EP3030706A1

EP3030706A1 - Printed capacitive touch screen on a molded substrate and having non-flush reverse mounted leds

Info

Publication number: EP3030706A1
Application number: EP13795289.1A
Authority: EP
Inventors: Tony DMYTRIW; Robert Alvord; Sam TOKTAENG
Original assignee: Diehl AKO Stiftung and Co KG
Current assignee: Diehl AKO Stiftung and Co KG
Priority date: 2013-08-05
Filing date: 2013-08-05
Publication date: 2016-06-15
Also published as: CN105452555A; WO2015019126A1; CN105452555B

Abstract

A capacitive touch screen functions as a control panel for a domestic appliance. The capacitive touch screen contains a substrate having at least one recess, a printed conductive trace layer disposed on the substrate, and at least one component disposed on the printed conductive trace layer. A reverse mounted LED is disposed in the recess of the substrate in a non-flush manner.

Description

Printed Capacitive Touch Screen On A Molded Substrate And Having Non-

Flush Reverse Mounted LEDs Technical Field:

The invention relates to a printed capacitive touch screen on a molded substrate and having non-flush, reverse mounted LEDs.

Household appliances such as ovens, stoves, refrigerators, washers, dryers, dishwashing machines, freezers, etc. nowadays have interface designs formed from capacitive touch screens (e.g. touch operated control panels). Capacitive touch screens are formed from printed circuit boards (PCBs) containing light emitting diodes (LEDs) with light guides and light shields. More specifically, capacitive touch pads are etched onto the printed circuit boards. Further electronic components and further mechanical button assemblies are also mounted on the PCBs. The mounted mechanical and electronic components result in various air gaps between the components and this leads to the generation of light noise from light emitted by the LEDs radiating to unwanted areas. Therefore light-blocking and/or light routing fixtures are additionally mounted on the PCB. Finally, the PCBs are then covered with plastic structures for further assisting in blocking and channeling of the light emitted from the LEDs for lighting only desired areas.

Today's touch screen interfaces require the use of large printed circuit boards to cover the large area of the appliance control panel. Relatively expensive flush mounted LED packages are then mounted on the large area PCB resulting in the need for engineering in mechanical strain relief measures of the LED packages.

As with all manufactured items there is a constant desire to

manufacture a product that is less complex and therefore easier to

manufacture and to eliminate component parts and/or use less expensive component parts to manufacture the item.

Disclosure of the Invention: It is accordingly an object of the invention to provide a printed capacitive touch screen on a molded substrate and having non-flush reverse mounted LEDs which overcomes the above-mentioned disadvantages of the prior art devices of this general type, which is more robust, less complex and less expensive to manufacture.

With the foregoing and other objects in view there is provided, in accordance with the invention a capacitive touch screen functioning as a control panel for a domestic appliance. The capacitive touch screen contains a substrate having at least one recess, a printed conductive trace layer disposed on the substrate, and at least one component disposed on the printed conductive trace layer. At least one reverse mounted LED is disposed in the recess of the substrate in a non-flush manner.

In accordance with an added feature of the invention, the substrate is a transparent substrate.

In accordance with a further feature of the invention, the at least one component is selected from the group consisting of electronic components and printed circuit boards.

In accordance with another feature of the invention, an adhesive layer attaches the component to the printed conductive trace layer.

In accordance with yet another feature of the invention, the reverse mounted LED is one of a plurality of reversed mounted LEDs disposed in recesses of the substrate in a non-flush manner.

With the foregoing and other objects in view there is provided, in accordance with the invention a domestic appliance. The domestic appliance includes a capacitive touch screen functioning as a control panel for the domestic appliance. The capacitive touch screen includes a substrate having at least one recess, a printed conductive trace layer disposed on the substrate, and at least one component disposed on the printed conductive trace layer. A reverse mounted LED is disposed in the recess of the substrate in a non-flush manner.

Other features which are considered as characteristic for the invention are set forth in the appended claims. Although the invention is illustrated and described herein as embodied in a printed capacitive touch screen on a molded substrate and having non- flush reverse mounted LEDs, it is nevertheless, not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.

The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best

understood from the following description of specific embodiments when read in connection with the accompanying drawings.

Brief Description of the Drawings:

Fig. 1 is a diagrammatic, exploded view of a capacitive touch screen according to the invention;

Fig. 2 is a diagrammatic, sectional view of the capacitive touch screen in the area of a non-flush reversed mounted LED; and

Fig. 3 is a diagrammatic, front view of a domestic appliance having the capacitive touch screen. Best Mode for Carrying out the Invention:

Referring now to the figures of the drawing in detail and first,

particularly, to Fig. 1 thereof, there is shown an exploded view of a capacitive touch screen 1 . The capacitive touch screen 1 functions as a touch operated control panel or front screen of a domestic appliance such as an oven, a stove, a refrigerator, a washer, a dryer, a dishwasher, a freezer, a cooker, etc.

