JPH0450911B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a flying particle observation device for observing flying particles such as ink droplets continuously ejected from an inkjet head of an inkjet printer. Regarding.

(Prior Art) For example, when testing an ink jet head in which ink droplets are continuously ejected according to a continuous pulse signal, a strobe light is emitted using a signal obtained by delaying the continuous pulse signal for ejecting ink droplets by a certain period of time. Ink droplets are irradiated, static images of these ink droplets are captured by a solid-state image sensor driven by a field accumulation start timing signal synchronized with the strobe light emission, and the frame image is processed by a computer to determine the center of the ink droplet. The coordinates are being determined.

(Problem to be Solved by the Invention) However, with this conventional configuration, when the period of the continuous pulse signal changes, the flash emission interval of the strobe also changes, and the imaging timing of the solid-state image sensor also changes, causing the TV (TV) monitor image becomes unstable. Furthermore, if the period of the continuous pulse signal becomes shorter than one field time of the solid-state image sensor, the solid-state image sensor will receive the strobe output light more than once within one field time, and the amount of light received by the solid-state image sensor will decrease. As the contrast increases and becomes saturated, the contrast changes, and in the case of a binarized image, the threshold level changes. On the other hand, when focusing on detecting the center coordinates of an ink droplet, a relatively large amount of memory is required, and since the calculations are processed by software, a certain amount of processing time is required to detect the coordinates, making real-time processing impossible. The drawback is that it cannot be done.

The present invention has been made in view of the above points, and
The purpose of this is to be able to stably image the flying particles as a static image with a solid-state image sensor even if the period of the connected pulse signal that forms the flying particles changes, and to obtain data on the center coordinates of the static image of the flying particles. The object of the present invention is to realize a device that can obtain the following information almost in real time with a relatively simple configuration.

(Means for Solving the Problems) The present invention, which solves the above problems, involves irradiating flying particles that fly in synchronization with continuous pulse signals with pulsed light that is output in synchronization with continuous pulse signals. In a flying particle observation device configured to form a static image of a flying particle on a fixed image sensor and detect the center coordinates of the flying particle based on the image output signal of the fixed image sensor, a continuous pulse signal is used. The fixed image sensor is driven by a field accumulation start timing signal given from the outside, and the continuous pulse signal and the field accumulation start timing signal are received at a timing independent from the field accumulation start timing signal. A strobe drive circuit that generates a light emission pulse, a strobe that emits light in response to a light emission pulse from the strobe drive circuit, and center coordinate generation that determines the center coordinates of a static image of a flying particle that is resolved on a solid-state image sensor when the strobe is emitted. means, the center coordinate generation means includes an addition detection means for detecting the flying particles by adding the sizes of the flying particles in the direction of multiple horizontal scanning lines; When the flying particle area detecting means generates a coincidence signal, the flying particle area detection means adds the center coordinate in the X-axis direction of the static image of the flying particle. The X coordinate counter obtained from the addition detection result, and the Y coordinate obtained from the addition detection result of the addition detection means, the center coordinate in the Y-axis direction of the still image of the flying particle when a coincidence signal is generated by the flying particle area detection means. It is characterized by being composed of a counter.

(Embodiments) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a configuration diagram showing an embodiment of a still image observation system according to the present invention. In Figure 1, IN1
is an input terminal for the continuous pulse signal S1, which is applied to the head drive circuit 1 and also to the strobe drive circuit 2.
IN2 is the field accumulation start timing signal S2
The field accumulation start timing signal S2 is applied to the solid-state image sensor 3 and also to the strobe drive circuit 2. Reference numeral 4 denotes an ink jet head, which is driven in accordance with the output signal S3 of the head drive circuit 1 and continuously ejects ink droplets D in synchronization with the continuous pulse signal S1.
A strobe 5 is arranged so as to irradiate the ink droplets D ejected from the ink jet head 4 from a direction intersecting the flight direction. The strobe 5 is driven in accordance with a drive signal S4 generated by a strobe drive circuit 2 based on a continuous pulse signal S1 and a field accumulation start timing signal S2, and outputs pulsed light intermittently.

