A cooking appliance having a dead-front display

Abstract

The invention relates to a cooking appliance comprising, a housing (10); a cover panel (20) provided at a front portion (12) of the housing (10) so as to face outward from a front face (22); and a display screen (50) having an illuminated display (54) arranged on an opaque background (52), the display screen (50) being arranged adjacent from a rear face (26) to a partially transparent region (24) defining a display window in the cover panel (20). The cover panel (20) is a glass or glass-ceramic substrate coated with a light filter film, wherein a portion outside the partially transparent region (24) has a grey tone defined according to the CIE Lab* color space as L* 25-60, a*: approximately -4 to +4, b*: approximately -4 to +4 and is adjusted to have a visible light transmittance between 1% and 69%, and wherein the visible light transmittance in the partially transparent region (24) is adjusted to be between 70% and 95%; and the background (52) is arranged adjacent at the rear face of the partially transparent region (24) such that, when the illuminated display (54) is in an OFF state, a dead-front effect is provided on the display screen (50) by a uniform grey color effect.

Description

[0001] A COOKING APPLIANCE HAVING A DEAD-FRONT DISPLAY

[0002] TECHNICAL FIELD

[0003] The invention relates to a cooking appliance, in particular to a cooking appliance having a dead- front display on a cover panel.

[0004] BACKGROUND ART

[0005] A cooking appliance such as a hob or an oven includes user interface components such as rotary adjustment knobs, buttons, and a display screen provided on a glass cover panel. The display screen enables information such as cooking time, the set temperature, and a cooking program to be visually conveyed to the user. The display screen is mounted from behind, on a light-transmissive window of the cover panel, on an electronic circuit board to which it is connected. The display screen generally includes illuminated display elements, driven by the electronic circuit board and obtained by electronic components such as LEDs. A window boundary is present between the window of the metal or glass cover panel and the display screen. The window boundary occurs due to differences in color or tone between the cover panel and the display screen.

[0006] In cooking appliances having a black cover panel, in order to obtain a dead-front display, an electronic display having a black-adjusted background color is placed behind the light-transmissive window. Thus, when the illuminated elements of the electronic display are activated, the displays formed by the light become visually accessible from the outside through the light-transmissive window of the cover panel; and even if the boundaries of the window and the electronic display background do not match in black color tone due to reasons such as color bleed, they are perceived as integrated by optical illusion. Thus, when power to the electronic display is cut off, the display cannot be seen and an optical effect is obtained as if the cover panel were a single piece. In this way, a dead-front display is obtained on the cover panel.

[0007] W02023200665 discloses a dead-front display arrangement suitable for an electronic user interface. This arrangement includes a masking layer, a coating layer, and a vacuum metalized layer. The masking layer includes an opening defining a two-dimensional graphic, allowing passage of emitted light for displaying user information. The vacuum metalized layerincludes a translucent metallic coating used to conceal the masking layer when the user interface is viewed from an external front view. The coating layer is configured to match a flat, non-metallic color of the component in which the user interface is arranged or mounted.

[0008] BRIEF SUMMARY OF THE INVENTION

[0009] An objective of the invention is to obtain a cover panel having a dead-front display and providing a uniform grey appearance.

[0010] In order achieve the above objective, the invention relates to a cooking appliance comprising a housing; a cover panel provided at a front portion of the housing so as to face outward from a front face; and a display screen having an illuminated display on a opaque background, the display screen being arranged adjacent from a rear face to a partially transparent region defining a display window in the cover panel. The cooking appliance comprises, together with the cover panel, a glass or glass-ceramic substrate coated with a light filter film, wherein the portion outside the partially transparent region has a grey tone defined according to the CIE Lab* color space as L* 25-60, a*: approximately -4 to +4, b*: approximately -4 to +4 and is adjusted to have a visible light transmittance between 1% and 69%, and wherein the visible light transmittance in the partially transparent region is adjusted to be between 70% and 95%; and the background is arranged adjacent to the rear face of the partially transparent region such that, when the illuminated display is in an OFF state, a dead-front effect is provided on the display screen by a uniform grey color effect.

[0011] In this way, even with a display screen having an opaque background, a dead-front display could be obtained on a front face of a housing having a grey-tone cover panel. With visible light not having full visible light transmittance in the partially transparent region, reflection of ambient light provides a grey optical illusion when the illuminated displays of the display screen are OFF. Tests show that both users and CCD visual sensor detectors perceive the cover panel as a single grey-tone panel without display-window boundaries. When the display screen is illuminated, the emitted light passes through the display window and renders information on the cooking appliance visible; however, the background regions remain opaque. Preferably, the background is black. It has been determined that a black opaque background supports the grey illusion in a manner that eliminates tone difference.

