JPS6226750B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a reading period control system for an apparatus that uses a fixed scanner to read bar codes, etc. of articles.

Prior Art and Problems A barcode reading device with a fixed scanner part that automates and speeds up payment, statistical processing, etc. by optically reading the barcode written on the exterior of a product is shown in Figure 1. The operator holds the product 1 in his hand and moves it in the direction of arrow A, and manually operates the product 1 so that the barcode 2 (indicated by the broken line) on the back side passes over the reading window 4 of the reading device 3. Inside the reading window 4, a light source for illumination and a conversion element that receives the reflected light (from the product 1) and obtains a photoelectric conversion output corresponding to the barcode 2 are arranged.

In this type of barcode reading device, in order to enable the scanner only during the period when the product 1 passes through the reading window 4, an input gate sensor G1 having a light emitting element 5 and a light receiving element 6 as a pair is installed on the input side of the window 4. Further, on the exit side, an exit gate sensor G2 including a light emitting element 7 and a light receiving element 8 as a pair is arranged. Then, from when the gate sensor G1 is turned on (product 1 means that light from the light-emitting element cannot enter the light-receiving element; off is the opposite; the same applies hereinafter) until the gate sensor G2 is turned on and then turned off. During the period, the scanner is enabled assuming that product 1 is passing in front of window 4.

This article detection method actually detects the entry of the front end and the withdrawal of the rear end of the product 1, so it is ideal for setting the scanning period. However, when transporting the product 1 while sitting, the operator's left hand or left elbow may block the optical path of the left gate sensor G2, making it impossible to detect the passage of the product 1. In this case, not only is there a mistake in detecting the passing of the product, but the notification of a reading error is delayed, and it takes time to redo the process.

OBJECTS OF THE INVENTION The present invention seeks to solve the above-mentioned drawbacks by locating the exit gate sensor in the center of the reading window. Also, if this is done, the detection of the exit time will not match the actual situation, but the purpose is to equivalently match it.

Structure of the Invention The present invention provides a reading period control method for a device that optically scans an article conveyed to a reading window to read a code written on the article. Of the optical article detection sensors disposed on each side, the exit side article detection sensor is set within the reading window, and after the tip of the article is detected by the input side article detection sensor, the exit side article detection sensor is set within the reading window. The time T ₁ until the article is detected by the article detection sensor is actually measured, the time T ₂ is calculated by multiplying the time T ₁ by a predetermined constant, and the time T ₂ is measured by the exit side article detection sensor. The feature is that the readable period of the code, etc. is set to the sum of times _T1 and _T2 starting from the time when the rear end of the article is detected, and this will be explained below with reference to the illustrated embodiment. will be explained in detail.

Embodiments of the Invention FIG. 2 is an explanatory diagram showing an overview of the present invention, and the same parts as in FIG. 1 are given the same reference numerals. The difference between this example and FIG. 1 is that the exit gate sensor G2 has been moved to the center of the reading window 4. FIG. 3a is a perspective view showing a specific example thereof. Gate sensor G
The optical path from the light emitting elements 5, 7 of No. 1, G2 to the light receiving elements 6, 8 is inclined as shown in FIG.

FIG. 4a shows the outputs of the sensors G1 and G2 when the product 1 is transferred in the direction of arrow A. When the optical path of sensor G2 is set within the range of reading window 4, the time from when sensor G1 is turned on until when sensor G2 is turned on is
Although _T1 can be measured, the time from when the sensor G2 is turned off until the rear end of the product 1 actually passes through the reading window 4 can only be determined (specified) by calculation. Figure b is an explanatory diagram of this diagram, which shows that if it is assumed that the transport speed of the product 1 remains unchanged in the vicinity of the window 4, T ₂ can be calculated from the relationship T ₂ =aT ₁ . Here, a is a proportionality constant determined by the distance between G1 and G2, the distance between the end of the window 4 and G2, etc.

By the way, if the distance between the sensors G1 and G2 is narrowed by moving G2 to the center of the window 4, the on-points of G1 and G2 may approach or overlap in products with a long overall length. For example, as shown in Figure 2, if the product is transferred correctly from the left side of gate G1 in direction A, there will be no problem, but if the product is approached from above the reading window 4 by mistake, G1 and G2 will be completely removed. Since they turn on at the same time, it is determined that T ₁ = 0, and therefore T ₂
=0. In this case, barcode reading is not performed, so in the present invention, if the actual measured value of T ₁ is less than a certain value T ₁ min, T ₂ is changed to T ₂ min (for example, 100 m
s) and guarantee a minimum value for T ₂ .

