JP2734472B2 - Measurement signal processing device of container thickness measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to various beverage products (hereinafter referred to as juices).
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring the thickness of a plastic container (hereinafter, referred to as a bottle) for filling a container, and more particularly to a measurement signal processing circuit in an apparatus for measuring by an optically non-contact, non-destructive method. 2. Description of the Related Art In order to inspect the quality of a bottle to be filled with juices, the thickness between the inner and outer walls of the bottle is measured. An optical method is used for thickness measurement for the purpose of non-contact and non-destructive inspection. In this case, infrared light is used as the measuring light. The thickness measuring device includes a pair of light emitters and light receivers arranged with the wall of the bottle interposed therebetween, and a calculator for calculating a thickness value based on the received light signal. The light receiver is configured using a so-called photoelectric conversion element. The output signal of this photoelectric conversion element includes a drift and an offset due to its characteristics. These drifts and offsets adversely affect the accuracy of the measurement signal and need to be removed. Therefore, in order to solve this problem, a method is employed in which the drift and offset are canceled out by receiving the waveform of the measurement light as a cross-waveform. The period of the measurement light having the alternating wave shape appears in the same period as the output voltage of the photoelectric conversion element. Since the signal processing is complicated if the intersect waveform is used, conversion to a DC signal is performed.
For this DC conversion, the peak value of the output voltage of the photoelectric conversion element is peak-held every cycle. [Problems to be Solved by the Invention] However, the photoelectric conversion element has a problem of responsiveness unique to the element. That is, the phase of the measurement light on the light source side does not always match the phase of the output signal of the photoelectric conversion element, and a phase delay always occurs. This is due to the response delay of the photoelectric conversion element. As a result, the sampling timing of the output voltage of the photoelectric conversion element does not coincide with the peak value, and the sampling is performed at a timing different from the timing at which sampling should be originally performed.
A problem arises in that measurement cannot be performed with high accuracy. SUMMARY OF THE INVENTION It is an object of the present invention to provide a measurement signal processing device capable of preventing a sampling waveform from vibrating due to a response delay of a photoelectric conversion element and accurately measuring the thickness of a bottle. [Means for Solving the Problems] In order to achieve the object of the present invention, the present invention provides a measuring signal of a container thickness measuring device for measuring a thickness between inner and outer walls of a transparent or translucent container. In the processing device, the wavelength 2-5
μm infrared light, a chopper plate such as a chopper circuit that transmits between the inner and outer walls after converting into an infrared light having a crossing waveform of a certain period, and the infrared light that has transmitted between the inner and outer walls is received. A light receiver that outputs a transmitted light amount measurement signal corresponding to the transmitted light amount of the infrared light; and a timing signal generator that generates a timing signal corresponding to a peak value of the transmitted light amount measurement signal based on a signal indicating a crossing cycle of the infrared light. A peak hold circuit that holds a peak value of the transmitted light amount measurement signal for each cycle of the timing signal. [Operation] According to the present invention, the chopper means converts infrared rays having a wavelength of 2 to 5 μm into infrared rays having a cross-seeding waveform with a constant period, and transmits the infrared rays between the inner and outer walls of the container. The light receiver receives the infrared light transmitted between the inner and outer walls and outputs a transmitted light amount measurement signal corresponding to the transmitted light amount of the infrared light. After that, the timing signal generation circuit generates a timing signal corresponding to the peak value of the transmitted light amount measurement signal based on the signal indicating the crossing cycle of the infrared rays. Thus, the peak hold circuit holds the peak value of the transmitted light amount measurement signal for each cycle of the timing signal. Therefore, since the transmitted light amount measurement signal is always sampled at the peak value corresponding to the crossing cycle, the transmitted light amount measured signal at other levels is not sampled. Therefore, since the waveform after sampling can be made into a simple shape close to a straight line, the thickness of the container can be accurately measured without the unnecessary waveform caused by the sampling timing being incorrect. Further, since the infrared light is converted into the cross-wavelength