[0012] Preferably, the visible light transmittance of the partially transparent region on the cover panel is adjusted between 75% and 80%. In this way, since the percentage difference in light transmittance between the portion outside the partially transparent region and said region isreduced, the visible light blocking gradient converges and production of the cover panel is facilitated.

[0013] Preferably, the light filter film coating of the cover panel comprises a layer selected from the group comprising black enamel, ceramic paint, or printed black ink. In this case, film coating can be easily applied to a desired thickness beneath a grey cover-panel glass substrate. Depending on the selected density, the visible light blocking gradient differs; that is, by adjusting the application density to be lower, the partially transparent region can be easily obtained in the form of a window on the same film structure.

[0014] Preferably, the thickness of the cover panel is selected between 2 mm and 8 mm. At the selected thickness, the signal of the illuminated display with a standard LED unit is refracted through the panel with minimal distortion so as to be clearly perceptible. In addition, it has been determined that a capacitive sensor application adjacent to the display screen provides voltage transmission within the selected thickness range.

[0015] Preferably, the glass substrate of the cover panel is tempered. This both guarantees sufficient light transmittance together with placement of the adjacent opaque background and provides a structure that is safe for household use against external effects.

[0016] Preferably, the partially transparent region is in a rectangular form aligned at the transverse center of the cover panel. This structure helps conceal the boundaries of the partially transparent region on the cover panel by the visible light reflections of the cover panel along a central line.

[0017] Preferably, the background of the display screen is arranged to extend beyond the partially transparent region. In this way, any possibility of backlight leakage in the display screen into the partially transparent region is eliminated.

[0018] Preferably, an opaque flat support panel bearing against the rear face of the cover panel along its full length comprises an opening arranged to correspond to the partially transparent region. The support panel prevents light reflection from the rear side of the cover-panel portions outside the partially transparent region. In addition, it prevents functional elements behind the cover panel from being visible.

[0019] Preferably, a tab is provided on the opening, extending inward and latching the display screen to the support panel from the outside. In this way, easy and safe mounting of thedisplay screen on the support panel is provided. This also prevents the display screen from shifting during mounting and causing backlight leakage into the partially transparent region.

[0020] Preferably, the support panel is in the form of sheet metal. In this way, the cover panel is protected against rear light leakage under operating conditions of the cooking appliance by an opaque plate having resistance to thermal stresses and high structural strength. In a possible configuration, the support panel may be selected as an opaque plastic panel.

[0021] Preferably, the cover panel substrate is lithium aluminosilicate (LAS) or borosilicate-based glass. This structure provides homogeneous color distribution along the cover panel.

[0022] Preferably, in an operating state, the light intensity of the illuminated display is adjusted to 200-400 cd / m2. In this way, it is ensured that the illuminated display generates a sufficiently visible light signal that can pass through the composite structure consisting of the film and the glass substrate.

[0023] BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a perspective view of a representative embodiment of a cooking appliance according to the invention having a cover panel with a dead-front display.

[0025] Figure 2 is an inner perspective view of the cover panel shown in Figure 1.

[0026] Figure 3 is a perspective disassembly view of the cover panel together with an electronic display element and its connection panel.

[0027] Figure 4a is a rear view of the cover panel.

[0028] Figure 4b is a front view of the cover panel with the display screen in a passive state.

[0029] Figure 4c is a front view of the cover panel with the display screen in an active state.

[0030] DETAILED DESCRIPTION OF THE INVENTION

[0031] In this detailed description, the development according to the invention is described, without any limitation and only to better explain the subject matter, by reference to examples.In Figure 1, a household built-in oven is shown in a front perspective view. The oven includes a prismatic housing (10) and a door panel (30) hinged at the bottom to the housing (10), covering from a front portion (12) an openable manner a cooking cavity surrounded by the housing. The front face of the door panel (30) comprises an outer plate entirely of glass, and an exhaust is formed in the structure of an opening extending transversely between an upper edge (32) and a cover panel (20). A handle (34) adjacent to the upper edge (32) of the door panel (30) is fixed at opposite ends to the outer panel. A middle portion of the door panel (30) provides visual access to the cooking cavity by means of a window having visible light transmittance.

[0032] The cover panel (20) comprises a glass substrate and a coating film applied beneath it, with a thickness of at least 50 nm and at most 2 microns. The glass substrate is a glass-ceramic substrate, and said glass-ceramic substrate has a coefficient of thermal expansion lower than ±6*10A-6 / K in a temperature range between 20°C and 300°C. Further, the glass transition temperature (Tg) is between 500°C and 650°C. The coating film of the cover panel (20) has a sheet resistance of at least 1 kQ / n (1 kiloohm per square) under a test voltage below 1000 V.

