Film assembly unit with ghost key prevention function

Abstract

A film assembly unit with a ghost key prevention function comprises a lower film, an induction circuit module and an upper film. The induction circuit module comprises a lower circuit part connected to the top side of the lower film, a plurality of flexible carbon ink sheet bodies arranged on the top side of the lower circuit part at intervals and an upper circuit part arranged on the top sides of the flexible carbon ink sheet bodies, and the lower circuit part and the upper circuit part are spaced through the flexible carbon ink sheet bodies. And the flexible carbon ink sheet bodies are pressure sensing resistors. The upper thin film is arranged on the top side of the lower thin film and the top side of the induction circuit module and is combined with the lower thin film. The lower circuit part, the flexible carbon ink sheet body and the upper circuit part are integrated on the lower film, so that the cost of materials such as a middle interlayer and anisotropic conductive adhesive can be saved, and the effect of reducing the overall cost is achieved.

Description

Technical Field

[0001] This invention relates to a thin film assembly unit, and more particularly to a thin film assembly unit with anti-ghosting function. Background Technology

[0002] An existing keyboard (e.g., as shown in Taiwan Patent Certificate No. M403696) includes a switch module, a comparator, a switching unit, and a processing module. The switch module includes multiple drive lines that receive multiple drive signals, multiple sensing lines, multiple switches, and multiple resistors. The comparator includes a first input terminal, a second input terminal that receives a reference signal, and an output terminal that outputs a comparison signal. The switching unit is controlled by a set of control signals to electrically connect at least one of the sensing lines to the first input terminal of the comparator. The processing module is used to set at least one of the drive signal, the reference signal, and the control signal so that the comparison signal indicates whether at least one of all switches is turned on, whether at least one of multiple switches is turned on, or whether a switch is turned on, to avoid "ghost keys".

[0003] As technology has evolved, membrane keyboards have gradually developed and become more common in daily life. However, it's equally important to avoid "ghosting" or other keyboard artifacts. (See also...) Figure 1 , Figure 2 and Figure 3 A conventional membrane keyboard includes a membrane assembly unit 1 comprising a lower circuit layer 11, a middle partition layer 12 located on top of the lower circuit layer 11, and an upper circuit layer 13 located on top of the middle partition layer 12. The lower circuit layer 11 has a lower thin film 111, a lower circuit portion 112 fixed to the top of the lower thin film 111, and a plurality of resistors (not shown) fixed to the top of the lower thin film 111. The middle partition layer 12 defines a plurality of switch spaces 121 and a plurality of conductive spaces 122 for inserting anisotropic conductive adhesive (not shown). The upper circuit layer 13 has an upper thin film 131 and an upper circuit portion 132 fixed to the bottom of the upper thin film 131. The middle partition layer 12 prevents short circuits between the lower circuit portion 112 and the upper circuit portion 132.

[0004] In actual operation, the positions in the upper circuit layer 13 corresponding to the respective switch spaces 121 are pressed to electrically connect the switch portions of the lower circuit section 112 and the switch portions of the upper circuit section 132, thereby jointly realizing the respective switches of the existing keyboard.

[0005] The lower circuit section 112 and the upper circuit section 132 are located on the lower film 111 and the upper film 131 respectively and are separated from each other. Therefore, it is necessary to use anisotropic conductive adhesive to electrically connect the conductive part of the lower circuit section 112 and the conductive part of the upper circuit section 132 to each other, so as to jointly achieve the anti-ghosting effect of the existing keyboard's drive line, sensing line and resistor.

[0006] However, this requires existing membrane keyboards to have at least three layers of film, thus preventing a reduction in overall material costs. Furthermore, the assembly process for existing membrane keyboards is quite cumbersome, increasing the time required for assembly. Clearly, existing membrane keyboards still have room for improvement. Summary of the Invention

[0007] The purpose of this invention is to provide a thin-film assembly unit with anti-ghosting function that simplifies the assembly process.

