Optical: systems and elements – Optical modulator – Light wave temporal modulation
Reexamination Certificate
1999-10-27
2001-12-11
Epps, Georgia (Department: 2873)
Optical: systems and elements
Optical modulator
Light wave temporal modulation
C359S265000, C359S604000, C345S049000, C345S105000
Reexamination Certificate
active
06330101
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to an electrochromic panel (EC panel) in which it is possible to alternate between a colored state and a colorless state when the panel is installed onto a rear-view mirror of a vehicle and a DC voltage polarity is applied in an inverted fashion. More specifically, the present invention pertains to a drive unit that provides a fail-safe function as well as an easy one-touch operation for alternating between the colored and colorless states.
2. Description of Prior Art
For example, when a passenger vehicle or a truck is driven at night, there are several cases in which the light beams from the head lamps of following vehicles reflect against the rear-view mirrors (both internal and external) and enter the driver's field of view, causing the driver to experience temporary blindness. Therefore, in order to solve such a problem EC panels (electrochromic panels) have been conventionally installed onto the glass substrates used for rear-view mirrors, and by applying a DC voltage to the EC panels, it has become possible to reduce the reflectivity and prevent this temporary blindness from occurring.
FIG. 3
shows one of conventional circuits that has been used as a drive circuit for EC panels, and by applying a switchable DC voltage polarity outputted from a DC power source
12
to the input terminal of an EC panel
11
as shown in
FIG. 3
, it is possible to obtain a blindness prevention state (hereinafter referred to as the colored state) by reducing the reflectivity of the rear-view mirror, as well as return the rear-view mirror from this colored state to its original state of reflectivity (hereinafter referred to as the colorless state).
In other words, through the operation of a two-way switch
13
(
13
-
1
and
13
-
2
) as shown in
FIG. 3
, connections are made between contacts
13
-
1
c
and
13
-
1
a,
as well as between contacts
13
-
2
c
and
13
-
2
a,
such that voltage is applied in a forward direction to the input terminal of the EC panel
11
, making it possible for the EC panel
11
to be in the colored state whereby the reflectivity is reduced. Conversely, by operating the switch
13
in a reverse fashion such that connections are made between contacts
13
-
1
c
and
13
-
1
b
, as well as between contacts
13
-
2
c
and
13
-
2
b,
the voltage is applied in a reverse direction to the input terminal of the EC panel
11
, causing it to return to its colorless state. Accordingly, through the operation of this switch
13
, the driver can change the reflectivity of a rear-view mirror and thus prevent temporary blindness from occurring as a result of light beams from the head lamps of following vehicles being reflected against the rear-view mirror during night driving.
However, since the use of the aforementioned EC panel drive circuit makes it necessary for the driver to press and hold the two-way switch
13
for a set period of time in order to change the EC panel
11
to and from the colored and colorless states, this operation may be burdensome for the driver. That is to say, the disadvantage here is that once the voltage is applied to the EC panel
11
, it does not immediately change it to either the colored or colorless state, but rather, it gradually changes to or from either state through the application of voltage in a forward or reverse direction for a set period of time, thus making it necessary for the driver to press and hold the two-way switch
13
.
Furthermore, since a two-way switch
13
is used in the case of the EC panel drive circuit shown in
FIG. 3
in order to switch the EC panel
11
back and forth between the colored and colorless states, it is impossible for a fail-safe function to actuate in cases where errors occur during the operation of the switch.
A detailed explanation of this is given below. Given the colored state of the EC panel
11
, in which case the reflectivity of the rear-view mirror is reduced, operating the switch
13
so that connections are made between contacts
13
-
1
c
and
13
-
1
b
as well as between contacts
13
-
2
c
and
13
-
2
b
will cause the EC panel
11
to return to its colorless state. When a problem occurs in this case, namely, a drop in the level of voltage from the DC power source
12
, it becomes impossible for the EC panel
11
to return to the colorless state from the colored state.
Thus, in comparing the safety between the colored state and the colorless state of the EC panel
11
, it is apparent that the colorless state is the safer of the two. Therefore, when considering a fail-safe function in the case where a failure has occurred, the colorless state of the EC panel
11
is preferable. However, as noted above, in conventional cases of drive units used for the EC panel
11
in which a drop has occurred in the level of the voltage supplied from the DC power source
12
, there occurs a problem that the EC panel
11
has become frozen in the colored state, and a fail-safe function which would allow the EC panel to return to its original state has not been realized.
In addition, a characteristic of the EC panel
11
is a change in the level of color in response to the amount of DC voltage applied. However, in the case of the EC panel drive unit shown in
FIG. 3
, the value of the voltage level applied to the EC panel
11
is fixed, and as a result, the level of color is always fixed. Accordingly, the disadvantage here is not only that the driver is unable to set the reflectivity of the rear-view mirror to a desired level, but also that it is impossible to change the reflectivity in response to the brightness of the surroundings.
As described above, in conventional drive units for EC panels, it is necessary to press and hold a two-way switch
13
in order to change the EC panel
11
to the colored state as well as to the colorless state, and this is a disadvantage from the standpoint of operation.
Furthermore, since no fail-safe function, such as the ability for the EC panel
11
to return to the colorless state in the case where there is a drop in the level of voltage from the DC power source
12
when the EC panel
11
is in the colored state, is available, the loss in the level of safety is a disadvantage. Also, since the value of the voltage applied to the EC panel
11
is fixed, the problem of the reflectivity of the rear-view mirror not being able to be set to a desired level has occurred.
This invention is designed to solve these conventional problems, and its objective is to obtain the ability to switch an EC panel back and forth between a colored state and a colorless state using a one-touch operation. Furthermore, the present invention makes it possible to achieve a fail-safe function and provide an EC panel drive unit for rear-view mirrors in which the reflectivity can be changed.
SUMMARY OF THE INVENTION
In one of the preferred aspects, the EC panel drive unit for rear-view mirrors according to the present invention comprises a colored state switch SWI that turns to the ON position instantaneously, at which point a one-shot multi-vibrator
8
puts out an output signal which turns a first transistor Tr
1
to the ON position for a fixed period of time. Also, when a contact SW
1
-
2
of the colored state switch SW
1
turns to the ON position, a fifth transistor Tr
5
and an eighth transistor Tr
8
also turn to the ON position due to the fact that the “Q
2
” of a D-type flip-flop circuit
9
is at the H-level while the “{overscore (Q
2
)} ”is at the L-level. Accordingly, voltage is applied such that the Ta terminal of an EC panel
7
is on the positive side and the Tb terminal is on the negative side, resulting in a colored state for the EC panel
7
.
Also, if a colorless state switch SW
2
is turned to the ON position instantaneously when the EC panel
7
is in the colored state, the one-shot multi-vibrator
8
puts out an output signal which turns the first transistor Tr
1
to the ON position for a fixed period of time. Furthermore, when a contact SW
2
-
2
of the colorless state switch SW
2
turns to the ON position
Fujikawa Yoshihiro
Nagao Mitsuyoshi
Sato Hidenori
Yamamoto Tetsuya
Epps Georgia
Lester Evelyn A.
Murakami Corporation
Striker Michael J.
LandOfFree
EC panel drive unit for a rear-view mirror does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with EC panel drive unit for a rear-view mirror, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and EC panel drive unit for a rear-view mirror will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2587305