JP3778795B2 - Electrical equipment with light receiving unit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to various electric devices such as a TV (television), a VTR (video tape recorder), an audio component, and the like provided with a light receiving unit that receives an infrared signal transmitted from a remote controller. In particular, the present invention relates to improvement of electrostatic withstand voltage of a remote control light receiving unit.
[0002]
[Prior art]
Various electronic devices such as a TV, a VTR, and an audio component usually include a light receiving unit that receives an infrared signal transmitted from a remote controller. First, the configuration of the light receiving unit will be described below.
[0003]
An integrated circuit unit including an amplifier, a photodiode, a chip resistor, and a chip capacitor are mounted on the lead frame by die bonding or wire bonding. A resin mold body is formed by molding the lead frame on which various elements are mounted in this manner with a light-transmitting resin. This resin mold body has a hemispherical lens part in the light receiving part facing the photodiode. By this lens unit, an infrared signal transmitted from the remote controller can be received at a wide angle. Further, the entire resin mold body excluding the lens portion is covered with a metal plate shield case. That is, the shield case is provided with a substantially circular opening that fits into the lens portion. This shield case protects the integrated circuit portion including the amplifier from external electromagnetic noise.
[0004]
A front view of the appearance of such a light receiving unit is shown in FIG. 7A, and a right side view thereof is shown in FIG. 7B. The lens part 11 of the resin mold body is provided in front of the light receiving unit. Locking portions 12 a and 12 a ′ are provided below the shield case 12. By providing the locking portions 12a and 12a ′, it is easy to mount the light receiving unit on the printed circuit board. The lead frame includes a ground terminal 13, a drive terminal 14, and an output terminal 15. From the ground terminal 13, a ground voltage is input to various elements mounted on the lead frame. A driving voltage is input from the driving terminal 14 to various elements mounted on the lead frame. An output voltage is output to the output terminal 15 from an element mounted on the lead frame.
[0005]
Some light receiving units have mesh-shaped openings provided in a shield case in order to improve shield characteristics. A front view of the appearance of such a light receiving unit is shown in FIG. 7C, and a right side view is shown in FIG. 7D. In addition, the same code | symbol is attached | subjected to the part same as the light-receiving unit of Fig.7 (a) (b), and description is abbreviate | omitted. By making the opening provided in the shield case into a mesh shape, it is possible to reduce external electromagnetic noise that enters the light receiving unit from the lens unit 11.
[0006]
As described above, the light receiving unit has an opening provided at a location facing the photodiode of the shielding means in a mesh shape (hereinafter referred to as a mesh light receiving unit), and an opening provided at a location facing the photodiode of the shielding means. It can be roughly divided into two types, one having a single perforation (hereinafter referred to as a non-mesh light receiving unit).
[0007]
Next, a printed circuit board on which the light receiving unit is mounted will be described. In the printed circuit board, copper foil conductive paths having a required pattern such as a ground potential line, a drive voltage supply line, and an output signal line are formed on a glass / epoxy substrate. As shown in FIG. 8, the ground terminal 13 of the light receiving unit 1 is connected to one end of the ground potential line 2 a of the printed circuit board 2. The drive terminal 14 of the light receiving unit 1 is connected to one end of the drive voltage supply line 2b. The output terminal 15 of the light receiving unit 1 is connected to one end of the output signal line 2c. Further, the other end of the ground potential line 2a is grounded. The other end of the drive voltage supply line 2 b is connected to the constant voltage source 7. The other end of the output signal line 2c is connected to a control circuit 8 that controls the operation of the electric device.
[0008]
The drive voltage supply line 2b is provided with a resistor R1, and the ground potential line 2a and the drive voltage supply line 2b are connected via a capacitor C1. Since the resistor R1 and the capacitor C1 form a low-pass filter, high frequency noise is removed from the drive voltage supply line 2b, and only the constant voltage Vcc is input to the drive terminal 14 from the drive voltage supply line 2b.
