Resistor device and generator for car charger

A cylindrical spacer type resistor device is connected to a metal fixing plate or a print circuit plate by its electrodes without lead wires only by fixing the resistor device. The operation for connecting the lead wires can be eliminated. When the resistor device is used as a disconnection detecting resistor of a rotor in a generator for a car charger, the resistor device can be easily fixed in a narrow space.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a cylindrical spacer type resistor device 
and a disconnection detecting resistor device of a rotor of a generator 
for a car charger and a preparation thereof. 
2. Description of the Prior Art 
Various forms of independent parts as such resistor have been proposed. 
There is no resistor which forms an electric circuit by contacting it with 
a circuit board. 
Referring to FIG. 1, the conventional device will be illustrated. 
In FIG. 1, the reference (100) designates a resistor device; (101) 
designates a resistant substrate of a resistor device made of a ceramic; 
(102) designates a winding resistor wound on a peripheral part of the 
resistant substrate; (103) designates an insulating coated layer coated on 
the outer surface of the winding resistor; (104), (105) designate 
respectively lead wires connected to the winding resistor; (107) 
designates a through-hole formed in the inner peripheral part of the 
resistant substrate (101); (201) designates a part of the printed circuit 
board; (202) designates a metal fixed plate for grounding; (203) 
designates a female screw formed in the metal fixed plate; (204) 
designates a fixing screw screwed on the female screw (203) through the 
through-hole (107) of the resistant substrate (101) and the printed 
circuit board (201) whereby the resistor device (100) is fixed on the 
metal fixing plate (202). 
The lead wires (104), (105) are respectively connected to the printed 
circuit board (201) and the electric conductive part of the metal fixing 
plate (202). 
In the conventional device, an electric circuit is not formed only by 
fixing the resistor device (100) on the metal fixing plate (202). It is 
necessary to connect one lead wires (104) to a part of the metal fixing 
plate (202) to connect the other lead wire (105) to a conductive part of 
the print circuit board (201) by soldering or by nipping. The operation is 
comprehensive so as to cause low productivity. 
Referring to FIG. 2, a conventional disconnection detecting resistor device 
of a rotor of a generator for a car charger, using a resistor device will 
be illustrated. In FIG. 2, the reference (7) designates a resistor device; 
(701), (702) respectively designate terminals of the resistor device (7); 
and (9) designates a bracket or fixing plate. The terminal (701) of the 
resistor device (7) is screwed to the second rectifier (222) and the 
terminal (702) is screwed to the bracket (9) as earth. 
As shown in FIG. 2, in the structure, the space required for the resistor 
device (7) limits the arrangement of the other parts and the assembling is 
not easy. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a resistor device by 
connecting a resistant layer on an outer surface of a cylindrical 
resistant substrate and connecting an electrode layer on both surfaces of 
the resistant substrate whereby no lead wire is needed for fixing the 
resistor device through the fixing part to the printed circuit board. 
It is another object of the present invention to provide a resistor device 
which easily connects the resistor device to the conductive part of the 
printed circuit board which is formed by baking the resistance layer and 
the electrode layer. 
Yet another object of the present invention is to provide a resistor device 
and which easily assembled when such resistor device is equipped with the 
generator for a car charger.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to FIGS. 3 to 9, embodiments of the present invention will be 
illustrated. 
In FIGS. 3 to 6, the reference (10) designates a resistor device; (11) 
designates a cylindrical resistant substrate prepared by baking a molded 
ceramic; (12) designates a resistance coated layer coated on the outer 
surface of the resistant or insulating substrate except on both end 
surfaces and near the end surfaces; (15), (16) respectively designate 
conductive coated layers as electrodes formed by coating with overlapping 
to the resistance coated layer (12), on all of both axial end surfaces of 
the resultant substrate (11); (17) designates a through-hole for fitting 
which is formed in the inner peripheral part of the resistant substrate 
(11). 
The preparation of the resistor device (10) having the structure will be 
described. 
The cylindrical resistant substrate (11) is prepared by baking a molded 
ceramic. A layer such as Pd-Ag type paste for a resistant layer (12) is 
coated on the outer surface of the resistance substrate (11). Each layer 
such as a Pd-Ag type paste made of electric conductive material (15), (16) 
is coated on each of both axial end surfaces of the resistant substrate 
(11). The coated layer (12) and the electric conductive layers (15), (16) 
are baked to prepare the resistor device (10). The resulted resultant 
device (10) is fixed through the printed circuit substrate (201) to the 
metal fixing plate (202) by screwing the fixing screw (204) through the 
hole (17) to the metal fixing plate (202). Thus, the electrode (16) is 
grounded through the fixing screw (204) on the metal fixing plate (202) 
and simultaneously the electrode (15) is connected to the electric 
conductive part of the printed circuit board (201). 
In this embodiment, the resistor device (10) is only fixed to the metal 
fixing plate (202) by the fixing screw (204) whereby the electrodes (15), 
(16) are respectively connected to the printed circuit board (201) and the 
metal fixing plate (202) without using lead wires (104), (105) which are 
required in the conventional one. It is possible to eliminate the 
complicated operations of soldering or nipping for connections of the lead 
wires (104), (105). 
