JPH0553540A - Liquid crystal display contrast adjustment device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a contrast adjusting device for a liquid crystal display, which can eliminate the previous inappropriate contrast setting value while utilizing the previous contrast setting value. [Structure] The liquid crystal display 10 is provided with touch keys 11 composed of 30 transparent electrodes. When switching to the mode for adjusting the contrast of the screen, the liquid crystal display 10
Are displayed as "pale" and "dark", and the touch keys of the display portion are assigned to the respective contrast setting keys 12. When these keys are operated to set the contrast arbitrarily and the power is turned off, the set value is set in the EEPROM 25.
Memorized in. When the power is turned on, the set value is read (S1), and if the value is within a predetermined range, the density is adjusted (S5). If it is not within the predetermined range, the density is adjusted with a preset standard value. (S4).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contrast adjusting device for adjusting the contrast of the display state of a liquid crystal display.

[0002]

2. Description of the Related Art Generally, a liquid crystal display includes a liquid crystal display, a display controller, a voltage adjusting circuit for adjusting a driving voltage for driving the liquid crystal display, and an operating member for setting a contrast of a display state of the liquid crystal display. When the contrast of the display state of the liquid crystal display is set by the operating member provided, the contrast setting value is stored in the EEPROM, the control signal corresponding to the contrast setting value read from the EEPROM is output to the voltage adjusting circuit, and the liquid crystal display is displayed. The contrast is adjusted by adjusting the voltage for driving the. As a method to set the initial contrast when the power is turned on, the contrast set value at the previous power off is set to EEP.
A method of storing the contrast in the ROM and setting the contrast with the contrast setting value, and a method of setting the contrast with the same contrast standard value every time have been put into practical use.

[0003]

In the method of setting the contrast by the contrast setting value when the power was turned off last time, the contrast is set to be extremely dark or light due to the influence of the previous illumination light or sunshine or due to an erroneous operation, and the power is turned on. O
In the case of FF, there is a problem that the display on the display cannot be seen because the contrast is extremely dark or thin when the power is turned on. Especially in recent electronic devices,
Since the operation is based on the initial menu displayed on the display, the next operation cannot be performed unless the initial screen of the display is visible. With the method of setting the contrast with the same standard value every time, if the display is difficult to see due to the influence of illumination light, etc., the contrast must be adjusted each time the power is turned on, and the frequency of contrast adjustment increases. There's a problem. An object of the present invention is to provide a contrast adjustment device for a liquid crystal display, which can eliminate an inappropriate contrast setting value of the previous time while utilizing the previous contrast setting value.

[0004]

A contrast adjusting device for a liquid crystal display according to a first aspect of the present invention, as shown in FIG. 1, includes a liquid crystal display, a display controller, and a voltage adjustment for adjusting a drive voltage for driving the liquid crystal display. A liquid crystal display including a circuit and an operating member for setting a contrast of a display state of a liquid crystal display, a nonvolatile memory for storing a contrast setting value set via the operating member, and a nonvolatile memory when power is turned on. Determining means for reading the contrast setting value from the property memory and determining whether or not the contrast setting value is within a predetermined range, and based on the determination result of the determining means, when the contrast setting value is within the predetermined range, the contrast setting value is set. Output the control signal to the voltage adjustment circuit, and the contrast control value When not a value within the range is obtained by a contrast control means for outputting to the voltage regulator circuit a control signal for controlling such that the preset contrast standard value.

[0005]

In the contrast adjusting device for the liquid crystal display according to the first aspect, when the contrast of the display state of the liquid crystal display is set through the operating member, the set contrast setting value is stored in the non-volatile memory. ..
When the power is turned on, the determining means reads the contrast setting value from the non-volatile memory and determines whether the contrast setting value is within a predetermined range. The contrast control means adjusts the control signal for controlling the contrast set value to be the contrast set value when the contrast set value is within the predetermined range, based on the result of the determination by the determination means, for adjusting the drive voltage for driving the liquid crystal display. A control signal is output to the circuit, and when the contrast control value is not within the predetermined range, a control signal for controlling to the preset contrast standard value is output to the voltage adjusting circuit. In this way, when the previously set contrast setting value is within the predetermined range, the contrast is adjusted so that the contrast setting value becomes that value, so that the frequency of contrast adjustment can be reduced. Also, when the previously set contrast setting value is not within the predetermined range, the contrast is adjusted so that it becomes the preset contrast standard value, so the previously set abnormal contrast setting value is eliminated and the contrast standard value is set. It is possible to display with a certain visible contrast based on the value.