[0009]
In general, an amplifier included in an integrated circuit in a light receiving unit is a high gain amplifier. For this reason, if the electromagnetic noise from the outside is not shielded, the receiving distance of the light receiving unit is shortened. Accordingly, in the conventional light receiving unit, the shield case 12 is grounded by connecting the shield case 12 and the ground terminal 13 and grounding the ground potential line 2a. This prevents electromagnetic noise from the outside from entering the light receiving unit.
[0010]
A plurality of mounting holes (not shown) are formed in the printed circuit board, and the grounding terminal 13, the drive terminal 14, the output terminal 15, and the shield case locking portions 12a and 12a ′ are formed in the mounting holes, respectively. The light receiving unit 1 is erected on the printed circuit board 2 (see FIG. 9).
[0011]
[Problems to be solved by the invention]
In general, the light receiving unit is installed in the vicinity of the front portion of the electric device. For example, when the electric device is a TV, the outline of the internal structure is as shown in FIG. An infrared signal transmitted from a remote controller (not shown) passes through a light receiving window 5 provided on the front panel 4 of the television 3, and is a circle provided in a horizontal state between the light receiving window 5 and the light receiving unit 1. The light receiving unit 1 is irradiated through the columnar light guide 6. The lens portion of the light receiving unit 1 faces the end face of the light guide 6. The infrared signal that has passed through the light guide 6 is applied to the lens portion of the light receiving unit 1 and is received by a photodiode inside the light receiving unit 1.
[0012]
In addition to the light receiving window 5, the front panel 4 is also provided with a main power push button switch (not shown). Since the push button switch of the main power source is operated by a human hand, the human hand may approach the light receiving unit 1. At this time, static electricity may be discharged from a human hand to the shield case of the light receiving unit 1. Since the shield case and the ground terminal of the light receiving unit 1 are directly connected as shown in FIG. 8, when static electricity is discharged to the shield case, static electricity enters the integrated circuit in the light receiving unit 1 from the ground terminal, In the worst case, the light receiving unit 1 may be broken.
[0013]
For this reason, in an electrical apparatus equipped with a conventional light receiving unit, the shield case 12 is grounded alone without being connected to the ground terminal 13, as shown in FIG. In FIG. 10, the same parts as those in FIG.
[0014]
However, since the shield case 12 and the ground terminal 13 are not connected in such a structure, the potential of the shield case 12 and the potential of the ground terminal 13 may be different. In such a case, since the shield case 12 cannot sufficiently shield electromagnetic noise from the outside, the reception distance of the light receiving unit has been shortened.
[0015]
An object of this invention is to provide the electric equipment provided with the light-receiving unit with favorable electrostatic withstand voltage in view of said problem. Another object of the present invention is to provide an electric device including a light receiving unit that does not shorten the reception distance even if the electrostatic withstand voltage of the light receiving unit is improved.
[0016]
[Means for Solving the Problems]
In order to achieve the above object, in an electrical apparatus according to the present invention, a photodiode, an integrated circuit that processes an output signal of the photodiode, and a conductive material that prevents electromagnetic noise from the outside from entering the integrated circuit. A remote control light-receiving unit having a shield means made of a member, and a ground terminal for inputting a ground potential to the integrated circuit, and a circuit board on which the remote-control light reception unit is mounted, and the shield means via a resistor It is connected to the ground terminal. Further, from the viewpoint of cost reduction, the resistor may be a wiring provided on the circuit board. From the viewpoint of not deteriorating the reception distance performance, and the shield means less substantially 1 00 kW approximately 100Ω or more the resistance value of the resistor when having an opening portion in a mesh shape which is opposed to the photodiode, the shield means may be less approximately 10 0 kW approximately 100Ω or a resistance value of the resistor when having an opening consisting of a single perforation portion opposed to the photodiode. Further, from the viewpoint of further improving the electrostatic withstand voltage, the shield means may be connected to the ground via a capacitor.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to the drawings. When the present invention is applied to a TV, the outline of the internal structure of the TV is the same as that of the conventional TV shown in FIG. FIG. 1 shows a configuration of a light receiving unit and a printed circuit board included in the electrical apparatus (TV) of the first embodiment. In addition, the same code | symbol is attached | subjected to the part same as FIG. 8, and description is abbreviate | omitted. The shield case 12 is connected to the ground terminal 13 via the resistor R2. When a mesh light-receiving unit as shown in FIGS. 7C and 7D is used as the light-receiving unit 1, the electrostatic withstand voltage as shown by E1 shown in FIG. 2 is obtained. Further, when a meshless light receiving unit as shown in FIGS. 7A and 7B is used as the light receiving unit 1, the electrostatic withstand voltage as shown by E2 in FIG. 2 is obtained. The electrostatic withstand voltages E1 and E2 include the electrostatic withstand voltage of the light receiving unit in the conventional TV in which the resistance value of the resistor R2 is zero, that is, the resistor R2 as shown in FIG. 8 is not provided.
