JPS5812018B2 - Fritzker Tokusei Kensa Sochi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flicker characteristic testing device that can test visual characteristics, particularly flicker characteristics such as brightness and chromaticity, in a very short time.

Conventionally, in order to test the flicker characteristics (also called temporal characteristics) in human vision, the flicker frequency is changed and the critical fusion frequency CFF (Cri-tioal Fus.
Methods have been used, such as measuring the ion frequency or changing the flicker contrast to find the threshold value.

However, in any case, the test requires a lot of time and subject fatigue becomes a problem.

An object of the present invention is to project flicker of a specific frequency and a specific contrast at a certain time and to sequentially change the flicker characteristics as described above in order to test the test subject's reaction. Instead of detecting flicker characteristics from ) by displaying a pattern in which the flicker contrast changes smoothly, and having the examinee observe the pattern and indicate the boundary between areas where flicker occurs and areas where flicker does not occur. , subject's flicker
It is an object of the present invention to provide a flicker characteristic testing device that can test the CFF or threshold value for an object in a very short time based on its boundary characteristics.

The present invention provides a television scanning type image display device, a sweep frequency oscillator having a repetition period equal to the horizontal scanning period of the display device, and an oscillation output continuously phase-shifted at a period equal to the horizontal scanning period. A flicker comprising a fixed frequency oscillator and means for gating the output of the swept frequency oscillator by means of a gate pulse formed in relation to the output of the fixed frequency oscillator, the signal being derived by the means as a signal source. - A pattern is displayed on the image display device.

The present invention will be explained below with reference to the drawings.

An example of the flicker characteristic testing device of the present invention, which displays the above-mentioned pattern on an image display device using a cathode ray tube, will be explained with reference to FIG.

In Figure 1, the television horizontal drive signal H is connected to terminal 1.
D (repetition frequency fH=15.75 KHz) is supplied, and the sweep frequency oscillator 2 oscillates a sine wave of a frequency (fo+ft) whose repetition period is phase-coupled with HD.

Here, ft is 0 to (n-1)fo(
However, n is an arbitrary constant).

That is, ft=0 at the left end of the display screen (hereinafter referred to as screen) of the cathode ray tube 12, which will be described later, and ft=(n-1)f at the right end.

Make it so.

As this sweep frequency oscillator 2, for example, a voltage controlled oscillator using a variable capacitance diode may be used.

On the other hand, the horizontal drive signal HD is divided into two and also supplied to the fixed frequency oscillator 3 to stably oscillate a sine wave with a frequency fo having a period equal to the HD period and a phase matching, and the oscillation output is supplied with a low frequency externally. (For example, a modulation signal of frequency δ) is added to enable phase modulation of the sine wave of frequency fo.

Now, if we do not perform phase modulation of this sine wave,
As described above, the frequency of the output of the oscillator 2 changes over the frequencies fo to nfo from the left end of the screen toward the right end.

Further, the output of the oscillator 3 has a frequency fo.

Since both have a specified phase relationship with respect to HD, the period is 1/f from the latter.

If you gate the former and pass its output through a low-pass filter and then display it on a cathode ray tube, you will see a static vertical stripe that gradually narrows from the left edge of the screen to the right edge. appear.

In the present invention, by continuously shifting the phase of the output of the oscillator 3 in the HD period, the vertical stripes are not always displayed on the screen as they are, but at a desired period corresponding to each position in the horizontal direction of the screen. Flicker that changes brightness and darkness
Convert to pattern.

FIG. 2 is an explanatory diagram illustrating the operating principle of the present invention, in which a is a waveform diagram of the output signal of the oscillator 2 during one horizontal scanning line period of the screen, and b to b' are sine wave diagrams of the output signal of the oscillator 3. It is a signal waveform diagram of a gate pulse obtained by supplying it to the wave-pulse converter 4 and converting it into a pulse train having the same period as a sine wave, and the gate pulse is converted into a 360° pulse train by the above-mentioned phase modulation.
° Shows how the phase shifts.

In Figure 2, while the gate pulse is phase shifted by 360°, signal waveform a changes level once (0 to 360°) at the left end, but changes level three times (0 to 1080°) at the right end. I know it will change.

Therefore, if we assume that the frequency at which the gate pulse has a 360° phase shift is 1 Hz, the gate pulse that is the output of the sine wave-pulse converter 4 is supplied to the gate 5 to gate the output of the oscillator 2, and then The frequency of the signal obtained through the pass filter 6 is 1Hz at the left end of the screen of the cathode ray tube 12.
The frequency increases as you go to the right, reaching 3Hz at the right end.
The cathode ray tube 12 displays a flicker pattern that changes in brightness and darkness in this frequency range.

Using this, the flicker characteristics (however, only CFF) of a subject can be tested.

Now, in order to obtain a flicker pattern of 0.5 to 20Hz from the left edge to the right edge of the screen, the above constant n should be set to 40.
(=20Hz 10.5Hz), and since it is necessary to change brightness and darkness 0.5 times per second at the left end of the screen, the frequency δ of the external signal for phase modulating the oscillator 3 is determined to be 0.5Hz.