[0006]

According to the contrast adjusting device for a liquid crystal display of the first aspect, as described in the above-mentioned action,
By providing the non-volatile memory, the discriminating means, and the contrast control means, it is possible to reduce the frequency of the contrast adjustment of the liquid crystal display, eliminate the abnormal contrast setting value set last time, and set the contrast standard. Based on the value, it is possible to obtain an effect such as being able to display with a surely visible contrast.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 2, the electronically controlled sewing machine M
The sewing machine main body has a bed portion 1, a pedestal portion 2, an arm portion 3 and a head portion 4. The head portion 4 is provided with a presser bar 7 to which a presser foot is attached and a sewing needle 6. The needle bar 5 is attached to the bed 1, and the bed 1 is provided with a feed dog, and a needle bar up-and-down moving mechanism for vertically driving the needle bar 5 is provided in the main body of the sewing machine as in a general electronically controlled sewing machine. A feed dog up-and-down moving mechanism that drives the feed dog up and down, a needle bar swinging mechanism that swings the needle bar 5 in the left-right direction, a feed tooth swinging mechanism that swings the feed dog in the front-rear direction, and a needle. The sewing machine motor 27 that drives the rod up-and-down moving mechanism and the feed dog up-and-down moving mechanism, the stepping motor 28 that drives the needle bar swinging mechanism, the stepping motor 29 that drives the feed tooth swinging mechanism, the control device 20, and the like. It is provided (see FIG. 3).

A large liquid crystal display 10 is provided on the front surface of the arm portion 3. The display 10 can display, for example, 20 characters × 3 lines of characters in a dot pattern. The display 10 is provided with touch keys 11 made up of 30 transparent electrodes for pattern selection and command signal input, and one of the touch keys 11 is pressed. By doing so, it is possible to select a desired one of the displayed stitch patterns. The arm portion 3 is provided with switches such as a start / stop switch 8, a thread trimming switch 14, a needle position changeover switch 15 and a reverse stitching switch 16 near the head 4, and the upper end front surface of the pedestal portion 2. An operation panel 9 is provided on the operation panel 9, and nine operation keys (practical sewing key 91, character sewing key 92, pattern sewing key 93, usage key 94, etc.) are provided on the operation panel 9.
Reference numeral 8 is a speed volume for adjusting the sewing speed.

Next, an outline of the control system of the sewing machine M will be described with reference to FIG. The control device 20 includes an input interface 21, a microcomputer including a CPU 22, a ROM 23, and a RAM 24, an output interface 26, and an EEPROM 25 that is a non-volatile memory. The input interface 21 includes a start / stop switch 13 Signals from the operation panel 9, the touch keys 11 of the display 10, the timing signal generator 40, and other keys and switches are supplied, and the output interface 26 supplies the sewing machine motor 27 and the needle bar. The moving stepping motor 28, the feed stepping motor 29, the display controller 30 that drives the display 10, and the voltage that drives the display 10 by being supplied with power from the driving power supply 32 and adjusts the voltage supplied to the display controller 30. Each drive current and a drive pulse signal and the control signal is supplied to the circuit 31. The timing signal generator 40 is provided in association with the upper shaft of the sewing machine M and detects the rotational phase of the upper shaft.

In the ROM 23 of the microcomputer, stitch data of a large number of stitch patterns relating to each of practical stitching, character stitching, and pattern stitching, a control program for selecting the stitch pattern and display data, and sewing machine data are displayed. A control program for displaying explanatory information on how to use the display 10 and data for display, a control program for contrast setting control, which will be described later, peculiar to the present invention, and the like are stored in advance.
Here, the contrast setting key 1 as an operation member for adjusting the contrast of the display state of the display 10
2 (see FIG. 6), when the sewing machine M is first turned on, the initial screen is displayed on the display 10 as shown in FIG. 4, but when adjusting the contrast density of the display state of the display 10, how to use it When the key 94 is operated, it is displayed on the display 10 as shown in FIG.
When is operated, the display as shown in FIG. 6 appears on the display 10, but the touch key 11 at the “light” display and the touch key 11 at the “dark” display in FIG. Correspondingly, the contrast can be adjusted to be lighter according to the number of times the "light" touch key 11 is operated, and the contrast can be adjusted to be higher depending on the number of times the "dark" touch key 11 is operated. Depending on the operation of the contrast setting key 12, the EE
The contrast setting value stored in the PROM 26 is updated.

The EEPROM 26 stores a set value memory for storing the contrast set value set by the contrast setting key 12, a maximum value memory for storing a predetermined maximum contrast value, and a predetermined minimum contrast value. A minimum value memory and a standard value memory that stores a predetermined contrast standard value approximately intermediate between the maximum contrast value and the minimum contrast value are provided.