[0018]
From the electrostatic withstand voltages E1 and E2 of the light receiving unit, by providing the resistor R2, the electrostatic withstand voltage of the light receiving unit is improved, and as the resistance value of the resistor R2 is increased, the electrostatic withstand voltage of the light receiving unit is improved. Recognize. By providing the resistor R2 in this way, the electrostatic withstand voltage of the light receiving unit is improved because the static electricity is consumed by the resistor R2 when the static electricity is discharged to the shield case 12, and the static electricity hardly reaches the ground terminal 13. Because. Moreover, the electrostatic withstand voltage of the light receiving unit is improved as the resistance value of the resistor R2 is increased because the amount of static electricity that can be consumed by the resistor R2 increases as the resistance value of the resistor R2 increases.
[0019]
Next, the reception distance of the light receiving unit 1 will be described. When a mesh light-receiving unit as shown in FIGS. 7C and 7D is used as the light-receiving unit 1, a state in which electromagnetic noise is low (a device that generates electromagnetic waves around the light-receiving unit 1 without operating a cathode ray tube of a TV, etc.) 3), the receiving distance is L1 shown in FIG. 3, and in a state with a lot of electromagnetic noise (the distance between the TV CRT and the light receiving unit is 1 cm and the TV CRT is operated), L1 shown in FIG. Receive distance like The reception distances L1 and L1 ′ include the reception distance of the light receiving unit in the conventional TV in which the resistance value of the resistor R2 is zero, that is, the resistor R2 as shown in FIG. 8 is not provided.
[0020]
In a state where there is little electromagnetic noise, it is possible to obtain a reception distance equivalent to a state where the resistance value of the resistor R2 is 100 kΩ or less and the resistor R2 is not provided. In a state where there is a lot of electromagnetic noise, a receiving distance equivalent to the state where the resistance value of the resistor R2 is 1 kΩ or less and the resistor R2 is not provided can be obtained. Therefore, the light receiving unit 1 provided in the electrical apparatus (TV) of the first embodiment is a mesh light receiving unit, and the resistance value of the resistor R2 is set to 1 kΩ or less, compared with a conventional TV not provided with the resistor R2, The receiving distance of the light receiving unit 1 is equal, and the electrostatic withstand voltage of the light receiving unit 1 can be improved. Since the electrostatic withstand voltage increases as the resistance value of the resistor R2 increases, the resistance value of the resistor R2 is preferably set to 100Ω or more.
[0021]
When the meshless light receiving unit as shown in FIGS. 7A and 7B is used as the light receiving unit 1, the electromagnetic noise is low (the electromagnetic wave is generated around the light receiving unit 1 without operating the cathode ray tube of the TV, etc. 3), the reception distance is L2 shown in FIG. 3, and in a state where there is a lot of electromagnetic noise (the distance between the TV cathode ray tube and the light receiving unit is 1 cm and the TV cathode ray tube is operated), the reception distance shown in FIG. The reception distance is L2 ′. The reception distances L2 and L2 ′ include the reception distance of the light receiving unit in the conventional TV in which the resistance value of the resistor R2 is zero, that is, the resistor R2 as shown in FIG. 8 is not provided.
[0022]
When a non-mesh light receiving unit is used as the light receiving unit 1, there is more electromagnetic noise entering from the opening of the shield case than when a mesh light receiving unit is used, so the resistance value of the resistor R2 is the same when there is a lot of electromagnetic noise. In comparison, the reception distance L2 ′ is shorter than the reception distance L1 ′.