and then transmitted between the inner and outer walls, the transmitted light amount measurement signal is output in a state where the drift and offset in the photodetector are canceled, and the thickness measurement of the container can be performed more accurately. it can. Example Next, an example of the thickness measuring apparatus according to the present invention will be described with reference to the drawings. Schematic Configuration First, FIG. 2 shows a schematic configuration of a thickness measuring apparatus. The wall thickness measuring device includes a projector 4 that is inserted into the bottle 1 from the opening 2 of the bottle 1 and emits measurement light 3 to the body wall of the bottle 1, and faces the projector of the projector 4 at a predetermined interval. A light receiver 5 arranged outside the bottle 1, a calculator 6 for calculating a thickness of a measured portion of the bottle 1 based on an output signal of the light receiver 5, and a light transmitter 4 and a light receiver 5. It comprises lifting means 8 for integrally lifting and lowering, and rotating means 9 for rotating the bottle 1 in the circumferential direction of the bottle 1 at the measurement position. In this configuration, the lifting means 8 and the rotating means 9
Constitutes a measurement position changing means. That is, the lifting means 8
Is a means for changing the axial measurement position of the bottle, and the rotating means is a means for changing the circumferential measurement position of the bottle. Bottle 1 The bottle 1 to be measured is made of a synthetic resin material in which a heat-resistant resin such as a polyarylate resin is mixed with a PET resin, and is transparent or translucent. The bottle 1 is formed by an injection molding method in which the two resins are simultaneously injected. The structure in the thickness direction of the wall portion has a three-layer structure in which a PET resin is interposed on both sides, and the above-mentioned heat-resistant resin is interposed in the intermediate layer. Light Projector 4 As shown in FIG. 2, the light projector 4 is roughly divided into a light emitting section 10 and a light guide section 11. The light emitting unit 10 is housed in a casing 12, and includes a light source 13, a concave mirror 14 located above the light source 13, a chopper 15 located below, and a pinhole 16 perforated at the bottom of the casing 12. It is composed. As the light source 13, a light source that emits infrared light as measurement light, such as a nichrome wire, is used. Infrared wavelength is 2-5μm
It is preferred to use The reason is that when infrared light having a long wavelength is used, the optical path formed by the lens system becomes long and the light guide section described later becomes long, which causes a practical problem in terms of the device configuration, and, for example, 15 to 18 μm This is because infrared light requires a black body furnace and is expensive. The concave mirror 14 collects infrared light from the light source 13 and
This is for positioning the focal point at 16. The chopper 15 is reflected by the concave mirror 14 and
This is for chopping the light traveling to the end to form an intermittent shape (that is, a crossing waveform). The reason for this chopping is that a drift and an offset occur due to the characteristics of the photoelectric conversion element provided in the light receiver 5 described later.
This is because it is necessary to remove these fluctuation factors and perform highly accurate measurement. For this purpose, the waveform is temporarily converted to a crossing waveform to cancel the drift and offset, and then converted to DC again. As a form of the chopper, an electric type for chopping an electric signal given to the light source 12 and a constant light emission from the light source 13 as in this embodiment, and the light is transmitted to the chopper plate 17 by the motor 18 at a predetermined rotation speed. A mechanical type that rotates and intermittently shields light is considered. The light guide section 11 extends downward from the bottom of the casing 12 at a position corresponding to the pinhole 16. The measurement light 3 reflected by the concave mirror 14 and formed into a cross-seeding waveform by the chopper 15 is guided to the light guide unit 11 via the pinhole 16. A lens system 19 composed of a plurality of lenses is formed in the light guide section 11, and a parallel ray is formed by using a concave lens 20 in the last-stage lens.
By the reflection mirror 21 provided at the tip of the
The light is projected toward the body wall of the bottle 1. The measuring light 3 projected on the body wall of the bottle 1 is a spot light. Light Receiver 5 As shown in FIG. 2, FIG. 3, and FIG. 4, the light receiver 5 faces the light projecting portion (reflection mirror 21) of the light guide portion 11 at a predetermined interval. It is attached to the casing 12 by a support member 21 to be positioned. Therefore, the light projector 4 and the light receiver 5 are integrated while always maintaining a constant relative positional relationship. The light receiver 5 includes a casing 22, an interference filter 24 provided on a light receiving window 24 'thereof, and a photoelectric conversion element 23 provided on the back thereof. The interference filter 24 adjusts to a specific wavelength (2.6 μm) according to the optical characteristics correlated with the thickness of the bottle.