The contrast setting control routine which is started when the power of the sewing machine M is turned on will be described below with reference to FIG.
This will be described with reference to the flowchart of In the figure, Si (i
= 1, 2, 3 ...) indicates each step.
This control is started when the power of the sewing machine M is turned on,
Next, the contrast setting value (which is set and stored through the contrast setting key 12 when the sewing machine was used last time or before), the maximum contrast value and the minimum contrast value are read from the EEPROM 25 (S1). ) Next, it is determined whether the contrast setting value is larger than the maximum contrast value (S2). If the determination result is Yes, the process proceeds to S4, and if No, the process proceeds to S3. In S3, it is determined whether the contrast setting value is smaller than the minimum contrast value. If the determination result is Yes, the process proceeds to S4, and if No, the process proceeds to S5. S4 is a case where the contrast setting value is not within the predetermined range between the minimum contrast value and the maximum contrast value. In this case, the EEP
The duty ratio of the PWM control signal (control pulse) output to the voltage adjustment circuit 31 is calculated based on the contrast standard value read from the ROM 25 (S4).

On the other hand, if both S2 and S3 are determined to be No, that is, if the contrast setting value is within the predetermined range between the minimum contrast value and the maximum contrast value, the contrast read from the EEPROM 25 in S5. The duty ratio of the PWM control signal output to the voltage adjusting circuit 31 is calculated based on the set value (S5). Next, in S6, the PWM control signal having the duty ratio determined in S5 or S4 is output to the voltage adjustment circuit 31. As a result, the voltage adjusting circuit 31 adjusts the voltage of the electric power supplied from the driving power source to the voltage corresponding to the duty ratio by PWM control and supplies the voltage to the display controller 30.
The contrast of the display state of the display 10 driven by 0 becomes the contrast corresponding to the duty ratio. While the sewing machine M is being used thereafter, the contrast is maintained until the contrast setting value is changed via the contrast setting key 12. However, when the contrast setting value is changed, the contrast setting value in the EEPROM 25 is updated. The contrast is also changed accordingly.

As described above, when the power supply is turned on, if the previously set contrast set value is not within the predetermined range, the contrast is adjusted to the preset contrast standard value. Even if the contrast setting value is set to an abnormal value outside the predetermined range due to the effect of sunlight, the display 10 can be surely displayed in a visible state. Therefore, based on the display of the display 10, the touch key 11 and the operation panel 9 are displayed. The sewing machine M can be operated by operating the switches. Moreover, when the power is turned on, if the previously set contrast setting value is within the predetermined range, the contrast is adjusted so that it becomes the contrast setting value. The frequency can be reduced.

It is needless to say that the sewing machine main body may be provided with a pair of touch switches, a volume and other contrast setting members instead of the contrast setting key 12, and the contrast maximum value and the contrast minimum value may be set. Values and contrast standard values are not always EEPRO
It does not need to be stored in M25, and can be incorporated as a predetermined constant in the control program for contrast setting control. In the above-mentioned embodiment, the case where the present invention is applied to the liquid crystal display provided in the sewing machine M has been described, but various electronic devices other than the sewing machine M (document processing device, typewriter,
The present invention can be similarly applied to liquid crystal displays of personal computers, copying machines, printers, etc.).

[Brief description of drawings]

FIG. 1 is a functional block diagram of an invention according to claim 1.

FIG. 2 is an overall perspective view of an electronically controlled sewing machine.

FIG. 3 is a configuration diagram of a control system of the sewing machine.

FIG. 4 is a diagram showing a display example of an initial screen of a display.

FIG. 5 is a diagram showing a display example of a display in the middle of reaching a contrast setting.

FIG. 6 is a diagram showing a display example in which a contrast setting key is displayed.

FIG. 7 is a flowchart of a contrast setting control routine.

[Explanation of symbols]

 M Electronically controlled sewing machine 9 Operation panel 10 Display 12 Contrast setting key 20 Control device 30 Display controller 31 Voltage adjustment circuit 94 Usage key

Claims (1)

[Claims] 1. A liquid crystal display comprising a liquid crystal display, a display controller, a voltage adjusting circuit for adjusting a drive voltage for driving the liquid crystal display, and an operating member for setting a contrast of a display state of the liquid crystal display, A non-volatile memory for storing the contrast setting value set via the operation member, and a discriminating means for discriminating whether or not the contrast setting value is within a predetermined range by reading the contrast setting value from the non-volatile memory when the power is turned on. Based on the discrimination result of the discriminating means, when the contrast setting value is within a predetermined range, a control signal for controlling the contrast setting value is output to the voltage adjusting circuit, and the contrast control value is within the predetermined range. If it is not the value of, the control to control to the preset standard contrast value A contrast adjusting device for a liquid crystal display, comprising: a contrast controlling means for outputting a signal to a voltage adjusting circuit.