[0023]
In a state where there is little electromagnetic noise, it is possible to obtain a reception distance equivalent to a state where the resistance value of the resistor R2 is 100 kΩ or less and the resistor R2 is not provided. Further, in a state where there is a lot of electromagnetic noise, a reception distance equivalent to a state where the resistance value of the resistor R2 is 10 kΩ or less and the resistor R2 is not provided can be obtained. Therefore, the light receiving unit 1 provided in the electrical apparatus (TV) of the first embodiment is a meshless light receiving unit, and the resistance value of the resistor R2 is 10 kΩ or less, compared with a conventional TV not provided with the resistor R2. In addition, the receiving distance of the light receiving unit 1 is equal, and the electrostatic withstand voltage of the light receiving unit 1 can be improved. Since the electrostatic withstand voltage increases as the resistance value of the resistor R2 increases, the resistance value of the resistor R2 is preferably set to 100Ω or more.
[0024]
Also, as shown in FIG. 4, the side of the resistor R2 that is not connected to the ground terminal 13 may be grounded via the capacitor C2. As a result, the static electricity generated in the shield case 12 can be not only consumed by the resistor R2 but also charged by the capacitor 2, so that the static electricity is more difficult to reach the ground terminal 13, and the electrostatic withstand voltage of the light receiving unit 1 is further increased. improves. Since the capacitor C2 may be provided between the shield case 12 and the ground, it may be provided between the ground potential line 2a and the ground instead of between the resistor R2 and the ground.
[0025]
Next, FIG. 5 shows a configuration of a light receiving unit and a printed circuit board included in the electric apparatus (TV) of the second embodiment. In addition, the same code | symbol is attached | subjected to the part same as FIG. 8, and description is abbreviate | omitted. The shield case 12 is connected to the ground potential line 2a via a wiring 2d provided on the printed circuit board 2. When the light receiving unit 1 is a mesh light receiving unit, the length and width of the wiring 2d are set so that the line resistance of the wiring 2d is 1 kΩ or less. When the light receiving unit 1 is a meshless light receiving unit, the line resistance of the wiring 2d is 10 kΩ. The length and width of the wiring 2d are set so as to be as follows. As a result, the shield case 12 is connected to the ground terminal 13 via the resistor. Therefore, when static electricity is discharged to the shield case 12, the static electricity is consumed by the wiring 2d, so that static electricity hardly reaches the ground terminal 13, and the electrostatic withstand voltage of the light receiving unit 1 is improved.
[0026]
The present invention is not limited to this embodiment, and for example, the terminal of the ground potential line 2a to which the connection terminal 13 is connected and one end of the wiring 2d may be shared.
[0027]
Further, as shown in FIG. 6, the wiring 2d may be grounded via the capacitor C2. As a result, the static electricity discharged to the shield case 12 can be consumed not only by the wiring 2d but also charged by the capacitor C2, so that the static electricity is more difficult to reach the ground terminal 13, and the electrostatic withstand voltage of the light receiving unit 1 is further increased. improves. Since the capacitor C2 may be provided between the shield case 12 and the ground, it may be provided between the ground potential line 2a and the ground instead of between the wiring 2d and the ground.
[0028]
In the electrical apparatus (TV) of the first and second embodiments described above, the light receiving unit shown in FIG. 9 is used. However, the present invention is not limited to this, for example, a printed circuit without using a lead frame. The light receiving unit having a configuration in which an integrated circuit portion including an amplifier circuit, a photodiode, a chip resistor, and a chip capacitor are mounted on a substrate can be applied as long as the light receiving unit has a shielding means. In addition, the light receiving unit included in the electric device according to the present invention may be configured such that the photodiode is included in the integrated circuit.
[0029]
However, in a light receiving unit having a configuration in which the shield means includes a ground terminal, static electricity is discharged to the ground terminal that is the shield means, and thus the present invention cannot be applied. As such a light receiving unit, for example, a lead frame disclosed in Japanese Patent Application Laid-Open No. 10-74662 is bent into a U-shape and a part of the lead frame is made to face various elements mounted on the lead frame. A light receiving unit having a frame as a shield means and a shield plate disposed so as to face various elements mounted on a lead frame disclosed in Japanese Patent Laid-Open No. 11-121770, and the lead frame and the shield plate are used as shield means. Examples include a light receiving unit.