Further, the frequency fo may be any frequency as long as it can be separated and removed by the low-pass filter 6 (Fig. 1). For example, if fo = 100 KHz (corresponding to the left edge of the screen), the right edge The output frequency of the oscillator 2 corresponding to nfo may be set to 40×100100 KHz=4.

Note that in the NTSC standard television system, the field frequency is 60 Hz, so it is not suitable for testing flicker characteristics of 20 Hz or higher, but in order to perform such testing, the field frequency must be doubled to 120 Hz. The inspection range can be expanded to 40Hz.

Next, in order to change the contrast of the flicker pattern displayed on the screen and also measure its threshold, a television vertical drive pulse VD is supplied to the terminal 7, and a sawtooth wave generator 8 is used to adjust the phase to VD. Generates a combined sawtooth wave.

Furthermore, the output of the low-pass filter 6, which is supplied to the amplitude modulator 9, is amplitude-modulated by this sawtooth wave.

At this time, if one part of the screen is not modulated as shown by the signal waveform in the figure corresponding to the flicker pattern in Figure 3a, the contrast of the flicker pattern will be the highest at the top of the screen. It is weak and becomes strongest at the bottom.

Note that the mixer 10 mixes the output of the amplitude modulator 9 and the blanking signal BL supplied to the terminal 11 to output the output signal to the cathode ray tube 1.
2, and the threshold value of flicker characteristics can also be displayed as a flicker pattern that can be inspected.

When the subject observes the flicker pattern obtained in the above manner, the flicker pattern on the screen is divided into an area A where the flicker is felt and an area B where the flicker is not felt, as shown in Figure 3a. , the boundary line (dotted line) indicates the flicker characteristics of the subject, and visual flicker characteristics such as CFF and threshold can be comprehensively tested at once.

The parts 13, 14, and 15 shown in FIG. 1 are a photodetection element, a low-pass filter, and a frequency counter, respectively, and are used to check the flicker frequency of each part of the flicker pattern displayed on the cathode ray tube 12. It is for.

That is, a photodetector 13 (for example, a solar cell or a phototransistor) detects the temporal change in brightness of that part of the display surface by converting it into an electrical signal, and a low-pass filter 14 detects it as the cathode ray tube 12 vertically scans. The existing high frequency components are removed and the flicker frequency is measured by a frequency counter 15.

As described above, according to the present invention, visual flicker characteristics can be tested in an extremely short period of time, thereby eliminating fatigue of the test subject, and providing stable test data with good reproducibility. Can be done.

In addition, in the apparatus of the present invention, a color cathode ray tube is used as the cathode ray tube 12, and a device for converting changes in brightness into sudden changes is interposed between the mixer 10 and the color cathode ray tube 12, so that the visual color can be It is also possible to check for degree flicker.

In this case, as a device for converting a change in brightness into a sudden change, the present inventor proposed a device previously proposed in Japanese Patent Application No. 48-57314.
It is preferable to use a sudden modulator such as that used in the "Color Vision Function Testing Apparatus" of No.

Furthermore, another application of the present invention is to measure the flicker characteristics of a television system.

That is, as shown in FIG. 4, the flicker characteristic (■) when a subject directly views the flicker pattern C produced by the apparatus of the present invention and the flicker characteristic (■) when the television system E is interposed. By taking the difference, only the flicker characteristics of the television system can be extracted.

The present invention is not limited to the above-mentioned examples, but can be implemented with various modifications.

For example, the flicker pattern shown in FIG. 3a can be displayed by interchanging the long and short sides of the screen, and in this case, the flicker can be displayed with a gradual change in contrast.

Furthermore, this contrast change can be made not only linearly but also in any arbitrary manner (including non-linear changes) to suit the desired purpose.

Furthermore, the flicker pattern according to the present invention does not necessarily have to be displayed using a display device using a cathode ray tube, but can also be displayed using other types of image display devices such as a fixed display device.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of the configuration of the flicker characteristic testing device of the present invention, FIG. 2 is an explanatory diagram for explaining the operating principle of the device of the present invention, and FIGS. A diagram showing an example and its signal waveform. FIG. 4 is a diagram for explaining another application example of the present invention. 1.7, 11... terminal, 2... sweep frequency oscillator, 3... fixed frequency oscillator, 4...
... Sine wave-pulse converter, 5 ... Gate, 6, 14 ... Low pass filter, 8 ...
... sawtooth wave generator, 9 ... amplitude modulator, 10
...Mixer, 12...Cathode ray tube, 13
......Photodetection element, 15...Frequency counter, C...Flinker pattern, D...
・Subject, E...Television system.

Claims (1)

[Claims] 1. A television scanning image display device, a swept frequency oscillator having a repetition period equal to the horizontal scanning period of the display device, and a fixed frequency oscillator whose oscillation output is continuously shifted in phase at a period equal to the horizontal scanning period. and means for gating and extracting the output of the swept frequency oscillator with a gate pulse formed in relation to the output of the fixed frequency oscillator, and a flicker pattern whose signal source is the signal extracted by the means. A flicker characteristic inspection device characterized in that a flicker characteristic is displayed on the image display device.