JPH0571959U - Slice level setting device - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a slice level setting device capable of accurately obtaining a digital signal corresponding to an image position in a short time even if a medium has local stains or curls. [Structure] A plurality of slice levels different from each other are prepared, an analog signal is sliced at all slice levels at the time of image reading, and among the obtained digital signals, a digital signal conforming to a predetermined code system is used as positive data.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a slice level setting device for converting an analog signal of an image read by an image reading device into a digital signal by binarizing it at a predetermined slice level.

[0002]

[Prior Art]

 FIG. 3 is a circuit diagram of a bar code reading device according to a conventional example. Reference numeral 1 denotes an image reading element, which includes an LED 1a for irradiating a bar code with light and a photodiode 1b for receiving the reflected light. Then, it is converted into an electric signal. 2 is an operational amplifier (OP amplifier), 3 is an auto slice level generation circuit, and 4 is a comparator.

Among bar code readers used in food, physical distribution, production control departments and the like, a pen-type scanner incorporating the above circuit is designed to manually scan the bar code label to read the bar code data. ing.

When the barcode is read by the image reading element 1, the image data is converted into an electric signal, and the weak signal is amplified by the operational amplifier 2 to generate a video signal (analog signal) A 1. The video signal A is input as a comparison signal, and the slice level signal from the auto slice level generation circuit 3 is input as a reference signal to the comparator 4. Here, a signal of a slice level or higher is a TTL (transistor / transistor logic) level signal. (Digital signal) B is output.

By the way, conventionally, the slice level setting method generated by the auto slice level generating circuit 3 reads the density of the background portion of the medium on which the barcode is printed, and the hardware automatically follows this density (reference). The white level was corrected). Generally, when the white level is V, it is automatically set to an intermediate level of 1 / 2V.

[0006]

[Problems to be solved by the device]

 In such a conventional device, when the background of the medium is uniformly soiled, an appropriate slice level can be set according to the density of the background, but local stains and curls are dealt with. There was a problem that I could not.

FIG. 4 is an explanatory diagram showing a bar code having a local stain and its read signal. However, there is a stain (a part having a higher density than other background parts) at the center of the bar code shown in (1). In this case, in the video signal A shown in (2), the output waveform of the portion corresponding to the stain is below the slice level because the amount of reflected light on the background portion received by the photodiode 1b is small due to the stain. No output pulse is output in the TTL level signal B shown in (3), and the digital signal (pulse) indicated by the broken line becomes a reading error. In such a case, there was a problem that the barcode reading data had to be manually input again with the keyboard.

The present invention solves the above-mentioned drawbacks of the conventional device and provides a slice level setting device capable of accurately obtaining a digitel signal corresponding to an image position in a short time even if the medium has local stains or curls. The purpose is to provide.

[0009]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention is achieved by preparing a plurality of different slice levels and comparing a digital signal resulting from simultaneous slices by each slice level with a predetermined code system.

[0010]

[Action]

 A plurality of different slice levels are prepared, and the analog signal is sliced at all slice levels during image reading, and among the obtained digital signals, the digital signal that matches the predetermined code system is used as the positive data.

[0011]

【Example】

 The present invention will be described below with reference to FIGS. FIG. 1 is a circuit diagram of a bar code reader according to an embodiment. The same parts as those of the conventional circuit shown in FIG. 3 are designated by the same reference numerals and duplicate description will be omitted. In this figure, 5 is a three-auto slice level generating circuit for inputting three slice levels L1, L2, L3 to each comparator 4a, 4b, 4c, and a video signal A is supplied to each comparator 4a, 4b, 4c. The slice levels L1, L2, L3 are compared with each other, and the signals of the respective slice levels or higher are output as TTL level signals B1, B2, B3.

As an example, the slice level L1 is set to 3/4 V when the white level voltage of the medium is V, L2 is set to 1/2 V, and L3 is set to 1/4 V. Then, the bar code is scanned at these three slice levels, the CPU 6 stores the data of the TTL level signals B1, B2, B3 at each slice level in the memory by the CPU 6, and after the bar code scanning, each data is subjected to the bar code code analysis. , Match the check digit at the end of the bar code data. At this time, if they match, it is judged as correct data (reading is normal), and if they do not match, it is judged as erroneous data (reading error).

Similar to FIG. 4, FIG. 2 is an explanatory diagram showing a bar code and a reading result thereof. A video signal A obtained by reading a bar code in which a medium is locally stained is shown in (2). Are sliced at three slice levels L1, L2, and L3.

The TTL level signals B1 and B2 obtained as a result of slicing the video signal A at the slice levels L1 and L2 are as shown in (3), and the "1" level pulse indicated by the broken line is supposed to be output. The background portion of the medium due to dirt is output as "0" in the same way as the black level of the barcode, and a reading error occurs. However, the TTL level signal B3 as a result of slicing the video signal A at the slice level L3 becomes as shown in (4), the dirt of the medium is distinguished from the black level, and "1" which means the background part is output and read. It becomes normal.

The determination that the TTL level signals B1 and B2 shown in (3) are error data and the TTL level signal B3 shown in (4) is positive data is determined by the check digit by the CPU 6 as described above. Based on the comparison result of.

In the present embodiment, three slice levels are generated by the three-slice level generating circuit 5 having three output terminals, but three auto-slice levels that generate a single slice level are generated. A generation circuit may be provided. Further, the number of slice levels is not limited to three.

The present invention can be widely applied not only to bar code readers, but also to various image readers that convert an analog signal obtained by reading an image into a binary digital signal at a predetermined slice level. it can.

[0018]

[Effect of the device]

 As described above, according to the inventions of claims 1 and 2, by having a plurality of auto slice levels, it is possible to perform image recognition with high accuracy even with respect to local stains and curls of the medium. .. According to the third aspect of the present invention, it can be applied to a bar code reading device to read a bar code with high reliability, and a keyboard can be used when the media is locally soiled or curled. Input can be omitted or reduced.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a bar code reader according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a reading result of a barcode according to an embodiment of the present invention.

FIG. 3 is a circuit diagram of a bar code reader according to a conventional example.

FIG. 4 is an explanatory diagram showing a barcode reading result according to a conventional example.

[Explanation of symbols]

 1 Image Reading Element 4 Comparator 5 Multiple Auto Slice Level Generation Circuit A Video Signal B TTL Level Signal L1, L2, L3 Auto Slice Level

Claims (3)

[Scope of utility model registration request] 1. A slice level setting device for converting an analog signal of an image read by an image reading device into a digital signal by binarizing the analog signal at a predetermined slice level, and preparing a plurality of different slice levels for image reading. A slice level setting device characterized in that an analog signal is sliced simultaneously at all slice levels at the same time, and among the obtained digital signals, a digital signal that conforms to a predetermined code system is used as positive data. 2. A plurality of slice levels are obtained by a plurality of automatic slice level generation circuits each having a slice level output terminal, or a plurality of automatic slice level generation circuits for outputting a single slice level are provided. 2. The method according to claim 1, wherein
The slice level setting device described. 3. The image reading device is a bar code reading device for reading a bar code as an image, and
The slice level setting device according to claim 1, wherein the predetermined code system is a check digit at the end of the bar code data.