, And blocks unnecessary wavelengths of other disturbance noise. The photoelectric conversion element 23 can be used at a normal temperature or a constant temperature, and preferably has a peak spectral characteristic at a wavelength of 2 to 5 μm corresponding to the measurement light 3 in order to improve the SN ratio. As such a photoelectric conversion element, a “PbS (lead / sulfur) photoelectric conversion element can be used. Electric signal processing system The electric signal processing system in this device drives the chopper 15 as shown in FIG. A chopper circuit 26, a chopper output signal A as a timing signal, a signal processing circuit 27 for converting the output signal of the photoelectric conversion element into a DC waveform (peak hold waveform), and a circuit for the bottle 1 based on the processed output signal. Arithmetic circuit 28 for calculating thickness t of the measurement part
And a rotary encoder for detecting a rotational position of the rotating means 9 (that is, a circumferential position of the bottle 1) described later.
31, a potentiometer 32 for detecting the axial position of the light projecting portion of the light projecting device 4 and the bottle 1 of the light receiving device 5, and the circumferential thickness of the bottle 1 based on the arithmetic output signal (thickness value t) and the encoder output signal. A display device 29 for displaying the distribution and displaying the axial thickness distribution of the bottle 1 based on the calculated output signal (thickness value t) and the potentiometer output signal;
It is comprised including. The chopper circuit 26 rotates the DC motor 18 at a predetermined number of rotations and rotates the chopper plate 17 having intermittent cutouts (not shown) in the circumferential direction, so that the measurement light 3
Is to be output. From the chopper circuit 26, a timing signal A corresponding to the chopping cycle of the measurement light 3
Is output (FIG. 6 (a)). This timing signal A
Is input to the signal processing circuit 27. The signal processing circuit 27, as shown in FIG. 1, the timing signals A ₁ obtained by delaying the timing signal A by a predetermined time constant fraction
A primary delay circuit (integrating circuit) 46 for outputting a timing signal A ₂ which further delays the delayed timing signal A ₁
A secondary delay circuit (integration circuit) 47 for outputting an edge detection circuit (differentiator circuit) 34 for detecting the thus delayed rising edge of the timing signal A ₂ double, the edge detection signal A ₃ Connection circuit 35 for converting to TTL level signal voltage
And a peak hold circuit 36 that peak-holds the output signal of the photoelectric conversion element 23 using the converted signal as a reset input signal R. Note that the delay circuit does not necessarily need to have a two-stage configuration, and may be one stage if one circuit can secure a required delay time constant. The primary delay circuit 46 and the secondary delay circuit 47 are active circuits using CR integrators (C ₁ , C ₂ , R) and operational amplifiers, and output the chopper circuit output signal A shown in FIG.
The phase is delayed to the phases of A ₁ and A ₂ (FIGS. 6B and 6C).
The time constant τ can be adjusted by making the resistance R of the CR integration circuit variable. Edge detection circuit 34 is a differentiation circuit which is interposed a capacitor C _0, by detecting the rising edge of the timing signal A ₂ generated edge detection circuit output signal A ₃ (FIG. 6 (d)) output waveform actually Is a differential waveform. The connection circuit 35 outputs a reset signal R at a TTL level (logic signal level 5 V) in order to match the signal level of the peak hold circuit 36, and an open collector circuit is used as a circuit element. The reset signal R is supplied to a reset input terminal of the peak hold circuit 36. The peak hold circuit 36 uses an external holding capacitor _CH to hold the peak level of the output signal B from the photoelectric conversion element 23 until the next peak, and obtains a value corresponding to the thickness t of the measured portion of the bottle 1. Is output. This is equivalent to exchanging the chopper cycle intersecting signal with a DC signal. Reference numeral 33 denotes a high-pass filter, which is a high-pass filter for removing drift of a low-frequency component included in the output signal B of the photoelectric conversion element 23. The arithmetic circuit 28 calculates the thickness t based on the correlation between the output obtained by the photoelectric conversion element 23 (= the amount of measurement light transmitted through the body wall of the bottle 1) and the thickness T of the bottle 1. Here, FIG. 7 shows a graph of the correlation.