As shown in FIG. 7, the resistance can be easily controlled by 
sand-blasting method or forming a slit by a razor on the resistant layer 
(12) of the resistor device (10). 
As shown in FIG. 8, one end surface of the resistant substrate (11) is 
extended to form the cylindrical projection (17) whereby the projection 
(17) can be used for deciding the position of the resistor device (10) 
when the resistor device (10) is used as a spacer. 
As shown in FIG. 9, a plurality of holes (17) are formed on the resistant 
substrate (11) and the resistance layer (12) and the electric conductive 
layers (15), (16) are respectively printed on the resistant substrate (11) 
so as to discriminate the regions for each of the holes (17) and the 
resistant substrate is fixed to the print circuit board (201) and the 
metal fixing plate (202) whereby the productivity is further improved. The 
parts (18) are used for discriminating the regions of the resistor device. 
In accordance with the present invention, the resistance layer is formed on 
the outer surface of the resistant substrate except both end surfaces or 
near the cylindrical substrate and the electrode layers are formed on both 
the end surfaces of the resistant substrate and they are formed by baking 
the coated layers. Even when resistor device is fixed on the print circuit 
board by fixing screws the electric conductive part of the print circuit 
board can be connected to the resistor device only fixing the resistor 
device to the print circuit board. This operation is remarkably easy in 
comparison with the conventional connection of a resistor device to a 
print circuit board through lead wires by soldering or nipping. Moreover, 
the resistor circuit can be effectively formed with the effect of the 
spacer. 
The resistor device used for the generator for a car charger of the present 
invention will be illustrated. 
FIG. 10 is a circuit diagram for showing the positions on the circuit of 
the resistor device of the present invention. In FIG. 10, the reference 
(1) designates an armature coil; (2) designates a rectifier for rectifying 
the AC output of the armature coil which includes a first rectifying 
output terminal (221), a second rectifying output terminal (222) and a 
third rectifying output terminal (223); (3) designates a field coil for 
exciting by the second rectifying output terminal (222), (4) designates a 
voltage regulator which connects between the second rectifying output 
terminal (222) and the battery (8); (401) designates a switching element 
of the voltage regulator for intermittently feeding the current to the 
field coil (3); (501) designates a charge display lamp; (502) designates 
parallel resistors; (6) designates a key-switch; (7) designates a resistor 
device connecting one end to the middle point between the display lamp 
(501) and the second rectifying output terminal (222) and connecting the 
other end to earth; and (8) designates a battery. 
The operation of the embodiment will now be discussed. 
When the key-switch (8) is turned on, the current is fed from the battery 
(8) through display lamp (501), to the earth through the resistor device 
(7) for one loop and through the field coil (3) and the switching element 
(401) for the other loop whereby the display lamp (501) is turned on. When 
the generator rotates to start the generation, the voltage at the first 
rectifying output terminal (221) is the same as the second rectifying 
output terminal (222). When the voltage of the second rectifier (222) 
reaches substantially the same as that of the battery (8), the potential 
difference between both ends of the display lamp (501) is lost to turn off 
the light. The current is fed through the second rectifier (222) to the 
resistor device (7) and the field coil (3). If the field coil (3) is 
disconnected, the field current is lost whereby the generator can not 
generate and the potential between the first rectifying output terminal 
(221) and the second rectifying output (222) is lost and the potential at 
the second rectifying output terminal of the display lamp (501) is 
lowered. Therefore, the current is fed from the battery (8) through the 
display lamp (501) to the resistor device (7) whereby the display lamp 
(501) is turned on to display the fact of the disconnection of the field 
coil (3) of the generator. 
In FIGS. 11 to 14, the reference numeral (7) designates a hollow 
cylindrical resistor device and the hollow part of the resistor device (7) 
is fitted and the resistor device is fixed to the bracket or fixing plate 
(9) by the screw (402) for fixing the voltage regulator (4) to contact its 
one end with the terminal (401) of the voltage regulator (4) and to 
contact its other end with the bracket (9). 
Referring to FIGS. 13 and 14, the resistor device (7) will be further 
illustrated. In Figures, the reference numeral (711) designates ceramic 
substrate; (712) designates a resistance layer; (713) designates an 
electrode layer; (714) designates a hollow part in the hollow cylindrical 
form to be the same structure as the insulating spacer. 
In accordance with the embodiment of the present invention, the hollow 
cylindrical resistor device is used for forming a circuit for displaying 
by the display lamp when the field coil connected to earth and the middle 
point between the second rectifying output terminal for rectifying the AC 
output of the armature coil and the discharge lamp. The hollow resistor 
device is fastened on the body of the generator by the screw for fitting 
into the hollow part whereby the resistor device is connected between the 
middle point and earth. It is unnecessary to consider the space necessary 
for placing the resistor in the design. In the assembling operation, it is 
the same as the insertion of the spacer, whereby the complicate operation 
for connecting the resistor device can be eliminated. Thus remarkable 
advantages can be obtained.