JPH0364871B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a thin film EL display unit used in, for example, an image display device, and particularly to a structure for reducing the generation of sound due to vibration.

<Summary of the invention> The present invention provides, for example, transparent electrodes,
A thin film EL panel consisting of a thin film EL element with a double insulation structure, which is formed by sequentially laminating a first dielectric layer, a light emitting layer, a second dielectric layer, and a back electrode, and a sealing plate that protects the thin film EL element from moisture. , a thin film EL formed by incorporating the thin film EL panel into a frame-shaped envelope frame.
In the display unit, a light-transmitting plate made of at least a hard material is disposed on the display surface side of the glass substrate, and the light-transmitting plate is surrounded by a spacer, at least a part of which is made of a soft material, between the glass substrate and the light-transmitting plate. The thin film EL panel can be displayed in the space surrounded by the glass substrate, the spacer, and the transparent plate by fixing them at a certain interval and by fixing only the transparent plate in contact with the envelope frame. In addition to containing sound from the sides, the frame-shaped enclosure frame blocks sound from the sides of the thin-film EL panel, preventing sound from vibrations from transmitting into the air.

<Prior art> As shown in FIG. 3, a thin film EL device includes a glass substrate 1, a transparent electrode 2, a first dielectric layer 3, a light emitting layer 4, and a second dielectric layer 5, which are sequentially laminated on the glass substrate 1. and a back electrode 6, and the transparent electrode 2 and the back electrode 6 are formed in directions perpendicular to each other. The transparent electrode 2 is made of ITO (Insium Tin Oxide), etc.
The back electrode 6 is made of aluminum or the like. The light-emitting layer 4 is formed of a semiconductor material such as ZnS or ZnSe, and in particular, ZnS doped with Mn as a light-emitting center provides insufficient brightness for practical use. In addition, the first dielectric layer 3 and the second dielectric layer 5
are Y ₂ O ₃ , TiO ₂ , Ta ₂ O ₅ , Si ₃ N ₄ , SiO ₂ , SiON,
AI ₂ O ₃ etc. are known, especially Si ₃ N ₄ , SiO ₂ ,
By using a composite dielectric consisting of SiON and AI ₂ O ₃ , it is possible to realize a practical thin film EL device.

Such a thin film EL element is manufactured by connecting an AC power source 7 to the transparent electrode 2 and the back electrode 6, and applying an AC voltage between the two electrodes 2 and 6 to emit light from the light emitting layer 4 at a voltage higher than the emission starting voltage. Light is extracted from the glass substrate 1 side.

Further, as a drive circuit for a thin film EL display device, for example, a circuit as shown in FIG. 4 is known.

In FIG. 4, the thin film EL display device 101 is
Only the electrodes are shown, with direction electrodes X ₁ to Xj being data-side electrodes and Y-direction electrodes Y ₁ to Yi being scanning-side electrodes. The Y-direction electrodes Y ₁ to Yi are divided into odd lines and even lines, and the scanning side N-ch high-voltage MOSIC 102 for odd lines has MOS transistors NT ₁ to NTi individually connected to each line, and the even lines have MOS transistors NT 1 to NTi connected to each other. While connected to the scanning side N-ch high voltage MOSIC 103, it is connected to each line individually.
It is connected to a scan-side P-ch high-voltage MOSIC 104 for odd-numbered lines and a scan-side P-ch high-voltage MOSIC 105 for even-numbered lines, which includes MOS transistors PT ₁ to PTi. The X-direction electrodes X ₁ to Xj are individually connected MOS transistors NT ₁ to NTi.
While connected to the data side N-ch high breakdown voltage MOSIC 106 having a data side drive line, each of them is connected to the cathode of a corresponding diode of a diode array 107 for isolating the data side drive line and protecting the switching element from reverse bias. diode array 10
A pre-charging drive circuit 108 is connected to the anode of each diode 7, and the scanning side P-ch high breakdown voltage
MOS transistor PT ₁ of MOSIC104,105
~ Each source of PTi is a pull-up charging drive circuit 109
and write drive circuit 110 in common. In addition, the scanning side N-ch high voltage MOSIC10
The sources of the 2,103 MOS transistors NT ₁ to NTi are commonly connected to a switching circuit 111 at a source potential which is normally kept at ground potential.

In other words, N- is connected to the scanning side electrode as a drive circuit.
ch high voltage MOSIC102, 103 and P-ch high voltage
Equipped with MOSICs 104 and 105, it performs so-called field inversion drive in which the polarity is inverted for each field, and furthermore, by changing the polarity of the write waveform applied to the picture element for each scanning line, the emission intensity can be controlled by the applied voltage polarity of the thin film EL element. It averages out asymmetry and reduces flicker.

