, and a clamping screw 8 passes through each hole 6 and slot 7 to enable the user of the apparatus to maintain the bars in a selected vertical position. A height scale 9 is provided adjacent each slot 7 to indicate the selected vertical position.

A bridging member 10 is supported at each end by the bars 5, and comprises a lateral bar 11 bearing a scale 12 which indicates the lateral position of each of the longitudinal lines of the grid 3. The bridging member 10 includes a pair of pedestals 13, one mounted beneath each end of the lateral bar 11. Each pedestal 13 may be secured in a selected position along a corresponding bar 5 by means of a clamping screw 14 passing through a longitudinal slot 15 in the bar 5 and into a tapped hole (not shown) in the underside of the pedestal 13, a pointer 16 being provided on the pedestal 13 to indicate the selected longitudinal position on the corresponding scale 4. The pointers 16 are spaced longitudinally from the bar 11, as will presently be explained.

A set of stencil p]ates 17 is provided, each stencil plate 17 comprising a rectangular frame 18 surrounding a stretched silk screen 19 bearing an alphabetical, numerical or other character 20. The silk surrounding the character 20 is rendered impervious to ink, whilst the area of the character 20 remains pervious. Spacers 21 are fixed to the underside of the frame 18 and a lifting knob 22 is fixed to its upper surface. The upper surface of the frame 18 also carries line register marks 23 and a character leading edge mark 24, to facilitate alignment to the stencil plate 17. The spacing between the line register marks 23 and the lower edge of the frame 18 is the same as that between the bar 11 and pointers 16, so that when the lower edge of the stencil plate 17 is in contact with the bar 11, the pointers 16 are in line with the line register marks 23.

One or more squeegee guides 25 are provided, shaped to fit within the frame 18 above the screen 19 to guide a squeegee 26 across undercut characters 20. The squeegee guide 25 includes a lifting knob 27.

Also provided is a set of pre-printed character forms 28, each character form 28 comprising a rectangle of transparent plastics film bearing a character 29, line register marks 30 and a character leading edge register mark 31. One or more character forms 28 correspond to each stencil plate 17.

In use of the apparatus, the layout is initially determined by placing character forms 28 on the table 1 and adjusting their positions until the desired layout is obtained, correct alignment being checked by reference to the lines of the grid 3. The bridging member 10 is then slid along the bars 5 until the pointers 16 are level with the line register marks 30 and the longitudinal positions of the characters 29 are read from the scales 4. The lateral positions of the character leading edge register marks 31 are read from the scale 12.

The character forms 28 are then removed and the material (not shown) on to which the layout is to be printed is placed in position on the table, the height of the rails 5 and hence of the bridging member 10 being adjusted by means of the clamping screws 8 and scales 9 so that the bridging member 10 is just clear of the surface of the material.

The stencil plate 17 for the first character is placed with its lower edge in contact with the bar 11 and moved into its correct position using the readings already taken. Longitudinal adjustment is effected by moving the bridging member 10 until the pointers 16 show the longitudinal reading on the scales 4, and for lateral adjustment the stencil plate 17 is moved along the bar 11 until the character leading edge register mark 24 shows the lateral reading on the scale 12. Ink is then forced through the silk screen 19 by means of the squeegee 26 to print the character on to the material. The stencil plate 17 is removed and the stencil for the next character is placed in its correct position, an appropriate squeegee guide 25 being placed in the frame 18 to prevent smudging the previous character when printing the present one.

This process is repeated until all the char- acters have been printed.

Instead of removing the character forms 28 and printing in the same positions, as described above, the character forms 28 may be left in their positions and the layout printed on another part of the table by translating the longitudinal and/or lateral readings by addition or subtraction of a constant. As a further alternative, the required layout may be obtained from previously tabulated longitudinal and lateral readings.

The body of the table 1 is provided with a drawer - 32 for storage of, for example, paper, stencil plates 17, character forms 28 and other printing materials. The bars 5 may be reinforced by use of channel- or box-section members, in which case the clamping screws 14 pass through the pedestals 13 from above. When printing large characters, involving large stencil plates 17, it may be necessary for the operator to use both hands on the squeegee 26. A channel of inverted-T section can accordingly be provided along the length of the bar 11, adjacent the scale 12, to receive one or more adjustable clamps (not shown) to lock the stencil plate 17 in position. Such a slot may also receive a cursor which is used as a marker when aligning each stencil and moved away when printing. The cursor may be of clear plastics and formed with a marking for cooperation with the markings of the scale 12.