FIG. 2 is a circuit diagram showing a specific example of the main parts of the strobe drive circuit 2. As shown in FIG. In FIG. 2, 21 is a flip-flop, and a field accumulation start timing signal S2 is applied to the clear terminal CLR.
A continuous pulse signal S1 is applied to the clock terminal CK. Reference numeral 22 denotes a shot trigger, which generates a pulse signal S4 having a predetermined pulse width in accordance with an output signal SQ applied from an output terminal Q of the flip-flop 21.

FIG. 3 is a time chart explaining the operation of FIG. 2, in which a indicates the continuous pulse signal S1, and b
indicates the field accumulation start timing signal S2, c indicates the output signal SQ of the flip-flop 21, and d indicates the output pulse signal S4 of the shoot trigger 22. As shown in FIG. 3, the output signal SQ of the flip-flop 21 rises in accordance with the rise of the continuous pulse signal S1 immediately after the field accumulation start timing signal S2 is applied, and the output signal SQ of the flip-flop 21 rises in accordance with the rise of the continuous pulse signal S1 immediately after the field accumulation start timing signal S2 is applied. It falls following the rise. The output pulse signal S4 of the shot trigger 22 rises in accordance with the rise of the output signal SQ of the flip-flop 21, and falls after a predetermined period of time has elapsed. The output pulse signal S4 of the shot trigger 22 is used as the drive signal S4 for the strobe light 5 in FIG. Here, if we pay attention to the output pulse signal S4 of the shot trigger 22, even if the period of the continuous pulse signal S1 changes, only one pulse always appears within the field accumulation time, and the strobe 5 is activated once within the field accumulation time. will only emit light.

Referring again to FIG. 1, reference numeral 6 denotes a lens, which is arranged so as to form a still image of the ink droplet D irradiated by the output light of the strobe 5 on the surface of the solid-state image sensor 3.

In such a configuration, the continuous pulse signal S1
is stable at a predetermined period, the strobe 5 is also driven according to the continuous pulse signal S1 immediately after the field accumulation start timing signal S2 is applied, and outputs pulsed light intermittently at a predetermined period. The pulsed light is output only once within the field accumulation time, the amount of light received by the solid-state image sensor 3 is constant, and the threshold level of the binarized image is also stable. Furthermore, since the solid-state image sensor 3 operates in internal synchronization, the TV monitor image does not flicker. Next, even if the period of the continuous pulse signal S1 changes, the strobe 5 emits light only once within the field accumulation time, as described above. Therefore, there is no problem caused by the strobe 5 emitting light twice or more within one field time as in the conventional case. Furthermore, since the solid-state image sensor 3 is operated in internal synchronization, stable observation can be performed at all times without any inconvenience caused by external synchronization as in the prior art.

FIG. 4 is a block diagram showing an embodiment of a central coordinate detection system for a static image of a flying particle according to the present invention. In FIG. 4, IN3 is an input terminal for a scanning binary signal S5 containing an image of flying particles. Part 2
The value signal S5 is applied to one end of the delay line DL connected in series, and is also applied to an OR circuit OR and a counter.
It has been added to CTR1. The delay line DL delays the binary signal S5 by one horizontal line, and a plurality of delay lines DL, approximately the same number as the number of scanning lines included in the image of the flying particles, are connected in series. Note that this embodiment shows an example in which four delay lines DL1 to DL4 are connected in series. The input/output signals of these angular delay lines DL1 to DL4 are applied to an OR circuit OR and also to predetermined counters CTR2 to CTR5 provided corresponding to each delay line DL1 to DL4. The output signal S6 of the OR circuit OR is output from each counter CTR1 to
It is added to CTR5, as well as to adder circuit ADD and comparison circuit CMP. IN4 is an input terminal for the clock signal S7. The clock signal S
7 is added to each of the counters CTR1 to CTR5, and also added to the X coordinate counter XCTR.
The adder circuit ADD adds the count values of each counter CTR1 to CTR5 in accordance with the output signal S6 of the OR circuit OR, and sends the added value to the comparator circuit CMP. The comparison circuit CMP compares the added value of the comparison circuit CMP with a reference signal set in advance corresponding to the image of the flying particle, and outputs a coincidence signal S8 when the two coincide within a predetermined error range. IN5 is vertical synchronization signal S
9, and the vertical synchronizing signal S9 is applied to the Y coordinate counter YCTR. IN6 is an input terminal for the horizontal synchronization signal S10, and the horizontal synchronization signal S10 is applied to the X coordinate counter XCTR and the Y coordinate counter YCTR. The X-coordinate counter XCTR counts the clock signal S7 in accordance with the start of the horizontal synchronization signal S10, and when the coincidence signal S8 is output from the comparator circuit CMP, the pixels in the X direction of the image of the flying particle are calculated from the counted value. 1/ of the number
Output the value after subtracting 2. Y coordinate counter YCTR
The horizontal synchronizing signal S10 is counted according to the start of the vertical synchronizing signal S9, and when the matching signal S8 is output from the comparison circuit CMP, half of the number of scanning lines included in the image of the flying particle is counted. Output the subtracted value.