[0030]
【The invention's effect】
According to the present invention, since the shield means is connected to the ground terminal via the resistor, static electricity discharged to the shield case is difficult to enter the integrated circuit inside the remote control light receiving unit from the ground terminal. Thereby, the electrostatic withstand voltage characteristic of the remote control light receiving unit is improved, and the remote control light receiving unit is not damaged by static electricity.
[0031]
In addition, according to the present invention, since the resistor provided between the shield means and the ground terminal is the wiring provided on the circuit board, it is only necessary to change the setting of the width and length of the wiring. Thereby, cost can be reduced compared with the case where chip resistance etc. are used for resistance provided between a shield means and a ground terminal.
[0032]
Further, according to the present invention, since the shield means has the mesh-shaped opening at the position facing the photodiode, the intrusion of electromagnetic wave noise from the opening can be reduced and the shielding effect can be enhanced. As a result, the reception distance of the remote control light receiving unit becomes longer than when the opening is not mesh-shaped. Further, since the resistance value of the resistor provided between the shielding means and the ground terminal than approximately approximately 1 00 kW or more 100 [Omega, if the reception distance of the remote control light receiving unit with less of the electromagnetic noise resistance is not provided and Can be equivalent.
[0033]
Further, according to the present invention, the shield means has an opening made of one perforation at a position facing the photodiode, and the resistance value of the resistor provided between the shield means and the ground terminal is approximately 100Ω or more and approximately 100 0. Since it is set to kΩ or less, the reception distance of the remote control light receiving unit in a state where there is little electromagnetic noise can be made equal to the case where no resistor is provided.
[0034]
According to the present invention, since the shield means is connected to the ground via the capacitor, the static electricity discharged to the shield means can be consumed not only by the resistor but also charged by the capacitor. Thereby, the electrostatic withstand voltage of the remote control light receiving unit is further improved.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration of a light receiving unit and a printed circuit board included in an electrical apparatus (TV) according to a first embodiment of the present invention.
FIG. 2 is a diagram showing electrostatic withstand characteristics of the light receiving unit of FIG. 1;
FIG. 3 is a diagram showing reception distance characteristics of the light receiving unit of FIG. 1;
4 is a diagram illustrating a configuration in which a capacitor is added to the light receiving unit and the printed circuit board of FIG. 1;
FIG. 5 is a diagram illustrating a configuration of a light receiving unit and a printed circuit board included in an electrical apparatus (TV) according to a second embodiment of the present invention.
6 is a diagram showing a configuration in which a capacitor is added to the light receiving unit and the printed circuit board of FIG. 5;
FIG. 7 is a diagram illustrating an appearance of a light receiving unit.
FIG. 8 is a diagram illustrating a configuration of a light receiving unit and a printed circuit board included in a conventional electric device.
FIG. 9 is a diagram showing an outline of the internal structure of a TV equipped with a light receiving unit.
FIG. 10 is a diagram illustrating a configuration of a light receiving unit and a printed circuit board included in a conventional electric device that has taken countermeasures against static electricity.
[Explanation of symbols]
1 Photosensitive unit 2 Printed circuit board 2d Wiring 3 TV
12 Shield Case 13 Ground Terminal 14 Drive Terminal 15 Output Terminals C1, C2 Capacitors R1, R2 Resistance

Claims (3)

A photodiode; an integrated circuit that processes an output signal of the photodiode; a shield means that includes a conductive member that prevents external electromagnetic noise from entering the integrated circuit; and a ground that inputs a ground potential to the integrated circuit. A remote control light receiving unit having a terminal;
A circuit board on which the remote control light receiving unit is mounted;
Equipped with a,
The shield means is connected to the ground terminal via a resistor , the shield means has a mesh-shaped opening at a location facing the photodiode, and the resistance value of the resistor is about 100Ω to about 100 kΩ. Electrical equipment characterized by that. The electrical device according to claim 1, wherein the resistor is a wiring provided on the circuit board. The electric device according to claim 1, wherein the shield means is connected to the ground via a capacitor.

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