[0008] This invention provides a thin-film assembly unit with anti-ghosting functionality, comprising a lower thin film, a sensing circuit module, and an upper thin film. The sensing circuit module includes a lower circuit portion connected to the top side of the lower thin film, a plurality of flexible carbon ink sheets disposed on the top side of the lower circuit portion and spaced apart from each other, and an upper circuit portion disposed on the top side of the flexible carbon ink sheets. The lower circuit portion and the upper circuit portion are spaced apart from each other by the flexible carbon ink sheets. Each flexible carbon ink sheet is connected between a portion of the lower circuit portion and a portion of the upper circuit portion, and each flexible carbon ink sheet is a pressure-sensing resistor. The upper thin film is disposed on the top side of the lower thin film and the sensing circuit module and is combined with the lower thin film.

[0009] The thin-film assembly unit with anti-ghosting function of the present invention further includes a fixing adhesive layer laid on the top side of the lower thin film and the sensing circuit module, and the upper thin film covers the top side of the fixing adhesive layer to be disposed on the top side of the lower thin film and the sensing circuit module.

[0010] The thin-film assembly unit with anti-ghosting function of the present invention has each flexible carbon ink sheet having a bottom surface that contacts the lower circuit portion, a top surface that contacts the upper circuit portion, and a surrounding surface that connects the bottom surface and the top surface. When the top surface is pressed and approaches the bottom surface, the resistance value between the bottom surface and the top surface decreases accordingly.

[0011] The thin-film assembly unit with anti-ghosting function of the present invention further includes multiple detection circuit modules electrically connected to the sensing circuit module. The lower circuit section has multiple sensing lines and multiple voltage divider resistors electrically connected to the sensing lines respectively. The upper circuit section has multiple driving lines. Each flexible carbon ink sheet is connected between its respective sensing line and its respective driving line. The detection circuit modules are electrically connected to the sensing lines and the voltage divider resistors respectively to receive multiple voltage divider values ​​corresponding to the sensing lines respectively.

[0012] The thin-film assembly unit with anti-ghosting function of the present invention has the same number of detection circuit modules, the same number of drive lines, and the same number of sensing lines.

[0013] The thin-film assembly unit with anti-ghosting function of the present invention further includes a processing module electrically connected to the detection circuit module and the drive line. The detection circuit module is used to receive multiple voltage division values ​​corresponding to the sensing lines respectively, and to calculate multiple potential step values ​​based on the voltage division values. The processing module is used to supply power to the drive lines one by one, and to receive the potential step value corresponding to each drive line when it is energized from the detection circuit module, and then to calculate the difference between the potential step value and the preset potential step value.

[0014] The thin-film assembly unit with anti-ghosting function of the present invention is configured such that, after calculating the difference between each potential step value and the preset potential step value, the processing module determines whether the difference between each potential step value and the preset potential step value is not less than a preset threshold and a floating threshold.

[0015] The advantages of this invention are: by integrating the lower circuit section, the flexible carbon ink sheet, and the upper circuit section into the lower thin film, compared with the existing thin film keyboard assembly unit, it can not only simplify the assembly process, but also eliminate the cost of materials such as the intermediate layer and anisotropic conductive adhesive, thus reducing the overall cost. Attached Figure Description

[0016] Other features and effects of the present invention will be clearly presented in the embodiments with reference to the accompanying drawings, wherein:

[0017] Figure 1 This is an exploded perspective view of a membrane assembly unit of an existing membrane keyboard.

[0018] Figure 2 This is an incomplete three-dimensional assembly diagram of the membrane assembly unit of the existing membrane keyboard;

[0019] Figure 3 It is along Figure 2The cross-sectional view obtained by line II II II;

[0020] Figure 4 This is a partial exploded perspective view of an embodiment of the thin-film assembly unit with anti-ghosting function of the present invention;

[0021] Figure 5 This is a three-dimensional exploded view of a sensing circuit module in the embodiment described above;

[0022] Figure 6 This is an incomplete cross-sectional schematic diagram of the embodiment described;

[0023] Figure 7 This is a circuit diagram of the embodiment described;

[0024] Figure 8 It is similar Figure 7 The schematic diagram illustrates the conduction state when a processing module of the embodiment supplies power to one of the drive lines of the sensing circuit module. Detailed Implementation

[0025] See Figure 4 and Figure 5 An embodiment of the thin-film assembly unit with anti-ghosting function of the present invention includes a lower thin film 2, a sensing circuit module 3, a fixing adhesive layer 4, an upper thin film 5, and multiple detection circuit modules 6 (see reference). Figure 7 (To be introduced in subsequent paragraphs), a processing module 7 (see...) Figure 7 (To be described in subsequent paragraphs), and a storage module 8 (see below). Figure 7 (To be discussed in subsequent paragraphs).