By the way, thin film EL as shown in Fig. 5a and b
In the display unit, the thin-film EL panel 8 includes a glass substrate 1 and a sealing plate 9 for protecting the thin-film EL elements from moisture, and the thin-film EL panel 8 is adhesively fixed onto the base plate 10 with double-sided adhesive tape or the like. . A flexible printed circuit board FPC11 on which a plurality of driving ICs 11a are mounted is connected to each electrode terminal (not shown) on the data side and scanning side of the thin film EL panel 8.
The FPC 11 is connected to the circuit board 12 on the back side of the base plate 10 by a sumi card (not shown). Note that FIG. 5b is a line taken from A-A in FIG.
FIG.

Alternatively, as shown in Figure 6a and b, thin film EL
The panel 8 is fixed to a display frame 13 such as an AI via a rubber pad 14. The thin film EL
An FPC 11 is connected to each electrode terminal of the panel 8 in the same manner as shown in FIG.
Connected to 2. The display filter 15 is a thin film
It is attached to the display surface side of the EL panel 8,
It is pressed by a part of the display frame 13 and is fixed in contact with the glass substrate 1. Note that FIG. 6b is a sectional view taken along line AA in FIG. 6a.

<Problems to be solved by the invention> However, the light emitting layer 4 constituting the thin film EL panel
ZnS is a piezoelectric semiconductor and is a material that has a piezoelectric effect and an inverse piezoelectric effect (electrostriction). Electrostriction is a phenomenon in which slight deformation (strain) occurs when an electric field is applied to a crystal, and is a phenomenon in which alternating current electrical displacement is converted into mechanical vibration. There are several types of vibration modes, such as vertical vibration, thickness vibration, and flexural vibration, and these vibrations are propagated in solids and from solids into the air, and reach the human ear as sound.

Here, in the line sequential driving method as shown in FIG. 4 described above, the voltage waveform shown in FIG. 7 is applied to each picture element, and the vibration mode of the light emitting layer 4 also repeats vibrations similar to this waveform. There is. Especially modulation voltage ±1/
Since the application of 2 VM (raising and lowering periods) is applied to all display pixels, individual vibrations are superimposed and become larger. In such a PN inversion symmetric drive, the number of vibrations per second is {frame frequency ×
(Number of scanning electrodes + α)}/2 times, depending on the data signal, but when the frame frequency is 60Hz and the number of scanning electrodes is
In the case of 256 lines and α=4, a sound is generated due to vibrations with a fundamental frequency of 7.8kHz.

In the case of FIGS. 5a and 5b, this sound is caused by the vibration of the light emitting layer being propagated into the air from the display side of the glass substrate 1.
Some of the vibrations are propagated to the back side via the seal plate 9, but the vibrations propagated to the seal plate 9 side are described in Japanese Patent Application Laid-open No. 146593/1983 "Thin Film EL Display Panel"
Sound can be reduced by interposing a vibration absorber as shown in the figure below. However, no countermeasures have been taken for the vibration noise propagating from the display surface and side surfaces of the glass substrate 1, and the sound reaches the ears as it is.

In addition, as shown in Fig. 6a and b, the display filter 1
5, the display filter 15 is in direct contact with the display surface of the glass substrate 1, so vibrations of the glass substrate 1 are propagated to the display filter 15, and air is emitted from the display surface of the display filter 15. It is transmitted as sound inside. Also, even when you are not touching the screen, the display filter 15
Since the sound is propagated around the area, thin film
Sound from the display surface and sides of the EL panel 8 was transmitted through the air and reached the ears.

In this way, the sound caused by the vibration generated from the thin film EL panel 8 may impair its function as a display device.

The present invention has been made in view of the above points,
It is an object of the present invention to provide a thin film EL display unit in which sound propagating into the air from the display surface and side surfaces of a thin film EL panel 8 is reduced to an extremely low level.

<Means for solving the problems> The present invention provides, for example, transparent electrodes,
A thin film EL panel consisting of a thin film EL element with a double insulation structure, which is formed by sequentially laminating a first dielectric layer, a light emitting layer, a second dielectric layer, and a back electrode, and a sealing plate that protects the thin film EL element from moisture. , a thin film EL formed by incorporating the thin film EL panel into a frame-shaped envelope frame.
In the display unit, a light-transmitting plate made of at least a hard material is disposed on the display surface side of the glass substrate, and the light-transmitting plate is surrounded by a spacer, at least a part of which is made of a soft material, between the glass substrate and the light-transmitting plate. It has a structure in which the transparent plates are fixed at regular intervals and only the transparent plate is brought into contact with the envelope frame.

<Function> With the above structure, the sound emitted into the air from the display side of the glass substrate is difficult to propagate into hard materials, so it is reflected by the transparent plate, and the sound is reflected from the glass substrate by the soft spacer. The sound from the display surface of the thin-film EL panel is contained in the space surrounded by the glass substrate, spacer, and light-transmitting plate by preventing the vibrations from directly transmitting to the light-transmitting plate and the frame for the enclosure, and the thin-film EL panel Sound from the sides of the enclosure can be blocked by the enclosure frame.