FIG. 5 is a specific example of a frame image taken of three flying particles D1 to D3, and FIG. 6 is a time chart showing the operation of FIG. 4 focusing on the flying particle D1 in FIG. be. In FIG. 2, the frame image is scanned from left to right.

FIG. 5 shows that when the horizontal line i is being scanned, the output signal i-4 of the delay line DL4 becomes as shown in FIG. 6a in response to the flying particle D1, and the output signal of the delay line DL3 i-3 becomes as shown in FIG. 6b, and the output signal i-2 of the delay line DL2 becomes as shown in FIG. 6c, and the output signal i of the delay line DL1 becomes as shown in FIG.
-1 becomes as shown in Figure 6d, and the delay line DL1
The input signal i of is as shown in FIG. 6e, and the output signal S6 of the OR circuit OR is as shown in FIG. 6f. Each of these signals from i to i-4 is input to the OR circuit OR and each counter CTR1 to
It is input to CTR5, and each counter CTR1~
CTR5 is the output signal S6 of the OR circuit OR and each signal i to i added to each counter CTR1 to CTR5.
-4 is at high level, each clock pulse S7 applied from the input terminal IN4 is counted. Each of these counters CTR1 to CTR5
The counted values are all added up by the addition circuit ADD when the output signal S6 of the OR circuit OR becomes low level, and the addition output is added to the comparison circuit CMP.
The comparison circuit CMP compares the addition output with a reference signal corresponding to the number of pixels preset corresponding to the image of the flying particles. However, this number of pixels can be obtained by calculating the number of pixels in the image area of the inspection object by drawing from the size of the inspection object, the imaging magnification of the imaging means, the size of the position pixel, etc. In this case, the size of one pixel corresponds to the clock period of S3 for the X coordinate and to the scanning line interval for the Y coordinate. If both match within a predetermined tolerance range, a match signal S8 is output. Note that if they do not match, the image is not considered as the target image. The coincidence signal S8 is used as a read strobe signal for the X coordinate counter XCTR and the Y coordinate counter YCTR. That is, as described above, the X coordinate counter XCTR counts the clock signal S7 in accordance with the start of the horizontal synchronization signal S10, but this count value does not reflect the image of the flying particles at the time when the matching signal S8 is output from the comparator circuit CMP. XCTR, which is the X coordinate value of the right end of , that is, the X coordinate value of the center of the image. The value of 1/2 of the number of pixels in the X direction included in the image of the flying particles is a predetermined constant due to the above-mentioned drawing. On the other hand, as mentioned above, the Y coordinate counter YCTR counts the horizontal synchronization signal S10 in accordance with the start of the vertical synchronization signal S9, but at the time when the matching signal S8 is output from the comparator circuit CMP, the image of the flying particle is This is the Y coordinate value of the lower end. YCTR is synchronized with the CMP coincidence signal, and externally outputs the value obtained by subtracting 1/2 of the number of scanning lines in the Y direction included in the image of the flying particle from the above count value, that is, the Y coordinate value of the center of the image. Output. The value of 1/2 the number of scanning lines in the Y direction included in the image of the flying particles is a predetermined constant due to the above-mentioned drawing.