[0026] See Figure 4 , Figure 5 and Figure 6 The sensing circuit module 3 includes a lower circuit section 31 connected to the top side of the lower film 2, a plurality of flexible carbon ink sheets 32 disposed on the top side of the lower circuit section 31 and spaced apart from each other, and an upper circuit section 33 disposed on the top side of the flexible carbon ink sheets 32. The lower circuit section 31 and the upper circuit section 33 are spaced apart from each other by the flexible carbon ink sheets 32. All the flexible carbon ink sheets 32 are pressure sensing resistors.

[0027] In this embodiment, the lower circuit section 31 has a plurality of sensing lines 311 and a plurality of voltage divider resistors 312 respectively electrically connected to the sensing lines 311 (see Figure 312). Figure 7The upper circuit section 33 has multiple drive lines 331. The sensing lines 311 and the drive lines 331 are interleaved through the flexible carbon sheet 32 ​​without overlapping or short circuits. For simplicity, the following paragraphs will only use two sensing lines 311 paired with two drive lines 331 as an example.

[0028] It is worth mentioning that the components of the lower circuit section 31 and the upper circuit section 33 can be changed according to requirements. For example, in a variation of this embodiment, the lower circuit section 31 has a plurality of drive lines 331 (not shown), the upper circuit section 33 has a plurality of sensing lines 311, and a plurality of voltage divider resistors 312 (not shown) respectively electrically connected to the sensing lines 311.

[0029] See Figure 5 , Figure 6 and Figure 7 Each of the flexible carbon ink sheets 32 is connected between a portion of the lower circuit section 31 and a portion of the upper circuit section 33, and each of the flexible carbon ink sheets 32 is connected between its respective sensing line 311 and its respective driving line 331. Each flexible carbon ink sheet 32 ​​has a bottom surface 321 that contacts the lower circuit section 31, a top surface 322 that contacts the upper circuit section 33, and a surrounding surface 323 connecting the bottom surface 321 and the top surface 322. In actual use, when the top surface 322 is pressed closer to the bottom surface 321, the resistance between the bottom surface 321 and the top surface 322 decreases accordingly. In this embodiment, the flexible carbon ink sheet 32 ​​is an elastic thin-film resistor, constructed from thin, flexible polymer-mixed conductive particles (e.g., carbon nanotubes).

[0030] The fixing adhesive layer 4 is laid on the top side of the lower film 2 and the sensing circuit module 3 to bond the lower film 2, the sensing circuit module 3 and the upper film 5.

[0031] The upper film 5 covers the top side of the fixing adhesive layer 4, and is disposed on the top side of the lower film 2 and the sensing circuit module 3, and is combined with the lower film 2.

[0032] The detection circuit module 6 is electrically connected to the sensing circuit module 3, and is also electrically connected to the sensing line 311 and the voltage divider resistor 312. The detection circuit module 6 is used to acquire multiple voltage divider values ​​corresponding to the sensing line 311, and to calculate multiple potential level values ​​based on these voltage divider values. In this embodiment, the detection circuit module 6 is a 12-bit resolution analog-to-digital converter, meaning it can divide an analog signal into 2... 12The resolution requirement of the detection circuit module 6 is positively correlated with the number of driving lines 331 and sensing lines 311. That is, the more driving lines 331 and sensing lines 311 there are, the higher the resolution requirement of the detection circuit module 6. The number of detection circuit modules 6, driving lines 331, and sensing lines 311 are the same. However, it should be understood that the number of detection circuit modules 6, driving lines 331, and sensing lines 311 can be adjusted according to requirements and is not limited to this embodiment.