<Example> Hereinafter, different examples of the present invention will be described in detail using the drawings.

An embodiment of the present invention is shown in FIGS. 1a and 1b. Note that FIG. 5b is a cross-sectional view of FIG.
Items with the same symbol as b have the same function.

In FIGS. 1a and 1b, the thin film EL panel 8 has a thickness 2 larger than the glass substrate 1 on the glass substrate 1 side.
A transparent plate 16 such as an acrylic plate, a glass plate, a vinyl chloride plate, or a circularly polarizing plate with a dimming effect of 5 mm in width and a double-sided adhesive sponge tape, rubber, or foamed resin with a width of 5 mm and a thickness of 1 mm is arranged. Using spacers 17 that are difficult to transmit mechanical vibrations, the transparent plate 16
is fixed to the glass substrate 1 so that there are no gaps all around it. Further, a frame-shaped envelope frame 18 is fixed to the side surface of the thin film EL panel 8 so as to contact only the peripheral portion of the transparent plate 16.

In this structure, sound emitted from the display side of the thin-film EL panel 8 does not pass through the transparent plate 16 but is reflected on its surface and is confined in the space surrounded by the transparent plate 16 and the glass substrate 1. The sound passing through the light plate 16 becomes very small. Furthermore, the sound emitted from the side surface of the thin film EL panel 8 is blocked by the envelope frame 18. Further, since the transparent plate 16 is fixed at its periphery to the glass substrate 1 by a soft spacer 17, and the envelope frame 18 is connected only to the transparent plate 16, the vibration of the glass substrate 1 is directly transmitted. The light is not transmitted to the light-transmitting plate 16 and the envelope frame 18.

Figure 2 shows the sound pressure level of the thin film EL display unit with the above structure. In the figure, curves A and B show the sound pressure level in the conventional structure (FIGS. 5 and 6), and curve C shows the sound pressure level in the structure of the present invention (FIG. 1). In FIG. 2, the conventional structure has a large angle dependence, and when there is no display filter 15 as shown in FIG. 5, a peak exists around ±50° as shown by curve A. Further, even when the display filter 15 is attached as shown in FIG. 6, the sound decreases little as shown by curve B, and there is a peak around ±90°. However, in the structure of the present invention as shown in FIG. 1, there is almost no angle dependence as shown by curve C.
In addition, the sound pressure level is reduced in all directions. This is because the sound emitted from the display side of the thin film EL panel 8 is confined in the space surrounded by the transparent plate 16 and the glass substrate 1, and the sound emitted from the side surface of the thin film EL panel 8 is confined in the space surrounded by the envelope frame. 18, an excellent sound reduction effect can be obtained.

The transparent plate 16 may be made of an acrylic plate laminated with a soft material such as sponge, as long as at least a portion thereof is made of a hard material. Further, the spacer 17 may be made of an acrylic plate with double-sided adhesive tape, as long as at least a portion thereof is made of a soft material.

<Effects of the Invention> As described above, according to the present invention, sound is contained in the space surrounded by the glass substrate, the spacer, and the transparent plate, and the sound from the side surface of the thin film EL panel is contained in the frame-shaped envelope frame. The vibration sound emitted from the display surface and side surfaces of the glass substrate is reduced to an extremely low level by blocking the sound from being transmitted into the air. We can provide thin film EL display units.

[Brief explanation of drawings]

1A and 1B are a plan view and a cross-sectional view showing an embodiment of the present invention, FIG. 2 is a graph showing the sound pressure level in FIG. 1, and FIG. 3 is a cross-sectional view showing a thin film EL element.
Figure 4 is a driving circuit diagram of a thin film EL display device, Figure 5,
Fig. 6 shows different conventional examples, where a is a plan view, b is a sectional view taken along line A-A in Fig. a, and Fig. 7 shows applied waveforms at picture elements A and B in Fig. 4. FIG. 1... Glass substrate, 8... Thin film EL panel, 9
... Seal plate, 16 ... Transparent plate, 17 ... Spacer, 18 ... Envelope frame.

Claims (1)

[Claims] 1. A thin film EL panel consisting of a thin film EL element formed on a glass substrate, a sealing plate that protects the thin film EL element from moisture, and a thin film EL display unit comprising the thin film EL panel assembled into a frame-shaped envelope frame. A light-transmitting plate made of at least a hard material is disposed on the display surface side of the glass substrate, and the light-transmitting plate has a spacer at least partially made of a soft material around the periphery of the light-transmitting plate so as to be in constant contact with the glass substrate. 1. A thin film EL display unit, characterized in that the thin film EL display unit is fixed at intervals, and the envelope frame is fixed with only the transparent plate in contact with the envelope frame.