As described above, according to the configuration shown in FIG. 4, the X and Y coordinates representing the center of the image of the flying particle are output at the same time as the scanning of one flying particle is completed, unlike the conventional method. The processing time can be significantly reduced compared to traditional software processing. When measuring ink droplets in an inkjet, it is only necessary to distinguish between the droplets involved in recording and the minute droplets surrounding them, so-called satellite particles.
When determining the center coordinates of an image of a droplet involved in recording, the permissible error range may be about 20%.

In addition, the number of flying particles is not limited to one, but the number of flying particles is not limited to one.
As long as they are two-dimensionally separated as shown in the figure, there may be a plurality of them.

In the above embodiment, an example was shown in which a static image of an ink droplet by irradiation with the output light of a strobe is formed on the surface of a solid-state image sensor using a lens. It is also possible to irradiate drops. By configuring like this,
It is possible to remove the restriction imposed by the focal length of the lens.

Further, the pulsed light is not limited to a strobe, and the output light of a continuous light source may be intermittent by rotating a disk provided with slits.

Furthermore, the object to be observed is not limited to ink droplets ejected from an ink jet head, but can be applied to flying particles of the same type.

(Effects of the Invention) As explained above, according to the present invention, even if the period of the continuous pulse signal that forms the flying particles changes, the flying particles can be stably imaged as a static image with a solid-state image sensor. Furthermore, it is possible to realize a flying particle observation device that can obtain data on the center coordinates of a static image of the flying particle in substantially real time with a relatively simple configuration.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the static image observation system according to the present invention, FIG. 2 is a circuit diagram showing a specific example of the strobe drive circuit in FIG. 1, and FIG.
4 is a block diagram showing an embodiment of the center coordinate detection system for a static image of a flying particle in the present invention. FIG. 5 is a frame image to be processed in FIG. 4. FIG. 6 is a time chart focusing on the flying particle D1 in FIG. 5. DESCRIPTION OF SYMBOLS 1... Head drive circuit, 2... Strobe drive circuit, 21... Flip-flop, 22... Schmitt trigger, 3... Solid-state image sensor, 4... Inkjet head, 5... Strobe, 6... Lens, D... ...flying particles (ink droplets), DL...delay line, OR...OR circuit, CTR...counter,
ADD...Addition circuit, CMP...Comparison circuit, XCTR
...X coordinate counter, YCTR...Y coordinate counter.

Claims (1)

[Claims] 1. A static image of the flying particles is formed on a fixed image sensor by irradiating the flying particles in synchronization with a continuous pulse signal with pulsed light output in synchronization with the continuous pulse signal. In a flying particle observation device configured to detect the center coordinates of a flying particle based on the image output signal of a fixed image sensor, field accumulation starts at a timing independent of the continuous pulse signal and is given from the outside. A solid-state image sensor driven by a timing signal, a strobe drive circuit that receives a continuous pulse signal and a field accumulation start timing signal and generates a light emission pulse according to the first continuous pulse signal after the field accumulation start timing, and a strobe drive circuit. a strobe that emits light in response to a light emission pulse; and a center coordinate generation means for determining the center coordinates of a static image of a flying particle formed on a solid-state image sensor when the strobe is emitted, and the center coordinate generation means is configured to perform multiple horizontal scanning. Addition detection means that detects by adding the sizes of flying particles in the linear direction, and flying particle area detection that generates a coincidence signal when the addition detection value obtained by the addition detection means is within a predetermined range. an X-coordinate counter that calculates the center coordinate in the X-axis direction of a static image of the flying particle from the addition detection result of the addition detection means when a coincidence signal is generated by the flying particle area detection means; A flying particle comprising: a Y-coordinate counter that calculates the center coordinate in the Y-axis direction of a static image of the flying particle from the addition detection result of the addition detection means when a coincidence signal is generated by the detection means; Observation equipment.