The capacitive touch screen 1 is formed with a molded transparent substrate 3 having a front side (user side) 5 and a rear side 7. A plurality of recesses 9 are formed in the rear side 7 of the substrate 3. A layer of decorative screen printed graphics 1 1 are disposed on the substrate 3 and as the substrate 3 is transparent are visible on the front (user) side 5. The graphics 1 1 show the control functions available via the capacitive touch screen 1 to be performed by the domestic appliance. Disposed behind the layer of decorative screen printed graphics 1 1 is a printed conductive trace board 13. The printed conductive trace board 13 provides the electrical traces and connections for all to be mounted

components. Attached to the printed conductive trace board 13 is a conductive adhesive layer 15 upon which surface mounted components 17 or printed circuit boards (PCB) 19 are attached too. The conductive adhesive layer 15 securely mounts the components 17 and the PCB 19 and provides a connection to the traces on the printed conductive trace board 13.

A plurality of reverse mounted LEDs 21 are mounted in the recesses 9 of the substrate 3 via the conductive adhesive layer 15. More specifically, non-flush reverse mounted LEDs 21 are preferably used. The use of non- flush, reserve mounted LEDs 21 has never been used in control panels before. As non-flush reverse mounted LEDs are less expensive than regular LED or flush, reverse-mounted LED packages, the cost of the control panel decreases, in addition to the complexity.

Fig. 2 shows a cross-sectional view through the control panel 1 in a region of the non-flush reverse mounted LED 21 . As shown, the substrate 3 has the recess (well) 9 formed therein for receiving an LED lens 23 of the LED 21 . An LED substrate 25 of the LED 21 is bonded to the printed conductive trace layer 13 via the conductive adhesive layer 15 in a non-flush

configuration. Via the recesses 9 formed in the substrate 3, a simple mounting of the LEDs 21 is possible and production tolerances are less significant as no flush mounting is necessary. The recesses 9 allow for the placement of the non-flush reversed mounted LEDs 21 onto the substrate 3 eliminating the need for printed circuit boards or more expensive LED package types.

In essence, the invention teaches the mounting of non-flush, reverse mounted LEDs 21 directly on a decoratively printed substrate 3, 1 1 with the printed conductive traces 13 providing the electrical connections. The advantages from integrating non-flush, reverse mounted LEDs 21 directly on a decoratively printed substrate 3, 1 1 are now described. First, the use of the printed touch traces 13 elinninates issues associated with varying air gaps caused by mechanical and manufacturing processes. Therefore light noise issues are lessened.

Second, mounting the electrical and electronic components directly on the printed decorative substrate 3, 1 1 , 13 eliminates the need for a large printed circuit board. This results in costs reductions, reliability increasing and robustness being increased.

Third, mounting the light emitting diodes directly on the decorative substrate eliminates the need for additional light blocking and/or light routing fixtures to be used. Therefore light noise is greatly reduced, production tolerances are less important, and light noise reduction devices are greatly simplified.

Fig. 3 shows a domestic appliance 30 having the capacitive touch screen 1 being a touch operated control panel for the domestic appliance 30.

Claims

1 . A capacitive touch screen functioning as a control panel for a domestic appliance, the capacitive touch screen comprising:

a substrate having at least one recess formed therein;

a printed conductive trace layer disposed on said substrate;

at least one component disposed on said printed conductive trace layer; and

a reverse mounted LED disposed in said recess of said substrate in a non-flush manner.

2. The capacitive touch screen according to claim 1 , wherein said substrate is a transparent substrate.

3. The capacitive touch screen according to claim 1 , wherein said least one component is selected from the group consisting of electronic components and printed circuit boards.

4. The capacitive touch screen according to claim 1 , further comprising an adhesive layer for attaching said component to said printed conductive trace layer.

5. The capacitive touch screen according to claim 1 , wherein said reverse mounted LED is one of a plurality of reversed mounted LEDs disposed in recesses of said substrate in a non-flush manner.

6. A domestic appliance, comprising:

a capacitive touch screen functioning as a control panel for the domestic appliance, said capacitive touch screen including:

a substrate having at least one recess formed therein;

a printed conductive trace layer disposed on said substrate;

at least one component disposed on said printed conductive trace layer; and a reverse mounted LED disposed in said recess of said substrate in a non-flush manner.