Further, even when transporting the product 1 in the direction of the arrow A, if the speed is slow, T ₁ and T ₂ will become large, and the notification (display) of the reading result will be delayed. Especially if it cannot be read, it is necessary to retry, so
It is preferable that the results be notified quickly. Therefore, in the present invention, an upper limit is set for _T2 . T ₂ max is that,
Everything above T ₁ max is limited to this value. however,
If T ₁ becomes too long, it is handled abnormally as a time over.

FIG. 5 is a schematic block diagram of the present barcode reading device 3, in which 31 is an input gate circuit having an input gate sensor G1, 32 is an exit gate circuit having an exit gate sensor G2, and 33 is a device for scanning the barcode of the product 1. A reading operation circuit including a circuit for generating light, etc.; 34 a demodulation circuit for receiving the reflected light of the light irradiating the bar code 2 and demodulating the data represented by the code; 35 for receiving gate signals G1, G2, etc.; In response, a read ready signal RDY is sent to the read operation circuit 33.
This is a control circuit that sends

FIG. 6 is a block diagram showing one embodiment of the present invention, showing parts added to the configuration of FIG. 5. The control circuit 35 is the same as that shown in FIG.
Count T ₁ . That is, as shown in FIG. 7, the signal CNT is on from the rising edge of G1 to the rising edge of G2, causing the counter 41 to count an appropriate clock during that period. 42 is a multiplication circuit,
T ₂ is obtained by multiplying the obtained T ₁ by the constant a described above. 43 compares T ₁ with T ₁ min in Figure 4b, and T ₁
<T ₁ min, the selection circuit 44 receives a selection signal of T ₂ min.
Output SEL ₁ . Further, 44 compares T ₁ with T ₁ max, and outputs a selection signal SEL ₂ of T ₂ max to the selection circuit 44 when T ₁ >T ₁ max. The selection circuit 44 is a signal
T ₂ is always selected when SEL ₁ and SEL ₂ are not occurring. That is, when SEL ₁ is output, T ₂ min is selected, and when SEL ₂ is output, T ₂ max is selected. The counter circuit 46 is loaded with the output of _the selection circuit at the timing _of the load signal LOAD _shown in FIG.
Count down one of the. The clock at this time is the same as the counter 41. Then, when the down count is finished and the count value becomes 0, an end signal END is sent back to the control circuit 35 and a signal is sent to the control circuit 35.
Turn off DW. As a result, the read ready signal
The length of RDY is T ₁ + T ₂ (strictly speaking, the pulse width of G2 is added).

Effects of the Invention As described above, according to the present invention, since the exit side gate sensor position for detecting articles in a barcode reading device etc. is set at the center of the reading position,
The gate sensor is prevented from malfunctioning due to an operator's hand, and of course reading can be performed without any problem.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an article detection method in a conventional barcode reading device, FIG. 2 is an explanatory diagram showing an outline of the present invention, FIG. 3 is an external view of a barcode reading device to which the present invention is applied, and FIG. The figure is an explanatory diagram of the period in which a barcode can be read by a scanner, FIG. 5 is a schematic block diagram of a barcode reading device, FIG. 6 is a block diagram showing an embodiment of the present invention, and FIG. 7 is a time chart thereof. . In the figure, 1 is an article, 2 is a barcode, 3 is a barcode reader, 4 is a reading window, G1 is an input side article detection sensor, G2 is an exit side article detection sensor, and 41 is an article detection sensor on the exit side.
T ₁ counter circuit, 42 T ₂ calculation circuit, 46
is a T ₂ counter circuit.

Claims (1)

[Scope of Claims] 1. In a reading period control method of a device that optically scans an article conveyed to a reading window to read a code written on the article, the article input side and exit side of the reading window are read. Of the optical article detection sensors disposed on each side, the exit side article detection sensor is set within the reading window, and after the tip of the article is detected by the input side article detection sensor, the exit side article detection sensor is set within the reading window. Time until detection by article detection sensor T ₁
At the same time, the time _T2 is calculated by multiplying the time _T1 by a predetermined constant, and the time _T2 is started from the time when the exit side article detection sensor detects the rear end of the article. A reading period control method characterized in that the readable period of the code, etc. is set to the sum of times _T1 and _T2 . 2. The reading period control method according to claim 1, wherein even if time T ₁ is less than a certain value T _{1 min} , the minimum value T ₂ min is guaranteed at time T 2 . 3. A maximum value _T2max is provided for time _T2 even if time _T1 is equal to or greater than a certain value _T1max ,
A reading period control method according to claim 1.