[0033] The processing module 7 is electrically connected to the detection circuit module 6 and the drive line 331. The processing module 7 is used to supply power to each drive line 331 one by one, and to receive the potential level value corresponding to each drive line 331 when it is energized from the detection circuit module 6.

[0034] In this embodiment, the processing module 7 can be implemented by hardware or firmware such as a field-programmable gate array, a microprocessor, or a system on a chip.

[0035] The storage module 8 is electrically connected to the processing module 7. In this embodiment, the storage module 8 may be implemented as a flash ROM electrically connected to the processing module 7.

[0036] See Figure 7 and Figure 8 For simplicity, in this embodiment, the number of detection circuit modules 6, driving lines 331, and sensing lines 311 are all assumed to be two, and the number of flexible carbon ink sheets 32 is assumed to be four (2×2). For ease of explanation in subsequent paragraphs, the voltage value supplied by the processing module 7 to the driving line 331 on the left is defined as Vi1, and the voltage value supplied by the processing module 7 to the driving line 331 on the right is defined as Vi2. The voltage divided by the detection circuit module 6 located on the upper side is defined as Vo1, and the voltage divided by the detection circuit module 6 located on the lower side is defined as Vo2. The resistance value of the voltage dividing resistor 312 is defined as Rx. The resistance values ​​of the flexible carbon ink sheet 32 ​​are defined as R11, R12, R21, and R22, respectively. Before the flexible carbon ink sheet 32 ​​is pressed, its resistance is 2KΩ; after the flexible carbon ink sheet 32 ​​is pressed, its resistance is 1.8KΩ. The resistance value of the voltage divider resistor 312 is 1KΩ. Actual operation is as follows:

[0037] Step 1: The processing module 7 will supply power to each of the drive lines 331 one by one. (See reference...) Figure 8 The processing module 7 first supplies power to the drive line 331 located on the left side.

[0038] Step 2: The detection circuit module 6 receives the divided voltage values ​​from the sensing line 311. The following details the calculation method for the divided voltage values ​​received by the detection circuit modules 6 located on the upper and lower sides.

[0039] Reference Figure 8 The calculation formula for the voltage divider value received by the detection circuit module 6 located on the upper side is as follows:

[0040] It is not difficult to see that the reduction of R11 leads to The change in the corresponding value will be less than that in R12, R21, and R22, thus leading to The magnitude of the corresponding change is more significant. Therefore, The change in pressure indicates whether R11 has been pressed.

[0041] Similarly, the calculation formula for the voltage divider value received by the detection circuit module 6 located on the lower side is as follows:

[0042] It is not difficult to see that the reduction of R12 leads to The change in the corresponding change will be less than that in R11, R21, and R22, thus leading to The magnitude of the corresponding change is more significant. Therefore, The change in pressure indicates whether R12 has been pressed.

[0043] Based on the above, it can be imagined that when switching to power supply to the drive line 331 located on the right, the calculation formula for the voltage divider value received by the detection circuit module 6 located on the upper side is as follows:

[0044] It is not difficult to see that the reduction of R21 leads to The change in the corresponding change will be less than that of R11, R12, and R22, thus leading to The magnitude of the corresponding change is more significant. Therefore, The change in pressure indicates whether R21 has been pressed.

[0045] Similarly, the calculation formula for the voltage divider value received by the detection circuit module 6 located on the lower side is as follows:

[0046] It is not difficult to see that the reduction of R22 leads to The change in the corresponding value will be less than that in R11, R12, and R21, thus leading to The magnitude of the corresponding change is more significant. Therefore, The change in pressure indicates whether R22 has been pressed.

[0047] It should be understood that the voltage value supplied by the processing module 7 to the drive line 331 located on the left is substantially the same as the voltage value supplied by the processing module 7 to the drive line 331 located on the right. The different designations are used only for distinction in the above calculation formula. Substituting the data provided earlier, if none of the flexible carbon ink sheets 32 are pressed, All are equal to 0.4; if only the flexible carbon sheet 32 ​​(R11) located in the upper left is pressed, Rounded to three decimal places, the values ​​are 0.419, 0.402, 0.402, and 0.402 respectively; if only the flexible carbon ink sheets 32 (R11, R12) located at the upper left and lower left are pressed, Rounded to three decimal places, the values ​​are 0.421, 0.421, 0.404, and 0.404, respectively. It is not difficult to observe that when multiple flexible carbon ink sheets 32 are pressed simultaneously, the voltage values ​​corresponding to the pressed flexible carbon ink sheets 32 will theoretically be substantially the same.