WHAT I CLAIM IS: 1. Silk screen printing apparatus comprising means for supporting an article or material to which printing is to be applied, a first longitudinal scale fixed in relation to the supporting means, a second, lateral scale extending at right angles to the first scale and adjustable along the first scale, at least one silk screen stencil having first indicating means which can cooperate with the longitudinal scale to enable the or each stencil to be placed in a predetermined longitudinal position, and second indicating means which can cooperate with the lateral scale to enable the or each stencil to be placed in a predetermined lateral position.

2. Printing apparatus according to claim 1, wherein the laterally extending scale is adjustable in a direction normal to the surface of the article or material.

3. Printing apparatus according to claim I or claim 2 and including a squeegee guide.

4. Printing apparatus according to any preceding claim and including at least one pre-printed character form bearing indicating means which can cooperate with the laterally extending scale to predetermine the lateral position for the or each stencil.

5. Printing apparatus according to claim 4, wherein the or each pre-printed character form includes indicating means which may cooperate with the longitudinally extending scale to predetermine the longitudinal position for the or each stencil.

6. Printing apparatus substantially as hereinbefore described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. across undercut characters 20. The squeegee guide 25 includes a lifting knob 27. Also provided is a set of pre-printed character forms 28, each character form 28 comprising a rectangle of transparent plastics film bearing a character 29, line register marks 30 and a character leading edge register mark 31. One or more character forms 28 correspond to each stencil plate 17. In use of the apparatus, the layout is initially determined by placing character forms 28 on the table 1 and adjusting their positions until the desired layout is obtained, correct alignment being checked by reference to the lines of the grid 3. The bridging member 10 is then slid along the bars 5 until the pointers 16 are level with the line register marks 30 and the longitudinal positions of the characters 29 are read from the scales 4. The lateral positions of the character leading edge register marks 31 are read from the scale 12. The character forms 28 are then removed and the material (not shown) on to which the layout is to be printed is placed in position on the table, the height of the rails 5 and hence of the bridging member 10 being adjusted by means of the clamping screws 8 and scales 9 so that the bridging member 10 is just clear of the surface of the material. The stencil plate 17 for the first character is placed with its lower edge in contact with the bar 11 and moved into its correct position using the readings already taken. Longitudinal adjustment is effected by moving the bridging member 10 until the pointers 16 show the longitudinal reading on the scales 4, and for lateral adjustment the stencil plate 17 is moved along the bar 11 until the character leading edge register mark 24 shows the lateral reading on the scale 12. Ink is then forced through the silk screen 19 by means of the squeegee 26 to print the character on to the material. The stencil plate 17 is removed and the stencil for the next character is placed in its correct position, an appropriate squeegee guide 25 being placed in the frame 18 to prevent smudging the previous character when printing the present one. This process is repeated until all the char- acters have been printed. Instead of removing the character forms 28 and printing in the same positions, as described above, the character forms 28 may be left in their positions and the layout printed on another part of the table by translating the longitudinal and/or lateral readings by addition or subtraction of a constant. As a further alternative, the required layout may be obtained from previously tabulated longitudinal and lateral readings. The body of the table 1 is provided with a drawer - 32 for storage of, for example, paper, stencil plates 17, character forms 28 and other printing materials. The bars 5 may be reinforced by use of channel- or box-section members, in which case the clamping screws 14 pass through the pedestals 13 from above. When printing large characters, involving large stencil plates 17, it may be necessary for the operator to use both hands on the squeegee 26. A channel of inverted-T section can accordingly be provided along the length of the bar 11, adjacent the scale 12, to receive one or more adjustable clamps (not shown) to lock the stencil plate 17 in position. Such a slot may also receive a cursor which is used as a marker when aligning each stencil and moved away when printing. The cursor may be of clear plastics and formed with a marking for cooperation with the markings of the scale 12. WHAT I CLAIM IS:

1. Silk screen printing apparatus comprising means for supporting an article or material to which printing is to be applied, a first longitudinal scale fixed in relation to the supporting means, a second, lateral scale extending at right angles to the first scale and adjustable along the first scale, at least one silk screen stencil having first indicating means which can cooperate with the longitudinal scale to enable the or each stencil to be placed in a predetermined longitudinal position, and second indicating means which can cooperate with the lateral scale to enable the or each stencil to be placed in a predetermined lateral position.