Figure 7 shows a case where (including variation is.) The initial output voltage of the photoelectric conversion elements 23 in consideration of the output voltage V obtained by dividing dimensionless an initial output voltage V _0. That is, the dimensionless output voltage V ^* is given by V ^* = 83 × exp (−1.367t) in the experimental example. Is required. Here, V ^* = V / V ₀ × 100, V: actual output voltage, V ₀ : initial output voltage. Therefore, if the voltage V of the output signal B of the photoelectric conversion element 23 is obtained, the thickness t can be calculated immediately. The arithmetic circuit 28 can be realized by using a logarithmic amplifier set to a constant satisfying the above equation (1), or by using a computer such as a personal computer. As the display device 29, for example, an XY recorder or the like can be used. When displaying the thickness distribution of the bottle 1 in the circumferential direction, the circumferential direction measurement position signal E is input from the encoder 31 to the X-axis input terminal, and the output signal D of the arithmetic circuit 28 is input to the Y-axis input terminal.
(Thickness t) can be easily obtained by inputting, and it can be checked whether or not it conforms to the standard. When the axial thickness distribution of the bottle 1 is displayed, the axial measurement position signal F from the potentiometer 32 is input to the X-axis input terminal, and the output signal D of the arithmetic circuit 28 is input to the Y-axis input terminal. You can ask. Elevating means 8 As shown in FIGS. 3 and 4, the elevating means 8 includes an elevating motor 37 attached to the casing 12, an elevating guide 39 provided on a column 38, and a mechanism for accurately performing the elevating operation. The lift guide rod 40 and a holding member 41 for supporting the lift guide rod 40 are provided. Casing 12
A rack (not shown) is provided at a portion of the elevating guide 39, and a pinion (not shown) meshing with the rack is
The casing 12 is moved up and down by rotating the pinion by an elevating motor 37. Reference numeral 43 denotes a lock lever for locking and holding the light projecting surface of the light guide section 11 of the light projector 4 at an arbitrary position, and restricts the movement of the elevating guide rod 40 by tightening the lock lever. Therefore, the light guide unit 11 and the light receiver 5 integrated with the casing 12 move up and down at the same time, and the axial measurement of the bottle 1 becomes possible. Rotating means 9 The rotating means 9 is, as shown in FIGS.
, And a transmission 45 that transmits the rotation of the motor 30 at an appropriate rotation speed while transmitting the rotation to the turntable 44. The rotation cycle of the turntable 44 is not synchronized with the chopper output signal A and rotates independently. Therefore, in order to clarify the circumferential position of the bottle 1 on the turntable 44, the encoder 31 is provided. In this way, the circumferential measurement of the bottle 1 becomes possible. The reason why the turntable 44 can be independently rotated is to take into account the rotation of the bottle 1 and the convenience of arbitrarily changing the rotation. Next, a series of measurement operations will be described. First, the bottle 1 to be measured is placed on the turntable 39 (see FIG. 5). Next, the light guide portion 11 is lowered together with the casing 12 by the elevating means 8, and inserted into the bottle 1 from the opening 2 of the bottle 1 (see FIG. 5). After stopping at a predetermined measurement position, the measurement light 3 is transmitted from the light emitting unit 10. At this time, the measuring light 3 is chopped by the chopper 15. The measuring light 3 is transmitted to the light guide section 11.
The light is radiated from the inside of the bottle 1 through the reflecting mirror 21 through the lens system 19 inside. The measurement light that has passed through the body wall of the bottle 1 reaches the photoelectric conversion element 23 of the light receiver 5, and an output signal B corresponding to the amount of transmission is output (FIGS. 1 and 6 (f)). The output signal B of the photoelectric conversion element 23 is a signal processing circuit.
Entered in 27. On the other hand, the chopper output signal A from the chopper circuit 26 is also input to the signal processing circuit 27 (FIGS. 5 and 6 (a)). In the signal processing circuit 27, the phase of the chopper circuit output signal A is delayed by two-stage delay circuits 46 and 47 (FIG. 6 (c)). The purpose of this delay is to synchronize the peak value with the peak hold circuit 36 (FIG. 6 (e)). This delay phase τ is captured by the edge detection circuit 34, and at this timing, a reset signal R (that is, the output signal A ₃ of the edge detection circuit, FIG. 6C) is supplied to the peak hold circuit 36. Therefore, when the reset signal R is given, the peak hold circuit 36 resets the peak value held until then, and newly samples the peak value at that time (FIG. 6 (e)). This sampling value C corresponds to the thickness value t of the bottle 1 at that time. The sampling value C is provided to the arithmetic circuit 28. The arithmetic circuit 28 outputs a signal D of the corresponding thickness value t according to the equation (1). At this time, the rotational position of the turntable 44 (ie,
A signal E indicating the position (circumferential position of the bottle 1) is input to the display device 29, and a thickness calculation signal D is also input, and the thickness distribution in the same direction is displayed. On the other hand, when the rotation of the turntable 44 is stopped and the light guide unit 11 is moved up and down, the axial measurement position signal F is input from the potentiometer 32 to the display device 29, and the thickness corresponding to each measurement position signal F By recording the calculation signal D, the axial thickness distribution can be obtained. [Effects of the Invention] As described above, according to the present invention, the wavelength is 2 to 5 μm.