[0048] Step 3: When the detection circuit module 6 receives the divided voltage value (corresponding to the timing when the drive line 331 on the left is energized), it maps the ratio of the divided voltage value to the voltage value supplied to each drive line 331 to the potential level value according to the resolution (4096 levels) of the detection circuit module 6. In other words, if none of the flexible carbon ink sheets 32 are pressed, The mapped potential values ​​are all equal to 1638; if only the flexible carbon sheet 32 ​​(R11) located in the upper left is pressed, The mapped potential values ​​are 1716, 1647, 1647, and 1647, respectively. If only the flexible carbon ink sheets 32 (R11, R12) located at the upper left and lower left are pressed, The mapped potential values ​​are 1724, 1724, 1655, and 1655, respectively.

[0049] Step 4: The processing module 7 receives the potential level value corresponding to the energization of the drive line 331 on the left side from the detection circuit module 6, and calculates the difference between the potential level value and a preset potential level value. The preset potential level value is the potential level value pre-calculated when the flexible carbon ink sheet 32 ​​is not pressed, which is 1638.

[0050] Step 5: The processing module 7 first determines whether the difference between each potential step value and the preset potential step value is not less than a preset threshold, and then determines whether the difference between each potential step value and the preset potential step value is not less than a floating threshold. This determines whether the flexible carbon ink sheet 32 ​​pointed to by each potential step value is pressed, thereby generating a first pressing result information corresponding to the flexible carbon ink sheet 32 ​​(R11) and the flexible carbon ink sheet 32 ​​(R12), and storing it in the storage module 8. The processing module 7 finds the maximum and minimum values ​​from the differences between the potential step values ​​and the preset potential step values, and takes the average of the maximum and minimum values ​​as the floating threshold. It is worth noting that if none of the flexible carbon ink sheets 32 are pressed, the difference between the potential step value and the preset potential step value is theoretically equal to 0, resulting in a floating threshold of 0, which can easily lead to misjudgment. Therefore, the processing module 7 needs to have the preset threshold built in to avoid such misjudgment. In this embodiment, the preset threshold is preset to 20.

[0051] Furthermore, if only the flexible carbon sheet 32 ​​(R11) located in the upper left corner is pressed, The mapped potential levels are 1716, 1647, 1647, and 1647, respectively. The differences between the potential levels and the preset potential levels are 78, 9, 9, and 9, respectively. The floating threshold is 44, thereby determining... If the difference between the mapped potential level value and the preset potential level value is not less than the preset threshold and the floating threshold, the first pressing result information indicates that only the flexible carbon ink sheet 32 ​​(R11) located in the upper left corner is pressed; if only the flexible carbon ink sheets 32 (R11, R12) located in the upper left and lower left corners are pressed, The mapped potential step values ​​are 1724, 1724, 1655, and 1655 respectively, and the differences between the potential step values ​​and the preset potential step values ​​are 86, 86, 17, and 17 respectively. The floating threshold is 52, thereby determining... If the difference between the mapped potential level value and the preset potential level value is not less than the preset threshold and the floating threshold, the first pressing result information indicates that only the flexible carbon ink sheet 32 ​​(R11, R12) located in the upper left and lower left corners is pressed.

[0052] Similarly, steps one through five are executed again to supply power to the drive line 331 located on the right side, thereby generating a second pressing result information corresponding to the flexible carbon ink sheet 32 ​​(R21) and the flexible carbon ink sheet 32 ​​(R22), and storing it in the storage module 8.

[0053] In this way, the processing module 7 can jointly determine whether all flexible carbon ink sheets 32 have been pressed based on the first pressing result information and the second pressing result information, thereby realizing the anti-ghost key function.