[0033] As the substrate, a 4 mm thick transparent, colorless LAS glass-ceramic panel was selected. The coating film was selected to have a maximum spectral reflectance of at most 8% between 380 and 780 nm. The glass substrate of the cover panel (20), together with the coating film applied to the substrate, has a light transmittance of at least 30% at a wavelength of 1500 nm, and at least 3% at a wavelength range between 850 and 1000 nm, outside the partially transparent region. The film applied onto the substrate comprises spinel and is on the rear face (26) of the cover panel (20). On the opposite front face (22) of the cover panel (20), the glass-ceramic substrate is located.

[0034] The outer periphery (21) of the cover panel (20) is arranged laterally aligned with the door panel (30). Corresponding knob holes (23), into which respective rotary adjustment knobs (1) are placed, are cut and opened in the cover panel (20). Apart from this, there are no other holes or protrusions in the cover panel (20), and it has a flat planar form. A partially transparent region (24) is formed at the geometric center of the cover panel (20). This region is obtained by reducing the density of the light-blocking coloring material of the coating film on the glass substrate of the cover panel (20). In the partially transparent region (24), the visible light transmittance is 80%.

[0035] In Figure 2, the cover panel (20) is shown from an inner perspective view in a state mounted face-to-face, from its rear face (26) opposite to its front face (22), with a support panel (40).The support panel (40) is made of a flat planar sheet metal and its dimensions are arranged equal to the cover panel (20). Thus, the outer periphery of the cover panel (20) and the support panel (40) are arranged aligned. Along an upper edge of the support panel (40), a flange (41) is formed by bending perpendicularly inward. The flange (41) helps secure the support panel (40) carrying the cover panel (20) to the housing (10) above the door panel (30) in planar alignment. Additionally, respective knob holes (43) of the support panel (40), into which the rotary adjustment knobs (1) are fully received in a rotatable manner, are aligned exactly with the knob holes (23) of the cover panel (20) having the same diameter.

[0036] Except for an opening (44) corresponding to the partially transparent region (24), the support panel (40) is fully masked with its opaque structure such that light passage to the cover panel (20) is sealed. The opening (44) has an offset width in the partially transparent region (24), and a pair of tabs (45) are formed near the corners by bending perpendicularly inward at the upper and lower edges.

[0037] As shown in Figure 3, a display screen (50) is mounted and fixed to the support panel (40) in the opening (44) by means of the tabs (45). In this state, the outward-facing part of the display screen (50) protrudes outward along the opening (44) from a planar front face (46) of the support panel (40). Thus, when the rear face (26) of the cover panel (20) is joined to the front face (46) of the support panel (40), the front portion of the display screen (50) directly bears against the partially transparent region (24) along its full length.

[0038] On the display screen (50), LED illuminated displays (54) placed on a PCB circuit board, and a black and opaque background (52) surrounding them, are provided. The background (52), like a stage, surrounds the illuminated displays (54) on the display screen (50) with a lightabsorbing structure, preventing light leakage from behind or from one illuminated display (54) to another. When the illuminated display (54) operates, it emits light in the visible wavelength at a light intensity of 250 cd / m2.

[0039] Capacitive sensors (55) extend outward from the front face (46) adjacent to the display screen and contact, from the rear face (26), a corresponding touch region (25) on the cover panel (20). In this way, by touching the relevant icon on the touch region (25) on the front face (22), the capacitive sensor (55) arranged adjacent from the rear face (26) is actuated and pre-determined and assigned cooking functions can be executed.

[0040] In the cover panel (20), in addition to the display window defined by the partially transparent region (24), a second display window (27) is formed in an area of the knob hole (23) facingthe side edge. Its structure and function are the same as those of the partially transparent region (24), and another display screen similar to the display screen (50) is placed behind the second display window (27). Similarly, it is possible to form display windows in different sizes and positions.

[0041] As seen in the rear view in Figure 4a, the cover panel (20) is a long strip panel structure in rectangular form. The coating film of the cover panel (20) covers the rear face (26) along its full length. The coating film has a lower spinel density in the partially transparent region (24) on the rear face (26) and in the second display window (27) having the same structure and function, and thus the visible-region light transmittance is lower than that of the other sections.

[0042] The knob holes (23) are through-holes, and there is no substrate or coating film present in any manner. As shown in Figure 4b, when the illuminated displays (54) on the display screen (50) are not energized, no light leaks from behind due to the opaque background (52) behind the partially transparent region (24). Therefore, since the display screen (50) does not provide backlight to the display window in which it is positioned in the partially transparent region (24), only the cover panel (20) is visible by ambient light incident on the front face (22).

