Any person, firm, employee, corporation, association, who shall violate or shall fail, neglect or refuse to comply with any provision of this article, shall, upon conviction thereof, be sentenced to pay a fine of not more than $600, plus costs, and in default of payment of said fine and costs, to a term of imprisonment not to exceed 30 days; provided, however, that each sign and each day of violation shall constitute a separate offense (Ordinance No. 2145).