[0054] In summary, this embodiment achieves the following effects:

[0055] (i) By integrating the lower circuit section 31, the flexible carbon ink sheet 32, and the upper circuit section 33 on the lower thin film 2, the lower circuit section 31 and the upper circuit section 33 can also perform the function of switching without being separated from each other. Compared with the existing thin film keyboard assembly unit, it can not only simplify the assembly process, but also eliminate the cost of materials such as the middle layer and anisotropic conductive adhesive, thus reducing the overall cost.

[0056] (ii) Under this premise, by setting the detection circuit module 6, the processing module 7 and the storage module 8, the flexible carbon ink sheet 32 ​​is judged to be pressed based on the characteristic that the flexible carbon ink sheet 32 ​​changes its own resistance value when it is pressed, thereby realizing the anti-ghost key function with a circuit design that is different from the existing membrane keyboard.

[0057] Therefore, the thin film assembly unit with anti-ghosting function of the present invention simplifies the overall structure by setting the flexible carbon ink sheet 32, and can indeed achieve the purpose of the present invention.

[0058] The above description is merely an embodiment of the present invention and should not be construed as limiting the scope of the present invention. Any simple equivalent changes and modifications made in accordance with the claims and description of the present invention shall still fall within the scope of the present invention.

Claims

1. A thin-film assembly unit with anti-ghosting function, characterized in that: The device comprises a lower thin film, a sensing circuit module, and an upper thin film. The sensing circuit module includes a lower circuit portion connected to the top side of the lower thin film, a plurality of flexible carbon ink sheets disposed on the top side of the lower circuit portion and spaced apart from each other, and an upper circuit portion disposed on the top side of the flexible carbon ink sheets. The lower circuit portion and the upper circuit portion are spaced apart from each other by the flexible carbon ink sheets. Each flexible carbon ink sheet is connected between a portion of the lower circuit portion and a portion of the upper circuit portion, and each flexible carbon ink sheet is a pressure sensing resistor. The upper thin film is disposed on the top side of the lower thin film and the sensing circuit module and is combined with the lower thin film.

2. The thin-film assembly unit with anti-ghosting function according to claim 1, characterized in that: The thin film assembly unit further includes a fixing adhesive layer laid on the top side of the lower thin film and the sensing circuit module, and the upper thin film covers the top side of the fixing adhesive layer to be disposed on the top side of the lower thin film and the sensing circuit module.

3. The thin-film assembly unit with anti-ghosting function according to claim 1, characterized in that: Each of the flexible carbon ink sheets has a bottom surface that contacts the lower circuit portion, a top surface that contacts the upper circuit portion, and a surrounding surface that connects the bottom surface and the top surface. When the top surface is pressed and approaches the bottom surface, the resistance between the bottom surface and the top surface decreases accordingly.

4. The thin-film assembly unit with anti-ghosting function according to claim 1, characterized in that: The thin-film assembly unit also includes multiple detection circuit modules electrically connected to the sensing circuit modules. The lower circuit section has multiple sensing lines and multiple voltage divider resistors electrically connected to the sensing lines respectively. The upper circuit section has multiple drive lines. Each of the flexible carbon ink sheets is connected between its respective sensing line and its respective drive line. The detection circuit modules are electrically connected to the sensing lines and the voltage divider resistors respectively to receive multiple voltage divider values ​​corresponding to the sensing lines respectively.

5. The thin-film assembly unit with anti-ghosting function according to claim 4, characterized in that: The number of detection circuit modules, the number of drive lines, and the number of sensing lines are the same.

6. The thin-film assembly unit with anti-ghosting function according to claim 4, characterized in that: The thin-film assembly unit further includes a processing module electrically connected to the detection circuit module and the drive line. The detection circuit module is used to receive multiple voltage division values ​​corresponding to the sensing lines respectively, and to calculate multiple potential step values ​​based on the voltage division values. The processing module is used to supply power to the drive lines one by one, and to receive the potential step value corresponding to each drive line when it is energized from the detection circuit module, and then to calculate the difference between the potential step value and the preset potential step value.

7. The thin-film assembly unit with anti-ghosting function according to claim 6, characterized in that: The processing module is used to determine whether the difference between each potential step value and the preset potential step value is not less than a preset threshold and a floating threshold after calculating the difference between each potential step value and the preset potential step value.

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