m is converted into an infrared light having a cross-seeding waveform at a constant cycle, and then transmitted between the inner and outer walls of the container. The infrared light is received and a transmitted light amount measurement signal corresponding to the transmitted light amount between the inner and outer walls is output. Since a timing signal corresponding to the peak value of the transmitted light amount measurement signal is generated based on the signal indicating the crossing cycle of the infrared ray, and the peak value of the transmitted light amount measurement signal is held for each cycle of the timing signal,
The transmitted light amount measurement signal is always sampled at the peak value corresponding to the crossing cycle, and the transmitted light amount measured signal at other levels is not sampled. Therefore, since the waveform after sampling can be made into a simple shape close to a straight line, the thickness of the container can be accurately measured without the unnecessary waveform caused by an error in sampling timing. In addition, since the infrared light is converted into a cross-shape waveform and then transmitted between the inner and outer walls, the transmitted light amount measurement signal is output in a state where the drift and offset in the light receiver are canceled, and the thickness measurement of the container can be performed more accurately. it can.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a schematic diagram showing a measuring apparatus according to the present invention, and FIG. 3 is a front view showing a mechanical configuration according to the present invention. Fig. 4 is a side view of the bottle, Fig. 5 is a perspective view showing the mounted state of the bottle and the arrangement of the projector and the light receiver, Fig. 6 is a time chart of the output signals of each part, and Fig. 7 is the thickness of the bottle. FIG. 5 is an explanatory diagram showing a correlation between the output voltage of the photoelectric conversion element and the output voltage of the photoelectric conversion element. DESCRIPTION OF SYMBOLS 1 ... Bottle 2 ... Opening 4 ... Floodlight 5 ... Light receiver 6 ... Calculator 8 ... Lifting means 26 ... Chopper circuit 46 ... Primary delay circuit 47 ... ... Secondary delay circuit, 34 ...
... Edge detection circuit, 35 ... Connection circuit, 36 ... Peak hold circuit, A ... Chopper output signal (timing signal), A ₁ ... Delay timing signal, A ₂ ... Delay timing signal, A ₃ ... Edge Detection signal.

Claims (1)

(57) [Claims] In a measurement signal processing device of a container thickness measuring device for measuring the thickness between the inner and outer walls of a transparent or translucent container, after converting an infrared ray having a wavelength of 2 to 5 μm into an infrared ray having a periodic wave pattern, A chopper means for transmitting light between the inner and outer walls; a light receiver for receiving the infrared light transmitted between the inner and outer walls and outputting a transmitted light amount measurement signal corresponding to the transmitted light amount of the infrared light; A timing signal generating circuit for generating a timing signal corresponding to a peak value of the transmitted light amount measurement signal based on a signal indicating the following, and a peak hold circuit for holding the peak value of the transmitted light amount measurement signal for each cycle of the timing signal A measurement signal processing device for a container thickness measuring device, comprising: 2. The measurement signal processing device for a container thickness measurement device according to claim 1, wherein the timing signal generation circuit generates a signal indicating the infrared interfering cycle, the signal and the transmitted light amount measurement signal. A measurement signal processing device for a container thickness measuring device, comprising: a phase shift circuit that shifts a phase by a phase difference; and an edge detection circuit that detects an edge of the phase shift signal. 3. 3. The measurement signal processing device for a container thickness measurement device according to claim 2, wherein the phase shift circuit corresponds to a phase difference between a signal indicating the infrared interfering cycle and the transmitted light amount measurement signal. A measurement signal processing device for a container thickness measuring device, comprising a integrating circuit having a time constant. 4. 4. The measurement signal processing apparatus according to claim 2, wherein said edge detection circuit is a differentiating circuit. 4. The measurement signal processing apparatus according to claim 2, wherein said edge detection circuit is a differentiation circuit. apparatus.