[0043] In this state, outside the partially transparent region (24), the cover panel (20) does not reflect light other than the light incident from the outside onto its front face (22), due to masking by the support panel (40) behind it. Here, the film layer on the transparent glass substrate of the cover panel (20), in the portion outside the partially transparent region (24), has a grey tone defined according to the CIE Lab* color space as L* 40, a*: approximately -1 to +1 , b*: approximately -1 to +1 , and is adjusted to have a visible light transmittance of 30%.

[0044] On the other hand, in the partially transparent region (24), the film coating on the substrate, with 80% light transmittance, is masked by the opaque and black background (52) from behind. Experimental studies show that, in the given configuration, the cover panel (20) appears as a single-piece grey structure having color homogeneity, and that the partially transparent region (24) and the surrounding front face (22) of the cover panel (20) have the same color and tone appearance. In this way, the display screen (50) is completely concealed on the front face (22) and a dead-front effect is obtained. The same applies to the second display window (27).

[0045] As shown in Figure 4c, when the display screen (50) is energized during operation of the oven, the illuminated display (54) emits light, and this light passes first through the coating film and then through the substrate, passes through the cover panel (20), and reaches theoutside. In this state, the illuminated display (54) becomes visible. However, light emission is blocked by the opaque and black background (52), and in the partially transparent region (24) only the illuminated display (54) is directly visible, while the color of the front face (22) appears grey in the partially transparent region (24) and the remaining portion.

[0046] REFERENCE NUMERALS

[0047] 1 Rotary adjustment knob

[0048] 10 Housing

[0049] 12 Front portion

[0050] 20 Cover panel

[0051] 21 Outer periphery

[0052] 22 Front face

[0053] 23 Knob hole

[0054] 24 Partially transparent region

[0055] 25 Touch region

[0056] 26 Rear face

[0057] 27 Second display window

[0058] 30 Door panel

[0059] 32 Upper edge

[0060] 34 Handle

[0061] 40 Support panel

[0062] 41 Flange

[0063] 42 Rear face

[0064] 43 Knob hole

[0065] 44 Opening

[0066] 45 Tab

[0067] 46 Front face

[0068] 50 Display screen

[0069] 52 Background

[0070] 54 Illuminated display

[0071] 55 Capacitive sensor

Claims

CLAIMS1. A cooking appliance comprising, a housing (10); a cover panel (20) provided at a front portion (12) of the housing (10) so as to face outward from a front face (22); and a display screen (50) having an illuminated display (54) arranged on an opaque background (52), the display screen (50) being arranged adjacent from a rear face (26) to a partially transparent region (24) defining a display window in the cover panel (20); characterized in that the cover panel (20) comprises together a glass or glass-ceramic substrate coated with a light filter film, wherein a portion outside the partially transparent region (24) has a grey tone defined according to the CIE Lab* color space as L* 25-60, a*: approximately -4 to +4, b*: approximately -4 to +4 and is adjusted to have a visible light transmittance between 1% and 69%, and wherein the visible light transmittance in the partially transparent region (24) is adjusted to be between 70% and 95%; and the background (52) is arranged adjacent at the rear face of the partially transparent region (24) so as to provide, on the display screen (50), a deadfront effect with a uniform grey color effect when the illuminated display (54) is in an OFF state.

2. The cooking appliance according to claim 1, wherein the visible light transmittance of the partially transparent region (24) on the cover panel (20) is adjusted between 75% and 80%.

3. The cooking appliance according to any one of the preceding claims, wherein the light filter film coating of the cover panel (20) comprises a layer selected from the group comprising black enamel, ceramic paint, or printed black ink.

4. The cooking appliance according to any one of the preceding claims, wherein the thickness of the cover panel (20) is selected between 2 mm and 8 mm.

5. The cooking appliance according to any one of the preceding claims, wherein the glass substrate of the cover panel (20) is tempered glass.

6. The cooking appliance according to any one of the preceding claims, wherein the partially transparent region (24) is in a rectangular form aligned at the transverse center of the cover panel (20).

7. The cooking appliance according to any one of the preceding claims, wherein the background (52) of the display screen (50) is arranged to extend beyond the partially transparent region (24).

8. The cooking appliance according to any one of the preceding claims, comprising an opaque flat support panel (40) bearing against the rear face (26) of the cover panel (20) along its full length and including an opening (44) arranged to correspond to the partially transparent region (24).

9. The cooking appliance according to claim 8, comprising a tab (45) provided on the opening (44), extending inward and latching the display screen (50) to the support panel (40) from the outside.

10. The cooking appliance according to one of claims 8-9, wherein the support panel (40) is in the form of sheet metal.

11. The cooking appliance according to any one of the preceding claims, wherein the substrate of the cover panel (20) is lithium aluminosilicate (LAS) or borosilicate-based glass.

12. The cooking appliance according to any one of the preceding claims, wherein, in an operating state of the illuminated display (54), the light intensity is adjusted to 200- 400 cd / m2.

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