JPH0522955Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a liquid crystal display device for consumer electronic equipment, etc.

Conventional technology Among the items to be displayed on the liquid crystal panel, if there are items that should always be displayed when the equipment is turned on, such as the title of the display item or the scale for level display, the segment If a lighting signal that allows the display to be lit at all times is output from the liquid crystal drive integrated circuit (hereinafter simply referred to as liquid crystal drive IC), it is sufficient to use that signal, but if the output is output from an existing IC, etc. If not, conventionally they were placed on the glass surface of the liquid crystal panel or inside the liquid crystal panel, such as a polarizing plate inserted between the glass and the liquid crystal, or a transparent plate made of vinyl chloride sheet etc. attached to the front of the liquid crystal panel. It was displayed using silk screen printing.

Problems that the invention aims to solve However, when printing as described above, not only does it reduce the effective area that can be displayed as a liquid crystal, but also the liquid crystal part and the printed part are not on the same surface, so when viewing the liquid crystal panel. There was a problem in that the printed part and the illuminated display part were misaligned depending on the angle. In particular, in the case of scales for level display, etc., this deviation must be minimized, so the printing location is inevitably the glass surface of the liquid crystal panel or the polarizing plate, but this is printed on a transparent plate etc. The cost was considerably higher than in the case of

In view of the above-mentioned problems, the present invention has been developed to
The present invention aims to provide a liquid crystal display device that can display a lighting signal even if the lighting signal is not output from the liquid crystal driving IC used, rather than by means such as printing.

Means for Solving the Problems In order to solve the above problems, the liquid crystal display device of the present invention connects a comparator with hysteresis characteristics to the common signal output terminal of the liquid crystal drive IC, and outputs the comparator to the liquid crystal display panel. This is configured to be used as a segment lighting signal.

Function: With the above-described configuration, the present invention allows an item to be always displayed on the liquid crystal display to be turned on without using printing or other means, even if the liquid crystal drive IC used does not have a corresponding lighting signal output. It is designed so that it can be displayed.

Embodiment FIG. 1 shows an embodiment of the present invention. In Figure 1, 1 is a liquid crystal drive IC, 2 is a liquid crystal panel, 3 is a comparator with hysteresis characteristics, 4 is a common signal output terminal, 5 is a common signal input terminal, 6 is a segment lighting signal input terminal (always lit) 7, 8, 9 are other segment lighting signal input terminals, 10, 11, 12
is a segment lighting signal output terminal.

The operation of the liquid crystal display device configured as described above will be explained below.

In FIG. 1, the signal output from the common signal output terminal 4 of the liquid crystal driving IC 1 is as shown in a in FIG. 2. Now, if you want to turn on the liquid crystal in response to this common output, all you have to do is input the signal shown in b in FIG. 2 to the segment lighting signal input terminal of the liquid crystal panel corresponding to that segment. Here, the input/output relationship of the comparator 3 has a hysteresis characteristic as shown in FIG. In other words, input V _i is 0
When V _i =V ₁ (V/2<V ₁ <
V) for the first time, the output V ₀ changes from V to 0, and V _i changes to V
When decreasing from V _i =V ₂ (0<V ₂ <V/
2) If the characteristics are such that the output changes from 0 to V for the first time, the output signal of comparator 3 when the signal shown in Figure 2 a is input is exactly the signal b in Figure 2.
Therefore, it is only necessary to add this to the segment lighting signal input terminal 6 corresponding to the segment that you want to keep lit at all times.

Note that this comparator can be easily constructed using a transistor, an operational amplifier, a gate IC, or the like.

Effects of the invention As described above, according to the invention, a comparator with hysteresis characteristics is connected to the common signal output terminal of the liquid crystal drive IC, and its output is used as a segment lighting signal for the liquid crystal panel.
Items that should always be displayed on the liquid crystal display can be displayed on the LCD without using printing or other means, even if the drive IC used does not have a corresponding lighting signal output.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the liquid crystal display device according to the present invention, and FIG. 2 is a waveform diagram showing the common output signal and segment lighting signal of the liquid crystal drive IC.
FIG. 3 is an input/output characteristic diagram of the comparator. 1...Liquid crystal drive IC, 2...Liquid crystal panel, 3...
...Comparator, 4...Common signal output terminal, 5
...Common signal input terminal, 6 to 9...Segment lighting signal input terminal, 10 to 12...Segment lighting output terminal.

Claims (1)

[Scope of utility model registration request] Voltage value 0 in the first period, voltage value V/2 in the next second period, voltage value V in the next third period, voltage value V/2 in the next fourth period
When the input Vi is increased from a voltage value of 0 to the common signal output terminal of a liquid crystal drive integrated circuit that repeatedly outputs a voltage change with a voltage change of 4 periods as one cycle, Vi=V1(V/2<V1<V)
For the first time, the output Vo changes from the voltage value V to 0, and the input
When Vi is decreased from the voltage value V, Vi=V2
(0<V2<V/2), the output Vo is voltage value 0 for the first time
1. A liquid crystal display device, characterized in that a comparator having an input/output characteristic of hysteresis that changes from to V is connected, and the output thereof is used as a segment lighting signal for a constantly lit segment of a liquid crystal panel.